Hide Infill in the Shell Drag Mode Only Where the Profile Covers It

A profile with no top or bottom shell layers, or no walls, leaves the infill on the surface,
so hiding it changed the picture. The viewer now reads the print's default region settings
when it loads a print and leaves the infill in place for such a print; per-object overrides
are not consulted.

.github/workflows/ofl-ota-cronjob.yml

@@ -12,9 +12,9 @@ name: Daily OFL OTA Update
 # vendor-dispatch path is also what makes post_merge_profiles.yml call the OTA auto-publish API after
 # uploading - see post_merge_profiles.yml for both sides of that contract.
 #
-# If at least one branch was dispatched this run, a final step clears OFL's pending-publish
+# At the start of each run, the pending-publish table is cleared up to a captured
-# table (POST /api/v1/ota/ofl/pending/clear) - the daily "published everything, reset" signal.
+# timestamp (POST /api/v1/ota/ofl/pending/clear?timestamp=...). Changes merged after
-# That table is populated only by this pipeline's own auto-publish calls.
+# that timestamp remain pending for the next run.
 
 on:
   schedule:
@@ -34,6 +34,32 @@ jobs:
     if: ${{ github.repository == 'OrcaSlicer/OrcaSlicer' }}
     runs-on: ubuntu-24.04
     steps:
+      - name: Capture start timestamp and clear OFL pending queue
+        id: start
+        shell: bash
+        env:
+          OTA_API_BASE_URL: ${{ vars.OTA_API_BASE_URL }}
+          OTA_API_KEY: ${{ secrets.OFL_OTA_PUBLISH_KEY }}
+        run: |
+          set -euo pipefail
+          [ -n "$OTA_API_BASE_URL" ] || { echo "::error::vars.OTA_API_BASE_URL is not set"; exit 1; }
+          [ -n "$OTA_API_KEY" ] || { echo "::error::secrets.OFL_OTA_PUBLISH_KEY is not set"; exit 1; }
+
+          timestamp="$(date -u +%s)"
+          echo "timestamp=$timestamp" >> "$GITHUB_OUTPUT"
+
+          resp_file="$RUNNER_TEMP/ota-pending-clear-response.json"
+          status="$(curl -sS -o "$resp_file" -w '%{http_code}' -X POST \
+            "${OTA_API_BASE_URL%/}/api/v1/ota/ofl/pending/clear?timestamp=$timestamp" \
+            -H "Authorization: Bearer $OTA_API_KEY")"
+          body="$(cat "$resp_file")"
+          echo "$body"
+
+          if [ "$status" != "200" ]; then
+            echo "::error::OTA pending-clear call failed with HTTP $status"
+            exit 1
+          fi
+
       - name: Checkout repository
         uses: actions/checkout@v7
         with:
@@ -46,13 +72,12 @@ jobs:
         run: git fetch origin '+refs/heads/*:refs/remotes/origin/*'
 
       - name: Scan branches and publish changed OFL profiles
-        id: scan
         shell: bash
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          SCAN_UNTIL: ${{ steps.start.outputs.timestamp }}
         run: |
           set -euo pipefail
-          published_any=false
 
           mapfile -t branches < <(
             gh api "repos/${{ github.repository }}/branches" --paginate --jq '.[].name' \
@@ -79,68 +104,36 @@ jobs:
               --jq '.workflow_runs[0].run_started_at // empty')"
 
             if [ -z "$since" ]; then
-              echo "No prior successful run for $branch; treating OFL as changed."
+              echo "No prior successful run for $branch; checking OFL changes up to $SCAN_UNTIL."
-              changed=true
+              changed_files="$(git log --until="$SCAN_UNTIL" --name-only --pretty=format: "origin/$branch" -- \
-            else
-              changed_files="$(git log --since="$since" --name-only --pretty=format: "origin/$branch" -- \
                 resources/profiles/OrcaFilamentLibrary resources/profiles/OrcaFilamentLibrary.json \
                 | sed '/^$/d')"
+            else
+              changed_files="$(git log --since="$since" --until="$SCAN_UNTIL" --name-only --pretty=format: "origin/$branch" -- \
+                resources/profiles/OrcaFilamentLibrary resources/profiles/OrcaFilamentLibrary.json \
+                | sed '/^$/d')"
+            fi
+
             if [ -n "$changed_files" ]; then
-                echo "OFL changed on $branch since $since:"
+              echo "OFL changed on $branch from ${since:-the beginning} through $SCAN_UNTIL:"
               echo "$changed_files"
               changed=true
             else
-                echo "No OFL changes on $branch since $since."
+              echo "No OFL changes on $branch through $SCAN_UNTIL."
               changed=false
             fi
-            fi
 
             if [ "$changed" = true ]; then
               # Tolerate a per-branch failure (e.g. a pre-existing release branch
               # whose post_merge_profiles.yml predates the vendor/auto_publish
               # inputs) rather than aborting the whole scan under set -e.
-              if gh workflow run post_merge_profiles.yml \
+              if ! gh workflow run post_merge_profiles.yml \
                 --repo "${{ github.repository }}" \
                 --ref "$branch" \
                 -f vendor="$VENDOR" -f auto_publish=true; then
-                published_any=true
-              else
                 echo "::warning::failed to dispatch post_merge_profiles.yml for $branch - its post_merge_profiles.yml at this ref may predate the vendor/auto_publish inputs"
               fi
             fi
 
             echo "::endgroup::"
           done
-
-          echo "published_any=$published_any" >> "$GITHUB_OUTPUT"
-
-      - name: Clear OFL pending queue
-        # Only when this run actually kicked off at least one publish - the
-        # daily reset is scoped to today's real activity, not called on a day
-        # where every branch reported no changes. Note "published_any" reflects
-        # a successful DISPATCH, not a confirmed live publish: gh workflow run
-        # is fire-and-forget, so this workflow never learns whether the
-        # dispatched post_merge_profiles.yml run actually reached its own
-        # auto-publish call. Acceptable since the table is populated only by
-        # our own auto-publish calls, not by anything else.
-        if: steps.scan.outputs.published_any == 'true'
-        shell: bash
-        env:
-          OTA_API_BASE_URL: ${{ vars.OTA_API_BASE_URL }}
-          OTA_API_KEY: ${{ secrets.OFL_OTA_PUBLISH_KEY }}
-        run: |
-          set -euo pipefail
-          [ -n "$OTA_API_BASE_URL" ] || { echo "::error::vars.OTA_API_BASE_URL is not set"; exit 1; }
-          [ -n "$OTA_API_KEY" ] || { echo "::error::secrets.OFL_OTA_PUBLISH_KEY is not set"; exit 1; }
-
-          resp_file="$RUNNER_TEMP/ota-pending-clear-response.json"
-          status="$(curl -sS -o "$resp_file" -w '%{http_code}' -X POST \
-            "${OTA_API_BASE_URL%/}/api/v1/ota/ofl/pending/clear" \
-            -H "Authorization: Bearer $OTA_API_KEY")"
-          body="$(cat "$resp_file")"
-          echo "$body"
-
-          if [ "$status" != "200" ]; then
-            echo "::error::OTA pending-clear call failed with HTTP $status"
-            exit 1
-          fi

CMakeLists.txt

@@ -56,9 +56,9 @@ You can do this in Environment Variables settings.
 endif ()
 
 if (APPLE)
-    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 11.3
+    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 12.0 (the lowest Xcode 27 accepts)
     if (NOT CMAKE_OSX_DEPLOYMENT_TARGET)
-        set(CMAKE_OSX_DEPLOYMENT_TARGET "11.3" CACHE STRING "Minimum OS X deployment version" FORCE)
+        set(CMAKE_OSX_DEPLOYMENT_TARGET "12.0" CACHE STRING "Minimum OS X deployment version" FORCE)
     endif ()
     message(STATUS "CMAKE_OSX_DEPLOYMENT_TARGET: ${CMAKE_OSX_DEPLOYMENT_TARGET}")
 endif ()
@@ -279,6 +279,11 @@ if (APPLE)
     endif()
     SET(CMAKE_XCODE_ATTRIBUTE_PRODUCT_BUNDLE_IDENTIFIER "com.orcaslicer.OrcaSlicer")
 
+    # The macOS CI jobs build with Ninja (build_release_macos.sh -x), so the Xcode generator
+    # is not covered. Xcode adds -Wshorten-64-to-32 by default ("Implicit Conversion to 32 Bit
+    # Type"); Ninja/-Wall does not, and under -Werror it fails Xcode builds on code CI accepts.
+    set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_64_TO_32_BIT_CONVERSION "NO")
+
     message(STATUS "Orca: IS_CROSS_COMPILE: ${IS_CROSS_COMPILE}")
 elseif (CMAKE_SYSTEM_NAME STREQUAL "Linux")
     set(CMAKE_INSTALL_RPATH "$ORIGIN")

build_release_macos.sh

@@ -53,7 +53,7 @@ while getopts ":dpa:snt:xbc:i:j:Tuh" opt; do
         echo "   -s: Build slicer only"
         echo "   -u: Build universal app only (requires existing arm64 and x86_64 app bundles)"
         echo "   -n: Nightly build"
-        echo "   -t: Specify minimum version of the target platform, default is 11.3"
+        echo "   -t: Specify minimum version of the target platform, default is 12.0"
         echo "   -x: Use Ninja Multi-Config CMake generator, default is Xcode"
         echo "   -b: Build without reconfiguring CMake"
         echo "   -c: Set CMake build configuration, default is Release"
@@ -95,7 +95,7 @@ if [ -z "$DEPS_CMAKE_GENERATOR" ]; then
 fi
 
 if [ -z "$OSX_DEPLOYMENT_TARGET" ]; then
-  export OSX_DEPLOYMENT_TARGET="11.3"
+  export OSX_DEPLOYMENT_TARGET="12.0"
 fi
 
 if [ -z "$CMAKE_IGNORE_PREFIX_PATH" ]; then

deps/CMakeLists.txt

@@ -26,9 +26,9 @@ endif()
 
 cmake_minimum_required(VERSION 3.2)
 if (APPLE)
-    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 11.3
+    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 12.0 (the lowest Xcode 27 accepts)
     if (NOT CMAKE_OSX_DEPLOYMENT_TARGET)
-        set(CMAKE_OSX_DEPLOYMENT_TARGET "11.3" CACHE STRING "Minimum OS X deployment version" FORCE)
+        set(CMAKE_OSX_DEPLOYMENT_TARGET "12.0" CACHE STRING "Minimum OS X deployment version" FORCE)
     endif ()
     message(STATUS "CMAKE_OSX_DEPLOYMENT_TARGET: ${CMAKE_OSX_DEPLOYMENT_TARGET}")
 

docs/HLSD/deferred-page-construction.md

@@ -2,219 +2,136 @@
 
 ## Why it exists
 
-The main window is a notebook of tabs. When the first frame appears, one tab is on
+The main window is a notebook of tabs, and only one of them is on screen when the first
-screen and the others are not; some of them are opened later in the session, some
+frame appears. Others are opened later in the session, some never, and some only exist
-never, and some only exist for certain printers. Building a tab before the first frame
+for certain printers. Building every tab before the first frame makes each startup pay for
-adds its cost to every startup, whether or not the tab is used.
+tabs the user may never open.
 
-This subsystem builds a tab's panel the first time the tab is shown. It also builds the
+This subsystem builds a tab the first time it is shown, and builds the rest in small units
-remaining tabs while the user is idle after startup, in units of tens of milliseconds,
+while the user is idle after startup. Startup pays only for what the first frame shows,
-so a click that lands in the middle of one waits for that unit and no longer. Startup
+the other tabs are usually ready before anyone opens them, and a click that lands in the
-pays only for what the first frame shows, and the other tabs are usually built before
+middle of the idle build waits for one unit at most. Work that is not a tab, such as a
-anyone opens them.
+dialog or the 3D view's GL resources, uses the same machinery.
 
 ## The parts
 
-`src/slic3r/GUI/Lazy.hpp`, `LazyPage.hpp`, `StagedBuild.hpp` and `IdleScheduler.hpp/.cpp`
+The parts are independent. A holder can hold anything a factory makes, a placeholder page
-(with its wx-free `PrebuildQueue.hpp`) are independent. A holder can hold anything a
+is a holder with a widget, a staged object can live outside a holder, and the scheduler
-factory makes, a page is a holder with a placeholder widget, a staged object can live
+knows none of them; it runs tasks, which the main window makes from the holders.
-outside a holder, and the scheduler knows none of them; it runs tasks, which `MainFrame`
-makes from the holders.
 
-### Lazy<T>: the holder
+### The holder: `Lazy<T>`
 
-Holds an object that a factory makes on first use, under a name for the log and a place
+A holder keeps one object and the factory that makes it. The rest of the app reads the
-in the idle queue, both given by the owner. The header has no wx dependency; the busy
+object if it exists, makes sure it exists now when about to show or navigate to it, or runs
-cursor for an on-demand build lives in `Lazy.cpp` and is skipped when there is no app,
+something once it exists. A type with one instance in the app gets these as statics
-so the holder is unit-tested.
+through `LazyInstance<T>`, so callers need no reference to the main window, and all of them
+are harmless while no holder exists.
 
-- `get()` is null until the object is completely built; `built()` says the same.
+The holder guarantees that callers see the object only once it is completely built. A
-- `ensure()` builds whatever is left now, under a busy cursor, and returns the object, or
+build cannot re-enter itself, so a nested request finds nothing yet, and a factory that
-  null in the two cases below. A click on an unbuilt tab or a first open of a dialog goes
+returns null or a unit that throws leaves the holder and the scheduler able to carry on.
-  through this, and it logs the units and time it took.
+The holder does not own the object; its wx parent does, as for any window. The holder has
-- `build_step()` runs one unit of construction and returns true while more remain. The
+no wx dependency and is unit-tested.
-  first unit is the factory call, and each later unit is one `StagedBuild` step if the
-  type has them.
-- `when_built(fn)` runs `fn(object)` now if it exists, otherwise once it is built.
-- `pending()` says whether the idle prebuild has work here: not built, and the factory
-  has not returned null. A null factory result is logged and the holder stays unbuilt.
-- A unit that pumps the event loop cannot re-enter the holder; a nested `build_step()`
-  does nothing and a nested `ensure()` returns null.
-- After a unit throws, the holder and the scheduler still run the next one.
 
-The holder does not own the object; its wx parent does, as for any window. A type with
+### The placeholder page: `LazyPage<Panel>`
-one instance in the app derives from `LazyInstance<T>`, which points at that instance's
-holder (the holder registers itself, and a recreated `MainFrame`'s holder replaces the
-old frame's) and gives the type the static entry points the rest of the app uses,
-`T::if_built()`, `T::ensure()` and `T::when_built(fn)`. They return null, or do
-nothing, while no holder exists, so a caller needs no `mainframe` check.
 
-`built()` is an atomic flag, since a job worker reads it through the statics
+The notebook needs a page object for a tab to exist and for tabs to be inserted and
-(`MainFrame::get_calibration_curr_tab()`); it is set after the object is complete.
+removed by pointer, and the placeholder is that object. It builds the real panel inside
+itself the first time it is shown and forwards showing and hiding afterwards, so a panel's
+own show handling stays its activation hook. Nothing builds while the main window is
+hidden; the window's first show builds the start page. A page that is out of the book is
+not prebuilt. A panel built while its page is hidden stays hidden, and gets the theming
+the window applied before the panel existed.
 
-`LazyBase` is the holder's type-free interface (`name()`, `built()`, `pending()`,
+### Staged construction: `StagedBuild`
-`build_step()`, `prebuild_order()`) and is what the scheduler side sees.
 
-### LazyPage<Panel>: the placeholder
+A constructor too big to be one unit builds a skeleton and queues the rest as steps, which
+run one per unit. A child panel's steps can be forwarded to its parent, and the parent is
+complete only once the child is. Nothing may use what a step builds before the last step
+has run, so staged panels follow these constraints:
 
-A `wxPanel` placed in the parent in place of the real panel, and a `Lazy<Panel>` whose
+- members created in steps start out null, so a partly built panel can be destroyed;
-factory makes the panel inside it (by default `new Panel(parent)`). The notebook needs a
+- timers, event handlers and destructors that touch step content check that the panel is
-page object for the tab to exist and for `show_device()` to insert and remove tabs by
+  complete first;
-pointer, and the placeholder is that object. `MainFrame` creates every page once, named
+- nothing takes focus while off screen, since a unit may run while the user is typing
-after its `TAB_ID_*`, and keeps it for the frame's life; `show_device()` only moves
-pages in and out of the book.
-
-- `Show()` is forwarded to the panel, so a panel's own `Show()` override stays its
-  activation hook (refresh timers, machine sync) and `SelectPageByName()` works
-  unchanged. A show builds the panel unless the frame itself is still hidden, because
-  the book selects its first page as it is inserted; `MainFrame::Show()` shows the
-  current page again when the frame becomes visible, which builds it.
-- `in_book()` says whether the parent notebook currently lists the page, and
-  `pending()` is that and not built, so a tab `show_device()` has taken out of the book
-  is not prebuilt.
-- A panel built while its page is hidden stays hidden, and a completed panel gets the
-  dark-mode pass the frame ran before it existed.
-
-The Compare presets dialog is a holder without a page. `MainFrame` keeps a
-`Lazy<DiffPresetDialog>` whose factory constructs the dialog and binds its events, the
-dialog derives from `LazyInstance`, and its callers use
-`DiffPresetDialog::ensure()->show()` and `DiffPresetDialog::if_built()` like a tab's
-callers do. Saving a preset refreshes the dialog only while it is shown, since `show()`
-reloads the presets.
-
-### StagedBuild: construction in units
-
-A mixin for a panel whose constructor is too big to be one unit. The constructor builds
-the skeleton (sizers, and the parts other code may touch) and queues the rest with
-`add_build_step()`. `build_step()` runs one step, and `add_build_steps_of(child)`
-forwards a child's steps so a nested panel is spread the same way; the parent is built
-only once the child is, including steps the child queues later. Steps run in order, on
-the main thread. A `Lazy<T>` recognises a staged type at compile time and runs its steps
-one per unit.
-
-Nothing may touch what a step builds before the last step has run. In practice:
-
-- nothing paints the panel before it is complete, since a panel built at idle is hidden
-  with its page and one built on demand finishes inside `ensure()` before the event loop
-  runs again;
-- members created in steps are initialised to null in the header, so a partially built
-  panel can be destroyed;
-- timers and event handlers that use step content check `built()` first
-  (`MonitorPanel::update_all()`, `CalibrationPanel::update_all()`), and a child's steps
-  are queued before anything in the constructor can fire such a handler;
-- a destructor that disconnects from step content checks `built()` first;
-- a constructor or step does not take focus while the panel is off screen
-  (`IsShownOnScreen()` before `SetFocus()`), since it may run while the user is typing
   elsewhere;
-- where a step's widgets must keep their place in a sizer that later steps also fill, the
+- a widget added by a step keeps its place in the sizer through an empty slot the skeleton
-  constructor adds an empty slot sizer in that position and the step fills the slot
+  creates.
-  (`StatusBasePanel`).
 
-### IdleScheduler: when to build
+### The scheduler: `IdleScheduler` and `PrebuildQueue`
 
-A task is any `LazyBase`: a name for the log, `pending()`, `build_step()` and
+The queue holds tasks in order, and a slice runs units of the first pending task until
-`prebuild_order()`. `PrebuildQueue` holds the tasks by order (equal order in the order
+the task finishes, the time budget is spent, or input arrives. It has no wx dependency and
-added) and runs a slice, the units of the first pending task until it completes, the
+is unit-tested with a fake clock. A task whose work goes away, such as a tab removed from
-budget is spent on the clock it is given, or the interrupt predicate says input arrived.
+the book, is skipped, and becomes pending again if the work comes back.
-It has no wx dependency and is unit-tested with a fake clock. A task whose work is gone
-is passed over and stays in the queue, so a tab that `show_device()` removes and later
-re-inserts is pending again.
 
-`IdleScheduler` drives the queue with the real clock, the app's input timestamp and the
+A slice runs only once the user has been idle for a short quiet time, and each slice is its
-Windows queue check, and logs each unit and slice. Each slice is a timer message: a
+own timer message, so paint, timers and input queued in between are handled before the
-period of 250 ms while waiting for the user to go quiet, and a one-shot of zero after a
+next slice. Posting slices as pending events would not do that, because wx drains every
-slice that left work, so the event loop dispatches whatever it has queued (paint,
+pending event before the next native message. On GTK a timer that is always due starves
-timers, input) before the next slice runs. Chaining slices with `CallAfter` would not do
+the lower-priority sources that repaint and deliver posted events, so slices are a few
-this: wx drains pending events fully before the next native message, on every platform.
+milliseconds apart. On Windows a slice also waits while the native queue holds input,
-On GTK the one-shot is 5 ms, because a due GLib timeout runs ahead of the redraw and
+not counting mouse moves, which Windows synthesizes whenever a window appears under the
-idle sources that paint and deliver posted events.
+cursor. A slice never runs inside a `wxYield()`, where it would build pages in the middle of
-A slice runs only once the user has been idle for the quiet time, and the timer stops
+the code that yielded. A unit cannot be interrupted, so the largest unit bounds how long a
-itself once no task is pending. The tick period, quiet time and slice length are
+click can wait.
-constants in `IdleScheduler.cpp`. A unit cannot be interrupted once started, so the
+When nothing is pending the timer stops and the subsystem costs nothing.
-largest unit bounds click latency on Windows; on the other platforms a click also waits
-for the rest of the slice. A unit that pumps the event loop lets the timer fire inside
-its own slice, and that tick does nothing.
 
-The tasks are made by their owners. `MainFrame::prebuild_pages_when_idle()` registers
+The main window owns the scheduler because it owns what the tasks build, and clearing the
-every `LazyPage` the frame created, in or out of the book (`pending()` is false for a
+queue with the window keeps a task from outliving its object. Each owner provides its own
-page out of the book), the Compare presets holder, and the Prepare sidebar's settings
+tasks, such as a tab, a dialog, the Prepare tab's settings page one option group at a
-page from `ParamsPanel::settings_page_prebuild()`, whose first unit selects the default
+time, the Prepare page's layout at the size the book gives its pages, or the 3D view's GL
-tab if none is selected yet and whose later units build one option group each.
+resources.
-`show_device()` only restarts the timer. `MainFrame` owns the scheduler because it owns
-everything the tasks build, and clearing the queue with the frame is what keeps a task
-from outliving its object.
 
-Idle time comes from `GUI_App::FilterEvent`, which timestamps mouse and keyboard events
+### The 3D view's GL resources
-(`wxEVT_CATEGORY_USER_INPUT` minus command events, which all claim that category), and
-`GUI_App::input_idle_ms()` reports it. On Windows a slice additionally refuses to start
-when the message queue holds keyboard, button, touch or pen input. Mouse moves are
-excluded because Windows synthesises one whenever a window appears under the cursor,
-which every unit does. Other platforms use the timestamp alone.
 
-Once every registered page is built the timer is stopped and the subsystem costs
+OpenGL is loaded on the Prepare tab's canvas. When the start page is not Prepare, loading
-nothing.
+it is an idle task that makes the context current on the hidden canvas, so the start page
+paints first and Prepare never appears. Loading it on a shown canvas under `Freeze()` holds
+back the start page's paint, and on GTK `Freeze()` cannot hide the canvas, which is a
+native child window or a Wayland subsurface drawn outside GTK. A hidden Windows child
+window keeps its device context, macOS attaches the context to a hidden view, and GTK
+creates the canvas's surface when the widget is realized, so on GTK the task realizes the
+canvas first. If the context cannot be made current, the canvas's first render loads the
+resources.
 
 ## Rules
 
-**What builds before the first frame.** The Prepare tab's plater, because `post_init()`
+**Before the first frame.** Only the start page and the Prepare tab's plater are built
-needs its GL canvas on screen to initialise OpenGL in every startup state, and the start
+before the first frame. Everything else goes through a holder.
-page the user configured. Home is built by the first `MainFrame::Show()`, Prepare's
-settings page by selecting the tab. `post_init()` passes through the Prepare tab for GL
-init under `Freeze()` with `MainFrame::select_prepare_for_gl_init()`, which changes the
-selection without the page-changed event, so nothing else is built for that pass.
 
-**Reaching a lazy object.** A caller uses the type's own statics. `T::if_built()` may
+**Reaching a lazy object.** Callers use the type's statics. Reading it if built is for
-return null and is for telling the object something it can live without (a rescale, a
+things the object can live without, such as a rescale, a color change or a status refresh.
-colour change, a status update). `T::ensure()` builds the object and is for navigating
+Making sure it exists is for navigating to it or showing it. Running something once it is
-to it or for a caller that is about to show it. A caller that tells the object something
+built is for state it would not fetch for itself on construction. A panel that pulls its
-it would not fetch for itself on construction uses `T::when_built()`, which keeps the
+state when constructed only ever needs to be read if built.
-message until the object exists. A panel that pulls its state when constructed (the Home
-page requests the recent list on load, the Device tab reads the device manager on show)
-is reached with `if_built()`; one that cannot pull gets `when_built()`.
 
-**Unit size.** A unit cannot be interrupted, so it should stay within the slice length on
+**Unit size.** A unit should fit in one slice on a fast machine. A constructor over that is
-a fast machine. A constructor above that is staged. A single widget above it is the
+staged, and a single widget over it is accepted unless the widget itself can be split.
-floor unless the widget itself is split.
 
-**Order.** Cheapest and most likely to be opened first, given where `MainFrame` creates
+**Order.** Tasks run cheapest and most likely to be opened first. Each holder's order is
-each holder. The settings page is 0 (the Prepare tab's own content), Home 10, Device 20
+given where it is created, with gaps so a new task fits between its neighbors. A negative
-(a Bambu user's usual second stop), Calibration 30, Multi-device 40, the web Device
+order is never prebuilt, for something few sessions open that costs more to build unasked
-view 50, Project 60 (a second WebView2 instance) and the Compare presets dialog 100;
+than it saves.
-steps of ten so a new tab takes a value between its neighbours without renumbering
-them. `MainFrame::prebuild_pages_when_idle()` registers the tasks once, from
-`post_init()`.
-
-**Never prebuilt.** A holder with a negative order, for a tab that few sessions open
-and that costs more to build unasked than it saves (the Design tab), and plugin-provided
-tabs, which are Python-side and not lazy pages.
 
 ## Adopting it
 
-A lazy tab needs:
+A lazy tab needs a panel type deriving from `LazyInstance`, a placeholder page the main
+window creates once with its order and registers for the idle build, and every use of the
+panel outside the main window going through the statics. Its constructor has to cope with
+the main window already existing and the user being busy elsewhere, so it takes no focus
+while off screen, and it does all of its own setup, since the main window does nothing to a
+panel after creating it.
 
-1. The panel derived from `LazyInstance<Panel>`, since a tab's panel has one instance.
+To stage a heavy constructor, keep the skeleton in the constructor, move the rest into
-2. A `LazyPage<Panel>*` member in `MainFrame`, created once in `init_tabpanel()` with
+steps in its original order, and follow the staged-construction constraints. Measure the
-   its `TAB_ID_*` as the name, its place by the order rule (and a factory if
+units; a step that is still one big widget is split inside the widget or accepted.
-   `new Panel(parent)` is not enough), added to `m_lazy_pages`, and used wherever the
-   tab is added to or looked up in the notebook.
-3. Every use of the panel outside `MainFrame` going through one of the panel's statics,
-   chosen by the rule above. When converting an existing member, `grep` for it; the
-   compiler finds the rest.
-4. A constructor that copes with the frame already existing and the user being busy
-   elsewhere, since `wxGetApp().mainframe` is set, the frame may be shown, and the user
-   may be typing when a lazy panel is built: no `SetFocus()` while off screen, and
-   whatever the constructor did through a `MainFrame` accessor before (a mode update, a
-   deferred URL) done in the constructor itself.
 
-To stage a heavy constructor, inherit `StagedBuild`, keep the skeleton in the constructor,
+## Verifying
-move the rest into `add_build_step()` lambdas in the original order, and follow the
-staged-panel rules above. Measure the units. A step that is still one big widget has to
-be split inside that widget or accepted as the floor.
 
-Verification is by log. `MainFrame::prebuild_pages_when_idle` lists the queue it
+The log lists the queue when it is registered, reports each completed task at info level
-registered, `IdleScheduler::tick` reports each completed task by name at info level and
+and each slice and unit at debug level, and reports every on-demand build with its units
-each slice and unit at debug level, and `Lazy::ensure` reports an object a user built
+and time. A task's completion line counts only the slice it finished in. A run from the
-on demand with the units and time it took. A run from the configured start
+configured start page should show every registered task complete in order, with no unit
-page shows every registered page complete, in order, with no unit longer than intended.
+longer than intended. A click on a tab during the idle build should show an on-demand
-A click on a tab mid-prebuild shows the finished panel with an `ensure` line for what was
+build for what was left, with the slices resuming once the user is idle again.
-left, and the slices resume for the remaining tasks once the user is idle again.

docs/HLSD/gcode-preview-dragging.md

@@ -0,0 +1,80 @@
+# G-code preview while dragging
+
+The sliced preview draws every toolpath segment of the plate as an instanced box. On a large
+plate that is tens of millions of segments, and the frame is GPU-bound: the cost is the number of
+instances drawn, not anything the CPU does per frame. Dragging the camera over such a plate cannot
+keep up. The `preview_reduced_detail_mode` preference (*Graphics > G-code Preview*, off by
+default) lets the preview draw less while the user drags and put the full toolpaths back when they
+let go.
+
+| Preference | Values | Effect |
+|---|---|---|
+| `preview_reduced_detail_mode` | `off`, `solid`, `shell` | what is drawn while dragging |
+
+libvgcode (`src/libvgcode`) builds and binds the reduced toolpath set, `GCodeViewer` maps the
+preferences onto it and draws the solid model, and `GLCanvas3D` decides when the user is dragging.
+The OpenGL ES path keeps a single set and ignores the preference.
+
+## Two sets, one walk
+
+`ViewerImpl::update_enabled_entities()` walks the visible vertex range once and fills two segment
+index buffers side by side: the **full** set and the **reduced** set (segments and options).
+Building them together is what makes switching free: starting or ending a drag is a buffer
+binding, never a rebuild. A change of mode does rebuild. Nothing is built while the mode
+is off, and the reduced buffers are then uploaded empty so that the last set does not stay
+allocated.
+
+Whatever the mode leaves out, the bottom and top layers of the visible range are kept whole: they
+are the faces the range cuts open, and the top is what the user is looking at.
+
+### Modes
+
+- `EndLayersOnly` (`solid` in the preference) keeps only the two end layers. `GCodeViewer` then
+  draws the sliced objects and the prime tower as opaque solids, see below.
+- `ShellOnly` (`shell`) keeps every role but the sparse infill, internal solid infill, internal
+  bridge infill and gap fill, which lie under the skins or between the walls. Walls, top and
+  bottom surfaces, bridges, supports and the prime tower are drawn whole, so from outside the
+  print looks as it does at rest. The roles come from
+  the slicer, so the classification is exact wherever the slicer's is; what it cannot express is
+  the inside of the prime tower and of a support, which share one role with their outside and are
+  kept whole. A profile with no top or bottom shell layers, or no walls, leaves the infill on the
+  surface, so `GCodeViewer` turns the hiding off for such a print when it loads it, from the
+  print's default region settings; per-object overrides are not consulted.
+
+## The solid model
+
+The preview already loads the sliced objects as shells for its translucent ghost.
+`GCodeViewer::render_solid_model()` draws those shells opaque, in their filament colors, with the
+`gouraud` shader, whose z range cuts them to the visible layer range. The two toolpath layers of
+the reduced set are drawn afterwards and cap the cut with what was really printed there. The
+shells hold only the objects, so while this mode is on the prime tower is added from its sliced
+mesh, positioned as the print placed it. It is added or removed on its own when the mode changes,
+without reloading the objects, keeps its opaque color so that it never appears among the
+translucent shells, and stays out of their bounding box. Supports have no mesh and are not shown,
+and `load_shells()` drops every non-model-part volume, so a negative volume is not cut out.
+
+A plate whose shells are not loaded keeps drawing toolpaths, since the solid model would leave
+only the end layers.
+
+## Deciding that the user is dragging
+
+`GLCanvas3D::_update_preview_interaction()` runs at the top of every preview frame, before the
+canvas decides whether to reuse its cached scene, so that the switch lands in that frame. Dragging
+is `GLCanvas3D::is_user_interacting()`, the same answer the scene cache reads: the camera, the
+navigator, a gizmo, the rectangle selection or either slider being held. A slider reports this from
+ImGui's active id rather than its dirty flag, which is raised and consumed inside one frame. A
+wheel step has no duration, so it holds the reduced set for a 150 ms settle time instead, and the
+frame that restores the toolpaths is scheduled for when that time runs out, since the render timer
+only wakes the idle loop. A drag cut short by focus or capture loss is ended explicitly, and a
+button release wakes the idle loop, because on some platforms nothing else would until the next
+input.
+
+## Reused scene frames
+
+`GLCanvas3D` keeps its last scene pass for frames that only rebuild the overlay (`SceneCache`). Its
+key covers the canvas size, the camera and hover state, not what the toolpath sets draw, so a frame
+that reuses the scene must never be one on which the set is switched.
+`_update_preview_interaction()` therefore reports whether the bound set changed, and a frame on
+which it did redraws the scene. The canvas neither captures nor reuses the scene while the user
+drags, so no reduced frame outlives a drag, and the frame that ends a wheel's settle time is
+requested as a full frame.

