fix: timestamp format for OFL OTA update endpoint (#15936)

# Description

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  > * What issue does this PR address or fix?
  > * What new features or enhancements does this PR introduce?
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The OFL OTA workflow sent an ISO-8601 timestamp to the pending-clear
endpoint, which only accepts Unix epoch seconds. This caused the
scheduled workflow to fail with HTTP 400.

Use `data -u +%s` so that request matches the endpoint contract. 

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## Tests

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.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
-# table (POST /api/v1/ota/ofl/pending/clear) - the daily "published everything, reset" signal.
-# That table is populated only by this pipeline's own auto-publish calls.
+# At the start of each run, the pending-publish table is cleared up to a captured
+# timestamp (POST /api/v1/ota/ofl/pending/clear?timestamp=...). Changes merged after
+# 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 $branch; treating OFL as changed."
-              changed=true
-            else
-              changed_files="$(git log --since="$since" --name-only --pretty=format: "origin/$branch" -- \
+              echo "No prior successful run for $branch; checking OFL changes up to $SCAN_UNTIL."
+              changed_files="$(git log --until="$SCAN_UNTIL" --name-only --pretty=format: "origin/$branch" -- \
                 resources/profiles/OrcaFilamentLibrary resources/profiles/OrcaFilamentLibrary.json \
                 | sed '/^$/d')"
-              if [ -n "$changed_files" ]; then
-                echo "OFL changed on $branch since $since:"
-                echo "$changed_files"
-                changed=true
-              else
-                echo "No OFL changes on $branch since $since."
-                changed=false
-              fi
+            else
+              changed_files="$(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 from ${since:-the beginning} through $SCAN_UNTIL:"
+              echo "$changed_files"
+              changed=true
+            else
+              echo "No OFL changes on $branch through $SCAN_UNTIL."
+              changed=false
             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
-screen and the others are not; some of them are opened later in the session, some
-never, and some only exist for certain printers. Building a tab before the first frame
-adds its cost to every startup, whether or not the tab is used.
+The main window is a notebook of tabs, and only one of them is on screen when the first
+frame appears. Others are opened later in the session, some never, and some only exist
+for certain printers. Building every tab before the first frame makes each startup pay for
+tabs the user may never open.
 
-This subsystem builds a tab's panel the first time the tab is shown. It also builds the
-remaining tabs while the user is idle after startup, in units of tens of milliseconds,
-so a click that lands in the middle of one waits for that unit and no longer. Startup
-pays only for what the first frame shows, and the other tabs are usually built before
-anyone opens them.
+This subsystem builds a tab the first time it is shown, and builds the rest in small units
+while the user is idle after startup. Startup pays only for what the first frame shows,
+the other tabs are usually ready before anyone opens them, and a click that lands in the
+middle of the idle build waits for one unit at most. Work that is not a tab, such as a
+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`
-(with its wx-free `PrebuildQueue.hpp`) are independent. A holder can hold anything a
-factory makes, a page is a holder with a placeholder widget, a staged object can live
-outside a holder, and the scheduler knows none of them; it runs tasks, which `MainFrame`
-makes from the holders.
+The parts are independent. A holder can hold anything a factory makes, a placeholder page
+is a holder with a widget, a staged object can live outside a holder, and the scheduler
+knows none of them; it runs tasks, which the main window 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
-in the idle queue, both given by the owner. The header has no wx dependency; the busy
-cursor for an on-demand build lives in `Lazy.cpp` and is skipped when there is no app,
-so the holder is unit-tested.
+A holder keeps one object and the factory that makes it. The rest of the app reads the
+object if it exists, makes sure it exists now when about to show or navigate to it, or runs
+something once it exists. A type with one instance in the app gets these as statics
+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.
-- `ensure()` builds whatever is left now, under a busy cursor, and returns the object, or
-  null in the two cases below. A click on an unbuilt tab or a first open of a dialog goes
-  through this, and it logs the units and time it took.
-- `build_step()` runs one unit of construction and returns true while more remain. The
-  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 guarantees that callers see the object only once it is completely built. A
+build cannot re-enter itself, so a nested request finds nothing yet, and a factory that
+returns null or a unit that throws leaves the holder and the scheduler able to carry on.
+The holder does not own the object; its wx parent does, as for any window. The holder has
+no wx dependency and is unit-tested.
 
-The holder does not own the object; its wx parent does, as for any window. A type with
-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.
+### The placeholder page: `LazyPage<Panel>`
 
-`built()` is an atomic flag, since a job worker reads it through the statics
-(`MainFrame::get_calibration_curr_tab()`); it is set after the object is complete.
+The notebook needs a page object for a tab to exist and for tabs to be inserted and
+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()`,
-`build_step()`, `prebuild_order()`) and is what the scheduler side sees.
+### Staged construction: `StagedBuild`
 
-### 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
-factory makes the panel inside it (by default `new Panel(parent)`). The notebook needs a
-page object for the tab to exist and for `show_device()` to insert and remove tabs by
-pointer, and the placeholder is that object. `MainFrame` creates every page once, named
-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
+- members created in steps start out null, so a partly built panel can be destroyed;
+- timers, event handlers and destructors that touch step content check that the panel is
+  complete first;
+- nothing takes focus while off screen, since a unit 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
-  constructor adds an empty slot sizer in that position and the step fills the slot
-  (`StatusBasePanel`).
+- a widget added by a step keeps its place in the sizer through an empty slot the skeleton
+  creates.
 
-### IdleScheduler: when to build
+### The scheduler: `IdleScheduler` and `PrebuildQueue`
 
-A task is any `LazyBase`: a name for the log, `pending()`, `build_step()` and
-`prebuild_order()`. `PrebuildQueue` holds the tasks by order (equal order in the order
-added) and runs a slice, the units of the first pending task until it completes, the
-budget is spent on the clock it is given, or the interrupt predicate says input arrived.
-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.
+The queue holds tasks in order, and a slice runs units of the first pending task until
+the task finishes, the time budget is spent, or input arrives. It has no wx dependency and
+is unit-tested with a fake clock. A task whose work goes away, such as a tab removed from
+the book, is skipped, and becomes pending again if the work comes back.
 
