Merge branch 'main' into feature/chromastack

Cache compiles in the macOS build script, including Xcode builds (#16553 )
fix: max filepath length on windows (#16552 )
2026-10-16 20:31:14 +00:00 · 2026-10-16 20:29:45 +08:00 · 2026-10-16 19:36:50 +08:00 · 2026-10-16 18:47:49 +08:00 · 2026-10-16 18:11:46 +08:00 · 2026-10-16 17:55:37 +08:00
150 changed files with 47498 additions and 6818 deletions
@@ -569,12 +569,18 @@ on the **first** call. So:
 #endif
 ```

-**Before GTK starts**, only the environment exists. `CLI::run` (`src/OrcaSlicer.cpp`) branches on
-`GDK_BACKEND` (an `x11` prefix means the X11 opt-in). On the default path it forces `GDK_BACKEND=x11`
-when wx lacks EGL and `WAYLAND_DISPLAY` is set. It sets `WEBKIT_DISABLE_COMPOSITING_MODE=1`
-(non-replacing) only when both `DISPLAY` and `WAYLAND_DISPLAY` are set, and calls `XInitThreads()`
+**Before GTK starts**, only the environment exists. `CLI::run` (`src/OrcaSlicer.cpp`) sets the NVIDIA
+DMABUF workaround and then branches on `GDK_BACKEND` (an `x11` prefix means the X11 opt-in). On both
+paths, when `/proc/driver/nvidia/version` exists and the linked WebKitGTK honours the switch (>= 2.44,
+`WebView::SupportsForceSharedMemory()`), it sets `WEBKIT_DMABUF_RENDERER_FORCE_SHM=1` and
+`WEBKIT_FORCE_DMABUF_RENDERER=1` (non-replacing): the proprietary driver cannot back WebKit's hardware
+DMABUF renderer. On the default path it forces `GDK_BACKEND=x11` when wx lacks EGL and `WAYLAND_DISPLAY`
+is set, and sets `WEBKIT_DISABLE_COMPOSITING_MODE=1` (non-replacing) inside that branch when the linked
+WebKitGTK is older than 2.42: a forced X11 backend in a Wayland session is the only default-path case
+that runs through XWayland, which `DISPLAY` and `WAYLAND_DISPLAY` alone do not tell you (a native
+Wayland app inherits both). It calls `XInitThreads()`
 only when `DISPLAY` is set. With neither variable set, the GUI refuses to start ("Neither DISPLAY nor
-WAYLAND_DISPLAY set"). The details and the WebKit rule (c12912e0df) are in
+WAYLAND_DISPLAY set"). The details and the WebKit rules (c12912e0df) are in
 `references/webview-gl-aui-media.md` §WebKitGTK on Linux sessions.

 **wx's own detectors**, for reference:
@@ -61,7 +61,8 @@ available; GTK2/WebKit1 is an opt-out configuration the GUI does not support.
 11. A web host that re-themes in place handles `EVT_WEBVIEW_RECREATED` without `Skip()`; one that
    needs a reload lets it through. §[Orca wrapper](#orca-webview-wrapper-widgetswebview)
 12. Keep `WebViewWebKit`'s destructor removing the `"wx"` handler. §[Orca wrapper](#orca-webview-wrapper-widgetswebview)
-13. Do not widen `WEBKIT_DISABLE_COMPOSITING_MODE` beyond Orca's default-path XWayland case, and never
+13. Do not widen `WEBKIT_DISABLE_COMPOSITING_MODE` beyond the no-EGL default path where Orca forces
+    `GDK_BACKEND=x11`, for WebKitGTK older than 2.42, and never
    make a page's progress depend only on a C++→JS callback. §[WebKitGTK on Linux](#webkitgtk-on-linux-sessions)
 14. GL attribute lists: legacy `int[]` lists end with `0` and spell out `WX_GL_RGBA` and
    `WX_GL_DOUBLEBUFFER`; `wxGLAttributes`/`wxGLContextAttrs` end with `EndList()`; MSAA is requested
@@ -567,33 +568,69 @@ vue-resize workaround script and sets a persistent SQLite cookie store on the vi
 ## WebKitGTK on Linux sessions

 **Mechanism.** `CLI::run` (`src/OrcaSlicer.cpp`, under `#ifdef __WXGTK__`, before GTK initialises)
-branches on `GDK_BACKEND`:
+sets the NVIDIA DMABUF workaround and then branches on `GDK_BACKEND`:
+- **Both paths**, before the split: when `/proc/driver/nvidia/version` exists and the linked WebKitGTK
+  honours the switch (>= 2.44, `WebView::SupportsForceSharedMemory()`), it sets
+  `WEBKIT_DMABUF_RENDERER_FORCE_SHM=1` and `WEBKIT_FORCE_DMABUF_RENDERER=1` non-replacing. The
+  proprietary driver cannot back WebKit's hardware DMABUF renderer, so the shared-memory transport keeps
+  accelerated compositing instead of dropping it; `WEBKIT_FORCE_DMABUF_RENDERER` clears the
+  Debian/Ubuntu/openSUSE `isNVIDIA()` early return, which otherwise returns before the FORCE_SHM check.