docs/HLSD/multiline-infill.md

@@ -0,0 +1,123 @@
+# Multiline infill — High Level Design
+
+## Purpose and scope
+
+`fill_multiline` prints every sparse infill wall as N adjacent lines instead of
+one, so a wall is `d1 = N * spacing` thick. Only internal sparse infill uses it.
+Each pattern first builds its single-line centerlines at N times the usual line
+spacing (so the density holds), and `multiline_fill()` then replaces each
+centerline by the lines of that wall: the centerline itself when N is odd, and
+closed outlines around it at every `spacing` out to `d1 / 2`. The outlines are
+clipped to the fill region contracted by half a line width, then connected like
+any other infill.
+
+Outlines of centerlines that cross each other overlap at every crossing, which
+over-extrudes the wall intersections. The line-crossing patterns Grid,
+Triangles, Tri-hexagon and Cubic therefore build centerlines that never cross
+(`FillRectilinear::fill_surface_trapezoidal()`), and so do Adaptive Cubic and
+Support Cubic (`FillAdaptive`); the other patterns outline their usual
+centerlines.
+
+## Non-crossing centerlines
+
+The crossing lines are resolved into x-monotone paths, the levels of the line
+arrangement: walking along x, the k-th path is always the k-th line from the
+bottom. At every crossing, the two paths bounce off each other instead of
+passing through. Adjacent paths meet only at crossings, so their outlines touch
+there and nowhere overlap.
+
+Where two paths meet, each is cut short by a line perpendicular to the bisector
+of its bend, `d1 / 2` from the crossing. The two cut segments are parallel and
+`d1` apart, so the outermost lines of the two walls sit exactly `spacing` apart,
+like the lines inside a wall. Where three lines meet at one point, the middle
+path runs straight through and the outer two are cut `d1` from it.
+
+Each pattern builds its rows along x in a rotated frame. Grid lines run at ±45°
+there, and its rows are trapezoid waves that transpose on alternate layers. The three families of Triangles, Tri-hexagon and
+Cubic run at 0°, 60° and 120°. Those rows rotate by 120° every layer about a
+3-fold center of the arrangement, so each family takes every role in turn.
+The pattern is phased on fixed positions, so it lines up across layers and
+across the regions of one layer. Rounding the corners with
+`sparse_infill_smooth_factor` happens before `multiline_fill()`.
+
+## Cubic
+
+Single-line Cubic draws the three families at the same spacing `h` and shifts
+them with z: by `+dx`, `-dx` and `+dx`, `dx = z / sqrt(2)`. The multiline paths
+follow the same lines. In the frame where one family is horizontal, the other two
+cross in rows `h` apart, alternating by half a period, at height
+`tau = -3 * dx (mod h)` above the horizontal line below them. The crossings split
+every band between horizontal lines into up-pointing triangles of height `tau`,
+down-pointing triangles of height `h - tau`, and hexagons. At `tau = 0` (and `h`)
+all three families meet at common points, as in Triangles. At `tau = h / 2` the
+triangles are equal, as in Tri-hexagon. The origin of that frame is always a
+3-fold center, whatever z is, so the per-layer rotation keeps the lines in place.
+
+Each band holds two paths that touch at its crossings: the upper one takes the
+V below the crossing and runs along the top horizontal line, and the lower one
+takes the inverted V above it and runs along the bottom line. Both are the same function
+of `tau`, the lower one mirrored with `h - tau`. `cubic_upper_level()` builds one
+period of the upper path as the lower envelope of five lines, clipped from below:
+
+- the two slanted lines through the crossings,
+- the horizontal line, lowered when the triangle above it is less than `1.5 * d1` high,
+- the two chamfers where the path turns onto and off the horizontal line, `d1 / 2`
+  from those crossings,
+- the flat cut into the V at the crossing.
+
+The cut height `clamp(tau - d1 / 2, 0, h - d1) + d1` is what makes the pattern
+continuous in z. While both triangles are at least `1.5 * d1` high, every
+crossing is a pair of bends `d1 / 2` from it, as in Tri-hexagon. When a triangle
+is thinner, its three paths stack like a triple crossing. The path through it
+flattens toward its base line and lies on it once the triangle is under `d1 / 2`
+high, and the paths beside it are pushed `d1` away. The layout thus reaches the
+Triangles one where the families meet. Adjacent paths stay at least `d1` apart
+at every `tau` and at every density up to 100%.
+
+## Adaptive Cubic
+
+Adaptive Cubic and Support Cubic take their lines from an octree of cubes
+standing on a corner. On each layer every cube cuts its three mid-planes into
+segments of the same three 60° families as Cubic, but the pattern is not
+periodic. Smaller cubes near the surface add finer lines, and a finer line ends
+where it meets the wall of its coarser cube, so the lines form crossings and
+T-junctions. `FillAdaptive::multiline_paths()` builds the paths from these
+segments directly, for each fill region and within `4 * d1` of it.
+
+At a crossing the two paths bounce as in Cubic. At a T-junction the through line
+runs straight on and the path of the ending line stops there. Every path still
+runs left to right in the frame where one family is horizontal, and that family
+rotates with the layer.
+
+Every line of every cube size lies on one fine lattice, so crossings closer than
+a few `d1` are the corners of one small triangle of that lattice, as in Cubic.
+The cuts follow the Cubic rules without a closed formula:
+
+- The two bends of a crossing are cut `d1` apart, `d1 / 2` each, perpendicular
+  to their bisector, so their walls touch. A cut goes no further than the path
+  end, and the other bend takes the rest of `d1`.
+- At the tip of a small triangle, between the two slanted families, a cut also
+  goes no further than the neighbouring bend turning the other way, and the
+  path beyond that bend is kept a wall away from it. The bends onto the
+  horizontal family are not limited this way: pushing their paths apart would
+  open gaps between walls that should touch.
+- A cut moves the path only where the cut line lies beyond it, near its bend.
+  The sharp bends between the two slanted families are cut after the bends onto
+  the horizontal family, so the tip of a small triangle wins, as in Cubic.
+- A path stopping at a T-junction is trimmed until it is `d1` less half a line
+  spacing from every other path, so that its end overlaps the wall it stops on
+  by half a line and bonds to it. The paths are trimmed one at a time against
+  the others as already trimmed, so two ends facing each other meet instead of
+  both backing off. A path stopping on the line of another is trimmed before
+  that one, so it gives way and the other still reaches the line it stops on. A
+  second round trims every path again from its full length, so an end grows
+  back where the ends it gave way to were trimmed later, and a last round only
+  shortens them, keeping them that far apart. Paths shorter than `d1` are left
+  out.
+- A line that ends on another less than `2 * d1` past a crossing stops at that
+  crossing instead, the shorter one where both do. The path along such a stub
+  would be trimmed away, leaving a hole between the walls that were cut to
+  touch it.
+
+Short paths enclosed by coarser lines still print as closed outlines, but most
+paths run on across several cells.

docs/HLSD/prime-tower-sparse-layers.md

@@ -0,0 +1,197 @@
+# Prime tower sparse layers — High Level Design
+
+## Purpose and scope
+
+A prime tower exists to absorb filament changes, but it is planned on every
+object layer below the topmost change, not only on the layers that purge. The
+layers in between carry no filament change and print nothing but a block of the
+tower's own footprint to keep its top level. They are called sparse layers, and
+on a print with few changes they are most of the tower: they cost time, filament
+and a travel to the tower on every layer.
+
+Two settings trade that cost against something else. `wipe_tower_no_sparse_layers`
+drops them, which sinks the tower below the model. `wipe_tower_sparse_layers_combination`
+merges runs of them into fewer, thicker layers, which keeps the tower level with
+the model. Both are off by default, and with both off the tower prints one layer
+per object layer as it always has.
+
+The decisions belong to tower planning and G-code emission. They do not change
+sliced object geometry, but they do change the emitted G-code, the filament and
+time estimates, and — for the compacted case — whether a plate is printable at
+all. Changing either setting invalidates the tower step.
+
+## What a sparse layer is
+
+`ToolOrdering::fill_wipe_tower_partitions` counts the filament changes per layer
+and propagates that count downwards, so every layer below the topmost change is
+marked as carrying a tower. It then fills any gap between two tower layers, so
+the tower is continuous from the bed to its last purge. `wipe_tower_layer_height`
+is the distance from the previous tower layer, which is the object's layer height
+whenever the tower prints on every layer.
+
+`Print::_make_wipe_tower` plans one tower layer per such object layer. A layer
+whose only call keeps the current filament leaves no toolchange in the plan, and
+the layer it generates is a single result whose initial and new tool are equal.
+That is what `wipe_tower_layer_is_sparse` recognises, and it is the unit both
+settings work on.
+
+The plan stays one entry per tower layer in every case. The G-code emitter walks
+`WipeTowerData::tool_changes` by layer index, advancing once per object layer
+that carries a tower, so a planner that removed entries would silently shift
+every later layer onto the wrong tower geometry. Layers that print nothing are
+therefore still planned and still generated; they are marked, and the emitter
+drops them.
+
+## Shared rules
+
+Tower planning, G-code emission and the plate validation all have to agree about
+which layers print and where. They ask one set of free functions, declared beside
+the tower classes, rather than each re-deriving the answer from the raw options:
+
+- `wipe_tower_sparse_layers_skipped` — whether sparse layers are really dropped.
+  Smooth timelapse and clumping detection park the nozzle on the tower every
+  layer, so with either of them on no layer is ever dropped and the option reads
+  as off everywhere.
+- `wipe_tower_sparse_layers_combined` — whether runs are really merged. The same
+  two rule it out, and so does `wipe_tower_no_sparse_layers`: dropping the layers
+  outright is the stronger answer to the same problem, so the two settings are
+  exclusive and the GUI greys out the second while the first is on.
+- `wipe_tower_layer_is_sparse`, `wipe_tower_layer_is_combined_away` — per-layer
+  questions the emitter asks about generated results.
+- `compute_compacted_wipe_tower_z` — the tower's print z per planned layer when
+  it is compacted.
+- `combine_sparse_wipe_tower_layers` and its `combine_sparse_wipe_tower_plan`
+  wrapper — the merge rule, applied to either generator's plan.
+
+Both tower generators are driven through these. `WipeTower` (Type 1, the block
+tower) and `WipeTower2` (Type 2, the default) keep separate plans with the same
+per-layer shape — print z, layer height, toolchanges, and a `combined_away` flag
+— so one template covers both.
+
+## Dropping sparse layers
+
+With `wipe_tower_no_sparse_layers`, the tower only grows on layers that carry a
+real change. It therefore falls one layer height behind the object for every
+sparse layer, and by the top of a tall print it can sit far below the model. The
+nozzle has to reach down to it at each purge.
+
+`compute_compacted_wipe_tower_z` derives that z once, from the generated results,
+so the emitter and the validator cannot disagree. Emission descends to it, but
+only once the nozzle is parked over the tower: descending while still over the
+model would drive the nozzle into the print, so a descent that would do that is
+deferred until after the travel to the tower. Extrusions emitted without an
+explicit z — the nozzle-change wipe in particular — are pulled down to the
+compacted z for the same reason.
+
+Reaching down is only safe if nothing tall stands near the tower. `Print.hpp`
+carries the clearance rule: a keep-out zone grown from the tower's footprint by
+the spiral z-hop envelope, and a per-object limit on how high an object may rise
+near it, tiered by the nozzle cone, the head body, the rod and the lid. The same
+rule serves the precise check on real extrusions, the pre-slice estimate that
+feeds the plater, and the outlines the plater draws while an object is dragged,
+so that the ring the user sees touches the object's outline exactly when the
+check trips.
+
+## Merging sparse layers
+
+With `wipe_tower_sparse_layers_combination`, no layer is dropped and nothing is
+compacted: the tower keeps following the object, and the nozzle never descends.
+Instead a run of consecutive sparse layers prints once, on the run's last layer,
+at the accumulated height of everything it covers — the same way infill
+combination merges sparse infill. The layers below it in the run print nothing.
+
+`combine_sparse_wipe_tower_plan` runs before the tower's depths are planned,
+because the heights it rewrites feed the extrusion flow of every later pass. It
+raises `height` in place on the layer that prints a run and sets `combined_away`
+on the rest; generation then proceeds unchanged, and the flag is copied onto the
+results so the emitter can drop them.
+
+Four constraints shape the rule:
+
+- **Whole layers only.** A tower layer is entered at the object's z, so a merged
+  layer has to end on an object layer boundary. The merged height is therefore a
+  sum of whole layer heights, never a clamped value.
+- **The nozzle's maximum layer height.** A run stops growing as soon as one more
+  layer would pass `max_layer_height` for the nozzle printing it — three quarters
+  of the nozzle diameter when that is left at 0, as elsewhere in slicing. The cap
+  is read through the filament-to-nozzle map, since `max_layer_height` is per
+  nozzle while the tower indexes filaments. This is what makes the setting inert
+  at common layer heights: two 0.2 mm layers are 0.4 mm and do not fit under a
+  0.3 mm maximum, so nothing merges until the layer height is 0.15 mm or below,
+  or the maximum is raised.
+- **A filament change purges at its own z.** A layer with a real change can
+  neither be merged away nor absorb the run below it, so a run always ends on its
+  own last sparse layer and the change above it is untouched.
+- **The first layer stays on the bed.** It carries the brim and is never merged.
+
+A run holds one filament throughout — that is what makes it sparse — so the cap
+is uniform across it, and the tower reserves depth only for the purges above a
+layer, so a run has one footprint and the merged layer covers exactly the area
+the layers it replaces would have.
+
+## Emission and accounting
+
+`WipeTowerIntegration` drops a layer whose results are marked, for both settings,
+through the same `ignore_sparse` path in `tool_change` and
+`is_empty_wipe_tower_gcode`. A dropped layer emits no travel to the tower and no
+extrusion.
+
+Filament used is accumulated by the generators while they write, so a layer that
+will be dropped must not be charged. Type 1 asks `layer_is_printed` at each of
+its accumulation points; Type 2 guards the equivalent block in `finish_layer`,
+which also stops a merged-away layer from adding height of its own — the layer
+that prints the run carries all of it.
+
+A merged layer is the only case where the tower's layer height differs from the
+object layer it sits on, and therefore the only case where the height the
+exporter already emitted for that layer is wrong for the tower. Both generators
+do declare a height, but each hardcodes a tag dialect — the block tower forces
+the BBL tag, the other writes the compatible one — while the G-code processor
+reads only the tag its printer uses. On a non-BBL printer with a Type 1 tower the
+declaration is dropped, and the merged layer is drawn and costed as a thin one.
+`WipeTowerIntegration::tower_height_tag` therefore declares it at export time,
+where the printer is known, and only when the tower's own G-code does not already
+carry the tag that will be read. The object's height returns on the next object
+path, because emission forces the processor role to the tower on any layer that
+carries one.
+
+## Constraints
+
+A layer that prints nothing prints nothing at all, including any interface work
+the tower planner scheduled there. The Type 1 block planner marks a layer as a
+contact layer when a filament category stops or starts being used relative to the
+layer below, and a sparse layer immediately above a change qualifies. Merging a
+run, like dropping its layers, replaces that interface with the run's single
+layer. Both settings are off by default for this among other reasons.
+
+Neither setting changes what the tower is for. A plate that needs a tower on
+every layer — smooth timelapse, clumping detection — gets one, and the settings
+read as off rather than compacting or merging in one place and not another.
+
+## Implementation and verification
+
+- [WipeTower.hpp](../../src/libslic3r/GCode/WipeTower.hpp) declares the shared
+  rules and the plan-merging template;
+  [WipeTower.cpp](../../src/libslic3r/GCode/WipeTower.cpp) implements them and
+  the Type 1 tower, [WipeTower2.cpp](../../src/libslic3r/GCode/WipeTower2.cpp)
+  the Type 2 tower.
+- [ToolOrdering.cpp](../../src/libslic3r/GCode/ToolOrdering.cpp) decides which
+  layers carry a tower at all, and
+  [Print.cpp](../../src/libslic3r/Print.cpp) plans it and runs the clearance
+  check whose rule lives in [Print.hpp](../../src/libslic3r/Print.hpp).
+- [GCode.cpp](../../src/libslic3r/GCode.cpp) emits the tower, drops the layers
+  that print nothing, and declares a merged layer's height;
+  [PrintConfig.cpp](../../src/libslic3r/PrintConfig.cpp) defines the settings and
+  [ConfigManipulation.cpp](../../src/slic3r/GUI/ConfigManipulation.cpp) their
+  mutual exclusion.
+- [GLCanvas3D.cpp](../../src/slic3r/GUI/GLCanvas3D.cpp) and
+  [PartPlate.cpp](../../src/slic3r/GUI/PartPlate.cpp) draw the compacted tower's
+  keep-out outlines live while the user drags.
+- [Rule tests](../../tests/libslic3r/test_wipe_tower.cpp) cover the gating of
+  both settings, the per-layer predicates, the compacted z, the merge rule's run
+  flushing, height conservation, the nozzle cap and the first-layer exemption,
+  and the clearance geometry the plater draws.
+- [Slicing tests](../../tests/fff_print/test_wipe_tower.cpp) slice a real print
+  and check that a run folds, that the tower still covers the object exactly
+  once, that a run too thin for the cap is left alone, and that a merged layer
+  declares its height in the tag the printer's processor reads.

resources/profiles/Elegoo.json

@@ -1,6 +1,6 @@
 {
 	"name": "Elegoo",
-	"version": "02.04.00.10",
+	"version": "02.04.00.11",
 	"force_update": "0",
 	"description": "Elegoo configurations",
 	"machine_model_list": [

resources/profiles/Elegoo/filament/BASE/Elegoo PLA @base.json

@@ -15,6 +15,6 @@
 		"Elegoo"
 	],
 	"filament_start_gcode": [
-		"; filament start gcode\n"
+		"; Elegoo PLA filament start gcode\n"
 	]
 }

resources/profiles/OrcaFilamentLibrary.json

@@ -1,6 +1,6 @@
 {
 	"name": "OrcaFilamentLibrary",
-	"version": "02.04.00.11",
+	"version": "02.04.00.12",
 	"force_update": "0",
 	"description": "Orca Filament Library",
 	"filament_list": [

resources/profiles/OrcaFilamentLibrary/filament/Elegoo/Elegoo PLA @base.json

@@ -39,7 +39,7 @@
 		"60"
 	],
 	"filament_start_gcode": [
-		"; filament start gcode\n"
+		"; Elegoo PLA filament start gcode\n"
 	],
 	"filament_end_gcode": [
 		"; filament end gcode \n"

resources/web/model/index.html

@@ -7,7 +7,6 @@
 
 <script type="text/javascript" src="../include/jquery-2.1.1.min.js"></script>
 <script type="text/javascript" src="../include/json2.js"></script>	
-<script type="text/javascript" src="../include/globalapi.js"></script>	
 
 <link rel="stylesheet" type="text/css" href="../include/swiper/swiper-bundle.min.css" />
 <script type="text/javascript" src="../include/swiper/swiper-bundle.min.js"></script>
@@ -18,6 +17,7 @@
 <link rel="stylesheet" type="text/css" href="model.css" />	
 <link rel="stylesheet" type="text/css" href="./css/dark.css" />	
 <link rel="stylesheet" type="text/css" href="../include/global.css" /> <!-- ORCA One for all-->
+<script type="text/javascript" src="../include/globalapi.js"></script>	
 	
 <script type="text/javascript" src="test.js"></script>
 <script type="text/javascript" src="model.js"></script>	

src/libslic3r/AppConfig.cpp

@@ -205,6 +205,13 @@ void AppConfig::set_defaults()
     if (get("seq_top_layer_only").empty())
         set("seq_top_layer_only", "1");
 
+    // what the preview draws while the user drags it
+    {
+        const std::string mode = get("preview_reduced_detail_mode");
+        if (mode != "off" && mode != "solid" && mode != "shell")
+            set("preview_reduced_detail_mode", "off");
+    }
+
     // ORCA: darken the layers the preview layer slider is not scrubbed to
     if (get("preview_dim_previous_layers").empty())
         set_bool("preview_dim_previous_layers", false);

src/libslic3r/Config.hpp

@@ -697,7 +697,8 @@ public:
                 }
             } else {
                 // Resize by duplicating the last value.
-                this->values.resize(n, this->values./*back*/front());
+                T v = this->values./*back*/front();
+                this->values.resize(n, v);
             }
         }
     }
@@ -772,8 +773,10 @@ public:
 
         if (this->values.empty())
             this->values.resize(rhs_vec->size());
-        else
+        else {
-            this->values.resize(rhs_vec->size(), this->values.front());
+            T v = this->values.front();
+            this->values.resize(rhs_vec->size(), v);
+        }
 
         assert(default_index.size() == rhs_vec->size());
 

src/libslic3r/Emboss.cpp

@@ -990,6 +990,7 @@ EmbossStyles Emboss::get_font_list_by_enumeration() {
     std::vector<std::wstring> font_names;
     EnumFontFamilies(hDC, (LPCTSTR) NULL, EnumFamCallBack,
                      (LPARAM) &font_names);
+    ReleaseDC(NULL, hDC);
 
     EmbossStyles font_list;
     for (const std::wstring &font_name : font_names) {

src/libslic3r/Feature/FuzzySkin/FuzzySkin.cpp

@@ -464,6 +464,16 @@ void group_region_by_fuzzify(PerimeterGenerator& g)
         }
     }
 
+    g.fuzzy_supported_area.reset();
+    if ((g.has_fuzzy_skin || g.has_fuzzy_hole) && g.lower_slices != nullptr) {
+        coord_t max_thickness = 0;
+        for (const auto& region : regions)
+            if (should_fuzzify(region.config, g.layer_id, 0, true) || should_fuzzify(region.config, g.layer_id, 0, false))
+                max_thickness = std::max(max_thickness, region.config.thickness);
+        // Walls farther than a line width plus the noise amplitude from the layer below are bridging; keep them smooth.
+        g.fuzzy_supported_area = offset_ex(*g.lower_slices, float(g.ext_perimeter_flow.scaled_width() + max_thickness));
+    }
+
     if (regions.size() == 1) { // optimization
         g.regions_by_fuzzify.push_back({regions.front().config, {}});
         return;
@@ -560,13 +570,23 @@ static std::vector<MergedFuzzyRegion> collect_merged_fuzzy_regions(const std::ve
     return merged_regions;
 }
 
+// Afterwards an empty region means nothing to fuzzify, no longer full coverage.
+static void restrict_to_supported(std::vector<MergedFuzzyRegion>& merged_regions, const std::optional<ExPolygons>& supported)
+{
+    if (!supported)
+        return;
+    for (auto& merged_region : merged_regions)
+        merged_region.expolygons = merged_region.expolygons.empty() ? *supported : intersection_ex(merged_region.expolygons, *supported);
+}
+
 Polygon apply_fuzzy_skin(const Polygon& polygon, const PerimeterGenerator& perimeter_generator, const size_t loop_idx, const bool is_contour)
 {
     Polygon fuzzified;
 
     const auto  slice_z = perimeter_generator.slice_z;
     const auto& regions = perimeter_generator.regions_by_fuzzify;
-    if (regions.size() == 1) { // optimization
+    const auto& supported = perimeter_generator.fuzzy_supported_area;
+    if (regions.size() == 1 && !supported) { // optimization
         const auto& config  = regions.begin()->first;
         const bool  fuzzify = should_fuzzify(config, perimeter_generator.layer_id, loop_idx, is_contour);
         if (!fuzzify) {
@@ -590,7 +610,7 @@ Polygon apply_fuzzy_skin(const Polygon& polygon, const PerimeterGenerator& perim
     // Fast path: single merged region — apply directly without splitting
     if (merged_regions.size() == 1) {
         const auto& mr = merged_regions.front();
-        if (mr.expolygons.empty()) {
+        if (mr.expolygons.empty() && !supported) {
             fuzzified = polygon;
             fuzzy_polyline(fuzzified.points, true, slice_z, *mr.config);
             return fuzzified;
@@ -626,6 +646,8 @@ Polygon apply_fuzzy_skin(const Polygon& polygon, const PerimeterGenerator& perim
             if (!merged_regions[i].expolygons.empty() && !merged_regions[j].expolygons.empty())
                 merged_regions[i].expolygons = diff_ex(merged_regions[i].expolygons, merged_regions[j].expolygons);
 
+    restrict_to_supported(merged_regions, supported);
+
     // Split the loops into lines with different config, and fuzzy them separately
     fuzzified = polygon;
     for (const auto& r : merged_regions) {
@@ -689,7 +711,8 @@ void apply_fuzzy_skin(Arachne::ExtrusionLine* extrusion, const PerimeterGenerato
     const auto  slice_z = perimeter_generator.slice_z;
     const auto  layer_height = perimeter_generator.layer_height;
     const auto& regions = perimeter_generator.regions_by_fuzzify;
-    if (regions.size() == 1) { // optimization
+    const auto& supported = perimeter_generator.fuzzy_supported_area;
+    if (regions.size() == 1 && !supported) { // optimization
         const auto& config  = regions.begin()->first;
         const bool  fuzzify = should_fuzzify(config, perimeter_generator.layer_id, extrusion->inset_idx, is_contour);
         if (fuzzify)
@@ -703,7 +726,7 @@ void apply_fuzzy_skin(Arachne::ExtrusionLine* extrusion, const PerimeterGenerato
         if (!merged_regions.empty()) {
 
             // Fast path: single merged region — apply directly without splitting
-            if (merged_regions.size() == 1 && merged_regions.front().expolygons.empty()) {
+            if (merged_regions.size() == 1 && merged_regions.front().expolygons.empty() && !supported) {
                 fuzzy_extrusion_line(extrusion->junctions, slice_z, perimeter_generator.layer_height, *merged_regions.front().config, closed);
                 return;
             }
@@ -753,6 +776,8 @@ void apply_fuzzy_skin(Arachne::ExtrusionLine* extrusion, const PerimeterGenerato
                     if (!merged_regions[i].expolygons.empty() && !merged_regions[j].expolygons.empty())
                         merged_regions[i].expolygons = diff_ex(merged_regions[i].expolygons, merged_regions[j].expolygons);
 
+            restrict_to_supported(merged_regions, supported);
+
             // Split the loops into lines with different config, and fuzzy them separately
             for (const auto& r : merged_regions) {
                 const auto splitted = Algorithm::split_line(*extrusion, r.expolygons, false);

src/libslic3r/Fill/FillAdaptive.cpp

@@ -1,3 +1,4 @@
+#include "../AABBTreeLines.hpp"
 #include "../ClipperUtils.hpp"
 #include "../ExPolygon.hpp"
 #include "../Surface.hpp"
@@ -14,7 +15,9 @@
 #include <cstdlib>
 #include <cmath>
 #include <algorithm>
+#include <functional>
 #include <numeric>
+#include <tuple>
 
 // Boost pool: Don't use mutexes to synchronize memory allocation.
 #define BOOST_POOL_NO_MT
@@ -1318,6 +1321,564 @@ bool has_no_collinear_lines(const Polylines &polylines)
 }
 #endif
 