-`IdleScheduler` drives the queue with the real clock, the app's input timestamp and the
-Windows queue check, and logs each unit and slice. Each slice is a timer message: a
-period of 250 ms while waiting for the user to go quiet, and a one-shot of zero after a
-slice that left work, so the event loop dispatches whatever it has queued (paint,
-timers, input) before the next slice runs. Chaining slices with `CallAfter` would not do
-this: wx drains pending events fully before the next native message, on every platform.
-On GTK the one-shot is 5 ms, because a due GLib timeout runs ahead of the redraw and
-idle sources that paint and deliver posted events.
-A slice runs only once the user has been idle for the quiet time, and the timer stops
-itself once no task is pending. The tick period, quiet time and slice length are
-constants in `IdleScheduler.cpp`. A unit cannot be interrupted once started, so the
-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.
+A slice runs only once the user has been idle for a short quiet time, and each slice is its
+own timer message, so paint, timers and input queued in between are handled before the
+next slice. Posting slices as pending events would not do that, because wx drains every
+pending event before the next native message. On GTK a timer that is always due starves
+the lower-priority sources that repaint and deliver posted events, so slices are a few
+milliseconds apart. On Windows a slice also waits while the native queue holds input,
+not counting mouse moves, which Windows synthesizes whenever a window appears under the
+cursor. A slice never runs inside a `wxYield()`, where it would build pages in the middle of
+the code that yielded. A unit cannot be interrupted, so the largest unit bounds how long a
+click can wait.
+When nothing is pending the timer stops and the subsystem costs nothing.
 
-The tasks are made by their owners. `MainFrame::prebuild_pages_when_idle()` registers
-every `LazyPage` the frame created, in or out of the book (`pending()` is false for a
-page out of the book), the Compare presets holder, and the Prepare sidebar's settings
-page from `ParamsPanel::settings_page_prebuild()`, whose first unit selects the default
-tab if none is selected yet and whose later units build one option group each.
-`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.
+The main window owns the scheduler because it owns what the tasks build, and clearing the
+queue with the window keeps a task from outliving its object. Each owner provides its own
+tasks, such as a tab, a dialog, the Prepare tab's settings page one option group at a
+time, the Prepare page's layout at the size the book gives its pages, or the 3D view's GL
+resources.
 
-Idle time comes from `GUI_App::FilterEvent`, which timestamps mouse and keyboard events
-(`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.
+### The 3D view's GL resources
 
-Once every registered page is built the timer is stopped and the subsystem costs
-nothing.
+OpenGL is loaded on the Prepare tab's canvas. When the start page is not Prepare, loading
+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()`
-needs its GL canvas on screen to initialise OpenGL in every startup state, and the start
-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.
+**Before the first frame.** Only the start page and the Prepare tab's plater are built
+before the first frame. Everything else goes through a holder.
 
-**Reaching a lazy object.** A caller uses the type's own statics. `T::if_built()` may
-return null and is for telling the object something it can live without (a rescale, a
-colour change, a status update). `T::ensure()` builds the object and is for navigating
-to it or for a caller that is about to show it. A caller that tells the object something
-it would not fetch for itself on construction uses `T::when_built()`, which keeps the
-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()`.
+**Reaching a lazy object.** Callers use the type's statics. Reading it if built is for
+things the object can live without, such as a rescale, a color change or a status refresh.
+Making sure it exists is for navigating to it or showing it. Running something once it is
+built is for state it would not fetch for itself on construction. A panel that pulls its
+state when constructed only ever needs to be read if built.
 
-**Unit size.** A unit cannot be interrupted, so it should stay within the slice length on
-a fast machine. A constructor above that is staged. A single widget above it is the
-floor unless the widget itself is split.
+**Unit size.** A unit should fit in one slice on a fast machine. A constructor over that is
+staged, and a single widget over it is accepted unless the widget itself can be split.
 
-**Order.** Cheapest and most likely to be opened first, given where `MainFrame` creates
-each holder. The settings page is 0 (the Prepare tab's own content), Home 10, Device 20
-(a Bambu user's usual second stop), Calibration 30, Multi-device 40, the web Device
-view 50, Project 60 (a second WebView2 instance) and the Compare presets dialog 100;
-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.
+**Order.** Tasks run cheapest and most likely to be opened first. Each holder's order is
+given where it is created, with gaps so a new task fits between its neighbors. A negative
+order is never prebuilt, for something few sessions open that costs more to build unasked
+than it saves.
 
 ## 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.
-2. A `LazyPage<Panel>*` member in `MainFrame`, created once in `init_tabpanel()` with
-   its `TAB_ID_*` as the name, its place by the order rule (and a factory if
-   `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, keep the skeleton in the constructor, move the rest into
+steps in its original order, and follow the staged-construction constraints. Measure the
+units; a step that is still one big widget is split inside the widget or accepted.
 
-To stage a heavy constructor, inherit `StagedBuild`, keep the skeleton in the constructor,
-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.
+## Verifying
 
-Verification is by log. `MainFrame::prebuild_pages_when_idle` lists the queue it
-registered, `IdleScheduler::tick` reports each completed task by name at info level and
-each slice and unit at debug level, and `Lazy::ensure` reports an object a user built
-on demand with the units and time it took. A run from the configured start
-page shows every registered page complete, in order, with no unit longer than intended.
-A click on a tab mid-prebuild shows the finished panel with an `ensure` line for what was
-left, and the slices resume for the remaining tasks once the user is idle again.
+The log lists the queue when it is registered, reports each completed task at info level
+and each slice and unit at debug level, and reports every on-demand build with its units
+and time. A task's completion line counts only the slice it finished in. A run from the
+configured start page should show every registered task complete in order, with no unit
+longer than intended. A click on a tab during the idle build should show an on-demand
+build for what was left, with the slices resuming once the user is idle again.