 - **Default path** (`GDK_BACKEND` unset or not starting with `x11`): if wx lacks EGL (`!wxHAS_EGL`) and
-  `WAYLAND_DISPLAY` is set, it forces `GDK_BACKEND=x11`; it sets `WEBKIT_DISABLE_COMPOSITING_MODE=1`
-  non-replacing **only** when both `DISPLAY` and `WAYLAND_DISPLAY` are non-empty (a Wayland session with
-  XWayland available — the session, not the backend GTK will pick); `XInitThreads()` runs only when
-  `DISPLAY` is set.
+  `WAYLAND_DISPLAY` is set, it forces `GDK_BACKEND=x11`, and in that same branch it sets
+  `WEBKIT_DISABLE_COMPOSITING_MODE=1` non-replacing when the linked WebKitGTK predates 2.42
+  (`WebView::NeedsCompositingWorkaround()`). That forced X11 backend in a Wayland session is the only
+  default-path case that really runs through XWayland; `DISPLAY` and `WAYLAND_DISPLAY` alone do not
+  identify it, because a native Wayland app inherits both. `XInitThreads()` runs only when `DISPLAY` is
+  set.
 - **`GDK_BACKEND=x11…` opt-in path**: sets `DRI_PRIME=1` (and the NVIDIA PRIME variables when
  `/proc/driver/nvidia/version` exists), calls `XInitThreads()`, and deliberately does **not** disable
-  compositing (the comment: the WebKit2GTK XWayland bug appears fixed in WebKit2GTK ≥ 2.42, and leaving
-  compositing on keeps hardware acceleration for Device / Setup Wizard / login pages).
+  compositing, which keeps hardware acceleration for Device / Setup Wizard / login pages.

 Runtime backend detection elsewhere uses Orca's `is_running_on_wayland()` / `is_running_on_x11()`
 (see `references/platforms.md`), not these environment variables.

 **Pitfall.**
- **Rule:** Set `WEBKIT_DISABLE_COMPOSITING_MODE` only on the default path in Wayland sessions,
-  non-replacing (`setenv(..., false)`, so a value the user already exported wins), before GTK
-  initialises; never unconditionally. Keep JS-side fallbacks so a page never
+- **Rule:** On NVIDIA reach for `WEBKIT_DMABUF_RENDERER_FORCE_SHM` before
+  `WEBKIT_DISABLE_COMPOSITING_MODE`. **Why:** the proprietary driver cannot back WebKit's hardware
+  DMABUF renderer, leaving web views blank or slow; FORCE_SHM keeps accelerated compositing and only
+  skips the hardware path, while disabling compositing drops it. Threaded scrolling is a separate,
+  release-dependent default (off in 2.44/2.45, on from 2.46). `WEBKIT_DISABLE_DMABUF_RENDERER` is not a
+  substitute — it is read first, leaves the transport set empty (no compositing from 2.44 on, where the
+  X11/Wayland fallback renderers were removed) and has a reported crash path. On Debian/Ubuntu and
+  openSUSE the `isNVIDIA()` patch returns before the FORCE_SHM check, so `WEBKIT_FORCE_DMABUF_RENDERER=1`
+  must clear it first; that variable exists only in those patches. WebKit reads all of these once per
+  process, before the first WebView.