+// Non-crossing centerlines for multiline adaptive cubic, see docs/HLSD/multiline-infill.md.
+namespace noncrossing {
+
+// y = x() * x + y() in the frame where the sweep family is horizontal.
+using Lin = Vec2d;
+
+static const Vec2d family_dir[3] { Vec2d(1., 0.), Vec2d(0.5, 0.5 * sqrt(3.)), Vec2d(0.5, -0.5 * sqrt(3.)) };
+
+struct SweepLine
+{
+    Vec2d                               a, b; // a.x() < b.x()
+    int                                 family;
+    Lin                                 lin;
+    std::vector<std::pair<double, int>> junctions; // (x, junction)
+};
+
+struct Junction
+{
+    Vec2d                            p;
+    std::vector<int>                 lines;
+    std::vector<std::pair<int, int>> pairs; // (left, right) line of each path through, bottom-up
+    std::vector<std::pair<int, int>> bends; // (path, bend) of each pair, -1 where it runs straight
+};
+
+struct LevelPath
+{
+    std::vector<Vec2d>               verts;     // start, bends, end
+    std::vector<int>                 lines;     // line of each piece
+    std::vector<int>                 junctions; // junction of each bend
+    std::vector<int>                 turn;      // 1 turning up, -1 turning down
+    std::vector<std::vector<Lin>>    cuts;
+    std::vector<std::pair<Lin, int>> pushes;    // (line, bend) keeping a wall away from a neighbour's cut
+    int                              start_term { -1 }; // junction where the path stops on another line, or -1
+    int                              end_term { -1 };
+};
+
+// Moves f onto line c (side 1: from below) wherever c lies beyond it, over the stretches overlapping [w0, w1].
+static void clip_profile(std::vector<Vec2d> &f, const Lin &c, int side, double w0, double w1, double lim0, double lim1, bool cut_at_window, bool drop_past_limits)
+{
+    const double r0 = std::max(lim0, f.front().x()), r1 = std::min(lim1, f.back().x());
+    if (r1 <= r0)
+        return;
+    const size_t ia = std::upper_bound(f.begin(), f.end(), r0, [](double x, const Vec2d &p) { return x < p.x(); }) - f.begin();
+    const size_t ib = std::lower_bound(f.begin() + ia, f.end(), r1, [](const Vec2d &p, double x) { return p.x() < x; }) - f.begin();
+    auto interpolate = [](const Vec2d &a, const Vec2d &b, double x) { return b.x() > a.x() ? a.y() + (x - a.x()) / (b.x() - a.x()) * (b.y() - a.y()) : b.y(); };
+    std::vector<Vec2d> local{ Vec2d(r0, interpolate(f[ia - 1], f[ia], r0)) };
+    local.insert(local.end(), f.begin() + ia, f.begin() + ib);
+    local.emplace_back(r1, interpolate(f[ib - 1], f[ib], r1));
+
+    const double tol    = 1.;
+    auto         beyond = [&c, side, tol](const Vec2d &p) { return side * (c.x() * p.x() + c.y() - p.y()) - tol; };
+    std::vector<std::pair<double, double>> stretches;
+    auto add = [&stretches](double x0, double x1) {
+        if (!stretches.empty() && stretches.back().second >= x0)
+            stretches.back().second = x1;
+        else
+            stretches.emplace_back(x0, x1);
+    };
+    for (size_t i = 1; i < local.size(); ++i) {
+        const Vec2d &p = local[i - 1], &q = local[i];
+        if (q.x() <= p.x())
+            continue;
+        const double bp = beyond(p), bq = beyond(q);
+        if (bp > 0. && bq > 0.)
+            add(p.x(), q.x());
+        else if (bp > 0. || bq > 0.) {
+            const double x = p.x() + bp / (bp - bq) * (q.x() - p.x());
+            if (bp > 0.)
+                add(p.x(), x);
+            else
+                add(x, q.x());
+        }
+    }
+    std::vector<std::pair<double, double>> keep;
+    for (auto [x0, x1] : stretches) {
+        if (x1 < w0 || x0 > w1)
+            continue;
+        if (drop_past_limits && ((x0 <= r0 && r0 == lim0) || (x1 >= r1 && r1 == lim1)))
+            continue;
+        keep.emplace_back(cut_at_window ? std::max(x0, w0) : x0, cut_at_window ? std::min(x1, w1) : x1);
+    }
+    if (keep.empty())
+        return;
+
+    auto y_local = [&](double x) {
+        size_t i = 1;
+        while (i + 1 < local.size() && local[i].x() < x)
+            ++i;
+        return interpolate(local[i - 1], local[i], x);
+    };
+    std::vector<Vec2d> out(f.begin(), f.begin() + ia);
+    auto push = [&out, tol](double x, double y) {
+        if (out.empty() || x > out.back().x() || std::abs(y - out.back().y()) > 2. * tol)
+            out.emplace_back(x, y);
+    };
+    size_t k = 0;
+    for (const Vec2d &p : local) {
+        for (; k < keep.size() && keep[k].second < p.x(); ++k) {
+            const auto [x0, x1] = keep[k];
+            push(x0, y_local(x0));
+            push(x0, c.x() * x0 + c.y());
+            push(x1, c.x() * x1 + c.y());
+            push(x1, y_local(x1));
+        }
+        if (k < keep.size() && keep[k].first <= p.x() && p.x() <= keep[k].second)
+            continue;
+        push(p.x(), p.y());
+    }
+    for (; k < keep.size(); ++k) {
+        const auto [x0, x1] = keep[k];
+        push(x0, y_local(x0));
+        push(x0, c.x() * x0 + c.y());
+        push(x1, c.x() * x1 + c.y());
+        push(x1, y_local(x1));
+    }
+    for (size_t i = ib; i < f.size(); ++i)
+        push(f[i].x(), f[i].y());
+    f = std::move(out);
+}
+
+static std::vector<Vec2d> path_points(const LevelPath &path, const std::vector<SweepLine> &lines, double reach)
+{
+    std::vector<Vec2d> f  = path.verts;
+    const int          nb = int(path.junctions.size());
+    auto x_of  = [&path](int b) { return path.verts[b + 1].x(); };
+    auto sharp = [&](int b) { return lines[path.lines[b]].family != 0 && lines[path.lines[b + 1]].family != 0; };
+    // The run of bends turning the same way as bend b, up to the neighbouring bends turning the other way.
+    auto window = [&](int b) {
+        int l = b - 1, r = b + 1;
+        while (l >= 0 && path.turn[l] == path.turn[b])
+            --l;
+        while (r < nb && path.turn[r] == path.turn[b])
+            ++r;
+        return std::make_pair(l >= 0 ? x_of(l) : f.front().x(), r < nb ? x_of(r) : f.back().x());
+    };
+    // Sharp bends between the slanted lines go last, so they win at the tip of a small triangle.
+    for (int b = 0; b < nb; ++b)
+        if (!sharp(b)) {
+            const auto [w0, w1] = window(b);
+            for (const Lin &c : path.cuts[b])
+                clip_profile(f, c, path.turn[b], w0, w1, x_of(b) - reach, x_of(b) + reach, true, false);
+        }
+    for (int b = 0; b < nb; ++b)
+        if (sharp(b))
+            for (const Lin &c : path.cuts[b])
+                clip_profile(f, c, path.turn[b], x_of(b), x_of(b), x_of(b) - reach, x_of(b) + reach, false, true);
+    for (const auto &[c, b] : path.pushes) {
+        const auto [w0, w1] = window(b);
+        clip_profile(f, c, path.turn[b], w0, w1, x_of(b) - reach, x_of(b) + reach, true, true);
+    }
+    std::vector<Vec2d> pts;
+    for (const Vec2d &p : f) {
+        while (pts.size() >= 2 && std::abs(cross2(Vec2d(pts.back() - pts[pts.size() - 2]), Vec2d(p - pts.back()))) <=
+                                      1e-9 * (pts.back() - pts[pts.size() - 2]).norm() * (p - pts.back()).norm())
+            pts.pop_back();
+        pts.push_back(p);
+    }
+    return pts;
+}
+
+static double polyline_length(const std::vector<Vec2d> &pts)
+{
+    double len = 0.;
+    for (size_t i = 1; i < pts.size(); ++i)
+        len += (pts[i] - pts[i - 1]).norm();
+    return len;
+}
+
+// Point at the given distance along pts, and the index of the segment it lies on.
+static std::pair<Vec2d, size_t> point_along(const std::vector<Vec2d> &pts, double t)
+{
+    for (size_t i = 1; i < pts.size(); ++i) {
+        const double len = (pts[i] - pts[i - 1]).norm();
+        if (t <= len)
+            return { pts[i - 1] + (len > 0. ? t / len : 0.) * (pts[i] - pts[i - 1]), i };
+        t -= len;
+    }
+    return { pts.back(), pts.size() - 1 };
+}
+
+} // namespace noncrossing
+
+Polylines multiline_paths(const Lines &lines_in, double d1, double end_overlap, int sweep, const BoundingBox &cover)
+{
+    using namespace noncrossing;
+    const double             eps = scale_(0.002);
+    const Eigen::Rotation2Dd to_sweep(-sweep * M_PI / 3.);
+    const BoundingBoxf       box(cover.min.cast<double>(), cover.max.cast<double>());
+
+    // Lines in the sweep frame, collinear pieces merged.
+    struct Piece { double c, s0, s1; };
+    std::array<std::vector<Piece>, 3> pieces;
+    for (const Line &line : lines_in) {
+        Vec2d a = line.a.cast<double>(), b = line.b.cast<double>();
+        if (!Geometry::liang_barsky_line_clipping(a, b, box) || (b - a).norm() < 10. * eps)
+            continue;
+        a = to_sweep * a;
+        b = to_sweep * b;
+        const double angle = std::atan2(b.y() - a.y(), b.x() - a.x()) / (M_PI / 3.);
+        if (std::abs(angle - std::round(angle)) > 0.01)
+            // Not one of the three families.
+            return {};
+        const int    f = (int(std::round(angle)) % 3 + 3) % 3;
+        const Vec2d &d = family_dir[f];
+        const Vec2d  n(-d.y(), d.x());
+        pieces[f].push_back({ n.dot(a), std::min(d.dot(a), d.dot(b)), std::max(d.dot(a), d.dot(b)) });
+    }
+    std::vector<SweepLine> lines;
+    for (int f = 0; f < 3; ++f) {
+        std::vector<Piece> &ps = pieces[f];
+        const Vec2d        &d  = family_dir[f];
+        const Vec2d         n(-d.y(), d.x());
+        const double        slope = d.y() / d.x();
+        std::sort(ps.begin(), ps.end(), [](const Piece &l, const Piece &r) { return l.c < r.c; });
+        for (size_t i = 0; i < ps.size();) {
+            size_t j = i + 1;
+            while (j < ps.size() && ps[j].c - ps[i].c < eps)
+                ++j;
+            std::sort(ps.begin() + i, ps.begin() + j, [](const Piece &l, const Piece &r) { return l.s0 < r.s0; });
+            double c = 0.;
+            for (size_t k = i; k < j; ++k)
+                c += ps[k].c / double(j - i);
+            double s0 = ps[i].s0, s1 = ps[i].s1;
+            for (size_t k = i + 1; k <= j; ++k) {
+                if (k < j && ps[k].s0 <= s1 + eps) {
+                    s1 = std::max(s1, ps[k].s1);
+                    continue;
+                }
+                const Vec2d a = s0 * d + c * n;
+                lines.push_back({ a, s1 * d + c * n, f, Lin(slope, a.y() - slope * a.x()), {} });
+                if (k < j) {
+                    s0 = ps[k].s0;
+                    s1 = ps[k].s1;
+                }
+            }
+            i = j;
+        }
+    }
+
+    auto along  = [](const SweepLine &l, const Vec2d &p) { return family_dir[l.family].dot(p - l.a); };
+    auto length = [](const SweepLine &l) { return (l.b - l.a).norm(); };
+
+    // Crossings, including the ends of lines stopping on another line.
+    std::vector<Junction> junctions;
+    auto detect_junctions = [&]() {
+        struct Hit { Vec2d p; int i, j; };
+        std::vector<Hit> hits;
+        std::vector<int> order(lines.size());
+        std::iota(order.begin(), order.end(), 0);
+        std::sort(order.begin(), order.end(), [&lines](int l, int r) { return lines[l].a.x() < lines[r].a.x(); });
+        for (size_t oi = 0; oi < order.size(); ++oi) {
+            const SweepLine &li = lines[order[oi]];
+            for (size_t oj = oi + 1; oj < order.size() && lines[order[oj]].a.x() <= li.b.x() + eps; ++oj) {
+                const SweepLine &lj = lines[order[oj]];
+                if (li.family == lj.family)
+                    continue;
+                const double x = (lj.lin.y() - li.lin.y()) / (li.lin.x() - lj.lin.x());
+                const Vec2d  p(x, li.lin.x() * x + li.lin.y());
+                const double ti = along(li, p), tj = along(lj, p);
+                if (ti > -eps && ti < length(li) + eps && tj > -eps && tj < length(lj) + eps)
+                    hits.push_back({ p, order[oi], order[oj] });
+            }
+        }
+        std::sort(hits.begin(), hits.end(), [](const Hit &l, const Hit &r) { return l.p.x() < r.p.x(); });
+        junctions.clear();
+        for (const Hit &hit : hits) {
+            int found = -1;
+            for (int k = int(junctions.size()) - 1; k >= 0 && junctions[k].p.x() > hit.p.x() - eps; --k)
+                if (std::abs(junctions[k].p.y() - hit.p.y()) < eps) {
+                    found = k;
+                    break;
+                }
+            if (found < 0) {
+                found = int(junctions.size());
+                junctions.push_back({ hit.p, {}, {}, {} });
+            }
+            std::vector<int> &jl = junctions[found].lines;
+            for (int li : { hit.i, hit.j })
+                if (std::find(jl.begin(), jl.end(), li) == jl.end())
+                    jl.push_back(li);
+        }
+        for (SweepLine &l : lines)
+            l.junctions.clear();
+        for (int ji = 0; ji < int(junctions.size()); ++ji)
+            for (int li : junctions[ji].lines)
+                lines[li].junctions.emplace_back(junctions[ji].p.x(), ji);
+        for (SweepLine &l : lines)
+            std::sort(l.junctions.begin(), l.junctions.end());
+    };
+    detect_junctions();
+    auto has_arm = [&](int ji, int li, bool right) {
+        const double t = along(lines[li], junctions[ji].p);
+        return right ? t < length(lines[li]) - eps : t > eps;
+    };
+
+    // A line ending on another just past a crossing stops at the crossing, where its stub would leave a hole.
+    auto crosses = [&](int ji, int li) { return has_arm(ji, li, false) && has_arm(ji, li, true); };
+    for (int pass = 0; pass < 3; ++pass) {
+        std::vector<bool> touched(lines.size(), false);
+        bool              changed = false;
+        for (int ji = 0; ji < int(junctions.size()); ++ji) {
+            const Junction &J = junctions[ji];
+            if (J.lines.size() != 2 || touched[J.lines[0]] || touched[J.lines[1]] || !crosses(ji, J.lines[0]) || !crosses(ji, J.lines[1]))
+                continue;
+            // Shortest arm of each line from J to the junction where it ends on another line.
+            struct DeadArm { double length; bool at_b; int end; };
+            std::array<DeadArm, 2> dead;
+            dead.fill({ std::numeric_limits<double>::max(), false, -1 });
+            for (int k = 0; k < 2; ++k) {
+                const SweepLine &l  = lines[J.lines[k]];
+                const size_t     at = std::find_if(l.junctions.begin(), l.junctions.end(), [ji](const std::pair<double, int> &j) { return j.second == ji; }) - l.junctions.begin();
+                const double     t  = along(l, J.p);
+                if (at + 1 < l.junctions.size() && length(l) - along(l, junctions[l.junctions[at + 1].second].p) < eps)
+                    dead[k] = { length(l) - t, true, l.junctions[at + 1].second };
+                if (at > 0 && along(l, junctions[l.junctions[at - 1].second].p) < eps && t < dead[k].length)
+                    dead[k] = { t, false, l.junctions[at - 1].second };
+            }
+            const int k = dead[0].length <= dead[1].length ? 0 : 1;
+            if (dead[k].length >= 2. * d1)
+                continue;
+            SweepLine &l = lines[J.lines[k]];
+            (dead[k].at_b ? l.b : l.a) = J.p;
+            // Only the shortened line and those it ended on have stale junctions until the next pass.
+            for (int li : junctions[dead[k].end].lines)
+                touched[li] = true;
+            changed = true;
+        }
+        if (!changed)
+            break;
+        detect_junctions();
+    }
+
+    // At every crossing the lines bounce off each other, so that every path keeps running left to right.
+    for (int ji = 0; ji < int(junctions.size()); ++ji) {
+        Junction        &J = junctions[ji];
+        std::vector<int> left, right;
+        for (int li : J.lines)
+            if (has_arm(ji, li, false) && has_arm(ji, li, true))
+                left.push_back(li);
+        right = left;
+        std::sort(left.begin(), left.end(), [&lines](int l, int r) { return lines[l].lin.x() > lines[r].lin.x(); });
+        std::sort(right.begin(), right.end(), [&lines](int l, int r) { return lines[l].lin.x() < lines[r].lin.x(); });
+        for (size_t k = 0; k < left.size(); ++k)
+            J.pairs.emplace_back(left[k], right[k]);
+        J.bends.assign(J.pairs.size(), { -1, -1 });
+    }
+
+    std::vector<LevelPath> paths;
+    for (int li = 0; li < int(lines.size()); ++li) {
+        const SweepLine &l     = lines[li];
+        const int        start = !l.junctions.empty() && !has_arm(l.junctions.front().second, li, false) ? l.junctions.front().second : -1;
+        LevelPath        path;
+        path.start_term = start;
+        path.verts.push_back(start >= 0 ? junctions[start].p : l.a);
+        path.lines.push_back(li);
+        int    cur = li;
+        double x   = path.verts.front().x();
+        for (;;) {
+            const auto &js = lines[cur].junctions;
+            const auto  it = std::find_if(js.begin(), js.end(), [x, eps](const std::pair<double, int> &j) { return j.first > x + 0.25 * eps; });
+            if (it == js.end()) {
+                path.verts.push_back(lines[cur].b);
+                break;
+            }
+            Junction    &J = junctions[it->second];
+            const size_t k = std::find_if(J.pairs.begin(), J.pairs.end(), [cur](const std::pair<int, int> &p) { return p.first == cur; }) - J.pairs.begin();
+            if (k == J.pairs.size()) {
+                path.verts.push_back(J.p);
+                path.end_term = it->second;
+                break;
+            }
+            if (const int next = J.pairs[k].second; next != cur) {
+                J.bends[k] = { int(paths.size()), int(path.junctions.size()) };
+                path.verts.push_back(J.p);
+                path.lines.push_back(next);
+                path.junctions.push_back(it->second);
+                path.turn.push_back(lines[next].lin.x() > lines[cur].lin.x() ? 1 : -1);
+                cur = next;
+            }
+            x = it->first;
+        }
+        path.cuts.resize(path.junctions.size());
+        paths.push_back(std::move(path));
+    }
+
+    // Cut the two bends of a crossing d1 apart, no further than the neighbouring bends turning the other way.
+    for (const Junction &J : junctions) {
+        if (J.pairs.size() < 2 || J.bends.front().first < 0 || J.bends.back().first < 0)
+            continue;
+        const Vec2d n = (family_dir[lines[J.pairs.back().second].family] - family_dir[lines[J.pairs.back().first].family]).normalized();
+        auto cut = [&J, &n](double offset) {
+            const Vec2d  q = J.p + offset * n;
+            const double s = -n.x() / n.y();
+            return Lin(s, q.y() - s * q.x());
+        };
+        LevelPath &lo = paths[J.bends.front().first], &hi = paths[J.bends.back().first];
+        const int  lb = J.bends.front().second, hb = J.bends.back().second;
+        if (J.pairs.size() == 3) {
+            lo.cuts[lb].push_back(cut(-d1));
+            hi.cuts[hb].push_back(cut(d1));
+            continue;
+        }
+        // Only the tip of a small triangle, between the two slanted families, stops at its neighbouring bends.
+        const bool sharp = lines[J.pairs.front().first].family != 0 && lines[J.pairs.front().second].family != 0;
+        auto room = [&](const LevelPath &P, int b, int away, double sign) {
+            double c = std::numeric_limits<double>::max();
+            for (int nb : { b - 1, b + 1 })
+                if (sharp && nb >= 0 && nb < int(P.junctions.size()) && P.turn[nb] == away)
+                    c = std::min(c, sign * n.dot(junctions[P.junctions[nb]].p - J.p));
+            if (b == 0 && P.start_term >= 0)
+                c = std::min(c, sign * n.dot(P.verts.front() - J.p));
+            if (b + 1 == int(P.junctions.size()) && P.end_term >= 0)
+                c = std::min(c, sign * n.dot(P.verts.back() - J.p));
+            return std::max(c, 0.);
+        };
+        const double c_lo = room(lo, lb, 1, -1.), c_hi = room(hi, hb, -1, 1.);
+        double       d_lo = 0.5 * d1;
+        if (d1 - c_hi <= c_lo)
+            d_lo = std::clamp(d_lo, d1 - c_hi, c_lo);
+        else if (c_lo + c_hi > 0.)
+            d_lo = d1 * c_lo / (c_lo + c_hi);
+        const double d_hi = d1 - d_lo;
+        lo.cuts[lb].push_back(cut(-d_lo));
+        hi.cuts[hb].push_back(cut(d_hi));
+        auto propagate = [&](const LevelPath &P, int b, int away, int step, double offset) {
+            for (int nb : { b - 1, b + 1 })
+                if (nb >= 0 && nb < int(P.junctions.size()) && P.turn[nb] == away) {
+                    const Junction &W = junctions[P.junctions[nb]];
+                    const int       k = int(std::find_if(W.pairs.begin(), W.pairs.end(), [&](const std::pair<int, int> &p) { return p.first == P.lines[nb]; }) - W.pairs.begin()) + step;
+                    if (k >= 0 && k < int(W.bends.size()) && W.bends[k].first >= 0)
+                        paths[W.bends[k].first].pushes.emplace_back(cut(offset), W.bends[k].second);
+                }
+        };
+        if (sharp) {
+            propagate(lo, lb, 1, -1, -d_lo - d1);
+            propagate(hi, hb, -1, 1, d_hi + d1);
+        }
+    }
+
+    std::vector<std::vector<Vec2d>>        geometry;
+    Linesf                                 segments;
+    std::vector<std::pair<int, double>>    segment_start; // path, distance along it
+    std::vector<std::pair<double, double>> kept;          // stretch of each path left by the trimming
+    for (const LevelPath &path : paths) {
+        geometry.push_back(path.junctions.empty() ? std::vector<Vec2d>{ path.verts.front(), path.verts.back() } : path_points(path, lines, 4. * d1));
+        double along_path = 0.;
+        for (size_t i = 1; i < geometry.back().size(); ++i) {
+            segments.emplace_back(geometry.back()[i - 1], geometry.back()[i]);
+            segment_start.emplace_back(int(geometry.size()) - 1, along_path);
+            along_path += (geometry.back()[i] - geometry.back()[i - 1]).norm();
+        }
+        kept.emplace_back(0., along_path);
+    }
+
+    // A path ending on another line stops end_overlap inside the walls of the others, as trimmed so far.
+    const double end_clearance = d1 - end_overlap;
+    AABBTreeLines::LinesDistancer<Linef> tree(segments);
+    auto clearance = [&](int pi, const Vec2d &q) {
+        double dist = std::numeric_limits<double>::max();
+        for (size_t s : tree.all_lines_in_radius(q, d1)) {
+            const auto [pj, start] = segment_start[s];
+            const Vec2d  a = segments[s].a, d = segments[s].b - a;
+            const double len = d.norm(), t0 = std::max(0., kept[pj].first - start), t1 = std::min(len, kept[pj].second - start);
+            if (pj != pi && len > 0. && t0 <= t1)
+                dist = std::min(dist, line_alg::distance_to(Linef(a + t0 / len * d, a + t1 / len * d), q));
+        }
+        return dist;
+    };
+    // Returns the length trimmed off.
+    auto trim_front = [&](int pi, std::vector<Vec2d> &pts) {
+        const double total = polyline_length(pts), step = d1 / 32.;
+        double t = 0.;
+        while (t <= total && clearance(pi, point_along(pts, t).first) < end_clearance)
+            t += step;
+        if (t > total) {
+            pts.clear();
+            return total;
+        }
+        if (t == 0.)
+            return 0.;
+        for (double lo = std::max(0., t - step); t - lo > step / 256.;)
+            if (const double mid = 0.5 * (lo + t); clearance(pi, point_along(pts, mid).first) < end_clearance)
+                lo = mid;
+            else
+                t = mid;
+        const auto [q, seg] = point_along(pts, t);
+        pts.erase(pts.begin(), pts.begin() + (seg - 1));
+        pts.front() = q;
+        return t;
+    };
+
+    // A path stopping on the line of another path is trimmed first, so that it gives way to that path.
+    std::vector<std::vector<std::tuple<double, double, int>>> carried(lines.size()); // x range and path of each piece
+    for (int pi = 0; pi < int(paths.size()); ++pi)
+        for (size_t i = 0; i < paths[pi].lines.size(); ++i)
+            carried[paths[pi].lines[i]].emplace_back(paths[pi].verts[i].x(), paths[pi].verts[i + 1].x(), pi);
+    std::vector<std::vector<int>> stopping_on(paths.size());
+    for (int pi = 0; pi < int(paths.size()); ++pi)
+        for (const auto &[ji, own] : { std::make_pair(paths[pi].start_term, paths[pi].lines.front()), std::make_pair(paths[pi].end_term, paths[pi].lines.back()) })
+            if (ji >= 0)
+                for (int li : junctions[ji].lines)
+                    if (li != own)
+                        for (const auto &[x0, x1, pj] : carried[li])
+                            if (pj != pi && x0 - eps <= junctions[ji].p.x() && junctions[ji].p.x() <= x1 + eps)
+                                stopping_on[pj].push_back(pi);
+    std::vector<int>  order;
+    std::vector<bool> visited(paths.size(), false);
+    std::function<void(int)> visit = [&](int pi) {
+        if (visited[pi])
+            return;
+        visited[pi] = true;
+        for (int child : stopping_on[pi])
+            visit(child);
+        order.push_back(pi);
+    };
+    for (int pi = 0; pi < int(paths.size()); ++pi)
+        visit(pi);
+    std::vector<std::vector<Vec2d>> trimmed(paths.size());
+    auto trim = [&](int pi) {
+        std::vector<Vec2d> &pts = trimmed[pi];
+        if (paths[pi].start_term >= 0)
+            kept[pi].first += trim_front(pi, pts);
+        if (paths[pi].end_term >= 0 && !pts.empty()) {
+            std::reverse(pts.begin(), pts.end());
+            kept[pi].second -= trim_front(pi, pts);
+            std::reverse(pts.begin(), pts.end());
+        }
+        if (pts.size() < 2 || polyline_length(pts) < d1) {
+            pts.clear();
+            kept[pi] = { 0., -1. };
+        }
+    };
+    // Ends grow back where the ends they gave way to were trimmed later; the last pass only shortens them.
+    for (int pass = 0; pass < 3; ++pass)
+        for (int pi : order) {
+            if (pass < 2) {
+                trimmed[pi] = geometry[pi];
+                kept[pi]    = { 0., polyline_length(geometry[pi]) };
+            } else if (trimmed[pi].empty())
+                continue;
+            trim(pi);
+        }
+
+    Polylines out;
+    const Eigen::Rotation2Dd to_world = to_sweep.inverse();
+    for (const std::vector<Vec2d> &pts : trimmed) {
+        if (pts.empty())
+            continue;
+        Polyline pl;
+        for (const Vec2d &p : pts) {
+            const Vec2d w = to_world * p;
+            pl.points.emplace_back(coord_t(std::round(w.x())), coord_t(std::round(w.y())));
+        }
+        out.emplace_back(std::move(pl));
+    }
+    return out;
+}
+
 void Filler::_fill_surface_single(
     const FillParams              &params,
     unsigned int                   thickness_layers,
@@ -1371,6 +1932,17 @@ void Filler::_fill_surface_single(
         all_polylines.reserve(lines.size());
         std::transform(lines.begin(), lines.end(), std::back_inserter(all_polylines), [](const Line& l) { return Polyline{ l.a, l.b }; });
 
+        if (params.multiline > 1) {
+            const double d1    = scale_(this->spacing) * params.multiline;
+            BoundingBox  cover = get_extents(expolygon);
+            cover.offset(coord_t(4. * d1));
+            // Rotate the family the paths run along with the layer, like the other multiline patterns.
+            const int sweep = int((this->layer_id / std::max(thickness_layers, 1u)) % 3);
+            // Line ends overlap the walls they stop on by half a line, so that they bond.
+            if (Polylines paths = multiline_paths(lines, d1, 0.5 * scale_(this->spacing), sweep, cover); !paths.empty())
+                all_polylines = std::move(paths);
+        }
+
         // Apply multiline offset if needed
         multiline_fill(all_polylines, params, spacing);
 

src/libslic3r/Fill/FillAdaptive.hpp

@@ -48,6 +48,9 @@ FillAdaptive::OctreePtr         build_octree(
     // If true, octree is densified below internal overhangs only.
     bool                         support_overhangs_only);
 
+// Multiline infill: lines of the three families to non-crossing paths d1 apart, ends reaching end_overlap into walls.
+Polylines                       multiline_paths(const Lines &lines, double d1, double end_overlap, int sweep, const BoundingBox &cover);
+
 //
 // Some of the algorithms used by class FillAdaptive were inspired by
 // Cura Engine's class SubDivCube

src/libslic3r/Fill/FillRectilinear.cpp

@@ -3047,12 +3047,56 @@ bool FillRectilinear::fill_surface_by_multilines(const Surface *surface, FillPar
     return true;
 }
 
+// Upper level of a cubic band [0, h] over one period, from the crossing at (0, tau) to the one at (period, tau).
+// See docs/HLSD/multiline-infill.md.
+static std::vector<Vec2d> cubic_upper_level(double tau, double h, double period, double d1)
+{
+    const double s3     = std::sqrt(3.);
+    const double y_cut  = std::clamp(tau - 0.5 * d1, 0., h - d1) + d1;
+    const double y_flat = std::min(h, h + y_cut - 2. * d1);
+    const double x2     = (h - tau) / s3 + d1;
+    const double x3     = (h + tau) / s3 - d1;
+    // (slope, intercept) of the rising line, its chamfer, the horizontal line, the falling chamfer and line.
+    const std::array<Vec2d, 5> lines{ Vec2d(s3, tau), Vec2d(1. / s3, h - x2 / s3), Vec2d(0., y_flat),
+                                      Vec2d(-1. / s3, h + x3 / s3), Vec2d(-s3, tau + s3 * period) };
+    auto y_at = [&lines, y_cut](double x) {
+        double y = std::numeric_limits<double>::max();
+        for (const Vec2d &l : lines)
+            y = std::min(y, l.x() * x + l.y());
+        return std::max(y, y_cut);
+    };
+
+    std::vector<double> xs;
+    for (size_t i = 0; i < lines.size(); ++i) {
+        if (lines[i].x() != 0.)
+            xs.emplace_back((y_cut - lines[i].y()) / lines[i].x());
+        for (size_t j = i + 1; j < lines.size(); ++j)
+            xs.emplace_back((lines[j].y() - lines[i].y()) / (lines[i].x() - lines[j].x()));
+    }
+    xs.erase(std::remove_if(xs.begin(), xs.end(), [period](double x) { return x <= 1. || x >= period - 1.; }), xs.end());
+    xs.insert(xs.end(), { 0., period });
+    std::sort(xs.begin(), xs.end());
+    xs.erase(std::unique(xs.begin(), xs.end(), [](double a, double b) { return b - a < 1.; }), xs.end());
+
+    std::vector<Vec2d> pts;
+    for (double x : xs) {
+        const Vec2d p(x, y_at(x));
+        if (pts.size() >= 2) {
+            const Vec2d &a = pts[pts.size() - 2], &b = pts.back();
+            if (std::abs((b.y() - a.y()) / (b.x() - a.x()) - (p.y() - b.y()) / (p.x() - b.x())) < EPSILON)
+                pts.pop_back();
+        }
+        pts.emplace_back(p);
+    }
+    return pts;
+}
+
 bool FillRectilinear::fill_surface_trapezoidal(
     const Surface*                            surface,
     FillParams                                params,
     const std::initializer_list<SweepParams>& sweep_params,
     Polylines&                                polylines_out,
-    int                                       Pattern_type) // 0=grid, 1=triangular, 2=stars
+    int                                       Pattern_type) // 0=grid, 1=triangular, 2=stars, 3=cubic
 {
     assert(params.multiline > 1);
 
@@ -3350,6 +3394,55 @@ bool FillRectilinear::fill_surface_trapezoidal(
         break;
     }
 
+    case 3: // Cubic
+    {
+        // Same z shifted lines as the single-line cubic; the slanted ones cross tau above the horizontal ones.
+        auto pos_mod = [](double a, double m) { const double r = std::fmod(a, m); return r < 0. ? r + m : r; };
+        const double h     = 0.5 * std::sqrt(3.0) * period;
+        const double shift = scale_(std::sqrt(0.5) * this->z);
+        const double tau   = pos_mod(-3. * shift, h);
+        const double y0    = pos_mod(-2. * shift, 2. * h);
+
+        std::array<std::vector<Vec2d>, 2> levels{ cubic_upper_level(h - tau, h, period, d1), cubic_upper_level(tau, h, period, d1) };
+        for (Vec2d &p : levels.front())
+            p.y() = h - p.y();
+
+        const size_t layer_mod = infill_layer_id % 3;
+        const double angle     = layer_mod * 2.0 * M_PI / 3.0;
+
+        // Only cover the surface, seen in the frame the pattern is built in.
+        ExPolygon local = expolygon;
+        local.translate(-rotate_vector.second.x(), -rotate_vector.second.y());
+        if (layer_mod)
+            local.rotate(-angle);
+        BoundingBox cover = get_extents(local);
+        cover.offset(period);
+
+        const int64_t n_min = int64_t(std::floor((cover.min.y() - y0) / h)) - 1;
+        const int64_t n_max = int64_t(std::ceil((cover.max.y() - y0) / h)) + 1;
+        for (int64_t n = n_min; n <= n_max; ++n) {
+            const double  x_off = (n & 1) ? 0.5 * period : 0.;
+            const double  base  = y0 + double(n) * h - tau;
+            const int64_t j_min = int64_t(std::floor((cover.min.x() - x_off) / period)) - 1;
+            const int64_t j_max = int64_t(std::ceil((cover.max.x() - x_off) / period));
+            for (const std::vector<Vec2d> &level : levels) {
+                Polyline row;
+                row.points.reserve(size_t(j_max - j_min + 1) * level.size());
+                for (int64_t j = j_min; j <= j_max; ++j)
+                    for (size_t i = (j == j_min) ? 0 : 1; i < level.size(); ++i)
+                        row.points.emplace_back(coord_t(std::round(x_off + double(j * period) + level[i].x())),
+                                                coord_t(std::round(base + level[i].y())));
+                polylines.emplace_back(std::move(row));
+            }
+        }
+
+        if (layer_mod)
+            for (Polyline &pl : polylines)
+                pl.rotate(angle, Point(0, 0));
+
+        break;
+    }
+
     default:
         // Handle unknown pattern type
         break;
@@ -3532,6 +3625,11 @@ Polylines FillStars::fill_surface(const Surface *surface, const FillParams &para
 Polylines FillCubic::fill_surface(const Surface *surface, const FillParams &params)
 {
     Polylines polylines_out;
+    if (params.multiline > 1) {
+        if (!this->fill_surface_trapezoidal(surface, params, {}, polylines_out, 3))
+            BOOST_LOG_TRIVIAL(error) << "FillCubic::fill_surface_trapezoidal() failed.";
+        return polylines_out;
+    }
     coordf_t dx = sqrt(0.5) * z;
     if (! this->fill_surface_by_multilines(
             surface, params, 

src/libslic3r/GCode.cpp

@@ -970,6 +970,27 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         return gcode;
     }
 
+    // A folded tower layer is thicker than the object layer it sits on, so the height process_layer
+    // emitted is not the tower's. Both writers declare one, but each hardcodes a tag dialect - Type 1
+    // forces s_IsBBLPrinter and writes "; LAYER_HEIGHT:", Type 2 writes ";HEIGHT:" - and the processor
+    // reads only its printer's, so a Type 1 tower on a non-BBL printer loses it and the merged layer
+    // is drawn and costed as a thin one. Declare it here, where the printer is known, unless the tower
+    // already wrote the right tag. _extrude puts the object's height back on the next object path,
+    // since process_layer forces the role to erWipeTower on any layer with a tower.
+    std::string WipeTowerIntegration::tower_height_tag(GCode &gcodegen, const WipeTower::ToolChangeResult &tcr,
+                                                       const std::string &tcr_gcode) const
+    {
+        const std::string tag = ";" + GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Height);
+        if (! m_sparse_layers_combined || std::abs(gcodegen.m_last_height - tcr.layer_height) <= EPSILON ||
+            tcr_gcode.find(tag) != std::string::npos)
+            return {};
+        // Keep m_last_height what the G-code last declared, so a second visit does not repeat it.
+        gcodegen.m_last_height = tcr.layer_height;
+        char buf[64];
+        sprintf(buf, "%s%g\n", tag.c_str(), tcr.layer_height);
+        return buf;
+    }
+
     std::string WipeTowerIntegration::append_tcr(GCode& gcodegen, const WipeTower::ToolChangeResult& tcr, int new_filament_id, double z) const
     {
         if (new_filament_id != -1 && new_filament_id != tcr.new_tool)
@@ -1467,6 +1488,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         config.set_key_value("filament_start_gcode", new ConfigOptionString(start_filament_gcode_str));
         std::string tcr_gcode, tcr_escaped_gcode = gcodegen.placeholder_parser_process("tcr_rotated_gcode", tcr_rotated_gcode, new_filament_id, &config);
         unescape_string_cstyle(tcr_escaped_gcode, tcr_gcode);
+        gcode += tower_height_tag(gcodegen, tcr, tcr_gcode);
         gcode += tcr_gcode;
         // Count the toolchange only when the emitted block really changed the tool —
         // tower visits without a filament change must not advance the ordinal.
@@ -1799,6 +1821,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         std::string tcr_gcode,
             tcr_escaped_gcode = gcodegen.placeholder_parser_process("tcr_rotated_gcode", tcr_rotated_gcode, new_extruder_id, &config);
         unescape_string_cstyle(tcr_escaped_gcode, tcr_gcode);
+        gcode += tower_height_tag(gcodegen, tcr, tcr_gcode);
         gcode += tcr_gcode;
         check_add_eol(toolchange_gcode_str);
 
@@ -1946,7 +1969,8 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
                     // Calculate where the wipe tower layer will be printed. -1 means that print z will not change,
                     // resulting in a wipe tower with sparse layers.
                     double wipe_tower_z  = -1;
-                    bool   ignore_sparse = false;
+                    // Folded into a later, thicker layer that prints at its own z: nothing to emit.
+                    bool   ignore_sparse = wipe_tower_layer_is_combined_away(m_tool_changes[m_layer_idx]);
                     if (m_sparse_layers_skipped) {
                         wipe_tower_z  = m_last_wipe_tower_print_z;
                         ignore_sparse = wipe_tower_layer_is_sparse(m_tool_changes[m_layer_idx]) && m_layer_idx != 0;
@@ -1964,7 +1988,8 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
             // Calculate where the wipe tower layer will be printed. -1 means that print z will not change,
             // resulting in a wipe tower with sparse layers.
             double wipe_tower_z  = -1;
-            bool   ignore_sparse = false;
+            // Folded into a later, thicker layer that prints at its own z: nothing to emit.
+            bool   ignore_sparse = wipe_tower_layer_is_combined_away(m_tool_changes[m_layer_idx]);
             if (m_sparse_layers_skipped) {
                 ignore_sparse = wipe_tower_layer_is_sparse(m_tool_changes[m_layer_idx]);
                 wipe_tower_z  = m_compacted_tower_z[m_layer_idx];
@@ -1994,7 +2019,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         if (m_layer_idx >= (int) m_tool_changes.size())
             return true;
 
-        bool   ignore_sparse = false;
+        bool   ignore_sparse = wipe_tower_layer_is_combined_away(m_tool_changes[m_layer_idx]);
         if (m_sparse_layers_skipped)
             ignore_sparse = wipe_tower_layer_is_sparse(m_tool_changes[m_layer_idx]);
 
@@ -2479,7 +2504,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(print->model().id().id);
+        ctx.id = std::to_string(print->model().id().id);
+        ctx.name = print->get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
         ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2531,7 +2557,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         }
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + err_msg;
             ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2555,7 +2582,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         boost::nowide::remove(path_tmp.c_str());
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + ex.what();
             ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2668,7 +2696,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
     if (ret) {
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\nFailed to rename the output G-code file: " + ret.message();
             ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2687,7 +2716,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(print->model().id().id);
+        ctx.id = std::to_string(print->model().id().id);
+        ctx.name = print->get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
         ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -3070,162 +3100,6 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     if (m_config.small_area_infill_flow_compensation.value && !m_config.small_area_infill_flow_compensation_model.empty())
         m_small_area_infill_flow_compensator = make_unique<SmallAreaInfillFlowCompensator>(print.config());
     