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/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
-            this->values.resize(rhs_vec->size(), this->values.front());
+        else {
+            T v = this->values.front();
+            this->values.resize(rhs_vec->size(), v);
+        }
 
         assert(default_index.size() == rhs_vec->size());
 

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]);
 
@@ -3070,162 +3095,6 @@ 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 +3229,6 @@ 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 +3580,157 @@ 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_internal The distance threshold to consider for proximity for a reference perimeter with inset index 1+
+ * @param threshold_external The minimum touching distance for a reference perimeter with inset index 0 
+ * @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);
-            double distance = MultiPoint::minimumDistanceBetweenLinesDefinedByPoints(referencePoints, points);
-            // Add to touchingIndices if within threshold distance
-            size_t threshold=0;
-            if(referenceEntity.extrusion->inset_idx == 0)
-                threshold = threshold_external;
-            else
-                threshold = threshold_internal;
-            if (distance <= threshold) {
+            // Add to touchingIndices if the lines touch.
+            const double threshold = double(referenceEntity.extrusion->inset_idx == 0 ? threshold_external : threshold_internal);
+            if (arachne_lines_touch(*referenceEntity.extrusion, *entity.extrusion, 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"

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/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/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);
@@ -7283,6 +7281,16 @@ 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 +7303,10 @@ 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

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);
@@ -1301,6 +1299,8 @@ 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;

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/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.
-#ifdef __WXGTK__
+// Delay before the next slice; on GTK a due timer runs ahead of repaints and posted events,
+// 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, {
@@ -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/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.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,
-        // its first unit selects the default one.
+        // Builds the selected page's option groups at idle and then shows them for the mode;
+        // 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()) {
-			m_partplate_list->m_logo_texture.reset();
+		if (!m_partplate_list->load_logo_texture())
 			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;
-	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();
+	load_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;
 }
 
-void PartPlateList::load_bedtype_textures()
+static GLint logo_texture_size()
 {
-	if (PartPlateList::is_load_bedtype_textures) return;
-
-	init_bed_type_info();
-	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)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 std::min<GLint>(OpenGLManager::get_gl_info().get_max_tex_size(), 2048);
 }
 
-void PartPlateList::load_extruder_only_area_textures() {
-    if (PartPlateList::is_load_extruder_only_area_textures) return;
+// 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;
+}
 
-    auto ok  = init_extruder_only_area_info();
-    if (!ok) {
+void PartPlateList::load_bedtype_textures()
+{
+	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();
+	if (load_next_part_texture(bed_texture_info, btCount, m_next_bedtype_texture, true))
+		return true;
+	PartPlateList::is_load_bedtype_textures = true;
+	return false;
+}
+
+bool PartPlateList::load_logo_texture()
+{
+	if (m_logo_texture_filename.empty()) {
+		m_logo_texture.reset();
+		return false;
+	}
+
+	if (m_logo_texture.get_id() != 0 && m_logo_texture.get_source() == m_logo_texture_filename) {
+		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;
-    }
-    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;
-            }
-        }
+        return false;
     }
+    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()) {}
+}
 
-	init_cali_texture_info();
-	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)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;
-			}
-		}
-	}
+bool PartPlateList::load_next_cali_texture()
+{
+	if (PartPlateList::is_load_cali_texture)
+		return false;
+	if (m_next_cali_texture == 0)
+		init_cali_texture_info();
+	if (load_next_part_texture(&cali_texture_info, 1, m_next_cali_texture, true))
+		return true;
 	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/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/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_step() builds one.
+	// page_build_pending() says whether the selected page has groups without controls or controls
+	// 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/Widgets/WebView.cpp

@@ -10,6 +10,7 @@
 
 #include <wx/webviewarchivehandler.h>
 #include <wx/webviewfshandler.h>
+#include <wx/weakref.h>
 #if wxUSE_WEBVIEW_EDGE
 #include <wx/msw/webview_edge.h>
 #elif defined(__WXMAC__)
@@ -235,7 +236,9 @@ class FakeWebView : public wxWebView
 wxDEFINE_EVENT(EVT_WEBVIEW_RECREATED, wxCommandEvent);
 
 static std::vector<wxWebView*> g_webviews;
-static std::vector<wxWebView*> g_delay_webviews;
+// Webviews waiting for their script handler while another one is added; adding it yields, so a
+// view can be destroyed while it waits.
+static std::vector<wxWeakRef<wxWebView>> g_delay_webviews;
 
 class WebViewRef : public wxObjectRefData
 {
@@ -340,8 +343,9 @@ wxWebView* WebView::CreateWebView(wxWindow * parent, wxString const & url)
                 addScriptMessageHandler(webView);
                 while (!g_delay_webviews.empty()) {
                     auto views = std::move(g_delay_webviews);
-                    for (auto wv : views)
-                        addScriptMessageHandler(wv);
+                    for (const wxWeakRef<wxWebView>& wv : views)
+                        if (wv)
+                            addScriptMessageHandler(wv.get());
                 }
             }
 #ifndef __WIN32__

tests/fff_print/test_fill.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <functional>
 #include <map>
 #include <numeric>
 #include <sstream>
@@ -11,8 +12,10 @@
 #include "libslic3r/ClipperUtils.hpp"
 #include "libslic3r/AABBTreeLines.hpp"
 #include "libslic3r/Fill/Fill.hpp"
+#include "libslic3r/Fill/FillAdaptive.hpp"
 #include "libslic3r/Flow.hpp"
 #include "libslic3r/Geometry.hpp"
+#include "libslic3r/IntersectionPoints.hpp"
 #include "libslic3r/Layer.hpp"
 #include "libslic3r/Print.hpp"
 #include "libslic3r/PrintConfig.hpp"
@@ -1196,6 +1199,231 @@ TEST_CASE("Trapezoidal grid infill rounds its corners only with more than one li
     REQUIRE(single_smooth.length == single_sharp.length);
 }
 