+  The test is `/proc/driver/nvidia/version`, so a hybrid laptop that renders on its iGPU also takes the
+  shared-memory path, which is a per-frame GPU readback rather than zero-copy; exporting
+  `WEBKIT_DMABUF_RENDERER_FORCE_SHM=0` in the environment restores the hardware path.
+  ```cpp
+  // Wrong: kills compositing and threaded scrolling (and can crash on modern WebKit)
+  ::setenv("WEBKIT_DISABLE_DMABUF_RENDERER", "1", false);
+  // Right: keep compositing, skip only the hardware DMABUF path
+  if (::access("/proc/driver/nvidia/version", F_OK) == 0 && WebView::SupportsForceSharedMemory()) {
+      ::setenv("WEBKIT_DMABUF_RENDERER_FORCE_SHM", "1", /*replace*/ false);
+      ::setenv("WEBKIT_FORCE_DMABUF_RENDERER", "1", /*replace*/ false);
+  }
+  ```
+  Cite: WebKit 2.52.6 `Source/WebKit/UIProcess/gtk/AcceleratedBackingStore.cpp`
+  (`rendererBufferTransportMode()`), Debian `disable-nvidia-dmabuf.patch`, WebKit bug 262607.
+- **Rule:** Set `WEBKIT_DISABLE_COMPOSITING_MODE` only on the default path, in the branch where wx
+  lacks EGL and Orca forces `GDK_BACKEND=x11`, non-replacing (`setenv(..., false)`, so a value the user
+  already exported wins), before GTK
+  initialises; never unconditionally, and only for the WebKitGTK releases that need it (older than
+  2.42, `WebView::NeedsCompositingWorkaround()`). Keep JS-side fallbacks so a page never
  waits forever for a C++→JS call.
-  **Why:** WebKit2GTK accelerated compositing could fail silently under XWayland, leaving web views
-  blank (Setup Wizard stuck on "Loading..."); disabling it everywhere needlessly drops hardware
-  acceleration; without the JS timeout the user is stuck when the signal is lost.
+  **Why:** WebKit2GTK accelerated compositing could fail silently under XWayland before 2.42, leaving
+  web views blank (Setup Wizard stuck on "Loading..."); the variable also turns off threaded scrolling,
+  so applying it on a newer WebKit needlessly drops both GPU compositing and async scrolling (the
+  Device tab loses its smoothness); without the JS timeout the user is stuck when the signal is lost.
  ```cpp
  // Wrong: unconditional, kills HW acceleration everywhere
  ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", false);
-  // Right (default path only): non-replacing, before GTK init, Wayland session with XWayland
-  if (display && *display && wayland && *wayland)
+  // Right (default path only): non-replacing, before GTK init, WebKitGTK < 2.42,
+  // and only in the branch that forces GDK_BACKEND=x11 (wx without EGL), the
+  // case that runs through XWayland
+  if (WebView::NeedsCompositingWorkaround() && wayland && *wayland)
      ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", /*replace*/ false);
  ```
  Cite: c12912e0df (`src/OrcaSlicer.cpp`; `resources/web/guide/0/load.js` `OnInit`
@@ -288,6 +288,19 @@ if (APPLE)
    # 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")

+    # The Xcode generator ignores CMAKE_<LANG>_COMPILER_LAUNCHER, so hand the launcher to
+    # Xcode's own Compiler Launcher setting, which wraps every clang compile (C, C++,
+    # Objective-C++ and the precompiled header) with one program: the C++ launcher wins when
+    # both are set. The setting takes a single program path, not a CMake launcher list.
+    # Xcode versions without it ignore it and build uncached.