-    // Process file_start_gcode - written at the very top of the file, before any header
-    {
-        std::string top_gcode_template = print.config().file_start_gcode.value;
-        if (!top_gcode_template.empty()) {
-            DynamicConfig top_config;
-            // file_start_gcode runs before the parser copy that normally restores these, so set them here.
-            PlaceholderParser::update_timestamp(top_config);
-            PlaceholderParser::update_user_name(top_config);
-            top_config.set_key_value("print_time_total_sec", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Print_Time_Total_Sec_Placeholder)));
-            top_config.set_key_value("print_time_day", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Print_Time_Day_Placeholder)));
-            top_config.set_key_value("print_time_hour", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Print_Time_Hour_Placeholder)));
-            top_config.set_key_value("print_time_minute", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Print_Time_Minute_Placeholder)));
-            top_config.set_key_value("print_time_sec", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Print_Time_Sec_Placeholder)));
-            top_config.set_key_value("used_filament_length", new ConfigOptionString(GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Used_Filament_Length_Placeholder)));
-            std::string top_gcode = print.placeholder_parser().process(top_gcode_template, 0, &top_config);
-            if (!top_gcode.empty())
-                file.writeln(top_gcode);
-        }
-    }
-
-    // Orca: Don't output Header block if BTT thumbnail is identified in the list
-    // Get the thumbnails value as a string
-    std::string thumbnails_value = print.config().option<ConfigOptionString>("thumbnails")->value;
-    // search string for the BTT_TFT label
-    bool has_BTT_thumbnail = (thumbnails_value.find("BTT_TFT") != std::string::npos);
-    
-    if(!has_BTT_thumbnail){   
-        file.write_format("; HEADER_BLOCK_START\n");
-        // Write information on the generator.
-        file.write_format("; generated by %s on %s\n", Slic3r::header_slic3r_generated().c_str(), Slic3r::Utils::local_timestamp().c_str());
-        if (is_bbl_printers)
-            file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Estimated_Printing_Time_Placeholder).c_str());
-        //BBS: total layer number
-        file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Total_Layer_Number_Placeholder).c_str());
-        //Orca: extra check for bbl printer
-        if (is_bbl_printers) {
-            if (print.calib_params().mode == CalibMode::Calib_None) { // Don't support skipping in cali mode
-                // list all label_object_id with sorted order here
-                m_enable_exclude_object = true;
-                m_label_objects_ids.clear();
-                m_label_objects_ids.reserve(print.num_object_instances());
-                for (const PrintObject *print_object : print.objects())
-                    for (const PrintInstance &print_instance : print_object->instances())
-                        m_label_objects_ids.push_back(print_instance.model_instance->get_labeled_id());
-  
-                std::sort(m_label_objects_ids.begin(), m_label_objects_ids.end());
-  
-                std::string objects_id_list = "; model label id: ";
-                for (auto it = m_label_objects_ids.begin(); it != m_label_objects_ids.end(); it++)
-                    objects_id_list += (std::to_string(*it) + (it != m_label_objects_ids.end() - 1 ? "," : "\n"));
-                file.writeln(objects_id_list);
-            } else {
-                m_enable_exclude_object = false;
-                m_label_objects_ids.clear();
-            }
-    }
-
-    {
-        std::string filament_density_list = "; filament_density: ";
-        (filament_density_list+=m_config.filament_density.serialize()) +='\n';
-        file.writeln(filament_density_list);
-
-        std::string filament_diameter_list = "; filament_diameter: ";
-        (filament_diameter_list += m_config.filament_diameter.serialize()) += '\n';
-        file.writeln(filament_diameter_list);
-
-        coordf_t max_height_z = -1;
-        for (const auto& object : print.objects())
-            max_height_z = std::max(object->layers().back()->print_z, max_height_z);
-
-        std::ostringstream max_height_z_tip;
-        max_height_z_tip<<"; max_z_height: " << std::fixed << std::setprecision(2) << max_height_z << '\n';
-        file.writeln(max_height_z_tip.str());
-    }
-
-    {
-        auto used_filaments = print.get_slice_used_filaments(false);
-        std::ostringstream out;
-        out << "; filament: ";
-        for (size_t idx = 0; idx < used_filaments.size(); ++idx) {
-            if (idx != 0)
-                out << ',';
-            out << used_filaments[idx] + 1;
-        }
-        file.writeln(out.str());
-    }
-
-    file.write_format("; HEADER_BLOCK_END\n\n");
-    }
-    
-      // BBS: write global config at the beginning of gcode file because printer
-      // need these config information
-      // Append full config, delimited by two 'phony' configuration keys
-      // CONFIG_BLOCK_START and CONFIG_BLOCK_END. The delimiters are structured
-      // as configuration key / value pairs to be parsable by older versions of
-      // PrusaSlicer G-code viewer.
-    {
-        if (is_bbl_printers && !skip_config_block) {
-            file.write("; CONFIG_BLOCK_START\n");
-            std::string full_config;
-            append_full_config(print, full_config);
-            if (!full_config.empty())
-                file.write(full_config);
-
-            // SoftFever: write compatiple image
-            int first_layer_bed_temperature = get_bed_temperature(0, true, print.config().curr_bed_type);
-            file.write_format("; first_layer_bed_temperature = %d\n",
-                                first_layer_bed_temperature);
-            file.write_format(
-                "; first_layer_temperature = %d\n",
-                print.config().nozzle_temperature_initial_layer.get_at(0));
-            file.write("; CONFIG_BLOCK_END\n\n");
-        } else if (thumbnail_cb != nullptr) {
-            // generate the thumbnails
-            auto [thumbnails, errors] = GCodeThumbnails::make_and_check_thumbnail_list(print.full_print_config());
-
-            if (errors != enum_bitmask<ThumbnailError>()) {
-                std::string error_str = format("Invalid thumbnails value:");
-                error_str += GCodeThumbnails::get_error_string(errors);
-                throw Slic3r::ExportError(error_str);
-            }
-
-            if (!thumbnails.empty())
-                GCodeThumbnails::export_thumbnails_to_file(
-                    thumbnail_cb, print.get_plate_index(), thumbnails, [&file](const char* sz) { file.write(sz); }, [&print]() { print.throw_if_canceled(); });
-        }
-    }
-
-
-    // Write some terse information on the slicing parameters.
-    const PrintObject *first_object         = print.objects().front();
-    const double       layer_height         = first_object->config().layer_height.value;
-    const double       initial_layer_print_height   = print.config().initial_layer_print_height.value;
-    for (size_t region_id = 0; region_id < print.num_print_regions(); ++ region_id) {
-        const PrintRegion &region = print.get_print_region(region_id);
-        file.write_format("; external perimeters extrusion width = %.2fmm\n", region.flow(*first_object, frExternalPerimeter, layer_height).width());
-        file.write_format("; perimeters extrusion width = %.2fmm\n",          region.flow(*first_object, frPerimeter,         layer_height).width());
-        file.write_format("; infill extrusion width = %.2fmm\n",              region.flow(*first_object, frInfill,            layer_height).width());
-        file.write_format("; solid infill extrusion width = %.2fmm\n",        region.flow(*first_object, frSolidInfill,       layer_height).width());
-        file.write_format("; top infill extrusion width = %.2fmm\n",          region.flow(*first_object, frTopSolidInfill,    layer_height).width());
-        if (print.has_support_material())
-            file.write_format("; support material extrusion width = %.2fmm\n", support_material_flow(first_object).width());
-        if (print.config().initial_layer_line_width.value > 0)
-            file.write_format("; first layer extrusion width = %.2fmm\n",   region.flow(*first_object, frPerimeter, initial_layer_print_height, true).width());
-        file.write_format("\n");
-    }
-
-    file.write_format("; EXECUTABLE_BLOCK_START\n");
-
-    // SoftFever
-    if( m_enable_exclude_object)
-        file.write(set_object_info(&print));
-
-    // adds tags for time estimators
-    file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::First_Line_M73_Placeholder).c_str());
-
     // Prepare the helper object for replacing placeholders in custom G-code and output filename.
     m_placeholder_parser_integration.parser = print.placeholder_parser();
     m_placeholder_parser_integration.parser.update_timestamp();
@@ -3360,16 +3234,6 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     // Orca: Initialise AdaptivePA processor filter
     m_pa_processor = std::make_unique<AdaptivePAProcessor>(*this, tool_ordering.all_extruders());
 
-    // Emit machine envelope limits for the Marlin firmware.
-    this->print_machine_envelope(file, print);
-
-    // Disable fan.
-    if (m_config.auxiliary_fan.value && print.config().close_fan_the_first_x_layers.get_at(initial_extruder_id)) {
-        file.write(m_writer.set_fan(0));
-        //BBS: disable additional fan
-        file.write(m_writer.set_additional_fan(0));
-    }
-
     // Update output variables after the extruders were initialized.
     m_placeholder_parser_integration.init(m_writer);
 
@@ -3721,6 +3585,157 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     // Sync variant-mapped params into placeholder_parser before processing start gcode
     update_placeholder_parser_with_variant_params();
 
+    // Expand the file header only after the start-up placeholders and writer state are ready.
+    // Use the regular custom G-code path so invalid placeholders report the template name.
+    if (!print.config().file_start_gcode.value.empty())
+        file.writeln(this->placeholder_parser_process("file_start_gcode", print.config().file_start_gcode.value, initial_extruder_id));
+
+    // Orca: Don't output Header block if BTT thumbnail is identified in the list
+    // Get the thumbnails value as a string
+    std::string thumbnails_value = print.config().option<ConfigOptionString>("thumbnails")->value;
+    // search string for the BTT_TFT label
+    bool has_BTT_thumbnail = (thumbnails_value.find("BTT_TFT") != std::string::npos);
+
+    if(!has_BTT_thumbnail){
+        file.write_format("; HEADER_BLOCK_START\n");
+        // Write information on the generator.
+        file.write_format("; generated by %s on %s\n", Slic3r::header_slic3r_generated().c_str(), Slic3r::Utils::local_timestamp().c_str());
+        if (is_bbl_printers)
+            file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Estimated_Printing_Time_Placeholder).c_str());
+        //BBS: total layer number
+        file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Total_Layer_Number_Placeholder).c_str());
+        //Orca: extra check for bbl printer
+        if (is_bbl_printers) {
+            if (print.calib_params().mode == CalibMode::Calib_None) { // Don't support skipping in cali mode
+                // list all label_object_id with sorted order here
+                m_enable_exclude_object = true;
+                m_label_objects_ids.clear();
+                m_label_objects_ids.reserve(print.num_object_instances());
+                for (const PrintObject *print_object : print.objects())
+                    for (const PrintInstance &print_instance : print_object->instances())
+                        m_label_objects_ids.push_back(print_instance.model_instance->get_labeled_id());
+
+                std::sort(m_label_objects_ids.begin(), m_label_objects_ids.end());
+
+                std::string objects_id_list = "; model label id: ";
+                for (auto it = m_label_objects_ids.begin(); it != m_label_objects_ids.end(); it++)
+                    objects_id_list += (std::to_string(*it) + (it != m_label_objects_ids.end() - 1 ? "," : "\n"));
+                file.writeln(objects_id_list);
+            } else {
+                m_enable_exclude_object = false;
+                m_label_objects_ids.clear();
+            }
+    }
+
+    {
+        std::string filament_density_list = "; filament_density: ";
+        (filament_density_list+=m_config.filament_density.serialize()) +='\n';
+        file.writeln(filament_density_list);
+
+        std::string filament_diameter_list = "; filament_diameter: ";
+        (filament_diameter_list += m_config.filament_diameter.serialize()) += '\n';
+        file.writeln(filament_diameter_list);
+
+        coordf_t max_height_z = -1;
+        for (const auto& object : print.objects())
+            max_height_z = std::max(object->layers().back()->print_z, max_height_z);
+
+        std::ostringstream max_height_z_tip;
+        max_height_z_tip<<"; max_z_height: " << std::fixed << std::setprecision(2) << max_height_z << '\n';
+        file.writeln(max_height_z_tip.str());
+    }
+
+    {
+        auto used_filaments = print.get_slice_used_filaments(false);
+        std::ostringstream out;
+        out << "; filament: ";
+        for (size_t idx = 0; idx < used_filaments.size(); ++idx) {
+            if (idx != 0)
+                out << ',';
+            out << used_filaments[idx] + 1;
+        }
+        file.writeln(out.str());
+    }
+
+    file.write_format("; HEADER_BLOCK_END\n\n");
+    }
+
+      // BBS: write global config at the beginning of gcode file because printer
+      // need these config information
+      // Append full config, delimited by two 'phony' configuration keys
+      // CONFIG_BLOCK_START and CONFIG_BLOCK_END. The delimiters are structured
+      // as configuration key / value pairs to be parsable by older versions of
+      // PrusaSlicer G-code viewer.
+    {
+        if (is_bbl_printers && !skip_config_block) {
+            file.write("; CONFIG_BLOCK_START\n");
+            std::string full_config;
+            append_full_config(print, full_config);
+            if (!full_config.empty())
+                file.write(full_config);
+
+            // SoftFever: write compatiple image
+            int first_layer_bed_temperature = get_bed_temperature(0, true, print.config().curr_bed_type);
+            file.write_format("; first_layer_bed_temperature = %d\n",
+                                first_layer_bed_temperature);
+            file.write_format(
+                "; first_layer_temperature = %d\n",
+                print.config().nozzle_temperature_initial_layer.get_at(0));
+            file.write("; CONFIG_BLOCK_END\n\n");
+        } else if (thumbnail_cb != nullptr) {
+            // generate the thumbnails
+            auto [thumbnails, errors] = GCodeThumbnails::make_and_check_thumbnail_list(print.full_print_config());
+
+            if (errors != enum_bitmask<ThumbnailError>()) {
+                std::string error_str = format("Invalid thumbnails value:");
+                error_str += GCodeThumbnails::get_error_string(errors);
+                throw Slic3r::ExportError(error_str);
+            }
+
+            if (!thumbnails.empty())
+                GCodeThumbnails::export_thumbnails_to_file(
+                    thumbnail_cb, print.get_plate_index(), thumbnails, [&file](const char* sz) { file.write(sz); }, [&print]() { print.throw_if_canceled(); });
+        }
+    }
+
+
+    // Write some terse information on the slicing parameters.
+    const PrintObject *first_object         = print.objects().front();
+    const double       layer_height         = first_object->config().layer_height.value;
+    const double       initial_layer_print_height   = print.config().initial_layer_print_height.value;
+    for (size_t region_id = 0; region_id < print.num_print_regions(); ++ region_id) {
+        const PrintRegion &region = print.get_print_region(region_id);
+        file.write_format("; external perimeters extrusion width = %.2fmm\n", region.flow(*first_object, frExternalPerimeter, layer_height).width());
+        file.write_format("; perimeters extrusion width = %.2fmm\n",          region.flow(*first_object, frPerimeter,         layer_height).width());
+        file.write_format("; infill extrusion width = %.2fmm\n",              region.flow(*first_object, frInfill,            layer_height).width());
+        file.write_format("; solid infill extrusion width = %.2fmm\n",        region.flow(*first_object, frSolidInfill,       layer_height).width());
+        file.write_format("; top infill extrusion width = %.2fmm\n",          region.flow(*first_object, frTopSolidInfill,    layer_height).width());
+        if (print.has_support_material())
+            file.write_format("; support material extrusion width = %.2fmm\n", support_material_flow(first_object).width());
+        if (print.config().initial_layer_line_width.value > 0)
+            file.write_format("; first layer extrusion width = %.2fmm\n",   region.flow(*first_object, frPerimeter, initial_layer_print_height, true).width());
+        file.write_format("\n");
+    }
+
+    file.write_format("; EXECUTABLE_BLOCK_START\n");
+
+    // SoftFever
+    if( m_enable_exclude_object)
+        file.write(set_object_info(&print));
+
+    // adds tags for time estimators
+    file.write_format(";%s\n", GCodeProcessor::reserved_tag(GCodeProcessor::ETags::First_Line_M73_Placeholder).c_str());
+
+    // Emit machine envelope limits for the Marlin firmware.
+    this->print_machine_envelope(file, print);
+
+    // Disable fan.
+    if (m_config.auxiliary_fan.value && print.config().close_fan_the_first_x_layers.get_at(initial_extruder_id)) {
+        file.write(m_writer.set_fan(0));
+        //BBS: disable additional fan
+        file.write(m_writer.set_additional_fan(0));
+    }
+
     std::string machine_start_gcode = this->placeholder_parser_process("machine_start_gcode", print.config().machine_start_gcode.value, initial_extruder_id);
     if (print.config().gcode_flavor != gcfKlipper) {
         // Set bed temperature if the start G-code does not contain any bed temp control G-codes.

src/libslic3r/GCode.hpp

@@ -107,7 +107,8 @@ public:
         m_is_first_print(true),
         m_print_config(&print_config),
         m_last_wipe_tower_print_z(print_config.z_offset.value),
-        m_sparse_layers_skipped(wipe_tower_sparse_layers_skipped(print_config))
+        m_sparse_layers_skipped(wipe_tower_sparse_layers_skipped(print_config)),
+        m_sparse_layers_combined(wipe_tower_sparse_layers_combined(print_config))
     {
         // Precomputed rather than accumulated while emitting, so that the clearance validator and
         // the emitter cannot disagree about where the compacted tower sits on any given layer.
@@ -138,6 +139,7 @@ public:
 private:
     WipeTowerIntegration& operator=(const WipeTowerIntegration&);
     std::string append_tcr(GCode &gcodegen, const WipeTower::ToolChangeResult &tcr, int new_extruder_id, double z = -1.) const;
+    std::string tower_height_tag(GCode &gcodegen, const WipeTower::ToolChangeResult &tcr, const std::string &tcr_gcode) const;
     Polyline generate_path_to_wipe_tower(const Point &start_pos, const Point &end_pos, const BoundingBox &avoid_polygon, const Polygons &bed_polygons) const;
     std::string append_tcr2(GCode &gcodegen, const WipeTower::ToolChangeResult &tcr, int new_extruder_id, double z = -1.) const;
     std::string travel_to_tower_gap(GCode &gcodegen, const Point &route_start, const Point &start_wipe_pos) const;
@@ -175,6 +177,9 @@ private:
     // wipe_tower_no_sparse_layers, as answered by the shared compaction rule rather than by the raw
     // option: smooth timelapse and wrapping detection keep a tower on every layer regardless.
     const bool                                                   m_sparse_layers_skipped;
+    // Combined tower layers are thicker than the object layer they sit on, the only case where the
+    // tower's height is not the one process_layer already declared.
+    const bool                                                   m_sparse_layers_combined;
     // Print z of the compacted tower per planned layer. Empty when the tower is not compacted.
     std::vector<float>                                           m_compacted_tower_z;
 };

src/libslic3r/GCode/WipeTower.cpp

@@ -49,6 +49,48 @@ std::vector<float> compute_compacted_wipe_tower_z(const std::vector<std::vector<
     return tower_z;
 }
 
+bool wipe_tower_sparse_layers_combined(const PrintConfig &config)
+{
+    return config.wipe_tower_sparse_layers_combination.value && ! wipe_tower_sparse_layers_skipped(config) &&
+           config.timelapse_type.value != TimelapseType::tlSmooth && ! config.enable_wrapping_detection.value;
+}
+
+bool wipe_tower_layer_is_combined_away(const std::vector<WipeTower::ToolChangeResult> &layer_tool_changes)
+{
+    return ! layer_tool_changes.empty() && layer_tool_changes.front().combined_away;
+}
+
+std::vector<char> combine_sparse_wipe_tower_layers(std::vector<float>       &layer_height,
+                                                   const std::vector<char>  &layer_is_sparse,
+                                                   const std::vector<float> &max_layer_height,
+                                                   size_t                    first_layer_idx)
+{
+    assert(layer_is_sparse.size() == layer_height.size() && max_layer_height.size() == layer_height.size());
+    std::vector<char> combined_away(layer_height.size(), 0);
+    float             pending_height = 0.f; // what the layers folded away so far add up to
+    for (size_t i = 0; i < layer_height.size(); ++i) {
+        // A toolchange has to purge at its own z, so it neither folds away nor takes over the run
+        // below it - and a run always flushes on its own last layer, so nothing is ever pending here.
+        if (! layer_is_sparse[i] || i <= first_layer_idx) {
+            pending_height = 0.f;
+            continue;
+        }
+        const float merged = pending_height + layer_height[i];
+        // Hand the run on only if the next layer can swallow the whole thing; a layer already past
+        // the cap is left alone rather than shrunk.
+        const bool next_takes_it = i + 1 < layer_height.size() && layer_is_sparse[i + 1] &&
+                                   merged + layer_height[i + 1] <= max_layer_height[i + 1] + float(EPSILON);
+        if (next_takes_it) {
+            combined_away[i] = 1;
+            pending_height   = merged;
+        } else {
+            layer_height[i] = merged;
+            pending_height  = 0.f;
+        }
+    }
+    return combined_away;
+}
+
 inline float align_round(float value, float base)
 {
     return std::round(value / base) * base;
@@ -1904,6 +1946,7 @@ WipeTower::WipeTower(const PrintConfig& config, int plate_idx, Vec3d plate_origi
     //m_bridging(float(config.wipe_tower_bridging)),
     m_bridging(10.f),
     m_sparse_layers_skipped(wipe_tower_sparse_layers_skipped(config)),
+    m_sparse_layers_combined(wipe_tower_sparse_layers_combined(config)),
     m_gcode_flavor(config.gcode_flavor),
     m_travel_speed(config.travel_speed.get_at(get_extruder_index(config, (unsigned int)initial_tool))),
     m_current_tool(initial_tool),
@@ -2028,6 +2071,16 @@ void WipeTower::set_extruder(size_t idx, const PrintConfig& config)
     float nozzle_diameter = float(config.nozzle_diameter.get_at(idx));
     m_filpar[idx].nozzle_diameter = nozzle_diameter; // to be used in future with (non-single) multiextruder MM
 
+    // Orca: max_layer_height is per nozzle, so read it through the filament->nozzle map rather than
+    // by filament id. Zero means three quarters of the nozzle diameter, as in Slicing.cpp.
+    {
+        const std::vector<int> &filament_map = config.filament_map.values; // 1 based nozzle indices
+        const size_t nozzle_idx = idx < filament_map.size() && filament_map[idx] > 0 ? size_t(filament_map[idx] - 1) : 0;
+        const float  max_layer_height = float(config.max_layer_height.get_at(nozzle_idx));
+        m_filpar[idx].max_layer_height = max_layer_height > 0.f ? max_layer_height
+                                                                : 0.75f * float(config.nozzle_diameter.get_at(nozzle_idx));
+    }
+
     float max_vol_speed = float(config.filament_max_volumetric_speed.get_at(idx));
     if (max_vol_speed!= 0.f)
         m_filpar[idx].max_e_speed = (max_vol_speed / filament_area());
@@ -3001,7 +3054,7 @@ WipeTower::ToolChangeResult WipeTower::finish_layer(bool extrude_perimeter, bool
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (! m_sparse_layers_skipped || toolchanges_on_layer)
+    if (layer_is_printed(toolchanges_on_layer))
         if (m_current_tool < m_used_filament_length.size())
             m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
 
@@ -3898,7 +3951,7 @@ WipeTower::ToolChangeResult WipeTower::finish_layer_new(bool extrude_perimeter,
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (!m_sparse_layers_skipped || toolchanges_on_layer)
+    if (layer_is_printed(toolchanges_on_layer))
         if (m_current_tool < m_used_filament_length.size())
             m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
 
@@ -4008,7 +4061,7 @@ WipeTower::ToolChangeResult WipeTower::finish_block(const WipeTowerBlock &block,
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (!m_sparse_layers_skipped || toolchanges_on_layer)
+    if (layer_is_printed(toolchanges_on_layer))
         if (filament_id < m_used_filament_length.size())
             m_used_filament_length[filament_id] += writer.get_and_reset_used_filament_length();
 
@@ -4125,7 +4178,7 @@ WipeTower::ToolChangeResult WipeTower::finish_block_solid(const WipeTowerBlock &
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (!m_sparse_layers_skipped || toolchanges_on_layer)
+    if (layer_is_printed(toolchanges_on_layer))
         if (filament_id < m_used_filament_length.size())
             m_used_filament_length[filament_id] += writer.get_and_reset_used_filament_length();
 
@@ -4668,6 +4721,15 @@ void WipeTower::calc_block_infill_gap()
      m_extra_spacing = 1.f;
 }
 
+// A folded layer is generated like any other but thrown away by the emitter, so its extrusions must
+// not be charged to the filament used.
+bool WipeTower::layer_is_printed(bool toolchanges_on_layer) const
+{
+    if (m_layer_info != m_plan.end() && m_layer_info->combined_away)
+        return false;
+    return ! m_sparse_layers_skipped || toolchanges_on_layer;
+}
+
 void WipeTower::plan_tower_new()
 {
     if (m_wipe_tower_brim_width < 0) m_wipe_tower_brim_width = get_auto_brim_by_height(m_wipe_tower_height);
@@ -4820,6 +4882,9 @@ void WipeTower::generate_new(std::vector<std::vector<WipeTower::ToolChangeResult
     if (m_plan.empty())
         return;
     //m_extra_spacing = 1.f;
+    // Before planning: the layer heights this rewrites feed the extrusion flow of every later pass.
+    if (m_sparse_layers_combined)
+        combine_sparse_wipe_tower_plan(m_plan, m_filpar, m_first_layer_idx, m_current_tool);
     m_wipe_tower_height = m_plan.back().z;//real wipe_tower_height
     plan_tower_new();
     m_layer_info = m_plan.begin();
@@ -5014,6 +5079,9 @@ void WipeTower::generate_new(std::vector<std::vector<WipeTower::ToolChangeResult
         if (only_generate_wall && !timelapse_wall.gcode.empty()) {
             layer_result.insert(layer_result.begin(), std::move(timelapse_wall));
         }
+        if (layer.combined_away)
+            for (WipeTower::ToolChangeResult &tcr : layer_result)
+                tcr.combined_away = true;
         result.emplace_back(std::move(layer_result));
     }
     assert(m_outer_wall.size() == m_plan.size());
@@ -5179,7 +5247,7 @@ WipeTower::ToolChangeResult WipeTower::only_generate_out_wall(bool is_new_mode)
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (!m_sparse_layers_skipped || toolchanges_on_layer)
+    if (layer_is_printed(toolchanges_on_layer))
         if (m_current_tool < m_used_filament_length.size()) m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
 
     return construct_tcr(writer, false, old_tool, true, false, 0.f, false);

src/libslic3r/GCode/WipeTower.hpp

@@ -152,6 +152,10 @@ public:
         bool               is_contact = false;
         NozzleChangeResult nozzle_change_result;
 
+        // Orca: folded into a later, thicker layer, so the emitter drops it. Set by the tower, so
+        // the two cannot disagree about which layers print.
+        bool               combined_away = false;
+
 		// Sum the total length of the extrusion.
 		float total_extrusion_length_in_plane() {
 			float e_length = 0.f;
@@ -391,6 +395,8 @@ public:
         float filament_tower_interface_pre_extrusion_dist = 0;
         float filament_tower_interface_pre_extrusion_length = 0;
         float filament_petg_pre_extrusion_offset_dist = 0;
+        // Tallest layer this filament's nozzle can lay down; caps the sparse layer combination.
+        float max_layer_height = 0.f;
     };
 
 
@@ -522,6 +528,7 @@ private:
     //float           m_extra_loading_move        = 0.f;
     float           m_bridging                  = 0.f;
     bool            m_sparse_layers_skipped     = false;
+    bool            m_sparse_layers_combined    = false;
     // BBS: remove useless config
     //bool            m_set_extruder_trimpot      = false;
     bool            m_adhesion                  = true;
@@ -595,6 +602,8 @@ private:
     }
 	// Calculates depth for all layers and propagates them downwards
 	void plan_tower();
+	// Whether the layer reaches the G-code, and so whether its extrusions count as filament used.
+	bool layer_is_printed(bool toolchanges_on_layer) const;
 
 	// Goes through m_plan and recalculates depths and width of the WT to make it exactly square - experimental
 	void make_wipe_tower_square();
@@ -634,6 +643,8 @@ private:
 		float depth;	// depth of the layer based on all layers above
 		float extra_spacing;
         bool  extruder_fill{true};
+		// Folded into a later, thicker layer, so this one prints nothing at all.
+		bool  combined_away{false};
 		float toolchanges_depth() const { float sum = 0.f; for (const auto &a : tool_changes) sum += a.required_depth; return sum; }
 
 		std::vector<ToolChange> tool_changes;
@@ -700,6 +711,62 @@ std::vector<float> compute_compacted_wipe_tower_z(const std::vector<std::vector<
                                                   float base_z = 0.f);
 
 
+// Combination rule for wipe_tower_sparse_layers_combination. Nothing is compacted - the tower keeps
+// following the object - but a run of consecutive toolchange-free layers prints as one thicker layer,
+// the way infill combination merges sparse infill. Shared so that neither tower generator nor the
+// G-code emitter can combine on its own.
+
+// Whether sparse layers are really combined. Skipping them outright is the stronger answer to the
+// same problem and wins over this; smooth timelapse and wrapping detection need a tower on every
+// layer, so they rule it out too.
+bool wipe_tower_sparse_layers_combined(const PrintConfig &config);
+
+// A planned layer folded into a later, thicker one prints nothing at all.
+bool wipe_tower_layer_is_combined_away(const std::vector<WipeTower::ToolChangeResult> &layer_tool_changes);
+
+// Folds runs of sparse layers into one. layer_height is raised in place on the layer that prints a
+// run - always its last, so the merged extrusion lands on top of what it covers - and the returned
+// mask marks the layers that now print nothing. A run stops growing once one more layer would pass
+// max_layer_height of the nozzle that prints it. first_layer_idx and below never combine: the
+// tower's first layer carries the brim.
+std::vector<char> combine_sparse_wipe_tower_layers(std::vector<float>       &layer_height,
+                                                   const std::vector<char>  &layer_is_sparse,
+                                                   const std::vector<float> &max_layer_height,
+                                                   size_t                    first_layer_idx);
+
+// Applies the rule above to a planned tower. Either generator's plan fits: both carry height,
+// tool_changes and combined_away per layer, and index their filament parameters by tool.
+template<class PlanLayers, class FilamentParams>
+void combine_sparse_wipe_tower_plan(PlanLayers &plan, const FilamentParams &filpar, size_t first_layer_idx, size_t initial_tool)
+{
+    const size_t       n = plan.size();
+    std::vector<float> heights(n);
+    std::vector<char>  sparse(n);
+    std::vector<float> caps(n);
+
+    // A layer with no toolchange prints with the filament the layer below left loaded.
+    size_t tool = initial_tool;
+    for (const auto &layer : plan)
+        if (! layer.tool_changes.empty()) {
+            tool = layer.tool_changes.front().old_tool;
+            break;
+        }
+    for (size_t i = 0; i < n; ++i) {
+        heights[i] = plan[i].height;
+        sparse[i]  = plan[i].tool_changes.empty() ? 1 : 0;
+        caps[i]    = tool < filpar.size() ? filpar[tool].max_layer_height : 0.f;
+        if (! plan[i].tool_changes.empty())
+            tool = plan[i].tool_changes.back().new_tool;
+    }
+
+    const std::vector<char> combined_away = combine_sparse_wipe_tower_layers(heights, sparse, caps, first_layer_idx);
+    for (size_t i = 0; i < n; ++i) {
+        plan[i].height        = heights[i];
+        plan[i].combined_away = combined_away[i] != 0;
+    }
+}
+
+
 } // namespace Slic3r
 
 #endif // WipeTowerPrusaMM_hpp_

src/libslic3r/GCode/WipeTower2.cpp

@@ -1033,6 +1033,7 @@ WipeTower2::WipeTower2(const PrintConfig& config, const PrintRegionConfig& defau
     m_z_pos(0.f),
     m_bridging(float(config.wipe_tower_bridging)),
     m_sparse_layers_skipped(wipe_tower_sparse_layers_skipped(config)),
+    m_sparse_layers_combined(wipe_tower_sparse_layers_combined(config)),
     m_gcode_flavor(config.gcode_flavor),
     m_travel_speed(config.travel_speed.get_at(get_extruder_index(config, (unsigned int)initial_tool))),
     m_infill_speed(default_region_config.sparse_infill_speed.get_at(get_extruder_index(config, (unsigned int)initial_tool))),
@@ -1150,6 +1151,16 @@ void WipeTower2::set_extruder(size_t idx, const PrintConfig& config)
     float nozzle_diameter = float(config.nozzle_diameter.get_at(idx));
     m_filpar[idx].nozzle_diameter = nozzle_diameter; // to be used in future with (non-single) multiextruder MM
 
+    // Orca: max_layer_height is per nozzle, so read it through the filament->nozzle map rather than
+    // by filament id. Zero means three quarters of the nozzle diameter, as in Slicing.cpp.
+    {
+        const std::vector<int> &filament_map = config.filament_map.values; // 1 based nozzle indices
+        const size_t nozzle_idx = idx < filament_map.size() && filament_map[idx] > 0 ? size_t(filament_map[idx] - 1) : 0;
+        const float  max_layer_height = float(config.max_layer_height.get_at(nozzle_idx));
+        m_filpar[idx].max_layer_height = max_layer_height > 0.f ? max_layer_height
+                                                                : 0.75f * float(config.nozzle_diameter.get_at(nozzle_idx));
+    }
+
     float max_vol_speed = float(config.filament_max_volumetric_speed.get_at(idx));
     if (max_vol_speed!= 0.f)
         m_filpar[idx].max_e_speed = (max_vol_speed / filament_area());
@@ -2103,7 +2114,9 @@ WipeTower::ToolChangeResult WipeTower2::finish_layer()
 
     // Ask our writer about how much material was consumed.
     // Skip this in case the layer is sparse and config option to not print sparse layers is enabled.
-    if (! m_sparse_layers_skipped || toolchanges_on_layer || first_layer) {
+    // A folded layer prints nothing, so it consumes nothing and adds no height of its own.
+    const bool combined_away = m_layer_info != m_plan.end() && m_layer_info->combined_away;
+    if ((! m_sparse_layers_skipped || toolchanges_on_layer || first_layer) && ! combined_away) {
         if (m_current_tool < m_used_filament_length.size())
             m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
         m_current_height += m_layer_info->height;
@@ -2435,6 +2448,10 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
 	if (m_plan.empty())
         return;
 
+    // Before planning: the layer heights this rewrites feed the extrusion flow of every later pass.
+    if (m_sparse_layers_combined)
+        combine_sparse_wipe_tower_plan(m_plan, m_filpar, m_first_layer_idx, m_current_tool);
+
 	plan_tower();
 #if 1
     for (int i=0;i<5;++i) {
@@ -2533,6 +2550,10 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
                 layer_result[idx] = merge_tcr(layer_result[idx], finish_layer_tcr);
         }
 
+        if (layer.combined_away)
+            for (WipeTower::ToolChangeResult &tcr : layer_result)
+                tcr.combined_away = true;
+
 		result.emplace_back(std::move(layer_result));
 
         if (m_used_filament_length_until_layer.empty() || m_used_filament_length_until_layer.back().first != layer.z)

src/libslic3r/GCode/WipeTower2.hpp

@@ -200,6 +200,8 @@ public:
         float               tower_interface_pre_extrusion_length = 0.f;
         float               tower_ironing_area = 4.f;
         float               tower_interface_purge_length = 0.f;
+        // Tallest layer this filament's nozzle can lay down; caps the sparse layer combination.
+        float               max_layer_height = 0.f;
     };
 
 private:
@@ -268,6 +270,7 @@ private:
     float           m_extra_loading_move        = 0.f;
     float           m_bridging                  = 0.f;
     bool            m_sparse_layers_skipped     = false;
+    bool            m_sparse_layers_combined    = false;
     bool            m_set_extruder_trimpot      = false;
     bool            m_adhesion                  = true;
     GCodeFlavor     m_gcode_flavor;
@@ -368,6 +371,8 @@ private:
 		float z;		// z position of the layer
 		float height;	// layer height
 		float depth;	// depth of the layer based on all layers above
+		// Folded into a later, thicker layer, so this one prints nothing at all.
+		bool  combined_away{false};
 		float toolchanges_depth() const { float sum = 0.f; for (const auto &a : tool_changes) sum += a.required_depth; return sum; }
 
 		std::vector<ToolChange> tool_changes;

src/libslic3r/PerimeterGenerator.cpp

@@ -2256,13 +2256,45 @@ void PerimeterGenerator::process_no_bridge(Surfaces& all_surfaces, coord_t perim
 
 // ORCA:
 // Inner Outer Inner wall ordering mode perimeter order optimisation functions
+
+// Whether two Arachne lines touch: somewhere the gap between their centrelines is no more than the
+// touching distance there. Each junction of one line is measured against the segments of the other,
+// both ways, and the search stops at the first spot that touches.
+// Arachne varies line width to fill the region (e.g. the odd centre line of a narrow wall is wider
+// than nominal), so the touching distance is half the combined width at the closest points, not the
+// nominal spacing. Widths are taken locally so a line widened in one place (a wedge tip, a wall
+// transition) does not count as touching where it passes close to other perimeters. min_threshold keeps
+// the nominal spacing threshold as the lower bound.
+static bool arachne_lines_touch(const Arachne::ExtrusionLine &a, const Arachne::ExtrusionLine &b, double min_threshold)
+{
+    auto one_way = [min_threshold](const Arachne::ExtrusionLine &from, const Arachne::ExtrusionLine &to) {
+        for (const Arachne::ExtrusionJunction &j : from.junctions) {
+            const Vec2d p = j.p.cast<double>();
+            for (size_t k = 0; k + 1 < to.junctions.size(); ++k) {
+                const Arachne::ExtrusionJunction &j0 = to.junctions[k];
+                const Arachne::ExtrusionJunction &j1 = to.junctions[k + 1];
+                const Vec2d  s0  = j0.p.cast<double>();
+                const Vec2d  seg = j1.p.cast<double>() - s0;
+                const double l2  = seg.squaredNorm();
+                const double t   = l2 > 0. ? std::clamp((p - s0).dot(seg) / l2, 0., 1.) : 0.;
+                const double w   = double(j0.w) + t * double(j1.w - j0.w); // width of `to` at the closest point
+                const double touch_distance = std::max(min_threshold, 0.5 * (double(j.w) + w));
+                if ((s0 + t * seg - p).norm() <= touch_distance)
+                    return true;
+            }
+        }
+        return false;
+    };
+    return one_way(a, b) || one_way(b, a);
+}
+
 /**
  * @brief Finds all perimeters touching a given set of reference lines, given as indexes.
  *
  * @param entities The list of PerimeterGeneratorArachneExtrusion entities.
  * @param referenceIndices A set of indices representing the reference points.
- * @param threshold_external The distance threshold to consider for proximity for a reference perimeter with inset index 0
+ * @param threshold_external The minimum touching distance for a reference perimeter with inset index 0 
- * @param threshold_internal The distance threshold to consider for proximity for a reference perimeter with inset index 1+
+ * @param threshold_internal The minimum touching distance for a reference perimeter with inset index 1+ 
  * @param considered_inset_idx What perimeter inset index are we searching for (eg. if we are searching for first internal perimeters proximate to the current reference perimeter, this value should be set to 1 etc).
  * @return std::vector<int> A vector of indices representing the touching perimeters.
  */
@@ -2271,7 +2303,6 @@ std::vector<int> findAllTouchingPerimeters(const std::vector<PerimeterGeneratorA
 
     for (const int refIdx : referenceIndices) {
         const auto& referenceEntity = entities[refIdx];
-        Points referencePoints = Arachne::to_points(*referenceEntity.extrusion);
         for (size_t i = 0; i < entities.size(); ++i) {
             // Skip already considered references and the reference entity
             if (referenceIndices.count(i) > 0) continue;
@@ -2282,15 +2313,9 @@ std::vector<int> findAllTouchingPerimeters(const std::vector<PerimeterGeneratorA
                 continue; // skip if they dont match
             }
             