+TEST_CASE("Multiline cubic infill follows the cubic lines without crossing itself", "[Fill]")
+{
+    const int    multiline = GENERATE(2, 3);
+    const double spacing   = 0.45;
+    const double density   = 0.3;
+    const double wall      = multiline * spacing;
+    CAPTURE(multiline);
+
+    const ExPolygon region{ Slic3r::Points{ Point::new_scale(0., 0.), Point::new_scale(40., 0.),
+                                            Point::new_scale(40., 40.), Point::new_scale(0., 40.) } };
+    auto fill = [&region, spacing](int lines, double density, size_t layer_id, double z) {
+        std::unique_ptr<Slic3r::Fill> filler(Slic3r::Fill::new_from_type("cubic"));
+        filler->spacing  = spacing;
+        filler->angle    = float(M_PI / 7.);
+        filler->layer_id = layer_id;
+        filler->z        = z;
+
+        FillParams params;
+        params.density           = float(density);
+        params.multiline         = lines;
+        params.dont_adjust       = true;
+        params.anchor_length_max = 0.f; // The bare pattern, without connections along the boundary.
+        Slic3r::Surface surface(stInternal, region);
+        return filler->fill_surface(&surface, params);
+    };
+    // Away from the boundary, where a line is clipped earlier than the side of its wall.
+    const Polygons inner = shrink(to_polygons(region), scale_(3.));
+    auto farthest = [&inner](const Polylines &from, const Polylines &to) {
+        const AABBTreeLines::LinesDistancer<Line> tree(to_lines(to));
+        double distance = 0.;
+        for (const Polyline &path : intersection_pl(from, inner))
+            for (const Point &point : path.equally_spaced_points(scale_(0.2)))
+                distance = std::max(distance, tree.distance_from_lines<false>(point));
+        return unscale<double>(distance);
+    };
+
+    // One z period of the pattern: sqrt(2) / 3 of the 3 * wall / density line spacing.
+    const double z_period = std::sqrt(2.) * wall / density;
+    const size_t layers   = 30;
+    for (size_t layer_id = 0; layer_id < layers; ++layer_id) {
+        const double z = z_period * (layer_id + 0.5) / layers;
+        CAPTURE(layer_id, z);
+        const Polylines walls = fill(multiline, density, layer_id, z);
+        REQUIRE_FALSE(walls.empty());
+        CHECK(get_intersections(to_lines(walls)).empty());
+        // Long paths running out to the boundary, not loops around the cells.
+        CHECK(std::none_of(walls.begin(), walls.end(), [](const Polyline &path) { return path.first_point() == path.last_point(); }));
+
+        // Single lines at the same spacing: the walls are drawn along them.
+        const Polylines lines = fill(1, density / multiline, layer_id, z);
+        REQUIRE_FALSE(lines.empty());
+        CHECK(farthest(lines, walls) < 0.5 * wall);
+        CHECK(farthest(walls, lines) < 1.5 * wall);
+    }
+}
+
+TEST_CASE("Multiline adaptive cubic infill keeps its lines apart without closing them around the cells", "[Fill]")
+{
+    const std::string pattern   = GENERATE("adaptivecubic", "supportcubic");
+    const int         multiline = GENERATE(2, 3);
+    CAPTURE(pattern, multiline);
+
+    // A sphere refines the octree all around, so the finer lines end on the coarser ones at every layer.
+    TriangleMesh sphere = Slic3r::Test::mesh(Slic3r::Test::TestMesh::sphere_50mm);
+    sphere.scale(0.3f);
+    Print print;
+    Slic3r::Test::init_and_process_print({sphere}, print,
+                                        {{"sparse_infill_pattern", pattern},
+                                         {"sparse_infill_density", "40%"},
+                                         {"fill_multiline", multiline},
+                                         {"infill_anchor", 0},
+                                         {"infill_anchor_max", 0},
+                                         {"layer_height", 0.3}});
+
+    size_t paths = 0, loops = 0;
+    for (const Layer *layer : print.objects().front()->layers()) {
+        Polylines printed;
+        Polygons  sparse;
+        double    spacing = 0.;
+        for (const LayerRegion *region : layer->regions()) {
+            for (const ExtrusionEntity *entity : region->fills.flatten().entities)
+                if (entity->role() == erInternalInfill)
+                    entity->collect_polylines(printed);
+            for (const Surface &surface : region->fill_surfaces.surfaces)
+                if (surface.surface_type == stInternal)
+                    append(sparse, shrink(to_polygons(surface.expolygon), scale_(1.)));
+            spacing = region->flow(frInfill).spacing();
+        }
+        if (printed.empty())
+            continue;
+        CAPTURE(layer->print_z);
+        paths += printed.size();
+        loops += std::count_if(printed.begin(), printed.end(), [](const Polyline &pl) { return pl.first_point() == pl.last_point(); });
+        CHECK(get_intersections(to_lines(printed)).empty());
+
+        // Neighbouring lines stay a line spacing apart, less the overlap of a line end with the wall it stops on.
+        // Pieces of one line that meet end to end are one line.
+        std::vector<size_t> line_of(printed.size());
+        std::iota(line_of.begin(), line_of.end(), 0);
+        std::function<size_t(size_t)> find = [&](size_t i) { return line_of[i] == i ? i : line_of[i] = find(line_of[i]); };
+        for (size_t i = 0; i < printed.size(); ++i)
+            for (size_t j = i + 1; j < printed.size(); ++j)
+                for (const Point &a : { printed[i].first_point(), printed[i].last_point() })
+                    for (const Point &b : { printed[j].first_point(), printed[j].last_point() })
+                        if ((a - b).cast<double>().norm() < SCALED_EPSILON)
+                            line_of[find(i)] = find(j);
+        Lines               lines;
+        std::vector<size_t> owner;
+        for (size_t i = 0; i < printed.size(); ++i)
+            for (const Line &line : printed[i].lines()) {
+                lines.push_back(line);
+                owner.push_back(find(i));
+            }
+        AABBTreeLines::LinesDistancer<Line> tree(lines);
+        double closest = spacing;
+        for (size_t i = 0; i < printed.size(); ++i)