+    if (CMAKE_GENERATOR STREQUAL "Xcode")
+        if (CMAKE_CXX_COMPILER_LAUNCHER)
+            set(CMAKE_XCODE_ATTRIBUTE_C_COMPILER_LAUNCHER "${CMAKE_CXX_COMPILER_LAUNCHER}")
+        elseif (CMAKE_C_COMPILER_LAUNCHER)
+            set(CMAKE_XCODE_ATTRIBUTE_C_COMPILER_LAUNCHER "${CMAKE_C_COMPILER_LAUNCHER}")
+        endif ()
+    endif ()
+
    message(STATUS "Orca: IS_CROSS_COMPILE: ${IS_CROSS_COMPILE}")
 elseif (CMAKE_SYSTEM_NAME STREQUAL "Linux")
    set(CMAKE_INSTALL_RPATH "$ORIGIN")
@@ -22,7 +22,7 @@ function usage() {
    echo "   -g: run the requested build steps inside a Docker/Podman Ubuntu 24.04 container similar to the GitHub Actions Linux runner"
    echo "   -h: prints this help text"
    echo "   -i: build the Orca Slicer AppImage (optional)"
-    echo "   -p: boost ccache hit rate by disabling precompiled headers (default: ON)"
+    echo "   -p: disable precompiled headers (on by default): more ccache hits after header changes, slower misses"
    echo "   -r: skip RAM and disk checks (low RAM compiling)"
    echo "   -s: build the Orca Slicer (optional)"
    echo "   -t: build tests (optional), requires -s flag"
@@ -549,6 +549,20 @@ fi
 if [ -n "${CMAKE_CCACHE}" ] ; then
    echo "${CMAKE_CCACHE} found, enabling compiler caching..."
    export CMAKE_CCACHE_ARGS=(-DCMAKE_C_COMPILER_LAUNCHER="${CMAKE_CCACHE}" -DCMAKE_CXX_COMPILER_LAUNCHER="${CMAKE_CCACHE}")
+    # The same ccache settings as the CI build. Without this sloppiness ccache refuses every
+    # compile that uses the precompiled header, which is most of OrcaSlicer, and skips headers
+    # a checkout has just written. It is added to the sloppiness already configured, and
+    # CCACHE_SLOPPINESS or CCACHE_(NO)DEPEND set in the environment win.
+    if [[ "$(basename "${CMAKE_CCACHE}")" == ccache ]] ; then
+        if [[ -z "${CCACHE_SLOPPINESS+x}" ]] ; then
+            CCACHE_SLOPPINESS=$("${CMAKE_CCACHE}" --get-config sloppiness 2>/dev/null || true)
+            export CCACHE_SLOPPINESS="${CCACHE_SLOPPINESS:+${CCACHE_SLOPPINESS},}pch_defines,time_macros,include_file_mtime,include_file_ctime"
+        fi
+        # Hash the includes the compiler reports instead of preprocessing every miss.
+        if [[ -z "${CCACHE_DEPEND+x}${CCACHE_NODEPEND+x}" ]] ; then
+            export CCACHE_DEPEND=1
+        fi
+    fi
 else
    echo "Note: ccache or sccache are not found. Install either of them for faster rebuilds."
 fi
@@ -111,6 +111,54 @@ else
  export CMAKE_POLICY_COMPAT=""
 fi

+# Compiler cache, as in build_linux.sh. The program comes from CMAKE_CCACHE, else from a
+# launcher already set in the environment (the CI build sets ccache there), else sccache or
+# ccache from PATH; one program serves both languages. Each run applies its own choice to the
+# build directories, replacing a launcher an earlier run or a hand-run configure recorded.
+CMAKE_CCACHE_ARGS=()
+CCACHE_VAR=""
+for var in CMAKE_CCACHE CMAKE_CXX_COMPILER_LAUNCHER CMAKE_C_COMPILER_LAUNCHER; do
+    if [ -n "${!var:-}" ]; then
+        CCACHE_VAR=$var
+        break
+    fi
+done
+if [ -n "$CCACHE_VAR" ]; then
+    CCACHE_PROGRAM=${!CCACHE_VAR}
+    echo "Checking ${CCACHE_VAR} environment variable for compiler cache program..."
+    CMAKE_CCACHE=$(command -v "${CCACHE_PROGRAM}") || {
+        echo "${CCACHE_VAR} environment variable is set to '${CCACHE_PROGRAM}' but it was not found in PATH."