-            Points points = Arachne::to_points(*entity.extrusion);
+            // Add to touchingIndices if the lines touch.
-            double distance = MultiPoint::minimumDistanceBetweenLinesDefinedByPoints(referencePoints, points);
+            const double threshold = double(referenceEntity.extrusion->inset_idx == 0 ? threshold_external : threshold_internal);
-            // Add to touchingIndices if within threshold distance
+            if (arachne_lines_touch(*referenceEntity.extrusion, *entity.extrusion, threshold)) {
-            size_t threshold=0;
-            if(referenceEntity.extrusion->inset_idx == 0)
-                threshold = threshold_external;
-            else
-                threshold = threshold_internal;
-            if (distance <= threshold) {
                 touchingIndices.insert(i);
             }
         }

src/libslic3r/PerimeterGenerator.hpp

@@ -2,6 +2,7 @@
 #define slic3r_PerimeterGenerator_hpp_
 
 #include "libslic3r.h"
+#include <optional>
 #include <vector>
 #include "Layer.hpp"
 #include "Flow.hpp"
@@ -105,6 +106,8 @@ public:
     bool                                            has_fuzzy_hole = false;
     // Preserve construction order so overlap precedence remains deterministic.
     std::vector<std::pair<FuzzySkinConfig, ExPolygons>> regions_by_fuzzify;
+    // Area resting on the layer below, where fuzzy skin is allowed. Unset means no restriction.
+    std::optional<ExPolygons>                       fuzzy_supported_area;
     
     PerimeterGenerator(
         // Input:

src/libslic3r/Preset.cpp

@@ -1199,6 +1199,7 @@ static std::vector<std::string> s_Preset_print_options{
     "enable_tower_interface_features",
     "enable_tower_interface_cooldown_during_tower",
     "wipe_tower_no_sparse_layers",
+    "wipe_tower_sparse_layers_combination",
     "compatible_printers",
     "compatible_printers_condition",
     "inherits",

src/libslic3r/Print.cpp

@@ -378,6 +378,7 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
             || opt_key == "wipe_tower_bridging"
             || opt_key == "wipe_tower_extra_flow"
             || opt_key == "wipe_tower_no_sparse_layers"
+            || opt_key == "wipe_tower_sparse_layers_combination"
             || opt_key == "flush_volumes_matrix"
             || opt_key == "prime_volume"
             || opt_key == "flush_into_infill"
@@ -2716,7 +2717,8 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceStarted, ctx);
@@ -3343,7 +3345,8 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceGeometryFinished, ctx);
@@ -4949,7 +4952,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
 {
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
         ctx.cancellation_check = [this]() { return canceled(); };
@@ -4979,7 +4983,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
         BOOST_LOG_TRIVIAL(error) << __FUNCTION__ <<  boost::format(": found errors when process gcode file %1%") %file.c_str();
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(m_model.id().id);
+            ctx.id = std::to_string(m_model.id().id);
+            ctx.name = get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = file + "\n" + ex.what();
             ctx.cancellation_check = [this]() { return canceled(); };
@@ -4993,7 +4998,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
         ctx.cancellation_check = [this]() { return canceled(); };

src/libslic3r/PrintConfig.cpp

@@ -6705,6 +6705,20 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionBool(false));
 
+    def = this->add("wipe_tower_sparse_layers_combination", coBool);
+    def->label = L("Combine sparse layers");
+    def->tooltip = L("If enabled, consecutive layers on which the prime tower has no filament change are printed as a single "
+                     "thicker tower layer instead of one thin layer each, the same way infill combination merges sparse infill. "
+                     "The merged layer is printed at the top of the run, at the height of everything it covers.\n\n"
+                     "Only whole layers are merged, and never past the maximum layer height of the nozzle printing the tower "
+                     "(three quarters of the nozzle diameter when that is left at 0). Two or more layers therefore have to fit "
+                     "under that limit before anything changes at all: at a 0.2 mm layer height under a 0.3 mm maximum nothing "
+                     "is merged, while at 0.1 mm three layers become one.\n\n"
+                     "Unlike \"No sparse layers\" the tower keeps following the model, so the toolhead never has to reach down to it. "
+                     "Has no effect with \"No sparse layers\", smooth timelapse or clumping detection, which need a tower on every layer.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("single_extruder_multi_material_priming", coBool);
     def->label = L("Prime all printing extruders");
     def->tooltip = L("If enabled, all printing extruders will be primed at the front edge of the print bed at the start of the print.");

src/libslic3r/PrintConfig.hpp

@@ -163,6 +163,7 @@ inline bool is_smoothable_infill_pattern(InfillPattern pattern, int multiline =
     case ipGrid:
     case ipTriangles:
     case ipStars:
+    case ipCubic:
         return multiline > 1;
     default:
         return false;
@@ -1631,6 +1632,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionString,              toolchange_cyclic_order))
     ((ConfigOptionBool,                toolchange_cyclic_first_layer))
     ((ConfigOptionBool,                wipe_tower_no_sparse_layers))
+    ((ConfigOptionBool,                wipe_tower_sparse_layers_combination))
     ((ConfigOptionString,              change_filament_gcode))
     ((ConfigOptionString,              change_extrusion_role_gcode))
     ((ConfigOptionString,              process_change_extrusion_role_gcode))

src/libvgcode/include/Types.hpp

@@ -158,6 +158,21 @@ enum class EGCodeExtrusionRole : uint8_t
 
 static constexpr std::size_t GCODE_EXTRUSION_ROLES_COUNT = static_cast<std::size_t>(EGCodeExtrusionRole::COUNT);
 
+//
+// What the reduced set, drawn while the user is dragging, holds in place of the full toolpaths
+//
+enum class EReducedDetailMode : uint8_t
+{
+    // nothing: no reduced set is built
+    Off,
+    // only the bottom and top layers of the visible range, for a caller that draws the print
+    // itself some other way
+    EndLayersOnly,
+    // every role but the infill under the skins and the gap fill: what can be seen from outside
+    ShellOnly,
+    COUNT
+};
+
 //
 // Option types
 //

src/libvgcode/include/Viewer.hpp

@@ -114,6 +114,19 @@ public:
     //
     bool is_dim_previous_layers() const;
     void set_dim_previous_layers(bool value);
+    //
+    // The reduced set drawn while the user drags: what the mode keeps, and always the bottom and
+    // top layers of the visible range. While a mode is set it is built alongside the full set, so
+    // set_reduced_detail() rebuilds nothing. Ignored on the OpenGL ES path.
+    //
+    EReducedDetailMode get_reduced_detail_mode() const;
+    void set_reduced_detail_mode(EReducedDetailMode mode);
+    // Whether the shell mode hides the infill roles; off for a profile that leaves them on the
+    // surface, with no top or bottom shell or no walls.
+    bool get_reduced_detail_hide_infill() const;
+    void set_reduced_detail_hide_infill(bool value);
+    void set_reduced_detail(bool value);
+    bool is_reduced_detail() const;
     float get_dim_previous_layers_brightness() const;
     void set_dim_previous_layers_brightness(float value);
     //

src/libvgcode/src/Settings.hpp

@@ -25,6 +25,11 @@ struct Settings
 		// ORCA: how bright those darkened layers are rendered, 1.0 = unchanged, 0.0 = black
 		float dim_previous_layers_brightness{ 0.4f };
 		bool spiral_vase_mode{ false };
+		// what the reduced set holds and whether it is drawn. Ignored on the OpenGL ES path.
+		EReducedDetailMode reduced_detail_mode{ EReducedDetailMode::Off };
+		// whether the shell mode may hide the infill roles: false when the profile leaves them on the surface
+		bool reduced_detail_hide_infill{ true };
+		bool reduced_detail{ false };
 		//
 		// Required update flags
 		//

src/libvgcode/src/Shaders.hpp

@@ -34,6 +34,10 @@ static const char* Segments_Vertex_Shader =
 // ORCA: 0 during the shadow caster pass - the bias below shifts eye_position but not
 // world_position, so the caster would write a depth the receiver never looks up.
 "uniform float bias_scale;\n"
+// draw the instances last to first, top layers before the ones they hide, so that early depth
+// rejection discards most of the hidden fragments; set when the camera looks down on the print
+"uniform int reverse_order;\n"
+"uniform int instance_count;\n"
 "in int vertex_id;\n"
 "out vec3 color;\n"
 "// ORCA: realistic view - the light the shadow map is able to block, kept apart from the\n"
@@ -59,7 +63,8 @@ static const char* Segments_Vertex_Shader =
 "  return top_diffuse + front_diffuse + top_specular;\n"
 "}\n"
 "void main() {\n"
-"  int id_a = int(texelFetch(segment_index_tex, gl_InstanceID).r);\n"
+"  int instance = (reverse_order != 0) ? instance_count - 1 - gl_InstanceID : gl_InstanceID;\n"
+"  int id_a = int(texelFetch(segment_index_tex, instance).r);\n"
 "  int id_b = id_a + 1;\n"
 "  vec3 pos_a = texelFetch(position_tex, id_a).xyz;\n"
 "  vec3 pos_b = texelFetch(position_tex, id_b).xyz;\n"

src/libvgcode/src/Viewer.cpp

@@ -92,6 +92,36 @@ bool Viewer::is_dim_previous_layers() const
     return m_impl->is_dim_previous_layers();
 }
 
+void Viewer::set_reduced_detail(bool value)
+{
+    m_impl->set_reduced_detail(value);
+}
+
+bool Viewer::is_reduced_detail() const
+{
+    return m_impl->is_reduced_detail();
+}
+
+EReducedDetailMode Viewer::get_reduced_detail_mode() const
+{
+    return m_impl->get_reduced_detail_mode();
+}
+
+void Viewer::set_reduced_detail_mode(EReducedDetailMode mode)
+{
+    m_impl->set_reduced_detail_mode(mode);
+}
+
+bool Viewer::get_reduced_detail_hide_infill() const
+{
+    return m_impl->get_reduced_detail_hide_infill();
+}
+
+void Viewer::set_reduced_detail_hide_infill(bool value)
+{
+    m_impl->set_reduced_detail_hide_infill(value);
+}
+
 void Viewer::set_dim_previous_layers(bool value)
 {
     m_impl->set_dim_previous_layers(value);

src/libvgcode/src/ViewerImpl.cpp

@@ -17,6 +17,7 @@
 #include <algorithm>
 #include <cmath>
 #include <numeric>
+#include <cfloat>
 
 namespace libvgcode {
 
@@ -763,6 +764,8 @@ void ViewerImpl::init(const std::string& opengl_context_version)
     m_uni_segments_height_width_angle_tex_id = glGetUniformLocation(m_segments_shader_id, "height_width_angle_tex");
     m_uni_segments_colors_tex_id             = glGetUniformLocation(m_segments_shader_id, "color_tex");
     m_uni_segments_segment_index_tex_id      = glGetUniformLocation(m_segments_shader_id, "segment_index_tex");
+    m_uni_segments_reverse_order_id          = glGetUniformLocation(m_segments_shader_id, "reverse_order");
+    m_uni_segments_instance_count_id         = glGetUniformLocation(m_segments_shader_id, "instance_count");
     // ORCA: realistic view
     m_uni_segments_shadow_map_id             = glGetUniformLocation(m_segments_shader_id, "shadow_map");
     m_uni_segments_shadow_light_vp_id        = glGetUniformLocation(m_segments_shader_id, "shadow_light_vp");
@@ -899,9 +902,17 @@ void ViewerImpl::reset()
 #else
     m_enabled_segments_count = 0;
     m_enabled_options_count = 0;
+    m_enabled_segments_reduced_count = 0;
+    m_enabled_options_reduced_count = 0;
+    m_enabled_segments_reduced_tex_size = 0;
+    m_enabled_options_reduced_tex_size = 0;
 
     m_settings_used_for_ranges = std::nullopt;
 
+    delete_textures(m_enabled_options_reduced_tex_id);
+    delete_buffers(m_enabled_options_reduced_buf_id);
+    delete_textures(m_enabled_segments_reduced_tex_id);
+    delete_buffers(m_enabled_segments_reduced_buf_id);
     delete_textures(m_enabled_options_tex_id);
     delete_buffers(m_enabled_options_buf_id);
     delete_textures(m_enabled_segments_tex_id);
@@ -1161,6 +1172,17 @@ void ViewerImpl::load(GCodeInputData&& gcode_data)
         glsafe(glGenTextures(1, &m_enabled_options_tex_id));
         glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_enabled_options_tex_id));
 
+        // create (but do not fill) the reduced counterparts of the two buffers above
+        glsafe(glGenBuffers(1, &m_enabled_segments_reduced_buf_id));
+        glsafe(glBindBuffer(GL_TEXTURE_BUFFER, m_enabled_segments_reduced_buf_id));
+        glsafe(glGenTextures(1, &m_enabled_segments_reduced_tex_id));
+        glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_enabled_segments_reduced_tex_id));
+
+        glsafe(glGenBuffers(1, &m_enabled_options_reduced_buf_id));
+        glsafe(glBindBuffer(GL_TEXTURE_BUFFER, m_enabled_options_reduced_buf_id));
+        glsafe(glGenTextures(1, &m_enabled_options_reduced_tex_id));
+        glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_enabled_options_reduced_tex_id));
+
         glsafe(glBindBuffer(GL_TEXTURE_BUFFER, 0));
         glsafe(glBindTexture(GL_TEXTURE_BUFFER, old_bound_texture));
 #endif // ENABLE_OPENGL_ES
@@ -1172,6 +1194,18 @@ void ViewerImpl::load(GCodeInputData&& gcode_data)
     update_colors();
 }
 
+#ifndef ENABLE_OPENGL_ES
+// the roles that lie under a skin or between walls, never seen from outside the print
+static bool is_hidden_in_shell(EGCodeExtrusionRole role)
+{
+    return role == EGCodeExtrusionRole::InternalInfill ||
+           role == EGCodeExtrusionRole::SolidInfill ||
+           role == EGCodeExtrusionRole::InternalBridgeInfill ||
+           role == EGCodeExtrusionRole::GapFill;
+}
+#endif // ENABLE_OPENGL_ES
+
+
 void ViewerImpl::update_enabled_entities()
 {
     if (m_vertices.empty())
@@ -1179,6 +1213,17 @@ void ViewerImpl::update_enabled_entities()
 
     std::vector<uint32_t> enabled_segments;
     std::vector<uint32_t> enabled_options;
+#ifndef ENABLE_OPENGL_ES
+    // the reduced set is filled by the same walk, so switching to it costs no rebuild. Whatever the
+    // mode leaves out, the bottom and top layers of the visible range are kept whole: they are the
+    // surfaces the range cuts open
+    const EReducedDetailMode reduced_mode = m_settings.reduced_detail_mode;
+    const bool build_reduced = reduced_mode != EReducedDetailMode::Off;
+    const bool hide_infill = m_settings.reduced_detail_hide_infill;
+    std::vector<uint32_t> enabled_segments_reduced;
+    std::vector<uint32_t> enabled_options_reduced;
+    const Interval& layers_range = m_layers.get_view_range();
+#endif // ENABLE_OPENGL_ES
     Interval range = m_view_range.get_visible();
 
     // when top layer only visualization is enabled, we need to render
@@ -1226,6 +1271,20 @@ void ViewerImpl::update_enabled_entities()
             enabled_options.push_back(static_cast<uint32_t>(i));
         else
             enabled_segments.push_back(static_cast<uint32_t>(i));
+
+#ifndef ENABLE_OPENGL_ES
+        if (build_reduced) {
+            const bool end_layer = v.layer_id == layers_range[0] || v.layer_id == layers_range[1];
+            if (end_layer)
+                (v.is_option() ? enabled_options_reduced : enabled_segments_reduced).push_back(static_cast<uint32_t>(i));
+            else if (reduced_mode == EReducedDetailMode::ShellOnly) {
+                if (v.is_option())
+                    enabled_options_reduced.push_back(static_cast<uint32_t>(i));
+                else if (!v.is_extrusion() || !hide_infill || !is_hidden_in_shell(v.role))
+                    enabled_segments_reduced.push_back(static_cast<uint32_t>(i));
+            }
+        }
+#endif // ENABLE_OPENGL_ES
     }
 
 #ifdef ENABLE_OPENGL_ES
@@ -1254,6 +1313,23 @@ void ViewerImpl::update_enabled_entities()
     else
         glsafe(glBufferData(GL_TEXTURE_BUFFER, 0, nullptr, GL_STATIC_DRAW));
 
+    m_enabled_segments_reduced_count = enabled_segments_reduced.size();
+    m_enabled_options_reduced_count = enabled_options_reduced.size();
+    m_enabled_segments_reduced_tex_size = enabled_segments_reduced.size() * sizeof(uint32_t);
+    m_enabled_options_reduced_tex_size = enabled_options_reduced.size() * sizeof(uint32_t);
+
+    // uploaded even when nothing was built, so that the last reduced set is released as soon as
+    // the preference is switched off
+    assert(m_enabled_segments_reduced_buf_id > 0);
+    glsafe(glBindBuffer(GL_TEXTURE_BUFFER, m_enabled_segments_reduced_buf_id));
+    glsafe(glBufferData(GL_TEXTURE_BUFFER, m_enabled_segments_reduced_tex_size,
+                        enabled_segments_reduced.empty() ? nullptr : enabled_segments_reduced.data(), GL_STATIC_DRAW));
+
+    assert(m_enabled_options_reduced_buf_id > 0);
+    glsafe(glBindBuffer(GL_TEXTURE_BUFFER, m_enabled_options_reduced_buf_id));
+    glsafe(glBufferData(GL_TEXTURE_BUFFER, m_enabled_options_reduced_tex_size,
+                        enabled_options_reduced.empty() ? nullptr : enabled_options_reduced.data(), GL_STATIC_DRAW));
+
     glsafe(glBindBuffer(GL_TEXTURE_BUFFER, 0));
 #endif // ENABLE_OPENGL_ES
 
@@ -1461,6 +1537,23 @@ void ViewerImpl::toggle_top_layer_only_view_range()
     update_colors_texture();
 }
 
+// Both decide which vertices land in the reduced set, so the sets are rebuilt.
+void ViewerImpl::set_reduced_detail_mode(EReducedDetailMode mode)
+{
+    if (m_settings.reduced_detail_mode == mode)
+        return;
+    m_settings.reduced_detail_mode = mode;
+    m_settings.update_enabled_entities = true;
+}
+
+void ViewerImpl::set_reduced_detail_hide_infill(bool value)
+{
+    if (m_settings.reduced_detail_hide_infill == value)
+        return;
+    m_settings.reduced_detail_hide_infill = value;
+    m_settings.update_enabled_entities = true;
+}
+
 // ORCA: enable/disable darkening of the layers the layer slider is not scrubbed to
 void ViewerImpl::set_dim_previous_layers(bool value)
 {
@@ -1854,6 +1947,8 @@ size_t ViewerImpl::get_used_gpu_memory() const
     ret += m_colors_tex_size;
     ret += m_enabled_segments_tex_size;
     ret += m_enabled_options_tex_size;
+    ret += m_enabled_segments_reduced_tex_size;
+    ret += m_enabled_options_reduced_tex_size;
 #endif // ENABLE_OPENGL_ES
     return ret;
 }
@@ -2070,7 +2165,8 @@ void ViewerImpl::render_segments(const Mat4x4& view_matrix, const Mat4x4& projec
 #ifdef ENABLE_OPENGL_ES
     if (m_texture_data.get_enabled_segments_count() == 0)
 #else
-    if (m_enabled_segments_count == 0)
+    const ActiveSet segments = active_segments();
+    if (segments.count == 0)
 #endif // ENABLE_OPENGL_ES
         return;
 
@@ -2090,6 +2186,15 @@ void ViewerImpl::render_segments(const Mat4x4& view_matrix, const Mat4x4& projec
     glsafe(glUniformMatrix4fv(m_uni_segments_view_matrix_id, 1, GL_FALSE, view_matrix.data()));
     glsafe(glUniformMatrix4fv(m_uni_segments_projection_matrix_id, 1, GL_FALSE, projection_matrix.data()));
     glsafe(glUniform3fv(m_uni_segments_camera_position_id, 1, camera_position.data()));
+    // The segments come in print order, bottom layer first. Seen from above, that is back to front,
+    // and every hidden fragment is shaded before the one that covers it. Drawing them last to first
+    // lets the depth test reject the hidden ones instead. The camera looks down when the world's
+    // up axis points towards it, which is the view matrix's (2, 2) entry being positive.
+    const bool top_down = !m_rendering_shadow_casters && view_matrix[10] > 0.0f;
+    glsafe(glUniform1i(m_uni_segments_reverse_order_id, top_down ? 1 : 0));
+#ifndef ENABLE_OPENGL_ES
+    glsafe(glUniform1i(m_uni_segments_instance_count_id, static_cast<int>(segments.count)));
+#endif // ENABLE_OPENGL_ES
     // ORCA: realistic view. The depth pass writes the map it would otherwise read, so it shades
     // with the lookup off.
     glsafe(glUniform1i(m_uni_segments_shadow_map_id, m_shadow_map_texture_unit));
@@ -2138,10 +2243,10 @@ void ViewerImpl::render_segments(const Mat4x4& view_matrix, const Mat4x4& projec
     glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_colors_tex_id));
     glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32F, m_colors_buf_id));
     glsafe(glActiveTexture(GL_TEXTURE3));
-    glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_enabled_segments_tex_id));
+    glsafe(glBindTexture(GL_TEXTURE_BUFFER, segments.tex_id));
-    glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32UI, m_enabled_segments_buf_id));
+    glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32UI, segments.buf_id));
 
-    m_segment_template.render(m_enabled_segments_count);
+    m_segment_template.render(segments.count);
 #endif // ENABLE_OPENGL_ES
 
     if (curr_cull_face)
@@ -2167,7 +2272,8 @@ void ViewerImpl::render_options(const Mat4x4& view_matrix, const Mat4x4& project
 #ifdef ENABLE_OPENGL_ES
     if (m_texture_data.get_enabled_options_count() == 0)
 #else
-    if (m_enabled_options_count == 0)
+    const ActiveSet options = active_options();
+    if (options.count == 0)
 #endif // ENABLE_OPENGL_ES
         return;
 
@@ -2225,10 +2331,10 @@ void ViewerImpl::render_options(const Mat4x4& view_matrix, const Mat4x4& project
     glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_colors_tex_id));
     glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32F, m_colors_buf_id));
     glsafe(glActiveTexture(GL_TEXTURE3));
-    glsafe(glBindTexture(GL_TEXTURE_BUFFER, m_enabled_options_tex_id));
+    glsafe(glBindTexture(GL_TEXTURE_BUFFER, options.tex_id));
-    glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32UI, m_enabled_options_buf_id));
+    glsafe(glTexBuffer(GL_TEXTURE_BUFFER, GL_R32UI, options.buf_id));
 
-    m_option_template.render(m_enabled_options_count);
+    m_option_template.render(options.count);
 #endif // ENABLE_OPENGL_ES
 
     if (!curr_cull_face)

src/libvgcode/src/ViewerImpl.hpp

@@ -109,6 +109,21 @@ public:
     // 0.0 = black
     bool is_dim_previous_layers() const { return m_settings.dim_previous_layers; }
     void set_dim_previous_layers(bool value);
+    //
+    // Draw from the reduced set; it is already built, so this is just a buffer binding.
+    //
+    void set_reduced_detail(bool value) {
+#ifdef ENABLE_OPENGL_ES
+        // no reduced set is built on OpenGL ES
+        value = false;
+#endif // ENABLE_OPENGL_ES
+        m_settings.reduced_detail = value;
+    }
+    bool is_reduced_detail() const { return m_settings.reduced_detail; }
+    EReducedDetailMode get_reduced_detail_mode() const { return m_settings.reduced_detail_mode; }
+    void set_reduced_detail_mode(EReducedDetailMode mode);
+    bool get_reduced_detail_hide_infill() const { return m_settings.reduced_detail_hide_infill; }
+    void set_reduced_detail_hide_infill(bool value);
     float get_dim_previous_layers_brightness() const { return m_settings.dim_previous_layers_brightness; }
     void set_dim_previous_layers_brightness(float value);
 
@@ -362,6 +377,8 @@ private:
     int m_uni_segments_height_width_angle_tex_id{ -1 };
     int m_uni_segments_colors_tex_id{ -1 };
     int m_uni_segments_segment_index_tex_id{ -1 };
+    int m_uni_segments_reverse_order_id{ -1 };
+    int m_uni_segments_instance_count_id{ -1 };
     int m_uni_segments_shadow_map_id{ -1 };
     int m_uni_segments_shadow_light_vp_id{ -1 };
     int m_uni_segments_shadow_intensity_id{ -1 };
@@ -499,6 +516,15 @@ private:
     unsigned int m_enabled_options_tex_id{ 0 };
     size_t m_enabled_options_count{ 0 };
     //
+    // OpenGL buffers to store the reduced set drawn while Settings::reduced_detail is set
+    //
+    unsigned int m_enabled_segments_reduced_buf_id{ 0 };
+    unsigned int m_enabled_segments_reduced_tex_id{ 0 };
+    size_t m_enabled_segments_reduced_count{ 0 };
+    unsigned int m_enabled_options_reduced_buf_id{ 0 };
+    unsigned int m_enabled_options_reduced_tex_id{ 0 };
+    size_t m_enabled_options_reduced_count{ 0 };
+    //
     // Caches for size of data sent to gpu, in bytes
     //
     size_t m_positions_tex_size{ 0 };
@@ -506,6 +532,27 @@ private:
     size_t m_colors_tex_size{ 0 };
     size_t m_enabled_segments_tex_size{ 0 };
     size_t m_enabled_options_tex_size{ 0 };
+    size_t m_enabled_segments_reduced_tex_size{ 0 };
+    size_t m_enabled_options_reduced_tex_size{ 0 };
+
+    // The set the next draw reads from: the reduced one while dragging, if one is built.
+    bool use_reduced_set() const { return m_settings.reduced_detail && m_settings.reduced_detail_mode != EReducedDetailMode::Off; }
+    struct ActiveSet
+    {
+        size_t count{ 0 };
+        unsigned int buf_id{ 0 };
+        unsigned int tex_id{ 0 };
+    };
+    ActiveSet active_segments() const {
+        if (use_reduced_set())
+            return { m_enabled_segments_reduced_count, m_enabled_segments_reduced_buf_id, m_enabled_segments_reduced_tex_id };
+        return { m_enabled_segments_count, m_enabled_segments_buf_id, m_enabled_segments_tex_id };
+    }
+    ActiveSet active_options() const {
+        if (use_reduced_set())
+            return { m_enabled_options_reduced_count, m_enabled_options_reduced_buf_id, m_enabled_options_reduced_tex_id };
+        return { m_enabled_options_count, m_enabled_options_buf_id, m_enabled_options_tex_id };
+    }
 #endif // ENABLE_OPENGL_ES
 
     //

src/slic3r/GUI/AmsMappingPopup.cpp

@@ -819,7 +819,7 @@ AmsMapingPopup::AmsMapingPopup(wxWindow *parent, bool use_in_sync_dialog) :
 
      m_scrolled_window = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL | wxHSCROLL);
      m_scrolled_window->SetBackgroundColour(*wxWHITE);
-     m_scrolled_window->SetScrollRate(0, FromDIP(10));
+     m_scrolled_window->SetScrollRate(0, FromDIP(20));
 
      wxBoxSizer *title_sizer_h= new wxBoxSizer(wxHORIZONTAL);
      wxBoxSizer *title_sizer_v = new wxBoxSizer(wxVERTICAL);
@@ -1000,13 +1000,13 @@ AmsMapingPopup::AmsMapingPopup(wxWindow *parent, bool use_in_sync_dialog) :
                   show_pos.x = screen_size.GetLeft();
                   m_scrolled_window->SetMaxSize(wxSize(screen_size.GetWidth(), popup_height));
                   m_scrolled_window->SetMinSize(wxSize(screen_size.GetWidth(), popup_height));
-                  m_scrolled_window->SetScrollRate(FromDIP(10), FromDIP(10));
+                  m_scrolled_window->SetScrollRate(FromDIP(10), FromDIP(20));
               }
               else
               {
                   m_scrolled_window->SetMaxSize(wxSize(popup_width, popup_height));
                   m_scrolled_window->SetMinSize(wxSize(popup_width, popup_height));
-                  m_scrolled_window->SetScrollRate(0, FromDIP(10));
+                  m_scrolled_window->SetScrollRate(0, FromDIP(20));
               }
 
               //Vertical Direction Processing
@@ -2117,7 +2117,7 @@ void AmsReplaceMaterialDialog::create()
     identical_filament->SetForegroundColour(StateColor::darkModeColorFor(wxColour("#009688"))); // Orca: accent teal (not brand green)
 
     m_scrollview_groups = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxHSCROLL | wxVSCROLL);
-    m_scrollview_groups->SetScrollRate(5, 5);
+    m_scrollview_groups->SetScrollRate(5, FromDIP(20));
     //m_scrollview_groups->SetMinSize(wxSize(400, 400));
     //m_scrollview_groups->SetMaxSize(wxSize(400, 400));
     m_scrollview_sizer = new wxBoxSizer(wxVERTICAL);

src/slic3r/GUI/Auxiliary.cpp

@@ -606,7 +606,7 @@ AuFolderPanel::AuFolderPanel(wxWindow *parent, AuxiliaryFolderType type, wxWindo
     wxBoxSizer *sizer_main = new wxBoxSizer(wxVERTICAL);
 
     m_scrolledWindow = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxHSCROLL | wxVSCROLL);
-    m_scrolledWindow->SetScrollRate(5, 5);
+    m_scrolledWindow->SetScrollRate(5, FromDIP(20));
     wxBoxSizer *sizer_body = new wxBoxSizer(wxVERTICAL);
     wxBoxSizer *sizer_top  = new wxBoxSizer(wxHORIZONTAL);
 

src/slic3r/GUI/BindDialog.cpp

@@ -558,7 +558,7 @@ PingCodeBindDialog::~PingCodeBindDialog() {
      //show bind failed info
      m_sw_bind_failed_info = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(450), FromDIP(300)), wxVSCROLL);
      m_sw_bind_failed_info->SetBackgroundColour(*wxWHITE);
-     m_sw_bind_failed_info->SetScrollRate(5, 5);
+     m_sw_bind_failed_info->SetScrollRate(5, FromDIP(20));
      m_sw_bind_failed_info->SetMinSize(wxSize(FromDIP(450), FromDIP(90)));
      m_sw_bind_failed_info->SetMaxSize(wxSize(FromDIP(450), FromDIP(90)));
 

src/slic3r/GUI/CAD/DesignPanel.cpp

@@ -3521,7 +3521,7 @@ DesignPanel::DesignPanel(wxWindow* parent)
     cards->Show(m_box_mate,        false, true);
 
     m_form->FitInside();
-    m_form->SetScrollRate(0, 10);   // vertical only, like Prepare's sidebar: never scroll labels out
+    m_form->SetScrollRate(0, FromDIP(20));   // vertical only, like Prepare's sidebar: never scroll labels out
     m_form->SetMinSize(wxSize(264, -1));
 
     // Right column: a small view toolbar over the live 3D viewport that mirrors

src/slic3r/GUI/CaliHistoryDialog.cpp

@@ -115,7 +115,7 @@ HistoryWindow::HistoryWindow(wxWindow* parent, const std::vector<PACalibResult>&
     auto main_sizer = new wxBoxSizer(wxVERTICAL);
 
     auto scroll_window = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxHSCROLL | wxVSCROLL);
-    scroll_window->SetScrollRate(5, 5);
+    scroll_window->SetScrollRate(5, FromDIP(20));
     scroll_window->SetBackgroundColour(*wxWHITE);
     scroll_window->SetMinSize(HISTORY_WINDOW_SIZE);
     scroll_window->SetSize(HISTORY_WINDOW_SIZE);

src/slic3r/GUI/CalibrationPanel.cpp

@@ -207,7 +207,7 @@ SelectMObjectPopup::SelectMObjectPopup(wxWindow* parent)
     m_scrolledWindow = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, SELECT_MACHINE_LIST_SIZE, wxHSCROLL | wxVSCROLL);
     m_scrolledWindow->SetBackgroundColour(*wxWHITE);
     m_scrolledWindow->SetMinSize(SELECT_MACHINE_LIST_SIZE);
-    m_scrolledWindow->SetScrollRate(0, 5);
+    m_scrolledWindow->SetScrollRate(0, SELECT_MACHINE_ITEM_SIZE.y);
     auto m_sizxer_scrolledWindow = new wxBoxSizer(wxVERTICAL);
     m_scrolledWindow->SetSizer(m_sizxer_scrolledWindow);
     m_scrolledWindow->Layout();

src/slic3r/GUI/CalibrationWizard.cpp

@@ -81,7 +81,7 @@ CalibrationWizard::CalibrationWizard(wxWindow* parent, CalibMode mode, wxWindowI
     wxBoxSizer* main_sizer = new wxBoxSizer(wxVERTICAL);
 
     m_scrolledWindow = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxHSCROLL | wxVSCROLL);
-    m_scrolledWindow->SetScrollRate(5, 5);
+    m_scrolledWindow->SetScrollRate(5, FromDIP(20));
     m_scrolledWindow->SetBackgroundColour(*wxWHITE);
 
     wxBoxSizer* padding_sizer = new wxBoxSizer(wxHORIZONTAL);

src/slic3r/GUI/CalibrationWizardPage.cpp

@@ -834,7 +834,7 @@ void CaliPageSendingPanel::create(wxWindow* parent)
 
     m_sw_print_failed_info = new wxScrolledWindow(parent, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(380), FromDIP(125)), wxVSCROLL);
     m_sw_print_failed_info->SetBackgroundColour(*wxWHITE);
-    m_sw_print_failed_info->SetScrollRate(0, 5);
+    m_sw_print_failed_info->SetScrollRate(0, FromDIP(20));
     m_sw_print_failed_info->SetMinSize(wxSize(FromDIP(380), FromDIP(125)));
     m_sw_print_failed_info->SetMaxSize(wxSize(FromDIP(380), FromDIP(125)));
 

src/slic3r/GUI/ConfigManipulation.cpp

@@ -1046,6 +1046,8 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, in
 
     // Orca: both tower generators skip sparse layers, so this is not a wipe tower 2 exclusive.
     toggle_line("wipe_tower_no_sparse_layers", have_prime_tower);
+    // Dropping the sparse layers outright leaves nothing to combine, so the two are exclusive.
+    toggle_line("wipe_tower_sparse_layers_combination", have_prime_tower && !config->opt_bool("wipe_tower_no_sparse_layers"));
 