+            for (const Point &p : printed[i].equally_spaced_points(scale_(0.1)))
+                if (contains(sparse, p))
+                    for (size_t k : tree.all_lines_in_radius(p, scale_(spacing)))
+                        if (owner[k] != find(i))
+                            closest = std::min(closest, unscale<double>(lines[k].distance_to(p)));
+        CHECK(closest > 0.45 * spacing);
+    }
+    REQUIRE(paths > 0);
+    // The lines run on through the cells instead of each cell getting its own loops.
+    CHECK(loops < paths / 4);
+}
+
+TEST_CASE("Multiline adaptive cubic paths touch where they bounce off each other", "[Fill]")
+{
+    const int    sweep = GENERATE(0, 1, 2);
+    // Offset of the third family in walls, so the three meet in points or in small triangles.
+    const double shift = GENERATE(0., 0.1, 0.5, 1., 2.5, -0.5, -1.);
+    // Like finer octree lines ending on coarser ones, the 60 degree lines may start on the horizontal line through 0.
+    const bool   starting = GENERATE(false, true);
+    CAPTURE(sweep, shift, starting);
+
+    const double d1 = scale_(0.8), pitch = scale_(8.), inner = scale_(12.);
+    Lines        lines;
+    for (int k = 0; k < 3; ++k) {
+        const Vec2d dir(std::cos(k * M_PI / 3.), std::sin(k * M_PI / 3.)), normal(-dir.y(), dir.x());
+        for (int i = -6; i <= 6; ++i) {
+            const Vec2d  mid   = (i * pitch + (k == 2 ? shift * d1 : 0.)) * normal;
+            const double start = k == 1 && starting ? -mid.y() / dir.y() : -10. * pitch;
+            lines.emplace_back((mid + start * dir).cast<coord_t>(), (mid + 10. * pitch * dir).cast<coord_t>());
+        }
+    }
+    const Polylines paths = FillAdaptive::multiline_paths(lines, d1, 0., sweep, BoundingBox(Point::new_scale(-20., -20.), Point::new_scale(20., 20.)));
+    REQUIRE_FALSE(paths.empty());
+    CHECK(get_intersections(to_lines(paths)).empty());
+
+    Lines               pieces;
+    std::vector<size_t> owner;
+    for (size_t i = 0; i < paths.size(); ++i)
+        for (const Line &line : paths[i].lines()) {
+            pieces.push_back(line);
+            owner.push_back(i);
+        }
+    AABBTreeLines::LinesDistancer<Line> tree(pieces);
+    auto clearance = [&](size_t i) {
+        const Line &a        = pieces[i];
+        double      distance = std::numeric_limits<double>::max();
+        for (size_t j : tree.all_lines_in_radius(a.midpoint(), 0.5 * a.length() + 2. * d1))
+            if (owner[j] != owner[i]) {
+                const Line &b = pieces[j];
+                distance      = std::min({ distance, a.distance_to(b.a), a.distance_to(b.b), b.distance_to(a.a), b.distance_to(a.b) });
+            }
+        return distance;
+    };
+    auto inside = [inner](const Point &p) { return std::abs(p.x()) < inner && std::abs(p.y()) < inner; };
+
+    double closest = std::numeric_limits<double>::max();
+    for (size_t i = 0; i < pieces.size(); ++i)
+        if (inside(pieces[i].midpoint()))
+            closest = std::min(closest, clearance(i));
+    CHECK(closest > 0.99 * d1);
+
+    // Each path at a crossing touches another one there, none stops short of it.
+    double widest = 0.;
+    for (size_t i = 0; i < lines.size(); ++i)
+        for (size_t j = i + 1; j < lines.size(); ++j)
+            if (Point crossing; line_alg::intersection(lines[i], lines[j], &crossing) && inside(crossing)) {
+                std::map<size_t, double> at;
+                for (size_t k : tree.all_lines_in_radius(crossing, 1.2 * d1))
+                    at.emplace(owner[k], std::numeric_limits<double>::max());
+                for (size_t k : tree.all_lines_in_radius(crossing, 2. * d1))
+                    if (auto it = at.find(owner[k]); it != at.end())
+                        it->second = std::min(it->second, clearance(k));
+                for (const auto &path : at)
+                    widest = std::max(widest, path.second);
+            }
+    CHECK(widest < 1.02 * d1);
+}
+
+TEST_CASE("Multiline adaptive cubic paths reach the line they end on when another path ends on them", "[Fill]")
+{
+    const int    sweep = GENERATE(0, 1, 2);
+    // Where the 120 degree line starts on the horizontal one, in walls from the 60 degree line.
+    const double start = GENERATE(0.3, 0.6, 1., 2.);
+    CAPTURE(sweep, start);
+
+    const double d1 = scale_(0.8), overlap = 0.1 * d1, length = scale_(30.);
+    const Vec2d  diagonal(0.5, 0.5 * std::sqrt(3.)), horizontal(1., 0.), steep(-0.5, 0.5 * std::sqrt(3.));
+    const Vec2d  on_horizontal = start * d1 * horizontal;
+    const Lines  lines{ Line((-length * diagonal).cast<coord_t>(), (length * diagonal).cast<coord_t>()),
+                        Line(Point(0, 0), (length * horizontal).cast<coord_t>()),
+                        Line(on_horizontal.cast<coord_t>(), (on_horizontal - length * steep).cast<coord_t>()) };
+    const Polylines paths = FillAdaptive::multiline_paths(lines, d1, overlap, sweep, BoundingBox(Point::new_scale(-40., -40.), Point::new_scale(40., 40.)));
+
+    // The end of the path along each line nearest to where that line starts.
+    auto end_along = [&paths](const Line &line) {
+        for (const Polyline &path : paths)
+            if (line.distance_to(path.first_point()) < SCALED_EPSILON && line.distance_to(path.last_point()) < SCALED_EPSILON)
+                return (path.first_point() - line.a).cast<double>().norm() < (path.last_point() - line.a).cast<double>().norm() ? path.first_point() : path.last_point();
+        return Point(std::numeric_limits<coord_t>::max(), 0);
+    };
+    const Point horizontal_end = end_along(lines[1]), steep_end = end_along(lines[2]);
+    REQUIRE(horizontal_end.x() != std::numeric_limits<coord_t>::max());
+    REQUIRE(steep_end.x() != std::numeric_limits<coord_t>::max());
+    // Both reach the overlap into the wall of the path they stop at, none stops short of it.
+    CHECK_THAT(line_alg::distance_to_infinite(lines[0], horizontal_end) / d1, Catch::Matchers::WithinAbs(0.9, 0.01));
+    CHECK(lines[1].distance_to(steep_end) / d1 < 0.91);
+    CHECK(get_intersections(to_lines(paths)).empty());
+}
+
 TEST_CASE("3D honeycomb infill rounds its octahedral waves with the smooth factor", "[Fill]")
 {
     auto shape_for = [](const std::string &smooth_factor) {