+        CMAKE_CCACHE=""
+    }
+elif command -v sccache >/dev/null 2>&1 ; then
+    CMAKE_CCACHE=$(command -v sccache)
+elif command -v ccache >/dev/null 2>&1 ; then
+    CMAKE_CCACHE=$(command -v ccache)
+fi
+if [ -n "${CMAKE_CCACHE}" ] ; then
+    echo "${CMAKE_CCACHE} found, enabling compiler caching..."
+    CMAKE_CCACHE_ARGS=(-DCMAKE_C_COMPILER_LAUNCHER="${CMAKE_CCACHE}" -DCMAKE_CXX_COMPILER_LAUNCHER="${CMAKE_CCACHE}")
+    # The same ccache settings as the CI build. Without this sloppiness ccache refuses every
+    # compile that uses the precompiled header, which is most of OrcaSlicer, and skips headers
+    # a checkout has just written. It is added to the sloppiness already configured, and
+    # CCACHE_SLOPPINESS or CCACHE_(NO)DEPEND set in the environment win.
+    if [[ "$(basename "${CMAKE_CCACHE}")" == ccache ]] ; then
+        if [[ -z "${CCACHE_SLOPPINESS+x}" ]] ; then
+            CCACHE_SLOPPINESS=$("${CMAKE_CCACHE}" --get-config sloppiness 2>/dev/null || true)
+            export CCACHE_SLOPPINESS="${CCACHE_SLOPPINESS:+${CCACHE_SLOPPINESS},}pch_defines,time_macros,include_file_mtime,include_file_ctime"
+        fi
+        # Hash the includes the compiler reports instead of preprocessing every miss.
+        if [[ -z "${CCACHE_DEPEND+x}${CCACHE_NODEPEND+x}" ]] ; then
+            export CCACHE_DEPEND=1
+        fi
+    fi
+else
+    echo "Note: ccache or sccache are not found. Install either of them for faster rebuilds."
+    # Clear a launcher recorded by an earlier configure. The entries must be set empty rather
+    # than removed: CMake fills a missing launcher entry from the environment.
+    CMAKE_CCACHE_ARGS=(-DCMAKE_C_COMPILER_LAUNCHER:STRING= -DCMAKE_CXX_COMPILER_LAUNCHER:STRING=)
+fi
+
 echo "Build params:"
 echo " - ARCH: $ARCH"
 echo " - BUILD_CONFIG: $BUILD_CONFIG"
@@ -162,6 +210,7 @@ function build_deps() {
                        -DCMAKE_OSX_ARCHITECTURES:STRING="${_ARCH}" \
                        -DCMAKE_OSX_DEPLOYMENT_TARGET="${OSX_DEPLOYMENT_TARGET}" \
                        -DCMAKE_IGNORE_PREFIX_PATH="${CMAKE_IGNORE_PREFIX_PATH}" \
+                        "${CMAKE_CCACHE_ARGS[@]}" \
                        ${CMAKE_POLICY_COMPAT}
                fi
                cmake --build . --config "$BUILD_CONFIG" --target deps
@@ -264,6 +313,7 @@ function build_slicer() {
                    -DCMAKE_OSX_ARCHITECTURES="${_ARCH}" \
                    -DCMAKE_OSX_DEPLOYMENT_TARGET="${OSX_DEPLOYMENT_TARGET}" \
                    -DCMAKE_IGNORE_PREFIX_PATH="${CMAKE_IGNORE_PREFIX_PATH}" \
+                    "${CMAKE_CCACHE_ARGS[@]}" \
                    ${CMAKE_POLICY_COMPAT}
            fi
            cmake --build . --config "$BUILD_CONFIG" --target "$SLICER_BUILD_TARGET"
@@ -1,22 +1,7 @@
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-    if (JPEG_VERSION STREQUAL "6")
-        message("Using Jpeg Lib 62")
-        set(jpeg_flag "")
-    elseif (JPEG_VERSION STREQUAL "7")
-        message("Using Jpeg Lib 70")
-        set(jpeg_flag "-DWITH_JPEG7=ON")
-    else ()
-        message("Using Jpeg Lib 80")
-        set(jpeg_flag "-DWITH_JPEG8=ON")
-    endif ()
-endif()
-
 orcaslicer_add_cmake_project(JPEG
-    URL https://github.com/libjpeg-turbo/libjpeg-turbo/archive/refs/tags/3.0.1.zip
-    URL_HASH SHA256=d6d99e693366bc03897677650e8b2dfa76b5d6c54e2c9e70c03f0af821b0a52f
-    DEPENDS ${ZLIB_PKG}
+    URL https://github.com/libjpeg-turbo/libjpeg-turbo/archive/refs/tags/3.2.0.zip
+    URL_HASH SHA256=1b4c2cb6cba1ca5e53b9e85eeeab02154cab4b70894c96e97a9c747a26d19d63
    CMAKE_ARGS