     WipeTowerWallType wipe_tower_wall_type = config->opt_enum<WipeTowerWallType>("wipe_tower_wall_type");
     bool have_rib_wall = (wipe_tower_wall_type == WipeTowerWallType::wtwRib)&&have_prime_tower;

src/slic3r/GUI/ConfigWizard.cpp

@@ -2710,7 +2710,7 @@ ConfigWizard::ConfigWizard(wxWindow *parent)
     SetSizerAndFit(vsizer);
 
     // We can now enable scrolling on hscroll
-    p->hscroll->SetScrollRate(30, 30);
+    p->hscroll->SetScrollRate(30, FromDIP(20));
 
     on_window_geometry(this, [this]() {
         p->init_dialog_size();

src/slic3r/GUI/CreatePresetsDialog.cpp

@@ -699,7 +699,7 @@ CreateFilamentPresetDialog::CreateFilamentPresetDialog(wxWindow *parent)
     m_scrolled_preset_panel = new wxScrolledWindow(this, wxID_ANY);
     m_scrolled_preset_panel->SetMaxSize(wxSize(-1, FromDIP(350)));
     m_scrolled_preset_panel->SetBackgroundColour(*wxWHITE);
-    m_scrolled_preset_panel->SetScrollRate(5, 5);
+    m_scrolled_preset_panel->SetScrollRate(5, FromDIP(20));
     m_scrolled_sizer = new wxBoxSizer(wxVERTICAL);
     m_scrolled_sizer->Add(create_item(FilamentOptionType::PRESET_FOR_PRINTER), 0, wxEXPAND | wxLEFT | wxRIGHT | wxBOTTOM, FromDIP(5));
     m_scrolled_sizer->Add(0, 0, 0, wxTOP, FromDIP(5));
@@ -1593,7 +1593,7 @@ CreatePrinterPresetDialog::CreatePrinterPresetDialog(wxWindow *parent)
 
     m_page1 = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize);
     m_page1->SetBackgroundColour(*wxWHITE);
-    m_page1->SetScrollRate(5, 5);
+    m_page1->SetScrollRate(5, FromDIP(20));
     m_page2 = new wxPanel(this, wxID_ANY, wxDefaultPosition, wxDefaultSize);    m_page2->SetBackgroundColour(*wxWHITE);
 
     create_printer_page1(m_page1);
@@ -2652,7 +2652,7 @@ wxBoxSizer *CreatePrinterPresetDialog::create_presets_template_item(wxWindow *pa
     wxBoxSizer *vertical_sizer = new wxBoxSizer(wxVERTICAL);
 
     m_scrolled_preset_window = new wxScrolledWindow(parent);
-    m_scrolled_preset_window->SetScrollRate(5, 5);
+    m_scrolled_preset_window->SetScrollRate(5, FromDIP(20));
     m_scrolled_preset_window->SetBackgroundColour(*wxWHITE);
     //m_scrolled_preset_window->SetMinSize(wxSize(FromDIP(1500), FromDIP(-1)));
     m_scrolled_preset_window->SetMaxSize(wxSize(FromDIP(1500), FromDIP(-1)));
@@ -4297,7 +4297,7 @@ wxBoxSizer *ExportConfigsDialog::create_select_printer(wxWindow *parent)
     optionSizer->SetMinSize(OPTION_SIZE);
     horizontal_sizer->Add(optionSizer, 0, wxEXPAND | wxALL, FromDIP(10));
     m_scrolled_preset_window = new wxScrolledWindow(parent);
-    m_scrolled_preset_window->SetScrollRate(5, 5);
+    m_scrolled_preset_window->SetScrollRate(5, FromDIP(20));
     m_scrolled_preset_window->SetBackgroundColour(*wxWHITE);
     m_scrolled_preset_window->SetMaxSize(wxSize(FromDIP(660), FromDIP(400)));
     m_scrolled_preset_window->SetSize(wxSize(FromDIP(660), FromDIP(400)));
@@ -4736,7 +4736,7 @@ wxBoxSizer *EditFilamentPresetDialog::create_preset_tree_sizer()
 {
     wxBoxSizer *filament_preset_tree_sizer = new wxBoxSizer(wxHORIZONTAL);
     m_preset_tree_window = new wxScrolledWindow(this);
-    m_preset_tree_window->SetScrollRate(5, 5);
+    m_preset_tree_window->SetScrollRate(5, FromDIP(20));
     m_preset_tree_window->SetBackgroundColour(PRINTER_LIST_COLOUR);
     m_preset_tree_window->SetMinSize(wxSize(-1, FromDIP(400)));
     m_preset_tree_window->SetMaxSize(wxSize(-1, FromDIP(300)));

src/slic3r/GUI/DeviceErrorDialog.cpp

@@ -39,7 +39,7 @@ DeviceErrorDialog::DeviceErrorDialog(MachineObject* obj, wxWindow* parent, wxWin
     m_line_top->SetBackgroundColour(wxColour(166, 169, 170));
 
     m_scroll_area = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_scroll_area->SetScrollRate(0, 5);
+    m_scroll_area->SetScrollRate(0, FromDIP(20));
     m_scroll_area->SetBackgroundColour(*wxWHITE);
     m_scroll_area->SetMinSize(wxSize(FromDIP(320), FromDIP(250)));
 

src/slic3r/GUI/GCodeViewer.cpp

@@ -1267,6 +1267,8 @@ void GCodeViewer::load_as_gcode(const GCodeProcessorResult& gcode_result, const
     if (current_top_layer_only != required_top_layer_only)
         m_viewer.toggle_top_layer_only_view_range();
 
+    read_reduced_detail_preferences();
+
     // ORCA: darken the layers the preview layer slider is not scrubbed to
     m_viewer.set_dim_previous_layers(get_app_config()->get_bool("preview_dim_previous_layers"));
     m_viewer.set_dim_previous_layers_brightness(0.01f * std::stoi(get_app_config()->get("preview_dim_previous_layers_brightness")));
@@ -1490,6 +1492,10 @@ void GCodeViewer::load_as_gcode(const GCodeProcessorResult& gcode_result, const
 
     // BBS: data for rendering color arrangement recommendation
     m_nozzle_nums = print.config().option<ConfigOptionFloats>("nozzle_diameter")->values.size();
+    // the shell drag mode hides the infill only where the profile covers it: with no top or bottom
+    // shell, or no walls, the infill is the surface. Per-object settings are not consulted.
+    const PrintRegionConfig& region = print.default_region_config();
+    m_viewer.set_reduced_detail_hide_infill(region.top_shell_layers.value > 0 && region.bottom_shell_layers.value > 0 && region.wall_loops.value > 0);
     // Orca hack: Hide filament group for non-bbl printers
     if (!print.is_BBL_printer()) m_nozzle_nums = 1;
     std::vector<int>         filament_maps = print.get_filament_maps();
@@ -1660,6 +1666,7 @@ void GCodeViewer::reset_shell()
 {
     m_shells.volumes.clear();
     m_shells.print_id = -1;
+    m_shells.with_wipe_tower = false;
     m_shell_bounding_box = BoundingBoxf3();
 }
 
@@ -1696,6 +1703,11 @@ void GCodeViewer::reset()
 void GCodeViewer::render_scene(int canvas_width, int canvas_height)
 {
     glsafe(::glEnable(GL_DEPTH_TEST));
+    // while dragging in the solid model mode, the objects stand in for their toolpaths, cut to the
+    // visible layer range; the toolpath set then holds only the range's bottom and top layers
+    if (m_viewer.is_reduced_detail() && solid_model_enabled())
+        render_solid_model(canvas_width, canvas_height);
+    else
         render_shells(canvas_width, canvas_height);
 
     if (m_viewer.get_extrusion_roles_count() == 0)
@@ -2019,6 +2031,56 @@ void GCodeViewer::update_layers_slider_mode()
     // TODO m_layers_slider->SetModeAndOnlyExtruder(one_extruder_printed_model, only_extruder);
 }
 
+void GCodeViewer::set_interacting(bool interacting)
+{
+    // with no shells to stand in for the toolpaths, the solid model would leave only the end layers
+    const bool usable = !solid_model_enabled() || !m_shells.volumes.empty();
+    m_viewer.set_reduced_detail(interacting && usable);
+}
+
+void GCodeViewer::read_reduced_detail_preferences()
+{
+    m_reduced_detail_mode = reduced_detail_mode_from_string(get_app_config()->get("preview_reduced_detail_mode"));
+    apply_reduced_detail_settings();
+}
+
+void GCodeViewer::apply_reduced_detail_settings()
+{
+    m_viewer.set_reduced_detail_mode(m_reduced_detail_mode);
+}
+
+void GCodeViewer::set_reduced_detail_mode(const std::string& mode)
+{
+    const bool was_solid = solid_model_enabled();
+    m_reduced_detail_mode = reduced_detail_mode_from_string(mode);
+    apply_reduced_detail_settings();
+    reload_shells_if_solid_model_changed(was_solid);
+}
+
+libvgcode::EReducedDetailMode GCodeViewer::reduced_detail_mode_from_string(const std::string& mode)
+{
+    if (mode == "solid")
+        return libvgcode::EReducedDetailMode::EndLayersOnly;
+    if (mode == "shell")
+        return libvgcode::EReducedDetailMode::ShellOnly;
+    return libvgcode::EReducedDetailMode::Off;
+}
+
+void GCodeViewer::reload_shells_if_solid_model_changed(bool was_enabled)
+{
+    if (was_enabled == solid_model_enabled() || m_shells.print_id == -1)
+        return;
+    // only the prime tower comes and goes with the mode: a full reload would drop the shells
+    // whenever the print has moved on since they were loaded, leaving the solid model nothing to draw
+    if (wxGetApp().plater() == nullptr)
+        return;
+    // the shells are loaded from the current plate's print, which is not the plater's own
+    const Print& print = wxGetApp().plater()->get_partplate_list().get_current_fff_print();
+    if (static_cast<int>(print.id().id) != m_shells.print_id)
+        return;
+    update_shell_wipe_tower(print, m_gl_data_initialized);
+}
+
 void GCodeViewer::set_layers_z_range(const std::array<unsigned int, 2>& layers_z_range)
 {
     m_viewer.set_layers_view_range(static_cast<uint32_t>(layers_z_range[0]), static_cast<uint32_t>(layers_z_range[1]));
@@ -2343,7 +2405,11 @@ void GCodeViewer::export_toolpaths_to_obj(const char* filename) const
 void GCodeViewer::load_shells(const Print& print, bool initialized, bool force_previewing)
 {
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": initialized=%1%, force_previewing=%2%")%initialized %force_previewing;
+    // the shells can load before the first G-code does, so the preferences are read here as well
+    read_reduced_detail_preferences();
     if ((print.id().id == m_shells.print_id)&&(print.get_modified_count() == m_shells.print_modify_count)) {
+        // the prime tower comes and goes on its own, without reloading the objects
+        update_shell_wipe_tower(print, initialized);
         //BBS: update force previewing logic
         if (force_previewing)
             m_shells.previewing = force_previewing;
@@ -2452,10 +2518,45 @@ void GCodeViewer::load_shells(const Print& print, bool initialized, bool force_p
     m_shells.print_id = print.id().id;
     m_shells.print_modify_count = print.get_modified_count();
     m_shells.previewing = true;
+    update_shell_wipe_tower(print, initialized);
     BOOST_LOG_TRIVIAL(debug) << __FUNCTION__ << boost::format(": shell loaded, id change to %1%, modify_count %2%, object count %3%, glvolume count %4%")
         % m_shells.print_id % m_shells.print_modify_count % object_count %m_shells.volumes.volumes.size();
 }
 
+// The prime tower as it was sliced, so that the solid model shows what the print shows. It keeps its
+// opaque colour, so it never appears among the translucent shells, and stays out of their bounding box.
+void GCodeViewer::update_shell_wipe_tower(const Print& print, bool initialized)
+{
+    const bool with_wipe_tower = solid_model_enabled() && print.is_step_done(psWipeTower) && print.wipe_tower_data().wipe_tower_mesh_data;
+    if (with_wipe_tower == m_shells.with_wipe_tower)
+        return;
+    m_shells.with_wipe_tower = with_wipe_tower;
+    GLVolumePtrs& volumes = m_shells.volumes.volumes;
+    if (!with_wipe_tower) {
+        volumes.erase(std::remove_if(volumes.begin(), volumes.end(), [](GLVolume* volume) {
+            if (!volume->is_wipe_tower)
+                return false;
+            delete volume;
+            return true;
+        }), volumes.end());
+        return;
+    }
+    const PrintConfig& config = print.config();
+    const int plate_idx = print.get_plate_index();
+    const Vec3d plate_origin = print.get_plate_origin();
+    const float x = static_cast<float>(config.wipe_tower_x.get_at(plate_idx) + plate_origin.x());
+    const float y = static_cast<float>(config.wipe_tower_y.get_at(plate_idx) + plate_origin.y());
+    const size_t first_new = volumes.size();
+    m_shells.volumes.load_real_wipe_tower_preview(1000 + plate_idx, x, y, print.wipe_tower_data().wipe_tower_mesh_data->real_wipe_tower_mesh,
+                                                  print.wipe_tower_data().wipe_tower_mesh_data->real_brim_mesh, true,
+                                                  static_cast<float>(config.wipe_tower_rotation_angle), false, initialized);
+    for (size_t i = first_new; i < volumes.size(); ++i) {
+        volumes[i]->zoom_to_volumes = false;
+        volumes[i]->force_native_color = true;
+        volumes[i]->set_render_color();
+    }
+}
+
 void GCodeViewer::render_toolpaths()
 {
     const Camera& camera = wxGetApp().plater()->get_camera();
@@ -2656,6 +2757,50 @@ void GCodeViewer::render_shells(int canvas_width, int canvas_height)
     glsafe(::glDepthMask(GL_TRUE));
 }
 
+// The sliced objects and the prime tower drawn opaque, in their filament colours, cut to the
+// visible layer range by the shader's z range. The toolpaths of the range's bottom and top layers
+// are drawn afterwards and cap the cut.
+void GCodeViewer::render_solid_model(int canvas_width, int canvas_height)
+{
+    if (m_shells.volumes.empty())
+        return;
+    // gouraud_light has no z range, so it could not cut the model
+    GLShaderProgram* shader = wxGetApp().get_shader("gouraud");
+    if (shader == nullptr)
+        return;
+
+    const libvgcode::Interval& layers = m_viewer.get_layers_view_range();
+    const float z_top = m_viewer.get_layer_z(layers[1]) - m_z_offset + 0.001f;
+    const float z_bottom = (layers[0] > 0) ? m_viewer.get_layer_z(layers[0] - 1) - m_z_offset - 0.001f : -FLT_MAX;
+
+    std::vector<float> alphas;
+    alphas.reserve(m_shells.volumes.volumes.size());
+    for (GLVolume* volume : m_shells.volumes.volumes) {
+        alphas.push_back(volume->color.a());
+        volume->color.a(1.0f);
+        volume->set_render_color();
+    }
+    m_shells.volumes.set_z_range(z_bottom, z_top);
+    // gouraud also clips by this plane, which nothing else sets on the shells
+    m_shells.volumes.set_clipping_plane(ClippingPlane::ClipsNothing().get_data());
+
+    shader->start_using();
+    // the 3D view leaves its shadow settings on the shared program
+    shader->set_uniform("shadow_intensity", 0.0f);
+    const Camera& camera = wxGetApp().plater()->get_camera();
+    shader->set_uniform("z_far", camera.get_far_z());
+    shader->set_uniform("z_near", camera.get_near_z());
+    m_shells.volumes.render(GLVolumeCollection::ERenderType::Opaque, false, camera.get_view_matrix(), camera.get_projection_matrix(), {canvas_width, canvas_height});
+    shader->stop_using();
+
+    m_shells.volumes.set_z_range(-FLT_MAX, FLT_MAX);
+    size_t k = 0;
+    for (GLVolume* volume : m_shells.volumes.volumes) {
+        volume->color.a(alphas[k++]);
+        volume->set_render_color();
+    }
+}
+
 //BBS
 void GCodeViewer::render_all_plates_stats(const std::vector<const GCodeProcessorResult*>& gcode_result_list, bool show /*= true*/) const {
     if (!show)

src/slic3r/GUI/GCodeViewer.hpp

@@ -174,6 +174,8 @@ public:
         int  print_id{-1};
         int  print_modify_count{-1};
         bool previewing{false};
+        // the prime tower was loaded with the objects, for the solid model
+        bool with_wipe_tower{false};
     };
     //BBS
     ConflictResultOpt m_conflict_result;
@@ -234,6 +236,17 @@ private:
 
     bool m_legend_visible{ true };
     bool m_legend_enabled{ true };
+    // the reduced-detail preferences, pushed to libvgcode by apply_reduced_detail_settings()
+    libvgcode::EReducedDetailMode m_reduced_detail_mode{ libvgcode::EReducedDetailMode::Off };
+    void read_reduced_detail_preferences();
+    void apply_reduced_detail_settings();
+    static libvgcode::EReducedDetailMode reduced_detail_mode_from_string(const std::string& mode);
+    // in the solid model mode, the sliced objects are drawn as solid shapes instead of toolpaths
+    bool solid_model_enabled() const { return m_reduced_detail_mode == libvgcode::EReducedDetailMode::EndLayersOnly; }
+    void render_solid_model(int canvas_width, int canvas_height);
+    // the prime tower is only among the shells for the solid model, so it is added or removed when that changes
+    void reload_shells_if_solid_model_changed(bool was_enabled);
+    void update_shell_wipe_tower(const Print& print, bool initialized);
 
     float m_legend_height;
     PrintEstimatedStatistics m_print_statistics;
@@ -291,7 +304,7 @@ public:
     // void _render_calibration_thumbnail_internal(ThumbnailData& thumbnail_data, const ThumbnailsParams& thumbnail_params, PartPlateList& partplate_list, OpenGLManager& opengl_manager);
     // void _render_calibration_thumbnail_framebuffer(ThumbnailData& thumbnail_data, unsigned int w, unsigned int h, const ThumbnailsParams& thumbnail_params, PartPlateList& partplate_list, OpenGLManager& opengl_manager);
     // void render_calibration_thumbnail(ThumbnailData& thumbnail_data, unsigned int w, unsigned int h, const ThumbnailsParams& thumbnail_params, PartPlateList& partplate_list, OpenGLManager& opengl_manager);
-    bool has_data() const { return !m_viewer.get_extrusion_roles().empty(); }
+    bool has_data() const { return m_viewer.get_extrusion_roles_count() != 0; }
 
     bool can_export_toolpaths() const;
     std::vector<int> get_plater_extruder();
@@ -363,6 +376,14 @@ public:
     void set_dim_previous_layers_brightness(float value) { m_viewer.set_dim_previous_layers_brightness(value); }
     float get_dim_previous_layers_brightness() const { return m_viewer.get_dim_previous_layers_brightness(); }
 
+    // whether the mouse is holding either slider's handle
+    bool is_slider_dragging() const { return m_layers_slider->is_dragging() || m_moves_slider->is_dragging(); }
+    // while the user drags the camera or a slider, draw the reduced set, if the preference asks for one
+    void set_interacting(bool interacting);
+    bool is_reduced_detail() const { return m_viewer.is_reduced_detail(); }
+    // the preference's string value: "off", "solid" or "shell"
+    void set_reduced_detail_mode(const std::string& mode);
+
     void set_layers_z_range(const std::array<unsigned int, 2>& layers_z_range);
 
     bool is_legend_shown() const { return m_legend_visible && m_legend_enabled; }

src/slic3r/GUI/GLCanvas3D.cpp

@@ -1088,8 +1088,6 @@ wxDEFINE_EVENT(EVT_GLCANVAS_MOUSE_DRAGGING_FINISHED, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_UPDATE_BED_SHAPE, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_TAB, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_RESETGIZMOS, SimpleEvent);
-wxDEFINE_EVENT(EVT_GLCANVAS_MOVE_SLIDERS, wxKeyEvent);
-wxDEFINE_EVENT(EVT_GLCANVAS_JUMP_TO, wxKeyEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_UNDO, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_REDO, SimpleEvent);
 wxDEFINE_EVENT(EVT_GLCANVAS_SWITCH_TO_OBJECT, SimpleEvent);
@@ -2086,6 +2084,11 @@ void GLCanvas3D::_render_frame(bool scene_dirty, bool only_init)
     const bool overlay_tick = m_fps_overlay_tick;
     m_fps_overlay_tick = false;
 
+    // Whether the preview draws its reduced set is decided before the cached scene is consulted,
+    // since switching changes what the scene pass draws.
+    if (m_canvas_type == ECanvasType::CanvasPreview && m_render_preview && m_gcode_viewer.has_data() && _update_preview_interaction())
+        scene_dirty = true;
+
     // An overlay-only frame reuses the last scene pass. The overlay is rebuilt either way, and drawn
     // below once it is known whether the frame differs from the one on screen.
     const bool reuse_scene = !scene_dirty && _can_reuse_cached_scene(camera);
@@ -3279,9 +3282,16 @@ void GLCanvas3D::bind_event_handlers()
                 if (m_selection_edit.kind != SelectionEdit::None)
                     finish_selection_edit();
                 ImGui::SetWindowFocus(nullptr);
+                // a drag cut short never sees its button release, which would leave the reduced set drawn
+                if (m_canvas_type == CanvasPreview && m_mouse.dragging && m_gcode_viewer.is_reduced_detail())
+                    mouse_up_cleanup();
                 render();
                 evt.Skip();
             });
+        m_canvas->Bind(wxEVT_MOUSE_CAPTURE_LOST, [this](wxMouseCaptureLostEvent&) {
+                if (m_canvas_type == CanvasPreview && m_mouse.dragging && m_gcode_viewer.is_reduced_detail())
+                    mouse_up_cleanup();
+            });
         m_event_handlers_bound = true;
 
         m_canvas->Bind(wxEVT_GESTURE_PAN, &GLCanvas3D::on_gesture, this);
@@ -3357,6 +3367,17 @@ void GLCanvas3D::on_idle(wxIdleEvent& evt)
     m_overlay_dirty |= imgui_requires_extra_frame;
 #endif // ENABLE_ENHANCED_IMGUI_SLIDER_FLOAT
     m_dirty |= GLTexture::Compressor::has_compressed_texture_to_refresh();
+    // the render timer only wakes the idle loop; the frame that puts the preview's toolpaths back
+    // after a wheel burst has to be asked for here, once the settle time is really up
+    if (m_preview_settle_pending) {
+        const auto now = std::chrono::steady_clock::now();
+        if (now >= m_preview_interaction_until) {
+            m_preview_settle_pending = false;
+            m_dirty = true;
+        }
+        else // the timer fired early
+            schedule_extra_frame(static_cast<int>(std::chrono::duration_cast<std::chrono::milliseconds>(m_preview_interaction_until - now).count()) + 1);
+    }
 
     if (!m_dirty && !m_overlay_dirty)
         return;
@@ -3887,6 +3908,10 @@ void GLCanvas3D::on_mouse_wheel(wxMouseEvent& evt)
         return;
     }
 
+    // only a wheel the panels did not take moves the camera
+    if (m_canvas_type == CanvasPreview)
+        note_preview_interaction();
+
 #ifdef __WXMSW__
 	// For some reason the Idle event is not being generated after the mouse scroll event in case of scrolling with the two fingers on the touch pad,
 	// if the event is not allowed to be passed further.
@@ -3987,6 +4012,11 @@ void GLCanvas3D::on_fps_overlay_timer(wxTimerEvent& evt)
     wxWakeUpIdle();
 }
 
+void GLCanvas3D::note_preview_interaction()
+{
+    m_preview_interaction_until = std::chrono::steady_clock::now() + std::chrono::milliseconds(150);
+}
+
 void GLCanvas3D::schedule_extra_frame(int milliseconds)
 {
     // Schedule idle event right now
@@ -5633,6 +5663,9 @@ void GLCanvas3D::mouse_up_cleanup()
     m_mouse.ignore_left_up = false;
     m_mouse.ignore_right_up = false;
     m_dirty = true;
+    // the frame that follows a release puts the preview's toolpaths back, and on some platforms
+    // no idle event follows a button release until the next input
+    wxWakeUpIdle();
 
     if (m_canvas->HasCapture())
         m_canvas->ReleaseMouse();
@@ -7283,6 +7316,16 @@ void GLCanvas3D::_resize(unsigned int w, unsigned int h)
     m_last_w = w;
     m_last_h = h;
 
+    set_imgui_scaling();
+
+    this->request_extra_frame();
+
+    // ensures that this canvas is current
+    _set_current();
+}
+
+void GLCanvas3D::set_imgui_scaling()
+{
     float font_size = wxGetApp().em_unit();
 
 #ifdef _WIN32
@@ -7295,15 +7338,10 @@ void GLCanvas3D::_resize(unsigned int w, unsigned int h)
 #endif
 
 #if ENABLE_RETINA_GL
-    imgui->set_scaling(font_size, 1.0f, m_retina_helper->get_scale_factor());
+    wxGetApp().imgui()->set_scaling(font_size, 1.0f, m_retina_helper->get_scale_factor());
 #else
-    imgui->set_scaling(font_size, m_canvas->GetContentScaleFactor(), 1.0f);
+    wxGetApp().imgui()->set_scaling(font_size, m_canvas->GetContentScaleFactor(), 1.0f);
 #endif
-
-    this->request_extra_frame();
-
-    // ensures that this canvas is current
-    _set_current();
 }
 
 BoundingBoxf3 GLCanvas3D::_max_bounding_box(bool include_gizmos, bool include_bed_model, bool include_plates) const
@@ -7776,13 +7814,20 @@ bool GLCanvas3D::_is_scene_cacheable() const
         return false;
 #endif
 
-    // The scene follows the cursor during a drag, under a gizmo that draws at the cursor, and while
+    // The scene follows the cursor while the user drags, under a gizmo that draws at the cursor, and
-    // the cursor is on the layer height bar, where the object shader draws a band at its height.
+    // while the cursor is on the layer height bar, where the object shader draws a band at its height.
     const GLGizmoBase* gizmo = m_gizmos.get_current();
     const bool cursor_on_layers_bar = is_layers_editing_enabled() &&
         m_layers_editing.bar_rect_contains(*this, (float)m_mouse.position.x(), (float)m_mouse.position.y());
-    return !m_mouse.dragging && !m_gizmos.is_dragging() && !m_rectangle_selection.is_dragging() &&
+    return !is_user_interacting() && (gizmo == nullptr || !gizmo->render_follows_cursor()) && !cursor_on_layers_bar;
-           (gizmo == nullptr || !gizmo->render_follows_cursor()) && !cursor_on_layers_bar;
+}
+
+// Whether the user is holding something that moves the scene: the camera, the navigator, a gizmo,
+// the rectangle selection or a preview slider.
+bool GLCanvas3D::is_user_interacting() const
+{
+    return m_mouse.dragging || m_navigator_dragging || m_gizmos.is_dragging() || m_rectangle_selection.is_dragging() ||
+           m_gcode_viewer.is_slider_dragging();
 }
 
 bool GLCanvas3D::_is_frame_skipping_enabled() const
@@ -8773,6 +8818,24 @@ void GLCanvas3D::_render_wireframe_overlay()
     shader->stop_using();
 }
 
+// The reduced set is drawn while the camera, the navigator or either slider is dragged. A wheel
+// step has no duration, so it holds the reduced set for a settle time instead, and the frame that
+// restores the full toolpaths is scheduled for when that time runs out. Returns whether what the scene
+// pass draws changed, since a frame that reuses the cached scene would hide the change.
+bool GLCanvas3D::_update_preview_interaction()
+{
+    const auto now = std::chrono::steady_clock::now();
+    const bool settling = now < m_preview_interaction_until;
+    const bool dragging = is_user_interacting();
+    const bool was_reduced = m_gcode_viewer.is_reduced_detail();
+    m_gcode_viewer.set_interacting(dragging || settling);
+    if (settling && !dragging && m_gcode_viewer.is_reduced_detail()) {
+        m_preview_settle_pending = true;
+        schedule_extra_frame(static_cast<int>(std::chrono::duration_cast<std::chrono::milliseconds>(m_preview_interaction_until - now).count()) + 1);
+    }
+    return m_gcode_viewer.is_reduced_detail() != was_reduced;
+}
+
 //BBS: GUI refactor: add canvas size as parameters
 void GLCanvas3D::_render_gcode(int canvas_width, int canvas_height)
 {

src/slic3r/GUI/GLCanvas3D.hpp

@@ -185,8 +185,6 @@ wxDECLARE_EVENT(EVT_GLCANVAS_MOUSE_DRAGGING_FINISHED, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_UPDATE_BED_SHAPE, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_TAB, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_RESETGIZMOS, SimpleEvent);
-wxDECLARE_EVENT(EVT_GLCANVAS_MOVE_SLIDERS, wxKeyEvent);
-wxDECLARE_EVENT(EVT_GLCANVAS_JUMP_TO, wxKeyEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_UNDO, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_REDO, SimpleEvent);
 wxDECLARE_EVENT(EVT_GLCANVAS_SWITCH_TO_OBJECT, SimpleEvent);
@@ -658,6 +656,10 @@ private:
     ECursorType m_cursor_type;
     GLSelectionRectangle m_rectangle_selection;
     bool m_navigator_dragging{ false };
+    // until when a wheel step keeps the preview's reduced set drawn
+    std::chrono::time_point<std::chrono::steady_clock> m_preview_interaction_until{};
+    // whether the frame that restores the toolpaths once that time is up is still owed
+    bool m_preview_settle_pending{ false };
 
     //BBS:add plate related logic
     mutable std::vector<int> m_hover_volume_idxs;
@@ -1224,6 +1226,10 @@ public:
     void msw_rescale() { m_gcode_viewer.invalidate_legend(); }
 
     void request_extra_frame() { m_extra_frame_requested = true; }
+    // whether the user is holding the camera, the navigator, a gizmo, the rectangle selection or a preview slider
+    bool is_user_interacting() const;
+    // a wheel step is over before the next frame, so it holds the preview's reduced set for a settle time
+    void note_preview_interaction();
 
     void schedule_extra_frame(int milliseconds);
 
@@ -1301,6 +1307,8 @@ public:
     Vec3d _mouse_to_3d(const Point& mouse_pos, float* z = nullptr);
 
     bool make_current_for_postinit();
+    // Sizes ImGui's fonts and style for this canvas; the fonts are rebuilt when the size changes.
+    void set_imgui_scaling();
 
 private:
     bool _is_shown_on_screen() const;
@@ -1372,6 +1380,9 @@ private:
     //BBS: GUI refactor: add canvas size as parameters
     void _render_gcode(int canvas_width, int canvas_height);
     void _render_gcode_overlay(int canvas_width, int canvas_height);
+    // decides whether the preview draws its reduced set this frame and returns whether what the scene
+    // pass draws changed; runs before the cached scene is consulted
+    bool _update_preview_interaction();
     //BBS: render a plane for assemble
     void _render_plane() const;
     void _render_selection();

src/slic3r/GUI/GLModel.cpp

@@ -456,8 +456,9 @@ void GLModel::init_from(const indexed_triangle_set& its)
     data.reserve_vertices(3 * its.indices.size());
     data.reserve_indices(3 * its.indices.size());
 
-    // Read user preference: smooth normals enabled
+    // CLI thumbnail generation can initialize models without a wx application.
-    const bool smooth_normals_enabled = wxGetApp().app_config != nullptr && wxGetApp().app_config->get_bool(SETTING_OPENGL_PHONG_SMOOTH_NORMALS);
+    const bool smooth_normals_enabled = wxApp::GetInstance() != nullptr && wxGetApp().app_config != nullptr &&
+                                        wxGetApp().app_config->get_bool(SETTING_OPENGL_PHONG_SMOOTH_NORMALS);
 
     if (smooth_normals_enabled) {
         // Use per-corner smooth normals (via IGL)

src/slic3r/GUI/GUI_App.cpp

@@ -857,7 +857,12 @@ void GUI_App::post_init()
         slow_bootup = true;
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ", slow bootup, won't render gl here.";
     }
-    if (!switch_to_3d) {
+    // Starting on Home, the GL resources load at idle so Home paints first and Prepare is never
+    // shown.
+    const bool gl_at_idle = !starts_on_prepare() && is_editor();
+    if (!switch_to_3d && gl_at_idle) {
+        plater_->select_view_3D("3D");
+    } else if (!switch_to_3d) {
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ", begin load_gl_resources";
 #ifndef __linux__
         mainframe->Freeze();
@@ -865,9 +870,6 @@ void GUI_App::post_init()
         plater_->canvas3D()->enable_render(false);
         mainframe->select_prepare_for_gl_init();
         plater_->select_view_3D("3D");
-        // The first render happens before the queued new_project() sets the same view.
-        plater_->get_camera().select_view("topfront");
-        plater_->get_camera().requires_zoom_to_bed = true;
         //BBS init the opengl resource here
         if (!plater_->canvas3D()->get_wxglcanvas()->IsShownOnScreen() ||
             !plater_->canvas3D()->make_current_for_postinit()) {
@@ -905,8 +907,6 @@ void GUI_App::post_init()
         }
         if (starts_on_prepare())
             mainframe->select_tab(TAB_ID_PREPARE);
-        else if (is_editor())
-            mainframe->select_tab(TAB_ID_HOME);
 #ifndef __linux__
         mainframe->Thaw();
 #endif
@@ -3423,6 +3423,10 @@ bool GUI_App::on_init_inner()
     }
     BOOST_LOG_TRIVIAL(info) << "create the main window";
     mainframe = new MainFrame();
+    // The first render can happen as soon as the frame is shown, before the queued
+    // new_project() sets the same view.
+    plater_->get_camera().select_view("topfront");
+    plater_->get_camera().requires_zoom_to_bed = true;
     if (is_editor()) {
         if (starts_on_prepare()) {
             mainframe->select_tab(TAB_ID_PREPARE);
@@ -8201,10 +8205,12 @@ int GUI_App::input_idle_ms() const
     return int(std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - m_last_input).count());
 }
 
-// Every wxCommandEvent claims the user-input category, so only real mouse and key events count.
+// Every wxCommandEvent claims the user-input category, so only real mouse and key events count,
+// plus main window resizes, since a border drag produces no mouse events.
 int GUI_App::FilterEvent(wxEvent& event)
 {
-    if (!event.IsCommandEvent() && (event.GetEventCategory() & wxEVT_CATEGORY_USER_INPUT))
+    if ((!event.IsCommandEvent() && (event.GetEventCategory() & wxEVT_CATEGORY_USER_INPUT)) ||
+        (event.GetEventType() == wxEVT_SIZE && event.GetEventObject() == mainframe))
         m_last_input = std::chrono::steady_clock::now();
     return Event_Skip;
 }

src/slic3r/GUI/GUI_App.hpp

@@ -389,7 +389,7 @@ public:
     bool is_editor() const { return m_app_mode == EAppMode::Editor; }
     bool is_gcode_viewer() const { return m_app_mode == EAppMode::GCodeViewer; }
     bool is_recreating_gui() const { return m_is_recreating_gui; }
-    // Milliseconds since the last mouse or keyboard event the app processed.
+    // Milliseconds since the last mouse or keyboard event the app processed, or main window resize.
     int  input_idle_ms() const;
     int  FilterEvent(wxEvent& event) override;
     // The Preferences "Default page" choice, stored as its index: 0 Home, 1 Prepare.