tests/fff_print/test_perimeters.cpp

@@ -630,3 +630,97 @@ TEST_CASE("A lower layer sliver too thin to print does not support the wall abov
     // A rib that does get printed takes the 20mm outer wall running along it out of the overhangs.
     CHECK(printable < no_rib - scale_(15.));
 }
+
+namespace {
+
+// Every setting the fuzzy skin assertions below depend on.
+DynamicPrintConfig fuzzy_skin_config(const char *wall_generator)
+{
+    DynamicPrintConfig config = DynamicPrintConfig::full_print_config();
+    config.set_deserialize_strict({
+        { "wall_generator",             wall_generator },
+        { "layer_height",               0.2 },
+        { "initial_layer_print_height", 0.2 },
+        // One wall, so every wall point along the long sides belongs to the fuzzed outer wall.
+        { "wall_loops",                 1 },
+        { "fuzzy_skin",                 "external" },
+        { "fuzzy_skin_noise_type",      "classic" },
+        { "fuzzy_skin_thickness",       0.3 },
+        { "fuzzy_skin_point_distance",  0.8 },
+    });
+    return config;
+}
+
+// How far the wall points over the middle 60% of the layer's length stray across its width, worst side.
+// A negative result means there is no layer at `print_z`.
+double mid_span_wall_spread(const Print &print, double print_z)
+{
+    for (const Layer *layer : print.objects().front()->layers()) {
+        if (std::abs(layer->print_z - print_z) > 1e-4)
+            continue;
+        const BoundingBox bbox  = get_extents(layer->lslices);
+        const coord_t     x_min = bbox.min.x() + bbox.size().x() / 5;
+        const coord_t     x_max = bbox.max.x() - bbox.size().x() / 5;
+        Points            points;
+        for (const LayerRegion *region : layer->regions())
+            region->perimeters.collect_points(points);
+        coord_t spread = 0;
+        for (const bool south : { true, false }) {
+            coord_t lo = bbox.max.y(), hi = bbox.min.y();
+            for (const Point &p : points)
+                if (p.x() > x_min && p.x() < x_max && (p.y() < bbox.center().y()) == south) {
+                    lo = std::min(lo, p.y());
+                    hi = std::max(hi, p.y());
+                }
+            spread = std::max(spread, hi - lo);
+        }
+        return unscale<double>(spread);
+    }
+    return -1.;
+}
+
+} // namespace
+
+// TestMesh::bridge is a 50x10mm deck from z=5 to z=8 on two 5mm-wide pillars, leaving a 40mm span. The deck's
+// first layer (print_z 5.2) crosses the span unsupported; the layers above it rest on the deck.
+TEST_CASE("Fuzzy skin leaves the walls of a bridge smooth", "[Perimeters]")
+{
+    const char *wall_generator = GENERATE("classic", "arachne");
+    CAPTURE(wall_generator);
+
+    Print print;
+    init_and_process_print({ TestMesh::bridge }, print, fuzzy_skin_config(wall_generator));
+    REQUIRE_FALSE(print.objects().empty());
+
+    // Control: one deck layer up the same walls rest on the deck, so they are fuzzed.
+    CHECK(mid_span_wall_spread(print, 5.6) > 0.1);
+    // Over the unsupported span the walls stay straight.
+    const double bridged = mid_span_wall_spread(print, 5.2);
+    CHECK(bridged >= 0.);
+    CHECK(bridged < 0.001);
+}
+
+// One object: a 20x20x3mm block on the bed and a second one floating above it from z=5 to z=8. The layers in
+// the gap are empty, so the floating block's first layer (print_z 5.2) has a layer below it with nothing
+// printed on it; the layers above rest on the floating block.
+TEST_CASE("Fuzzy skin leaves the walls over an empty layer smooth", "[Perimeters]")
+{
+    const char *wall_generator = GENERATE("classic", "arachne");
+    CAPTURE(wall_generator);
+
+    TriangleMesh mesh     = make_cube(20., 20., 3.);
+    TriangleMesh floating = make_cube(20., 20., 3.);
+    floating.translate(0.f, 0.f, 5.f);
+    mesh.merge(floating);
+
+    Print print;
+    init_and_process_print({ mesh }, print, fuzzy_skin_config(wall_generator));
+    REQUIRE_FALSE(print.objects().empty());
+
+    // Control: one layer up the walls rest on the floating block, so they are fuzzed.
+    CHECK(mid_span_wall_spread(print, 5.6) > 0.1);
+    // Nothing is printed under the first floating layer, so its walls stay straight.
+    const double floating_first_layer = mid_span_wall_spread(print, 5.2);
+    CHECK(floating_first_layer >= 0.);
+    CHECK(floating_first_layer < 0.001);
+}

tests/fff_print/test_wipe_tower.cpp

@@ -308,6 +308,119 @@ TEST_CASE("A single-filament plate reserves a tower only when one is actually pr
     }
 }
 