src/slic3r/GUI/GUI_ObjectTable.cpp

@@ -2764,12 +2764,12 @@ ObjectTablePanel::ObjectTablePanel( wxWindow* parent, wxWindowID id, const wxPoi
     //m_object_grid->AssignTable(m_object_grid_table);
 
     m_side_window = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(440),FromDIP(480)), wxVSCROLL);
-    m_side_window->SetScrollRate( 0, 5 );
+    m_side_window->SetScrollRate(0, FromDIP(20));
     m_page_sizer = new wxBoxSizer(wxVERTICAL);
     //m_page_top_sizer = new wxBoxSizer(wxHORIZONTAL);
     m_side_window->SetBackgroundColour(wxColour(0xff, 0xff, 0xff));
     m_side_window->SetSizer(m_page_sizer);
-    m_side_window->SetScrollbars(1, 20, 1, 2);
+    m_side_window->SetScrollbars(1, FromDIP(20), 1, 2);
     //m_side_window->ShowScrollbars(wxSHOW_SB_NEVER, wxSHOW_SB_NEVER);
 
     //m_side_window->EnableScrolling(false, true);

src/slic3r/GUI/GUI_Utils.cpp

@@ -247,7 +247,9 @@ int get_dpi_for_window(const wxWindow *window)
 
         const HDC hdc = GetDC(hwnd);
         if (hdc == NULL) { return DPI_DEFAULT; }
-        return GetDeviceCaps(hdc, LOGPIXELSX);
+        const int dpi = GetDeviceCaps(hdc, LOGPIXELSX);
+        ReleaseDC(hwnd, hdc); // GetDC's handle must be released, unlike GetWindowDC's
+        return dpi;
     }
 #elif defined __linux__
     // TODO

src/slic3r/GUI/HMSPanel.cpp

@@ -171,7 +171,7 @@ HMSPanel::HMSPanel(wxWindow *parent, wxWindowID id, const wxPoint &pos, const wx
 
     m_scrolledWindow = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
     m_scrolledWindow->SetBackgroundColour(*wxWHITE);
-    m_scrolledWindow->SetScrollRate(5, 5);
+    m_scrolledWindow->SetScrollRate(5, FromDIP(20));
 
     m_top_sizer = new wxBoxSizer(wxVERTICAL);
 

src/slic3r/GUI/IMSlider.cpp

@@ -483,6 +483,11 @@ void IMSlider::draw_background_and_groove(const ImRect& bg_rect, const ImRect& g
     ImGui::RenderFrame(groove.Min, groove.Max, groove_col, false, 0.5 * groove.GetWidth());
 }
 
+bool IMSlider::is_dragging() const
+{
+    return GImGui != nullptr && m_imgui_id != 0 && GImGui->ActiveId == m_imgui_id && GImGui->IO.MouseDown[0];
+}
+
 bool IMSlider::horizontal_slider(const char* str_id, int* value, int v_min, int v_max, const ImVec2& size, float scale)
 {
     ImGuiWindow* window = ImGui::GetCurrentWindow();
@@ -491,6 +496,7 @@ bool IMSlider::horizontal_slider(const char* str_id, int* value, int v_min, int
 
     ImGuiContext& context = *GImGui;
     const ImGuiID id = window->GetID(str_id);
+    m_imgui_id = id;
 
     const ImVec2 pos = window->DC.CursorPos;
     const ImRect draw_region(pos, pos + size);
@@ -883,6 +889,7 @@ bool IMSlider::vertical_slider(const char* str_id, int* higher_value, int* lower
 
     ImGuiContext& context = *GImGui;
     const ImGuiID id = window->GetID(str_id);
+    m_imgui_id = id;
 
     const ImVec2 pos = window->DC.CursorPos;
     const ImRect draw_region(pos, pos + size);

src/slic3r/GUI/IMSlider.hpp

@@ -118,6 +118,9 @@ public:
 
     //BBS update scroll value changed
     bool is_dirty() { return m_dirty; }
+    // whether the mouse is holding this slider's handle, read from ImGui's active id rather than
+    // from the dirty flag, which is raised and consumed inside a single frame
+    bool is_dragging() const;
     void set_as_dirty(bool dirty = true) { m_dirty = dirty; }
     bool is_need_post_tick_event() { return m_is_need_post_tick_changed_event; }
     void reset_post_tick_event(bool val = false) {
@@ -182,6 +185,8 @@ private:
     int  m_higher_value;
     int  m_one_layer_value; // ORCA
     bool m_dirty = false;
+    // the ImGui id of the slider widget, as of its last render
+    unsigned int m_imgui_id = 0;
 
     bool m_render_as_disabled{ false };
 

src/slic3r/GUI/IdleScheduler.cpp

@@ -3,6 +3,7 @@
 #include <chrono>
 
 #include <boost/log/trivial.hpp>
+#include <wx/evtloop.h>
 
 #include "libslic3r/Utils.hpp"
 
@@ -23,12 +24,9 @@ constexpr int quiet_ms = 500;
 // queued meanwhile are handled first; a click waits at most a slice plus the unit that
 // overran it.
 constexpr int slice_ms = 40;
-// On GTK a due timer runs ahead of repaints and posted events, so the next slice waits a few ms.
+// Delay before the next slice; on GTK a due timer runs ahead of repaints and posted events,
-#ifdef __WXGTK__
+// and wxOSX rejects a 0 ms timer.
 constexpr int next_slice_ms = 5;
-#else
-constexpr int next_slice_ms = 0;
-#endif
 
 // True when unhandled keyboard, button, touch or pen input is queued; only Windows can ask.
 bool input_pending()
@@ -42,6 +40,13 @@ bool input_pending()
 #endif
 }
 
+// True inside a wxYield(), where a slice would build pages in the middle of the code that yielded.
+bool yielding()
+{
+    const wxEventLoopBase* loop = wxEventLoopBase::GetActive();
+    return loop != nullptr && loop->IsYielding();
+}
+
 } // namespace
 
 IdleScheduler::IdleScheduler(std::function<int()> input_idle_ms) : m_input_idle_ms(std::move(input_idle_ms))
@@ -69,7 +74,7 @@ void IdleScheduler::tick()
         stop();
         return;
     }
-    if (m_input_idle_ms() < quiet_ms || input_pending()) {
+    if (m_input_idle_ms() < quiet_ms || input_pending() || yielding()) {
         start();
         return;
     }

src/slic3r/GUI/KBShortcutsDialog.cpp

@@ -159,8 +159,12 @@ void KBShortcutsDialog::fill_pages()
 
     if (wxGetApp().is_editor()) {
         page(_L("Global"), _L("Available anywhere in the window, even while typing in a text field."), ShortcutContext::Global, {
-            fixed(Section::Application, { alt, "1-9, 0" }, L("Run a speed dial favorite while the dial is open")),
+            fixed(Section::SpeedDial, { alt, "1-9, 0" }, L("Run favorite 1 to 10")),
+            fixed(Section::SpeedDial, { ctrl, "B" }, L("Pin or unpin the selected action")),
+            // wx cycles notebook pages on Ctrl+Tab, which is Cmd+Tab on macOS and never arrives there.
+#ifndef __APPLE__
             fixed(Section::Application, { ctrl, key(L_CONTEXT("Tab", "Keyboard Shortcut")) }, L("Switch to the next main tab")),
+#endif
         });
 
         page(_L("Prepare"), _L("Available while the 3D view on the Prepare tab has focus."), ShortcutContext::Plater, {
@@ -207,7 +211,7 @@ wxPanel* KBShortcutsDialog::create_page(wxWindow* parent, const Page& page)
     wxGetApp().UpdateDarkUI(scrollable_panel);
     const wxColour page_colour = StateColor::darkModeColorFor(*wxWHITE);
     scrollable_panel->SetBackgroundColour(page_colour);
-    scrollable_panel->SetScrollRate(0, 20);
+    scrollable_panel->SetScrollRate(0, FromDIP(20));
     const int page_width = FromDIP(PAGE_WIDTH);
     scrollable_panel->SetInitialSize(wxSize(page_width, FromDIP(450)));
 
@@ -454,7 +458,10 @@ ShortcutCaptureDialog::ShortcutCaptureDialog(wxWindow* parent, Shortcut shortcut
     capture_sizer->Add(m_chord_label, 0, wxALIGN_CENTER);
     capture_sizer->AddStretchSpacer();
     capture->SetSizer(capture_sizer);
-    capture->Bind(wxEVT_KEY_DOWN, &ShortcutCaptureDialog::on_key, this);
+    capture->Layout();   // the box is created at its final size, so nothing resizes it into laying the sizer out
+    // The hook runs before the window procedure, so Windows does not open its window menu
+    // over the dialog on Alt+Space.
+    Bind(wxEVT_CHAR_HOOK, &ShortcutCaptureDialog::on_key, this);
     capture->Bind(wxEVT_CHAR, &ShortcutCaptureDialog::on_char, this);
     capture->Bind(wxEVT_LEFT_DOWN, [capture](wxMouseEvent&) { capture->SetFocus(); });
     sizer->Add(capture, 0, wxLEFT | wxRIGHT | wxEXPAND, FromDIP(20));
@@ -531,10 +538,12 @@ void ShortcutCaptureDialog::record(const KeyChord& chord)
         m_ok->Enable(false);
     };
     const bool global = (shortcut_info(m_shortcut).contexts & context_bit(ShortcutContext::Global)) != 0;
-    if (global && !chord.is_menu_accelerator()) {
+    if (chord.is_system_shortcut()) {
+        reject(_L("The system uses this shortcut, so it cannot be assigned."));
+    } else if (global && !chord.is_menu_accelerator()) {
         reject(m_rejection);
     } else if (const std::optional<Shortcut> owner = wxGetApp().shortcuts().step_owner(m_shortcut, chord); owner.has_value()) {
-        reject(wxString::Format(_L("Already used as a step of %s."), _(shortcut_info(*owner).name)));
+        reject(wxString::Format(_L("Shift and Ctrl with this key belong to %s and cannot be assigned."), _(shortcut_info(*owner).name)));
     } else {
         m_conflicts = wxGetApp().shortcuts().conflicts(m_shortcut, chord);
         m_status->SetForegroundColour(m_status_colour);

src/slic3r/GUI/KeyChord.cpp

@@ -182,6 +182,16 @@ bool KeyChord::is_menu_accelerator() const
     return valid() && ((modifiers & (wxMOD_CONTROL | wxMOD_ALT | wxMOD_RAW_CONTROL)) != 0 || (!is_printable(key) && key != WXK_SPACE));
 }
 
+// Only a chord the desktop acts on while still delivering it to the app belongs here.
+bool KeyChord::is_system_shortcut() const
+{
+#ifdef _WIN32
+    return modifiers == wxMOD_ALT && (key == WXK_F4 || key == WXK_SPACE);
+#else
+    return false;
+#endif
+}
+
 std::string KeyChord::to_string() const
 {
     if (!valid())

src/slic3r/GUI/KeyChord.hpp

@@ -34,6 +34,9 @@ struct KeyChord
     // True when Ctrl or Alt is held or the key is non-printable, the chords a menu can own without
     // swallowing typing in text fields.
     bool is_menu_accelerator() const;
+    // True for a chord the desktop acts on although the app receives it, so a binding would
+    // take it from the system.
+    bool is_system_shortcut() const;
 
     // Platform-neutral text ("Ctrl+Shift+S") for persistence and wx accelerator strings.
     std::string to_string() const;

src/slic3r/GUI/MainFrame.cpp

@@ -81,6 +81,7 @@
 
 #ifdef __WXGTK__
 #include <gtk/gtk.h>
+#include <wx/glcanvas.h>
 #endif // __WXGTK__
 #include <slic3r/GUI/CreatePresetsDialog.hpp>
 
@@ -510,6 +511,9 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, BORDERLESS_FRAME_
         wxQueueEvent(wxGetApp().plater(), new SimpleEvent(EVT_NOTICE_CHILDE_SIZE_CHANGED));
 
         fit_tab_labels(); // ORCA on resize
+        // Restarts the idle build so a hidden Prepare page is laid out at the new size.
+        if (m_prebuild_started)
+            m_idle.start();
     });
 
     //BBS
@@ -4008,13 +4012,81 @@ bool MainFrame::Show(bool show)
     return changed;
 }
 
+bool MainFrame::GLResourcesPrebuild::built() const
+{
+    return m_frame.m_plater != nullptr && m_frame.m_plater->canvas3D()->is_initialized() &&
+           m_frame.m_plater->get_partplate_list().icon_textures_loaded();
+}
+
+bool MainFrame::GLResourcesPrebuild::build_step()
+{
+    GLCanvas3D* canvas = m_frame.m_plater->canvas3D();
+#ifdef __WXGTK__
+    // wx creates a GTK canvas's GL surface when the widget is realized, so the context can be
+    // made current on it while hidden.
+    gtk_widget_realize(canvas->get_wxglcanvas()->GetHandle());
+#endif
+    if (!canvas->make_current_for_postinit()) {
+        // The first render of the canvas loads everything instead.
+        BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << ": cannot make the GL context current on the hidden canvas";
+        m_failed = true;
+        return false;
+    }
+    switch (m_step) {
+    case 0:
+        m_failed = !wxGetApp().init_opengl();
+        break;
+    case 1: {
+        const Size size = canvas->get_canvas_size();
+        wxGetApp().imgui()->set_display_size(float(std::max(1, size.get_width())), float(std::max(1, size.get_height())));
+        canvas->set_imgui_scaling();
+        // Builds the font atlas without leaving a frame open at the hidden canvas's size.
+        wxGetApp().imgui()->new_frame();
+        wxGetApp().imgui()->end_frame();
+        break;
+    }
+    case 2:
+        // One texture per unit until none remain.
+        if (m_frame.m_plater->get_partplate_list().load_next_plate_texture())
+            return true;
+        break;
+    case 3:
+        m_failed = !canvas->init();
+        break;
+    default:
+        // Runs after init(), which sets the color mode the icons are drawn for.
+        m_frame.m_plater->get_partplate_list().load_icon_textures();
+        return false;
+    }
+    ++m_step;
+    return !m_failed;
+}
+
+bool MainFrame::PrepareLayoutPrebuild::built() const
+{
+    // The book lays out the page it shows.
+    const wxWindow* page = m_frame.m_tabpanel != nullptr ? m_frame.m_tabpanel->GetCurrentPage() : nullptr;
+    return page == nullptr || page == m_frame.m_plater || page->GetSize() == m_laid_out_size;
+}
+
+bool MainFrame::PrepareLayoutPrebuild::build_step()
+{
+    // Sized as the book sizes the page it selects, so the selection finds nothing to lay out.
+    const wxWindow* page = m_frame.m_tabpanel->GetCurrentPage();
+    m_laid_out_size      = page->GetSize();
+    m_frame.m_plater->SetSize(page->GetRect());
+    return false;
+}
+
 // A page out of the book stays registered and is passed over; a negative order is never
 // registered.
 void MainFrame::prebuild_pages_when_idle()
 {
     m_idle.clear();
+    m_idle.add(m_gl_prebuild);
     if (m_param_panel)
         m_idle.add(m_param_panel->settings_page_prebuild());
+    m_idle.add(m_prepare_layout_prebuild);
     for (LazyBase* page : m_lazy_pages)
         if (page->prebuild_order() >= 0)
             m_idle.add(*page);

src/slic3r/GUI/MainFrame.hpp

@@ -140,6 +140,38 @@ class MainFrame : public DPIFrame
     wxTimer* m_reset_title_text_colour_timer{ nullptr };
     IdleScheduler         m_idle;
     bool                  m_prebuild_started{ false };
+    // Loads the Prepare canvas's GL resources while its page is hidden.
+    class GLResourcesPrebuild : public LazyBase
+    {
+    public:
+        explicit GLResourcesPrebuild(MainFrame& frame) : m_frame(frame) {}
+        const std::string& name() const override { return m_name; }
+        bool               built() const override;
+        bool               pending() const override { return !m_failed && !built(); }
+        bool               build_step() override;
+        int                prebuild_order() const override { return 0; }
+
+    private:
+        MainFrame&  m_frame;
+        std::string m_name{ "gl_resources" };
+        int         m_step{ 0 };
+        bool        m_failed{ false };
+    } m_gl_prebuild{ *this };
+    // Lays out the hidden Prepare page at the size the book gives its pages.
+    class PrepareLayoutPrebuild : public LazyBase
+    {
+    public:
+        explicit PrepareLayoutPrebuild(MainFrame& frame) : m_frame(frame) {}
+        const std::string& name() const override { return m_name; }
+        bool               built() const override;
+        bool               build_step() override;
+        int                prebuild_order() const override { return 0; }
+
+    private:
+        MainFrame&  m_frame;
+        std::string m_name{ "prepare_layout" };
+        wxSize      m_laid_out_size;
+    } m_prepare_layout_prebuild{ *this };
     // Every LazyPage, in and out of the book; prebuild_pages_when_idle() registers them.
     std::vector<LazyBase*> m_lazy_pages;
     // The latest EVT_LOAD_PRINTER_URL, applied when the web Device view is built.

src/slic3r/GUI/MixedFilamentDialog.cpp

@@ -1125,7 +1125,7 @@ wxBoxSizer* MixedFilamentDialog::create_recommendation_grid()
     outer->Add(title_sizer, 0, wxEXPAND | wxBOTTOM, FromDIP(4));
 
     m_recommendation_scroll = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(-1, FromDIP(116)));
-    m_recommendation_scroll->SetScrollRate(0, 5);
+    m_recommendation_scroll->SetScrollRate(0, FromDIP(20));
     m_recommendation_scroll->SetBackgroundColour(StateColor::darkModeColorFor(wxColour("#F8F8F8")));
 
     m_recommendation_grid = new wxWrapSizer(wxHORIZONTAL, wxREMOVE_LEADING_SPACES);

src/slic3r/GUI/MsgDialog.cpp

@@ -194,9 +194,10 @@ Button* MsgDialog::add_button(wxWindowID btn_id, bool set_focus /*= false*/, con
     bd->button = btn;
     //bd->type   = type;
 
-    mb->id        = wxString::Format("%d", m_buttons.size());
+    // m_buttons.size() is a size_t, which does not match the %d conversion
+    mb->id        = wxString(std::to_string(m_buttons.size()));
     mb->buttondata = bd;
-    m_buttons[ wxString::Format("%d", m_buttons.size())] = mb;
+    m_buttons[ wxString(std::to_string(m_buttons.size()))] = mb;
     return btn;
 };
 
@@ -398,7 +399,7 @@ static void add_msg_content(wxWindow   *parent,
             }
             wxScrolledWindow *scrolledWindow = new wxScrolledWindow(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
             scrolledWindow->SetBackgroundColour(*wxWHITE);
-            scrolledWindow->SetScrollRate(0, 20);
+            scrolledWindow->SetScrollRate(0, scrolledWindow->FromDIP(20));
             scrolledWindow->EnableScrolling(false, true);
             wxBoxSizer *sizer_scrolled = new wxBoxSizer(wxHORIZONTAL);
             Label *wrapped_text = new Label(scrolledWindow, font, msg, LB_AUTO_WRAP, wxSize(info_width, -1));

src/slic3r/GUI/MultiMachineManagerPage.cpp

@@ -398,7 +398,7 @@ MultiMachineManagerPage::MultiMachineManagerPage(wxWindow* parent)
 
     m_machine_list = new wxScrolledWindow(m_main_panel, wxID_ANY, wxDefaultPosition, wxDefaultSize);
     m_machine_list->SetBackgroundColour(*wxWHITE);
-    m_machine_list->SetScrollRate(0, 5);
+    m_machine_list->SetScrollRate(0, FromDIP(DEVICE_ITEM_MAX_HEIGHT));
     m_machine_list->SetMinSize(wxSize(FromDIP(DEVICE_ITEM_MAX_WIDTH), 10 * FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
     m_machine_list->SetMaxSize(wxSize(FromDIP(DEVICE_ITEM_MAX_WIDTH), 10 * FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
 

src/slic3r/GUI/MultiMachinePage.cpp

@@ -323,7 +323,7 @@ MultiMachinePickPage::MultiMachinePickPage(Plater* plater /*= nullptr*/)
     scroll_macine_list->SetMinSize(wxSize(FromDIP(400), FromDIP(10 * 30)));
     scroll_macine_list->SetMaxSize(wxSize(FromDIP(400), FromDIP(10 * 30)));
     scroll_macine_list->SetBackgroundColour(*wxWHITE);
-    scroll_macine_list->SetScrollRate(0, 5);
+    scroll_macine_list->SetScrollRate(0, FromDIP(DEVICE_ITEM_MAX_HEIGHT));
 
     sizer_machine_list = new wxBoxSizer(wxVERTICAL);
     scroll_macine_list->SetSizer(sizer_machine_list);

src/slic3r/GUI/MultiTaskManagerPage.cpp

@@ -675,7 +675,7 @@ LocalTaskManagerPage::LocalTaskManagerPage(wxWindow* parent)
 
     m_task_list = new wxScrolledWindow(m_main_panel, wxID_ANY, wxDefaultPosition, wxDefaultSize);
     m_task_list->SetBackgroundColour(*wxWHITE);
-    m_task_list->SetScrollRate(0, 5);
+    m_task_list->SetScrollRate(0, FromDIP(DEVICE_ITEM_MAX_HEIGHT));
     m_task_list->SetMinSize(wxSize(FromDIP(CLOUD_TASK_ITEM_MAX_WIDTH), FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
     m_task_list->SetMaxSize(wxSize(FromDIP(CLOUD_TASK_ITEM_MAX_WIDTH), 10 * FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
 
@@ -1056,7 +1056,7 @@ CloudTaskManagerPage::CloudTaskManagerPage(wxWindow* parent)
 
     m_task_list = new wxScrolledWindow(m_main_panel, wxID_ANY, wxDefaultPosition, wxDefaultSize);
     m_task_list->SetBackgroundColour(*wxWHITE);
-    m_task_list->SetScrollRate(0, 5);
+    m_task_list->SetScrollRate(0, FromDIP(DEVICE_ITEM_MAX_HEIGHT));
     m_task_list->SetMinSize(wxSize(FromDIP(CLOUD_TASK_ITEM_MAX_WIDTH), FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
     m_task_list->SetMaxSize(wxSize(FromDIP(CLOUD_TASK_ITEM_MAX_WIDTH), 10 * FromDIP(DEVICE_ITEM_MAX_HEIGHT)));
 

src/slic3r/GUI/ObjColorDialog.cpp

@@ -355,7 +355,7 @@ ObjColorPanel::ObjColorPanel(wxWindow *parent, Slic3r::ObjDialogInOut &in_out, c
         //new color table
         m_scrolledWindow = new wxScrolledWindow(m_page_simple, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
         m_scrolledWindow->SetBackgroundColour(*wxWHITE);
-        m_scrolledWindow->SetScrollRate(0, 20);
+        m_scrolledWindow->SetScrollRate(0, FromDIP(20));
         m_scrolledWindow->EnableScrolling(false, true);
         m_scrolledWindow->ShowScrollbars(wxScrollbarVisibility::wxSHOW_SB_NEVER, wxScrollbarVisibility::wxSHOW_SB_DEFAULT);
         draw_new_table();

src/slic3r/GUI/OptionsGroup.hpp

@@ -112,7 +112,7 @@ public:
     bool split_multi_line{false};
     bool option_label_at_right{false};
     // BBS: new layout
-    wxWindow *     stb;
+    wxWindow *     stb{ nullptr };
     const wxString  icon;
     const wxString  title;
     bool            m_labels_hidden{false};

src/slic3r/GUI/ParamsPanel.cpp

@@ -391,7 +391,7 @@ ParamsPanel::ParamsPanel( wxWindow* parent, wxWindowID id, const wxPoint& pos, c
     m_page_sizer = new wxBoxSizer(wxVERTICAL);
 
     m_page_view->SetSizer(m_page_sizer);
-    m_page_view->SetScrollbars(1, 20, 1, 2);
+    m_page_view->SetScrollbars(1, FromDIP(20), 1, 2);
     //m_page_view->SetScrollRate( 5, 5 );
 
     if (m_mode_region)

src/slic3r/GUI/ParamsPanel.hpp

@@ -122,8 +122,8 @@ class ParamsPanel : public wxPanel
 
         wxPanel* m_current_tab { nullptr };
 
-        // Builds the selected page's option groups at idle; while no tab is selected yet,
+        // Builds the selected page's option groups at idle and then shows them for the mode;
-        // its first unit selects the default one.
+        // while no tab is selected yet, its first unit selects the default one.
         class SettingsPagePrebuild : public LazyBase
         {
         public:

src/slic3r/GUI/PartPlate.cpp

@@ -799,67 +799,8 @@ void PartPlate::render_logo(bool bottom, bool render_cali)
 {
 	if (!m_partplate_list->render_bedtype_logo) {
 		// render third-party printer texture logo
-		if (m_partplate_list->m_logo_texture_filename.empty()) {
+		if (!m_partplate_list->load_logo_texture())
-			m_partplate_list->m_logo_texture.reset();
 			return;
-		}
-
-		//GLTexture* temp_texture = const_cast<GLTexture*>(&m_temp_texture);
-
-		if (m_partplate_list->m_logo_texture.get_id() == 0 || m_partplate_list->m_logo_texture.get_source() != m_partplate_list->m_logo_texture_filename) {
-			m_partplate_list->m_logo_texture.reset();
-
-			if (boost::algorithm::iends_with(m_partplate_list->m_logo_texture_filename, ".svg")) {
-				/*// use higher resolution images if graphic card and opengl version allow
-				GLint max_tex_size = OpenGLManager::get_gl_info().get_max_tex_size();
-				if (temp_texture->get_id() == 0 || temp_texture->get_source() != m_texture_filename) {
-					// generate a temporary lower resolution texture to show while no main texture levels have been compressed
-					if (!temp_texture->load_from_svg_file(m_texture_filename, false, false, false, max_tex_size / 8)) {
-						render_default(bottom, false);
-						return;
-					}
-					canvas.request_extra_frame();
-				}*/
-
-				// starts generating the main texture, compression will run asynchronously
-				GLint max_tex_size = OpenGLManager::get_gl_info().get_max_tex_size();
-				GLint logo_tex_size = (max_tex_size < 2048) ? max_tex_size : 2048;
-				if (!m_partplate_list->m_logo_texture.load_from_svg_file(m_partplate_list->m_logo_texture_filename, true, true, true, logo_tex_size)) {
-					BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % m_partplate_list->m_logo_texture_filename;
-					return;
-				}
-			}
-			else if (boost::algorithm::iends_with(m_partplate_list->m_logo_texture_filename, ".png")) {
-				// generate a temporary lower resolution texture to show while no main texture levels have been compressed
-				/* if (temp_texture->get_id() == 0 || temp_texture->get_source() != m_logo_texture_filename) {
-					if (!temp_texture->load_from_file(m_logo_texture_filename, false, GLTexture::None, false)) {
-						render_default(bottom, false);
-						return;
-					}
-					canvas.request_extra_frame();
-				}*/
-
-				// starts generating the main texture, compression will run asynchronously
-				if (!m_partplate_list->m_logo_texture.load_from_file(m_partplate_list->m_logo_texture_filename, true, GLTexture::MultiThreaded, true)) {
-					BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % m_partplate_list->m_logo_texture_filename;
-					return;
-				}
-			}
-			else {
-				BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": can not load logo texture from %1%, unsupported format") % m_partplate_list->m_logo_texture_filename;
-				return;
-			}
-		}
-		else if (m_partplate_list->m_logo_texture.unsent_compressed_data_available()) {
-			// sends to gpu the already available compressed levels of the main texture
-			m_partplate_list->m_logo_texture.send_compressed_data_to_gpu();
-
-			// the temporary texture is not needed anymore, reset it
-			//if (temp_texture->get_id() != 0)
-			//    temp_texture->reset();
-
-			//canvas.request_extra_frame();
-		}
 
 		if (m_logo_triangles.is_initialized())
 			render_logo_texture(m_partplate_list->m_logo_texture, m_logo_triangles, bottom);
@@ -4232,6 +4173,7 @@ Vec2d PartPlateList::compute_shape_position(int index, int cols)
 //generate icon textures
 void PartPlateList::generate_icon_textures()
 {
+	m_icon_textures_dark = m_is_dark;
 	// use higher resolution images if graphic card and opengl version allow
 	GLint max_tex_size = OpenGLManager::get_gl_info().get_max_tex_size(), icon_size = max_tex_size / 8;
 	std::string path = resources_dir() + "/images/";
@@ -4447,6 +4389,9 @@ void PartPlateList::release_icon_textures()
 	PartPlateList::is_load_bedtype_textures = false;
     PartPlateList::is_load_extruder_only_area_textures = false;
 	PartPlateList::is_load_cali_texture = false;
+	m_next_bedtype_texture = 0;
+	m_next_extruder_only_area_texture = 0;
+	m_next_cali_texture = 0;
 	for (int i = 0; i < btCount; i++) {
 		for (auto& part: bed_texture_info[i].parts) {
 			if (part.texture) {
@@ -6002,12 +5947,7 @@ void PartPlateList::render(const Transform3d& view_matrix, const Transform3d& pr
 		plate_hover_action = hover_id % PartPlate::GRABBER_COUNT;
 	}
 
-	static bool last_dark_mode_status = m_is_dark;
+	load_icon_textures();
-	if (m_is_dark != last_dark_mode_status) {
-		last_dark_mode_status = m_is_dark;
-		generate_icon_textures();
-	} else if(m_del_texture.get_id() == 0)
-		generate_icon_textures();
 	for (it = m_plate_list.begin(); it != m_plate_list.end(); it++) {
 		int current_index = (*it)->get_index();
 		if (only_current && (current_index != m_current_plate))
@@ -6149,6 +6089,8 @@ bool PartPlateList::set_shapes(const Pointfs              &shape,
 	}
 	is_load_bedtype_textures = false; //reload textures
     is_load_extruder_only_area_textures = false; // reload textures
+	m_next_bedtype_texture = 0;
+	m_next_extruder_only_area_texture = 0;
 	calc_bounding_boxes();
 
 	update_logo_texture_filename(texture_filename);
@@ -7089,53 +7031,120 @@ bool PartPlateList::init_extruder_only_area_info()
     return true;
 }
 
+static GLint logo_texture_size()
+{
+	return std::min<GLint>(OpenGLManager::get_gl_info().get_max_tex_size(), 2048);
+}
+
+// Loads the texture of the next untried part across the parts of `infos`, in order, advancing
+// `next`; false once every part has been tried.
+static bool load_next_part_texture(PartPlateList::BedTextureInfo* infos, size_t count, size_t& next, bool compress_and_filter)
+{
+	size_t k = next;
+	for (size_t i = 0; i < count; ++i) {
+		if (k >= infos[i].parts.size()) {
+			k -= infos[i].parts.size();
+			continue;
+		}
+		++next;
+		PartPlateList::BedTextureInfo::TexturePart& part = infos[i].parts[k];
+		const std::string filename = resources_dir() + "/images/" + part.filename;
+		if (boost::filesystem::exists(filename)) {
+			part.texture = new GLTexture();
+			if (!part.texture->load_from_svg_file(filename, true, compress_and_filter, compress_and_filter, logo_texture_size()))
+				BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load texture from %1% failed!") % filename;
+		} else {
+			BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load texture from %1% failed!") % filename;
+		}
+		return true;
+	}
+	return false;
+}
+
 void PartPlateList::load_bedtype_textures()
 {
-	if (PartPlateList::is_load_bedtype_textures) return;
+	while (load_next_bedtype_texture()) {}
+}
 
+bool PartPlateList::load_next_bedtype_texture()
+{
+	if (PartPlateList::is_load_bedtype_textures)
+		return false;
+	if (m_next_bedtype_texture == 0)
 		init_bed_type_info();
-	GLint max_tex_size = OpenGLManager::get_gl_info().get_max_tex_size();
+	if (load_next_part_texture(bed_texture_info, btCount, m_next_bedtype_texture, true))
-	GLint logo_tex_size = (max_tex_size < 2048) ? max_tex_size : 2048;
+		return true;
-	for (int i = 0; i < (unsigned int)btCount; ++i) {
-		for (int j = 0; j < bed_texture_info[i].parts.size(); j++) {
-			std::string filename = resources_dir() + "/images/" + bed_texture_info[i].parts[j].filename;
-			if (boost::filesystem::exists(filename)) {
-				PartPlateList::bed_texture_info[i].parts[j].texture = new GLTexture();
-				if (!PartPlateList::bed_texture_info[i].parts[j].texture->load_from_svg_file(filename, true, true, true, logo_tex_size)) {
-					BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % filename;
-				}
-			} else {
-				BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % filename;
-			}
-		}
-	}
 	PartPlateList::is_load_bedtype_textures = true;
+	return false;
 }
 
-void PartPlateList::load_extruder_only_area_textures() {
+bool PartPlateList::load_logo_texture()
-    if (PartPlateList::is_load_extruder_only_area_textures) return;
+{
+	if (m_logo_texture_filename.empty()) {
+		m_logo_texture.reset();
+		return false;
+	}
 
-    auto ok  = init_extruder_only_area_info();
+	if (m_logo_texture.get_id() != 0 && m_logo_texture.get_source() == m_logo_texture_filename) {
-    if (!ok) {
+		if (m_logo_texture.unsent_compressed_data_available())
+			// sends to gpu the already available compressed levels of the main texture
+			m_logo_texture.send_compressed_data_to_gpu();
+		return true;
+	}
+
+	m_logo_texture.reset();
+	// starts generating the main texture, compression will run asynchronously
+	if (boost::algorithm::iends_with(m_logo_texture_filename, ".svg")) {
+		if (!m_logo_texture.load_from_svg_file(m_logo_texture_filename, true, true, true, logo_texture_size())) {
+			BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % m_logo_texture_filename;
+			return false;
+		}
+	}
+	else if (boost::algorithm::iends_with(m_logo_texture_filename, ".png")) {
+		if (!m_logo_texture.load_from_file(m_logo_texture_filename, true, GLTexture::MultiThreaded, true)) {
+			BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % m_logo_texture_filename;
+			return false;
+		}
+	}
+	else {
+		BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": can not load logo texture from %1%, unsupported format") % m_logo_texture_filename;
+		return false;
+	}
+	return true;
+}
+
+void PartPlateList::load_icon_textures()
+{
+	if (!icon_textures_loaded())
+		generate_icon_textures();
+}
+
+bool PartPlateList::load_next_plate_texture()
+{
+	if (!render_bedtype_logo) {
+		load_logo_texture();
+		return false;
+	}
+	return load_next_bedtype_texture() || load_next_cali_texture() || load_next_extruder_only_area_texture();
+}
+
+void PartPlateList::load_extruder_only_area_textures()
+{
+    while (load_next_extruder_only_area_texture()) {}
+}
+
+bool PartPlateList::load_next_extruder_only_area_texture()
+{
+    if (PartPlateList::is_load_extruder_only_area_textures)
+        return false;
+    if (m_next_extruder_only_area_texture == 0 && !init_extruder_only_area_info()) {
         PartPlateList::is_load_extruder_only_area_textures = true;
-        return;
+        return false;
-    }
-    GLint max_tex_size  = OpenGLManager::get_gl_info().get_max_tex_size();
-    GLint logo_tex_size = (max_tex_size < 2048) ? max_tex_size : 2048;
-    for (int i = 0; i < (unsigned int) ExtruderOnlyAreaType::btAreaCount; ++i) {
-        for (int j = 0; j < extruder_only_area_info[i].parts.size(); j++) {
-            std::string filename = resources_dir() + "/images/" + extruder_only_area_info[i].parts[j].filename;
-            if (boost::filesystem::exists(filename)) {
-                PartPlateList::extruder_only_area_info[i].parts[j].texture = new GLTexture();
-                if (!PartPlateList::extruder_only_area_info[i].parts[j].texture->load_from_svg_file(filename, true, false, false, logo_tex_size)) {
-                    BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % filename;
-                }
-            } else {
-                BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load logo texture from %1% failed!") % filename;
-            }
-        }
     }
+    if (load_next_part_texture(extruder_only_area_info, (size_t) ExtruderOnlyAreaType::btAreaCount, m_next_extruder_only_area_texture, false))
+        return true;
     PartPlateList::is_load_extruder_only_area_textures = true;
+    return false;
 }
 
 void PartPlateList::init_cali_texture_info()
@@ -7150,26 +7159,19 @@ void PartPlateList::init_cali_texture_info()
 
 void PartPlateList::load_cali_textures()
 {
-	if (PartPlateList::is_load_cali_texture) return;
+	while (load_next_cali_texture()) {}
+}
 
+bool PartPlateList::load_next_cali_texture()
+{
+	if (PartPlateList::is_load_cali_texture)
+		return false;
+	if (m_next_cali_texture == 0)
 		init_cali_texture_info();
-	GLint max_tex_size = OpenGLManager::get_gl_info().get_max_tex_size();
+	if (load_next_part_texture(&cali_texture_info, 1, m_next_cali_texture, true))
-	GLint logo_tex_size = (max_tex_size < 2048) ? max_tex_size : 2048;
+		return true;
-	for (int i = 0; i < (unsigned int)btCount; ++i) {
-		for (int j = 0; j < cali_texture_info.parts.size(); j++) {
-			std::string filename = resources_dir() + "/images/" + cali_texture_info.parts[j].filename;
-			if (boost::filesystem::exists(filename)) {
-				PartPlateList::cali_texture_info.parts[j].texture = new GLTexture();
-				if (!PartPlateList::cali_texture_info.parts[j].texture->load_from_svg_file(filename, true, true, true, logo_tex_size)) {
-					BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load cali texture from %1% failed!") % filename;
-				}
-			}
-			else {
-				BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(": load cali texture from %1% failed!") % filename;
-			}
-		}
-	}
 	PartPlateList::is_load_cali_texture = true;
+	return false;
 }
 
 void PartPlateList::on_extruder_count_changed(int extruder_count)

src/slic3r/GUI/PartPlate.hpp

@@ -644,6 +644,7 @@ class PartPlateList : public ObjectBase
     std::string m_hover_tooltip;
 
     bool m_is_dark = false;
+    bool m_icon_textures_dark = false;
 
     int m_filament_count = 1;
 
@@ -943,12 +944,25 @@ public:
     bool calc_extruder_only_area(Rect &left_only_rect, Rect &right_only_rect);
     void init_bed_type_info();
     bool init_extruder_only_area_info();
+    // Each load_*_textures() loads whatever of its set is not loaded yet; each load_next_*()
+    // loads one texture and returns false once none remain.
     void load_bedtype_textures();
+    bool load_next_bedtype_texture();
     void load_extruder_only_area_textures();
+    bool load_next_extruder_only_area_texture();
+    // Starts loading the printer's logo texture, or sends the levels compressed since; false when
+    // there is no logo to draw.
+    bool load_logo_texture();
 
     void show_cali_texture(bool show = true);
     void init_cali_texture_info();
     void load_cali_textures();
+    bool load_next_cali_texture();
+    bool icon_textures_loaded() const { return m_del_texture.get_id() != 0 && m_icon_textures_dark == m_is_dark; }
+    void load_icon_textures();
+    // Loads the next bed-type, calibration or extruder-area texture, or the logo, which rendering
+    // otherwise loads on first use; false once none remain.
+    bool load_next_plate_texture();
 
     void on_extruder_count_changed(int extruder_count);
 
@@ -960,6 +974,13 @@ public:
     BedTextureInfo bed_texture_info[btCount];
     BedTextureInfo cali_texture_info;
     BedTextureInfo extruder_only_area_info[(unsigned char) Slic3r::ExtruderOnlyAreaType::btAreaCount];
+
+private:
+    // The next part to load in each texture set, counted across the set's parts in order; reset
+    // with the set's is_load_* flag.
+    size_t m_next_bedtype_texture{ 0 };
+    size_t m_next_cali_texture{ 0 };
+    size_t m_next_extruder_only_area_texture{ 0 };
 };
 
 } // namespace GUI

src/slic3r/GUI/PartSkipDialog.cpp

@@ -148,7 +148,7 @@ PartSkipDialog::PartSkipDialog(wxWindow *parent) : DPIDialog(parent, wxID_ANY, _
     m_line->SetBackgroundColour(wxColor(238, 238, 238));
 
     m_list_view = new wxScrolledWindow(m_book_third_panel, wxID_ANY, wxDefaultPosition, wxSize(267, -1), wxHSCROLL | wxVSCROLL);
-    m_list_view->SetScrollRate(5, 5);
+    m_list_view->SetScrollRate(5, FromDIP(30));
     m_list_view->SetMinSize(wxSize(FromDIP(267), FromDIP(378)));
     m_list_view->SetMaxSize(wxSize(FromDIP(267), FromDIP(378)));
     m_list_view->SetBackgroundColour(*wxWHITE);

src/slic3r/GUI/Plater.cpp

@@ -3049,8 +3049,7 @@ Sidebar::Sidebar(Plater *parent)
 
     // add filament content
     p->m_panel_filament_content = new wxScrolledWindow(p->m_filament_area_wrapper, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL );
-    p->m_panel_filament_content->SetScrollbars(0, 100, 1, 2);
+    p->m_panel_filament_content->SetScrollRate(0, FromDIP(20));
-    p->m_panel_filament_content->SetScrollRate(0, 5);
     //p->m_panel_filament_content->SetMaxSize(wxSize{-1, FromDIP(174)});
     p->m_panel_filament_content->SetBackgroundColour(wxColour(255, 255, 255));
 
@@ -3142,8 +3141,7 @@ Sidebar::Sidebar(Plater *parent)
     // 3) Mixed filament rows, in their own scroll area so a long mixed list does not
     //    push the physical filament list off screen.
     p->m_mixed_scroll_area = new wxScrolledWindow(p->m_filament_area_wrapper, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
-    p->m_mixed_scroll_area->SetScrollbars(0, 100, 1, 2);
+    p->m_mixed_scroll_area->SetScrollRate(0, FromDIP(20));
-    p->m_mixed_scroll_area->SetScrollRate(0, 5);
     p->m_mixed_scroll_area->SetBackgroundColour(StateColor::darkModeColorFor(*wxWHITE));
     {
         auto* mix_scroll_sizer = new wxBoxSizer(wxVERTICAL);
@@ -12802,8 +12800,6 @@ void Plater::priv::on_process_completed(SlicingProcessCompletedEvent &evt)
     notification_manager->set_slicing_progress_export_possible();
 
     // Reset the "export G-code path" name, so that the automatic background processing will be enabled again.
-    const std::string lifecycle_job_name = this->background_process.fff_print() ?
-        this->background_process.fff_print()->output_filename() : std::string();
     this->background_process.reset_export();
     // This bool stops showing export finished notification even when process_completed_with_error is false
     bool has_error = false;
@@ -12850,8 +12846,18 @@ void Plater::priv::on_process_completed(SlicingProcessCompletedEvent &evt)
 
     {
         Slic3r::LifecycleEventContext ctx;
-        ctx.name = lifecycle_job_name;
+        if (const PrintBase* print = this->background_process.current_print()) {
-        ctx.code = evt.cancelled() ? Slic3r::LifecycleEvtCode::Warn : (has_error ? Slic3r::LifecycleEvtCode::Error : Slic3r::LifecycleEvtCode::Ok);
+            const Model& model = print->model();
+            ctx.id             = std::to_string(model.id().id);
+            if (model.model_info)
+                ctx.name = model.model_info->model_name;
+        } else {
+            // Realistically Printbase* print will never be null because select_technology already asserts an active print
+            // and the worker thread asserts it before processing.
+            BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << ": slicing completed without an active print; lifecycle event has no model ID";
+        }
+        ctx.code = evt.cancelled() ? Slic3r::LifecycleEvtCode::Warn :
+                                     (has_error ? Slic3r::LifecycleEvtCode::Error : Slic3r::LifecycleEvtCode::Ok);
         ctx.msg  = evt.cancelled() ? "cancelled" : (has_error ? lifecycle_error_msg : std::string());
         Slic3r::fire_lifecycle_event(Slic3r::LifecycleEvent::SlicingJobComplete, ctx);
     }

src/slic3r/GUI/Preferences.cpp

@@ -322,7 +322,7 @@ wxBoxSizer* PreferencesDialog::create_item_combobox(wxString title, wxString too
     return sizer;
 }
 
-wxBoxSizer *PreferencesDialog::create_item_combobox(wxString title, wxString tooltip, std::string param, std::vector<wxString> vlist, std::vector<std::string> config_name_index, const wxString wiki_url)
+wxBoxSizer *PreferencesDialog::create_item_combobox(wxString title, wxString tooltip, std::string param, std::vector<wxString> vlist, std::vector<std::string> config_name_index, std::function<void(std::string)> onchange, const wxString wiki_url)
 {
     assert(vlist.size() == config_name_index.size());
     unsigned int current_index = 0;
@@ -338,8 +338,9 @@ wxBoxSizer *PreferencesDialog::create_item_combobox(wxString title, wxString too
     auto [sizer, combobox] = create_item_combobox_base(title, tooltip, param, vlist, current_index);
 
     //// save config
-    combobox->GetDropDown().Bind(wxEVT_COMBOBOX, [this, param, config_name_index](wxCommandEvent& e) {
+    combobox->GetDropDown().Bind(wxEVT_COMBOBOX, [this, param, config_name_index, onchange](wxCommandEvent& e) {
         app_config->set(param, config_name_index[e.GetSelection()]);
+        if (onchange != nullptr) onchange(config_name_index[e.GetSelection()]);
         e.Skip();
     });
 
@@ -1475,7 +1476,7 @@ void PreferencesDialog::create()
     app_config = get_app_config();
 
     m_parent = new MyscrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_parent->SetScrollRate(5, 5);
+    m_parent->SetScrollRate(0, FromDIP(20));
     m_parent->SetBackgroundColour(*wxWHITE);
 
     m_sizer_body = new wxBoxSizer(wxVERTICAL);
@@ -2044,6 +2045,32 @@ void PreferencesDialog::create_items()
         "preview_default_view_type", PreviewViewTypeLabels, PreviewViewTypeValues);
     g_sizer->Add(item_preview_view_type);
 
+    auto item_reduced_detail_mode = create_item_combobox(
+        _L("Simplify preview while dragging"),
+        _L("What the sliced preview draws while you drag the camera or a preview slider, or zoom with the mouse wheel, so that large prints stay responsive. "
+           "The full toolpaths are restored as soon as you let go.\n"
+           "Off: the full toolpaths.\n"
+           "Solid model: the sliced objects and the prime tower as solid shapes in their filament colors, cut to the visible layer range, "
+           "with its bottom and top layers drawn as toolpaths. Supports are not shown, and negative volumes are not cut out.\n"
+           "Shell only: every layer without its sparse infill, internal solid infill and gap fill, which lie under the walls and skins. "
+           "Walls, top and bottom surfaces, bridges, supports and the prime tower are drawn whole, so the print looks the same from outside.\n"
+           "The bottom and top of the visible layer range are always drawn whole."),
+        "preview_reduced_detail_mode",
+        {_L("Off"), _L("Solid model"), _L("Shell only")},
+        {"off", "solid", "shell"},
+        // apply the new mode immediately to the currently loaded preview
+        [](std::string value) {
+            if (Plater* plater = wxGetApp().plater()) {
+                if (GLCanvas3D* canvas = plater->get_preview_canvas3D()) {
+                    canvas->get_gcode_viewer().set_reduced_detail_mode(value);
+                    canvas->set_as_dirty();
+                    canvas->request_extra_frame();
+                }
+            }
+        }
+    );
+    g_sizer->Add(item_reduced_detail_mode);
+
     auto item_dim_previous_layers = create_item_checkbox(
         _L("Dim lower layers"),
         _L("When scrubbing the layer slider in the sliced preview, render the layers below the current one darkened so that only the layer being viewed is shown at full brightness."),

src/slic3r/GUI/Preferences.hpp

@@ -93,7 +93,7 @@ public:
     wxBoxSizer *create_item_title(wxString title);
     wxBoxSizer *create_item_label(wxString label, const wxString tooltip = "", const wxString wiki_url = "");
     wxBoxSizer *create_item_combobox(wxString title, wxString tooltip, std::string param, std::vector<wxString> vlist, std::function<void(wxString)> onchange = {}, const wxString wiki_url = "");
-    wxBoxSizer *create_item_combobox(wxString title, wxString tooltip, std::string param, std::vector<wxString> vlist, std::vector<std::string> config_name_index, const wxString wiki_url = "");
+    wxBoxSizer *create_item_combobox(wxString title, wxString tooltip, std::string param, std::vector<wxString> vlist, std::vector<std::string> config_name_index, std::function<void(std::string)> onchange = {}, const wxString wiki_url = "");
     wxBoxSizer *create_item_region_combobox(wxString title, wxString tooltip);
     wxBoxSizer *create_item_language_combobox(wxString title, wxString tooltip);
     wxBoxSizer *create_item_loglevel_combobox(wxString title, wxString tooltip, std::vector<wxString> vlist);

src/slic3r/GUI/PrintOptionsDialog.cpp

@@ -32,7 +32,7 @@ PrintOptionsDialog::PrintOptionsDialog(wxWindow* parent)
 
 
     m_scrollwindow = new wxScrolledWindow(this, wxID_ANY);
-    m_scrollwindow->SetScrollRate(0, FromDIP(10));
+    m_scrollwindow->SetScrollRate(0, FromDIP(20));
     m_scrollwindow->SetBackgroundColour(*wxWHITE);
     m_scrollwindow->SetMinSize(wxSize(FromDIP(480), wxDefaultCoord));
     m_scrollwindow->SetMaxSize(wxSize(FromDIP(480), wxDefaultCoord));

src/slic3r/GUI/PublishSettingsDialog.cpp

@@ -1225,7 +1225,7 @@ size_t PublishSettingsDialog::category_index_for(
     }
 
     category.scroll = new wxScrolledWindow(category.page, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    category.scroll->SetScrollRate(0, 10);
+    category.scroll->SetScrollRate(0, FromDIP(20));
     category.scroll->SetBackgroundColour(GetBackgroundColour());
     category.list_sizer = new wxBoxSizer(wxVERTICAL);
     category.scroll->SetSizer(category.list_sizer);

src/slic3r/GUI/ReleaseNote.cpp

@@ -76,7 +76,7 @@ ReleaseNoteDialog::ReleaseNoteDialog(Plater *plater /*= nullptr*/)
     m_sizer_right->Add(0, 0, 1, wxTOP, FromDIP(15));
 
     m_vebview_release_note = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(560), FromDIP(430)), wxVSCROLL);
-    m_vebview_release_note->SetScrollRate(5, 5);
+    m_vebview_release_note->SetScrollRate(5, FromDIP(20));
     m_vebview_release_note->SetBackgroundColour(wxColour(0xF8, 0xF8, 0xF8));
     m_vebview_release_note->SetMaxSize(wxSize(FromDIP(560), FromDIP(430)));
 
@@ -142,7 +142,7 @@ UpdatePluginDialog::UpdatePluginDialog(wxWindow* parent /*= nullptr*/)
     operation_tips->SetMaxSize(wxSize(FromDIP(260), -1));
 
     m_vebview_release_note = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_vebview_release_note->SetScrollRate(5, 5);
+    m_vebview_release_note->SetScrollRate(5, FromDIP(20));
     m_vebview_release_note->SetBackgroundColour(wxColour(0xF8, 0xF8, 0xF8));
     m_vebview_release_note->SetMinSize(wxSize(FromDIP(260), FromDIP(150)));
     m_vebview_release_note->SetMaxSize(wxSize(FromDIP(260), FromDIP(150)));
@@ -277,7 +277,7 @@ UpdateVersionDialog::UpdateVersionDialog(wxWindow *parent)
     m_simplebook_release_note->SetBackgroundColour(wxColour(0xF8, 0xF8, 0xF8));
 
     m_scrollwindows_release_note = new wxScrolledWindow(m_simplebook_release_note, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(560), FromDIP(430)), wxVSCROLL);
-    m_scrollwindows_release_note->SetScrollRate(5, 5);
+    m_scrollwindows_release_note->SetScrollRate(5, FromDIP(20));
     m_scrollwindows_release_note->SetBackgroundColour(wxColour(0xF8, 0xF8, 0xF8));
 
     //webview
@@ -538,7 +538,7 @@ SecondaryCheckDialog::SecondaryCheckDialog(wxWindow* parent, wxWindowID id, cons
     m_sizer_right->Add(0, 0, 1, wxTOP, FromDIP(15));
 
     m_vebview_release_note = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_vebview_release_note->SetScrollRate(0, 5);
+    m_vebview_release_note->SetScrollRate(0, FromDIP(20));
     m_vebview_release_note->SetBackgroundColour(*wxWHITE);
     m_vebview_release_note->SetMinSize(wxSize(FromDIP(400), FromDIP(380)));
     m_sizer_right->Add(m_vebview_release_note, 0, wxEXPAND | wxRIGHT | wxLEFT, FromDIP(15));
@@ -823,7 +823,7 @@ PrintErrorDialog::PrintErrorDialog(wxWindow* parent, wxWindowID id, const wxStri
     m_sizer_right->Add(0, 0, 1, wxTOP, FromDIP(5));
 
     m_vebview_release_note = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_vebview_release_note->SetScrollRate(0, 5);
+    m_vebview_release_note->SetScrollRate(0, FromDIP(20));
     m_vebview_release_note->SetBackgroundColour(*wxWHITE);
     m_vebview_release_note->SetMinSize(wxSize(FromDIP(320), FromDIP(250)));
     m_sizer_right->Add(m_vebview_release_note, 0, wxEXPAND | wxRIGHT | wxLEFT, FromDIP(15));
@@ -1122,7 +1122,7 @@ ConfirmBeforeSendDialog::ConfirmBeforeSendDialog(wxWindow* parent, wxWindowID id
     m_sizer_right->Add(0, 0, 1, wxTOP, FromDIP(15));
 
     m_vebview_release_note = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
-    m_vebview_release_note->SetScrollRate(0, 5);
+    m_vebview_release_note->SetScrollRate(0, FromDIP(20));
     m_vebview_release_note->SetBackgroundColour(*wxWHITE);
     m_vebview_release_note->SetMinSize(wxSize(FromDIP(400), FromDIP(380)));
     m_sizer_right->Add(m_vebview_release_note, 0, wxEXPAND | wxRIGHT | wxLEFT, FromDIP(15));

src/slic3r/GUI/SafetyOptionsDialog.cpp

@@ -31,7 +31,7 @@ SafetyOptionsDialog::SafetyOptionsDialog(wxWindow* parent)
     SetSize(FromDIP(480),FromDIP(320));
 
     m_scrollwindow = new wxScrolledWindow(this, wxID_ANY);
-    m_scrollwindow->SetScrollRate(0, FromDIP(10));
+    m_scrollwindow->SetScrollRate(0, FromDIP(20));
     m_scrollwindow->SetBackgroundColour(*wxWHITE);
     m_scrollwindow->SetMinSize(wxSize(FromDIP(480), wxDefaultCoord));
     m_scrollwindow->SetMaxSize(wxSize(FromDIP(480), wxDefaultCoord));

src/slic3r/GUI/SelectMachine.cpp

@@ -148,7 +148,7 @@ SelectMachineDialog::SelectMachineDialog(Plater *plater)
 
     wxBoxSizer* m_scroll_sizer = new wxBoxSizer(wxVERTICAL);
     m_scroll_area              = new wxScrolledWindow(this);
-    m_scroll_area->SetScrollRate(0, 20);
+    m_scroll_area->SetScrollRate(0, FromDIP(20));
     m_scroll_area->SetBackgroundColour(m_colour_def_color);
     m_scroll_area->SetMinSize(wxSize(FromDIP(700), FromDIP(600)));
     m_scroll_area->SetMaxSize(wxSize(FromDIP(700), FromDIP(600)));
@@ -707,7 +707,7 @@ SelectMachineDialog::SelectMachineDialog(Plater *plater)
     //show bind failed info
     m_sw_print_failed_info = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(SELECT_MACHINE_DIALOG_SIMBOOK_SIZE2.x, FromDIP(125)), wxVSCROLL);
     m_sw_print_failed_info->SetBackgroundColour(*wxWHITE);
-    m_sw_print_failed_info->SetScrollRate(0, 5);
+    m_sw_print_failed_info->SetScrollRate(0, FromDIP(20));
     m_sw_print_failed_info->SetMinSize(wxSize(SELECT_MACHINE_DIALOG_SIMBOOK_SIZE2.x, FromDIP(125)));
     m_sw_print_failed_info->SetMaxSize(wxSize(SELECT_MACHINE_DIALOG_SIMBOOK_SIZE2.x, FromDIP(125)));
 

src/slic3r/GUI/SelectMachinePop.cpp

@@ -327,7 +327,7 @@ SelectMachinePopup::SelectMachinePopup(wxWindow *parent)
     m_scrolledWindow = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, SELECT_MACHINE_LIST_SIZE, wxHSCROLL | wxVSCROLL);
     m_scrolledWindow->SetBackgroundColour(*wxWHITE);
     m_scrolledWindow->SetMinSize(SELECT_MACHINE_LIST_SIZE);
-    m_scrolledWindow->SetScrollRate(0, 5);
+    m_scrolledWindow->SetScrollRate(0, SELECT_MACHINE_ITEM_SIZE.y);
     auto m_sizxer_scrolledWindow = new wxBoxSizer(wxVERTICAL);
     m_scrolledWindow->SetSizer(m_sizxer_scrolledWindow);
     m_scrolledWindow->Layout();

src/slic3r/GUI/SendMultiMachinePage.cpp

@@ -278,7 +278,7 @@ SendMultiMachinePage::SendMultiMachinePage(Plater* plater)
 
     m_main_scroll = new ScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
     m_main_scroll->SetBackgroundColour(*wxWHITE);
-    m_main_scroll->SetScrollRate(5, 5);
+    m_main_scroll->SetScrollRate(5, FromDIP(20));
 
     m_sizer_body = new wxBoxSizer(wxVERTICAL);
     m_main_page = create_page();
@@ -1353,7 +1353,7 @@ wxPanel* SendMultiMachinePage::create_page()
 
     scroll_macine_list = new wxScrolledWindow(main_page, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(800), FromDIP(300)), wxHSCROLL | wxVSCROLL);
     scroll_macine_list->SetBackgroundColour(*wxWHITE);
-    scroll_macine_list->SetScrollRate(5, 5);
+    scroll_macine_list->SetScrollRate(5, FromDIP(SEND_ITEM_MAX_HEIGHT));
     scroll_macine_list->SetMinSize(wxSize(FromDIP(DEVICE_ITEM_MAX_WIDTH), 10 * FromDIP(SEND_ITEM_MAX_HEIGHT)));
     scroll_macine_list->SetMaxSize(wxSize(FromDIP(DEVICE_ITEM_MAX_WIDTH), 10 * FromDIP(SEND_ITEM_MAX_HEIGHT)));
 

src/slic3r/GUI/SendToPrinter.cpp

@@ -384,7 +384,7 @@ SendToPrinterDialog::SendToPrinterDialog(Plater *plater)
     //show bind failed info
     m_sw_print_failed_info = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxSize(FromDIP(380), FromDIP(125)), wxVSCROLL);
     m_sw_print_failed_info->SetBackgroundColour(*wxWHITE);
-    m_sw_print_failed_info->SetScrollRate(0, 5);
+    m_sw_print_failed_info->SetScrollRate(0, FromDIP(20));
     m_sw_print_failed_info->SetMinSize(wxSize(FromDIP(380), FromDIP(125)));
     m_sw_print_failed_info->SetMaxSize(wxSize(FromDIP(380), FromDIP(125)));
 

src/slic3r/GUI/Shortcuts.cpp

@@ -147,9 +147,11 @@ constexpr std::array<ShortcutInfo, size_t(Shortcut::Count)> shortcut_table = {{
     SHORTCUT(Search,            "search",             L("Search"),                                               GLOBAL, { 'F', CTRL }),
     SHORTCUT(SwitchView,        "switch_view",        L("Switch between Prepare/Preview"),                       CANVAS, { WXK_TAB }),
     SHORTCUT(CollapseSidebar,   "collapse_sidebar",   L("Collapse/Expand the sidebar"),                          CANVAS, { WXK_TAB, SHIFT }),
-    SHORTCUT(SpeedDial,         "speed_dial",         L("Open the speed dial"),                              GLOBAL, { WXK_SPACE }),
     SHORTCUT(ReloadDevicePage,  "reload_device_page", L("Reload the device page"),                               CANVAS, { WXK_F5 }),
     SHORTCUT(KeyboardShortcuts, "keyboard_shortcuts", L("Show keyboard shortcuts list"),                         CANVAS, { '?' }),
+
+    // Speed Dial
+    SHORTCUT(SpeedDial,         "speed_dial",         L("Open the Speed Dial"),                                  GLOBAL, { WXK_SPACE }),
 }};
 
 #undef SHORTCUT
@@ -177,6 +179,7 @@ constexpr std::array<SectionInfo, size_t(ShortcutSection::Count)> section_table
     { Shortcut::ViewDefault,     L("Camera") },
     { Shortcut::ShowLabels,      L("Display") },
     { Shortcut::Preferences,     L("Application") },
+    { Shortcut::SpeedDial,       L("Speed Dial") },
 }};
 
 constexpr bool sections_follow_table_order()

src/slic3r/GUI/Shortcuts.hpp

@@ -47,7 +47,9 @@ enum class Shortcut : uint8_t {
     // Display
     ShowLabels, ShowWireframe, ToggleGcodeWindow, ToggleOneLayerMode,
     // Application
-    Preferences, Search, SwitchView, CollapseSidebar, SpeedDial, ReloadDevicePage, KeyboardShortcuts,
+    Preferences, Search, SwitchView, CollapseSidebar, ReloadDevicePage, KeyboardShortcuts,
+    // Speed Dial
+    SpeedDial,
     Count
 };
 
@@ -66,7 +68,7 @@ struct ShortcutInfo
 
 // Headings of the shortcuts dialog, in listing order.
 enum class ShortcutSection : uint8_t {
-    Project, SlicingAndPrinting, Selection, Editing, Objects, Placement, Gizmos, Sliders, PaintingTools, Camera, Display, Application,
+    Project, SlicingAndPrinting, Selection, Editing, Objects, Placement, Gizmos, Sliders, PaintingTools, Camera, Display, Application, SpeedDial,
     Count
 };
 

src/slic3r/GUI/StatusPanel.cpp

@@ -1302,7 +1302,7 @@ void PrintingTaskPanel::set_star_count(int star_count)
 StatusBasePanel::StatusBasePanel(wxWindow *parent, wxWindowID id, const wxPoint &pos, const wxSize &size, long style, const wxString &name)
     : wxScrolledWindow(parent, id, pos, size, wxHSCROLL | wxVSCROLL)
 {
-    this->SetScrollRate(25, 25);
+    SetScrollRate(25, FromDIP(20));
     Slic3r::DeviceManager* dev = Slic3r::GUI::wxGetApp().getDeviceManager();
     if (!dev) return;
     obj = dev->get_selected_machine();

src/slic3r/GUI/SyncAmsInfoDialog.cpp

@@ -700,7 +700,7 @@ SyncAmsInfoDialog::SyncAmsInfoDialog(wxWindow *parent, SyncInfo &info) :
     //wxBoxSizer *m_scroll_sizer = new wxBoxSizer(wxVERTICAL);
     m_scrolledWindow = new wxScrolledWindow(m_show_page, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
     m_scrolledWindow->SetBackgroundColour(*wxWHITE);
-    m_scrolledWindow->SetScrollRate(0, 20);
+    m_scrolledWindow->SetScrollRate(0, FromDIP(20));
     m_scrolledWindow->SetMinSize(wxSize(-1, SyncAmsInfoDialogHeightMAX));
     m_scrolledWindow->SetMaxSize(wxSize(-1, SyncAmsInfoDialogHeightMAX));
     m_scrolledWindow->EnableScrolling(false,true);

src/slic3r/GUI/Tab.cpp

@@ -3069,6 +3069,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("wipe_tower_rib_width", "multimaterial_settings_prime_tower#rib-width");
         optgroup->append_single_option_line("wipe_tower_fillet_wall", "multimaterial_settings_prime_tower#fillet-wall");
         optgroup->append_single_option_line("wipe_tower_no_sparse_layers", "multimaterial_settings_prime_tower#no-sparse-layers");
+        optgroup->append_single_option_line("wipe_tower_sparse_layers_combination", "multimaterial_settings_prime_tower#combine-sparse-layers");
         optgroup->append_single_option_line("single_extruder_multi_material_priming", "multimaterial_settings_prime_tower");
 
         optgroup = page->new_optgroup(L("Filament for Features"), L"param_filament_for_features");
@@ -7165,12 +7166,18 @@ void Tab::restore_last_select_item()
 
 bool Tab::page_build_pending() const
 {
-    return m_active_page != nullptr && m_active_page->build_pending();
+    return m_active_page != nullptr && (m_active_page->build_pending() || m_active_page->visibility_pending());
 }
 
 bool Tab::page_build_step()
 {
-    return m_active_page != nullptr && m_active_page->build_step(m_mode);
+    if (m_active_page == nullptr)
+        return false;
+    if (m_active_page->build_pending())
+        m_active_page->build_step(m_mode);
+    else
+        m_active_page->update_visibility(m_mode, true);
+    return page_build_pending();
 }
 
 void Tab::update_description_lines()
@@ -8601,6 +8608,8 @@ void Page::update_visibility(ConfigOptionMode mode, bool update_contolls_visibil
     }
 
     m_show = ret_val;
+    if (update_contolls_visibility)
+        m_visibility_applied = true;
 #ifdef __WXMSW__
     if (!m_show) return;
     // BBS: fix field control position
@@ -8654,6 +8663,7 @@ bool Page::activate_group(size_t i, ConfigOptionMode mode, std::function<void()>
     auto& group = m_optgroups[i];
     if (!group->activate(throw_if_canceled))
         return false;
+    m_visibility_applied = false;
     m_vsizer->Add(group->sizer, 0, wxEXPAND | (group->is_legend_line() ? (wxLEFT|wxTOP) : wxALL), m_parent->FromDIP(5)); // ORCA use less margin on parameters section
     group->update_visibility(mode);
 #if HIDE_FIRST_SPLIT_LINE
@@ -8688,6 +8698,7 @@ void Page::clear()
     for (auto group : m_optgroups)
         group->clear();
     m_page_title = NULL;
+    m_visibility_applied = false;
 }
 
 void Page::msw_rescale()

src/slic3r/GUI/Tab.hpp

@@ -71,6 +71,7 @@ class Page: public std::enable_shared_from_this<Page>// : public wxScrolledWindo
 	// BBS: new layout
 	wxStaticText*	m_page_title;
     bool            m_show = true;
+    bool            m_visibility_applied = false;
 public:
 	//BBS: GUI refactor
     Page(wxWindow* parent, const wxString& title, int iconID, wxPanel* tab_owner);
@@ -98,6 +99,8 @@ public:
     bool        build_pending() const;
     // Builds the next option group that has no controls yet; true while some remain.
     bool        build_step(ConfigOptionMode mode);
+    // Whether the controls have not been shown or hidden for a mode since they were built.
+    bool        visibility_pending() const { return !m_visibility_applied; }
     void        clear();
     void        msw_rescale();
     void        sys_color_changed();
@@ -443,8 +446,8 @@ public:
 	// BBS: new layout
 	void set_expanded(bool value);
 	void restore_last_select_item();
-	// page_build_pending() says whether the selected page has groups without controls, and
+	// page_build_pending() says whether the selected page has groups without controls or controls
-	// page_build_step() builds one.
+	// not yet shown for the mode, and page_build_step() does the next of those.
 	bool page_build_pending() const;
 	bool page_build_step();
 

src/slic3r/GUI/TextureImportDialog.cpp

@@ -534,7 +534,7 @@ public:
 
         m_content = new wxScrolledWindow(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxVSCROLL);
         m_content->SetBackgroundColour(pop_bg);
-        m_content->SetScrollRate(0, FromDIP(5));
+        m_content->SetScrollRate(0, FromDIP(20));
         auto* outer = new wxBoxSizer(wxVERTICAL);
 
         const int pop_w   = std::max(FromDIP(213), popup_width);
@@ -2274,7 +2274,7 @@ void TextureImportDialog::build_mapping_panel(wxWindow* parent, wxSizer* sizer)
 
     m_mapping_scroll = new wxScrolledWindow(parent, wxID_ANY, wxDefaultPosition,
                                              wxSize(-1, FromDIP(300)));
-    m_mapping_scroll->SetScrollRate(0, FromDIP(10));
+    m_mapping_scroll->SetScrollRate(0, FromDIP(20));
     m_mapping_scroll->SetBackgroundColour(StateColor::darkModeColorFor(*wxWHITE));
     m_mapping_scroll->Bind(wxEVT_MOUSEWHEEL, &TextureImportDialog::dismiss_filament_popup_on_wheel, this);
 
@@ -4335,7 +4335,7 @@ void TextureImportDialog::on_dpi_changed(const wxRect&)
 
     if (m_mapping_scroll) {
         m_mapping_scroll->SetMinSize(wxSize(-1, FromDIP(300)));
-        m_mapping_scroll->SetScrollRate(0, FromDIP(10));
+        m_mapping_scroll->SetScrollRate(0, FromDIP(20));
     }
 
     if (m_btn_skip) {

src/slic3r/GUI/UnsavedChangesDialog.cpp

@@ -942,7 +942,7 @@ void UnsavedChangesDialog::build(Preset::Type type, PresetCollection *dependent_
     m_sizer_tab->Add(m_table_top, 1, 0, 0);
 
     m_scrolledWindow = new wxScrolledWindow(m_panel_tab, wxID_ANY, wxDefaultPosition, UNSAVE_CHANGE_DIALOG_SCROLL_WINDOW_SIZE,  wxNO_BORDER|wxVSCROLL);
-    m_scrolledWindow->SetScrollRate(0, 5);
+    m_scrolledWindow->SetScrollRate(0, FromDIP(20));
     m_scrolledWindow->SetBackgroundColour(GREY200);
     m_sizer_bottom = new wxBoxSizer(wxVERTICAL);
     m_sizer_bottom->Add(m_scrolledWindow, 1, wxEXPAND, 0);