+// Filament 2 on the top surface only, so every layer below it is a toolchange-free tower layer: the
+// run "Combine sparse layers" folds. The two heights decide whether anything folds, so they are the
+// caller's business.
+static DynamicPrintConfig sparse_run_config(double layer_height, const char *max_layer_height, bool combine)
+{
+    DynamicPrintConfig config = multifilament_config(2, {
+        { "top_surface_filament_id",        2     },
+        { "enable_prime_tower",             true  },
+        { "wipe_tower_x",                   50    }, // inside the 200x200 test bed
+        { "wipe_tower_y",                   50    },
+        { "prime_tower_width",              35    },
+        { "min_layer_height",               "0.08"},
+        { "single_extruder_multi_material", true  },
+        { "timelapse_type",                 "0"   },
+        { "enable_wrapping_detection",      false },
+        { "raft_layers",                    "0"   } });
+    // A taller first layer would top the plan and hide what the run does, so slice at one height.
+    config.set_deserialize_strict({ { "layer_height",               std::to_string(layer_height) },
+                                    { "initial_layer_print_height", std::to_string(layer_height) },
+                                    { "max_layer_height", max_layer_height },
+                                    { "wipe_tower_sparse_layers_combination", combine ? "1" : "0" } });
+    return config;
+}
+
+// What a sliced tower did with its sparse run.
+struct SparseRunResult { size_t planned, sparse, folded; float tallest_printed, printed_height; std::string gcode; };
+
+static SparseRunResult slice_sparse_run(const DynamicPrintConfig &config)
+{
+    Print print;
+    Model model;
+    init_print({ cube(10) }, print, model, config);
+    print.apply(model, config);
+    print.process();
+    REQUIRE(print.is_step_done(psWipeTower));
+
+    SparseRunResult r{};
+    for (const std::vector<WipeTower::ToolChangeResult> &layer : print.wipe_tower_data().tool_changes) {
+        if (layer.empty())
+            continue;
+        ++r.planned;
+        if (wipe_tower_layer_is_sparse(layer))
+            ++r.sparse;
+        if (wipe_tower_layer_is_combined_away(layer)) {
+            ++r.folded;
+        } else {
+            r.tallest_printed = std::max(r.tallest_printed, layer.front().layer_height);
+            r.printed_height += layer.front().layer_height;
+        }
+    }
+    r.gcode = Slic3r::Test::gcode(print);
+    return r;
+}
+
+// How often the G-code declares `height` in the tag this printer's processor reads. The dialect is a
+// global the exporter sets from the printer, so this is only correct after a slice - the point below.
+static size_t count_height_tags(const std::string &gcode, const char *height)
+{
+    const std::string tag = ";" + GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Height) + height + "\n";
+    size_t n = 0;
+    for (size_t p = gcode.find(tag); p != std::string::npos; p = gcode.find(tag, p + 1))
+        ++n;
+    return n;
+}
+
+TEST_CASE("Combining sparse layers folds a run into whole layers the nozzle can lay down", "[WipeTower]")
+{
+    // 0.1 mm layers under a 0.32 mm cap: three fit (0.3), a fourth does not, so a run prints once
+    // every three layers at 0.3 mm.
+    const SparseRunResult plain    = slice_sparse_run(sparse_run_config(0.1, "0.32", false));
+    const SparseRunResult combined = slice_sparse_run(sparse_run_config(0.1, "0.32", true));
+
+    REQUIRE(plain.planned == combined.planned); // the plan still has one layer per object layer
+    REQUIRE(plain.sparse > 10);
+    CHECK(plain.folded == 0);
+    CHECK_THAT(plain.tallest_printed, Catch::Matchers::WithinAbs(0.1f, 1e-4f));
+
+    CHECK(combined.folded > 0);
+    CHECK_THAT(combined.tallest_printed, Catch::Matchers::WithinAbs(0.3f, 1e-4f));
+    // Two of every three sparse layers fold away, leaving the toolchange layers untouched.
+    CHECK(combined.folded <= plain.sparse);
+    CHECK(combined.folded >= plain.sparse / 2);
+    // What folds away comes back as height on the layer that prints the run: no gap, nothing twice.
+    CHECK_THAT(combined.printed_height, Catch::Matchers::WithinAbs(plain.printed_height, 1e-3f));
+}
+
+TEST_CASE("A run too thin to reach the nozzle's layer height is left alone", "[WipeTower]")
+{
+    // Only whole layers merge, so two 0.2 mm layers (0.4) do not fit a 0.32 mm maximum and the tower
+    // prints as if the option were off. This is the common 0.4 nozzle case; the tooltip says so.
+    const SparseRunResult plain    = slice_sparse_run(sparse_run_config(0.2, "0.32", false));
+    const SparseRunResult combined = slice_sparse_run(sparse_run_config(0.2, "0.32", true));
+
+    REQUIRE(plain.sparse > 10);
+    CHECK(combined.folded == 0);
+    CHECK(combined.planned == plain.planned);
+    CHECK_THAT(combined.tallest_printed, Catch::Matchers::WithinAbs(0.2f, 1e-4f));
+}
+
+TEST_CASE("A merged tower layer declares its own height to the G-code processor", "[WipeTower]")
+{
+    // Each writer declares a height in a hardcoded tag dialect while the processor reads only its
+    // printer's, so one of them is always dropped. A merged layer is the first time that shows, as a
+    // thick layer drawn and costed as a thin one. 0.2 mm layers under a 0.42 mm maximum merge in pairs.
+    const SparseRunResult plain    = slice_sparse_run(sparse_run_config(0.2, "0.42", false));
+    const SparseRunResult combined = slice_sparse_run(sparse_run_config(0.2, "0.42", true));
+
+    REQUIRE(combined.folded > 0);
+    CHECK_THAT(combined.tallest_printed, Catch::Matchers::WithinAbs(0.4f, 1e-4f));
+    // Every layer that prints a merged run has to say so, and nothing may say so without the option.
+    CHECK(count_height_tags(combined.gcode, "0.4") - count_height_tags(plain.gcode, "0.4") == combined.folded);
+}
+
 TEST_CASE("A tower printed without a tool change is still validated against the bed", "[WipeTower]")
 {
     // Wrapping detection prints a tower on a plate that purges one filament. Neither the old

tests/libslic3r/test_wipe_tower.cpp

@@ -278,6 +278,98 @@ TEST_CASE("Only the keep-out ring an object is measured against is drawn", "[Wip
     CHECK_THAT(unscaled(get_extents(zone.grown_body).max.x()), WithinAbs(10. + 0.5 * (40. - 0.2), 0.02));
 }
 
+// ---------------------------------------------------------------------------------------------
+// "Combine sparse layers": folding a run of toolchange-free layers into one thicker tower layer.
+// ---------------------------------------------------------------------------------------------
+
+TEST_CASE("Sparse layers are combined only when every layer is still the tower's to place", "[WipeTower][CombineSparseLayers]") {
+    PrintConfig cfg;
+    cfg.timelapse_type.value                     = TimelapseType::tlTraditional;
+    cfg.enable_wrapping_detection.value          = false;
+    cfg.wipe_tower_no_sparse_layers.value        = false;
+
+    cfg.wipe_tower_sparse_layers_combination.value = false;
+    CHECK_FALSE(wipe_tower_sparse_layers_combined(cfg));
+    cfg.wipe_tower_sparse_layers_combination.value = true;
+    CHECK(wipe_tower_sparse_layers_combined(cfg));
+
+    // Dropping the sparse layers outright leaves nothing to combine.
+    cfg.wipe_tower_no_sparse_layers.value = true;
+    CHECK_FALSE(wipe_tower_sparse_layers_combined(cfg));
+    CHECK(wipe_tower_sparse_layers_skipped(cfg));
+    cfg.wipe_tower_no_sparse_layers.value = false;
+
+    // Both of these park the nozzle on the tower every layer, so no layer may be folded away.
+    cfg.timelapse_type.value = TimelapseType::tlSmooth;
+    CHECK_FALSE(wipe_tower_sparse_layers_combined(cfg));
+    cfg.timelapse_type.value            = TimelapseType::tlTraditional;
+    cfg.enable_wrapping_detection.value = true;
+    CHECK_FALSE(wipe_tower_sparse_layers_combined(cfg));
+}
+
+TEST_CASE("A layer folded into a later one is marked on the results the emitter reads", "[WipeTower][CombineSparseLayers]") {
+    WipeTower::ToolChangeResult folded = make_tcr(1, 1, 0.2f);
+    folded.combined_away               = true;
+    CHECK(wipe_tower_layer_is_combined_away({folded}));
+    CHECK_FALSE(wipe_tower_layer_is_combined_away({make_tcr(1, 1, 0.2f)}));
+    CHECK_FALSE(wipe_tower_layer_is_combined_away({}));
+}
+
+TEST_CASE("A run of sparse layers prints once, on its last layer, at the height it covers", "[WipeTower][CombineSparseLayers]") {
+    // Eight 0.1 mm layers on a 0.3 mm cap: a toolchange on the first and the last, sparse between.
+    std::vector<float>      heights(8, 0.1f);
+    const std::vector<char> sparse{0, 1, 1, 1, 1, 1, 1, 0};
+    const std::vector<float> caps(8, 0.3f);
+
+    const std::vector<char> combined = combine_sparse_wipe_tower_layers(heights, sparse, caps, 0);
+    REQUIRE(combined.size() == heights.size());
+    // Three layers fill the cap exactly: the run flushes on layers 3 and 6, the two below each go.
+    CHECK(combined == std::vector<char>{0, 1, 1, 0, 1, 1, 0, 0});
+    CHECK_THAT(heights[3], WithinAbs(0.3f, 1e-5f));
+    CHECK_THAT(heights[6], WithinAbs(0.3f, 1e-5f));
+    // Layers that print keep the object covered: nothing is lost and nothing is printed twice.
+    float printed = 0.f;
+    for (size_t i = 0; i < heights.size(); ++i)
+        if (! combined[i])
+            printed += heights[i];
+    CHECK_THAT(printed, WithinAbs(0.8f, 1e-5f));
+    // A toolchange has to purge at its own z, so those layers are left exactly as planned.
+    CHECK_THAT(heights[0], WithinAbs(0.1f, 1e-5f));
+    CHECK_THAT(heights[7], WithinAbs(0.1f, 1e-5f));
+}
+
+TEST_CASE("The maximum layer height of the nozzle that prints the run caps the merge", "[WipeTower][CombineSparseLayers]") {
+    // The cap that counts belongs to the layer that prints the run; one that prints nothing lays
+    // nothing down, so its own cap cannot constrain it. Five 0.1 mm layers, sparse above the first,
+    // layer 3's nozzle taking only 0.15. (A real run holds one filament, so this only tests the
+    // look-ahead.)
+    std::vector<float>      heights(5, 0.1f);
+    std::vector<float>      caps(5, 0.3f);
+    caps[3]                          = 0.15f;
+    const std::vector<char> combined = combine_sparse_wipe_tower_layers(heights, {0, 1, 1, 1, 1}, caps, 0);
+    // Layer 2 cannot hand its 0.2 mm on to layer 3, so it prints there and a fresh run starts above.
+    CHECK(combined == std::vector<char>{0, 1, 0, 1, 0});
+    CHECK_THAT(heights[2], WithinAbs(0.2f, 1e-5f));
+    CHECK_THAT(heights[4], WithinAbs(0.2f, 1e-5f));
+
+    // A single layer already past the cap is printed as planned rather than shrunk.
+    std::vector<float> tall{0.2f, 0.4f, 0.4f};
+    const std::vector<char> tall_combined = combine_sparse_wipe_tower_layers(tall, {0, 1, 1}, {0.3f, 0.3f, 0.3f}, 0);
+    CHECK(tall_combined == std::vector<char>{0, 0, 0});
+    CHECK_THAT(tall[1], WithinAbs(0.4f, 1e-5f));
+}
+
+TEST_CASE("The tower's first layer is never folded away", "[WipeTower][CombineSparseLayers]") {
+    // It carries the brim and has to sit on the bed, however little it purges.
+    std::vector<float>      heights(4, 0.1f);
+    const std::vector<char> combined = combine_sparse_wipe_tower_layers(heights, {1, 1, 1, 1}, std::vector<float>(4, 0.5f), 0);
+    CHECK(combined.front() == 0);
+    CHECK_THAT(heights.front(), WithinAbs(0.1f, 1e-5f));
+    // Everything above it merges into the top layer, which the cap still fits.
+    CHECK(combined == std::vector<char>{0, 1, 1, 0});
+    CHECK_THAT(heights.back(), WithinAbs(0.3f, 1e-5f));
+}
+
 TEST_CASE("Footprint padding covers the brim and the extrusion half width on each side", "[WipeTower][NoSparseLayers]") {
     // A nominal outline hulls extrusion centre lines and is re-centred once the real wall is known,
     // so a line width per side on top of the brim is what keeps an estimate enclosing the real tower.

tests/slic3rutils/test_shortcuts.cpp

@@ -120,6 +120,20 @@ TEST_CASE("Only modified or non-printable chords qualify as menu accelerators",
     CHECK(registry.accelerator(Shortcut::KeyboardShortcuts).empty());
 }
 
+TEST_CASE("Chords the desktop keeps for itself are recognized", "[Shortcuts]")
+{
+#ifdef _WIN32
+    CHECK(KeyChord{ WXK_F4, wxMOD_ALT }.is_system_shortcut());
+    CHECK(KeyChord{ WXK_SPACE, wxMOD_ALT }.is_system_shortcut());
+#else
+    CHECK_FALSE(KeyChord{ WXK_F4, wxMOD_ALT }.is_system_shortcut());
+    CHECK_FALSE(KeyChord{ WXK_SPACE, wxMOD_ALT }.is_system_shortcut());
+#endif
+    CHECK_FALSE(KeyChord{ WXK_F4, wxMOD_ALT | wxMOD_SHIFT }.is_system_shortcut());
+    CHECK_FALSE(KeyChord{ WXK_F4, wxMOD_CONTROL }.is_system_shortcut());
+    CHECK_FALSE(KeyChord{ WXK_SPACE }.is_system_shortcut());
+}
+
 TEST_CASE("Chords convert to wx accelerator entries", "[Shortcuts]")
 {
     const wxAcceleratorEntry entry = KeyChord{ 'S', wxMOD_CONTROL | wxMOD_SHIFT }.to_accelerator_entry(42);