        -DENABLE_SHARED=OFF
        -DENABLE_STATIC=ON
-        ${jpeg_flag}
 )
@@ -0,0 +1,239 @@
+# ChromaStack - High Level Design
+
+## Purpose and scope
+
+ChromaStack prints a colour picture on a single face of a model: a few filaments are printed one on
+top of another, the printer swaps filament at fixed layer boundaries, and the *height* of every
+pixel decides how many of those layers reach it. Filament is translucent, so a pixel that stops
+part-way through a run shows a blend of that run's filament and whatever is under it, which is
+where the colours come from - far more of them than there are filaments loaded.
+
+This is that model inside OrcaSlicer, as a mode of a texture displacement layer. The picture and
+the filament stack are the input; the output is a grayscale height map and a set of filament swaps.
+Nothing about it is a new pipeline: the height map is handed to the layer the user painted, so the
+existing projection, preview and bake turn it into real geometry, and the swaps are handed to the
+object's height ranges, which is the slicer's own way of printing a Z band in another filament.
+
+It does not import other filament-painting tools' project files, and it does not choose the filaments or
+their order - that is the user's artistic decision, and the panel exists to make its result
+visible before the print.
+
+## The colour model
+
+`libslic3r/ChromaStack.hpp` holds the whole of it, free of any GUI dependency, which is what lets the
+solve run against plain image bytes and be unit tested.
+
+A **stack** (`ChromaStack`) is a list of **bands** (`ChromaBand`), bottom-up: a filament and
+how many layers it gets. Alongside them it carries the print's layer height, which the colours
+depend on directly, and the **base**: how many layers of solid backing the picture sits on.
+
+The base is not a band. It is a measurement of the model - everything below the painted face, often
+a hundred layers or more on a tall part - while a band is a handful of layers the user chooses. It
+prints in the bottom band's filament, because that is what is loaded when the print starts, so it
+extends that band's height range down to the first layer instead of being a swap of its own. Only
+the bands are quantized into the height map, which is why the 255-layer limit
+(`CHROMA_MAX_RELIEF_LAYERS`) bounds the picture and not the stack.
+
+Each filament carries its **transmission distance** (TD), the usual measure for how deep
+light gets into it: about 1 for an opaque filament, 4 to 7 for a usefully translucent one, 8 and
+above for a nearly clear one. TD lives in the filament preset, as
+`filament_transmission_distance` - it is a property of the material, so it belongs with the
+material and ships with a profile rather than being retyped per project. It has no effect on
+slicing.
+
+`chroma_palette()` turns a stack into the colour it shows at every possible column height, which
+is all the solver ever needs. The model is Beer-Lambert absorption, layer by layer: a layer of
+thickness `h` in a filament of transmission distance `TD` passes
+
+    T = exp(-h / (CHROMA_TD_OPAQUE_FRACTION * TD / 3))
+
+of the light from under it and shows its own colour with the rest, so walking up from an opaque
+base,
+
+    C_k = (1 - T_k) * c_k + T_k * C_(k-1),  C_0 = c_1
+
+The constants say what TD means in physical terms: a filament stops showing what is behind it at
+about a tenth of its TD number (`CHROMA_TD_OPAQUE_FRACTION`), and three e-folding lengths of
+absorption pass 5% of the light, which is where the eye stops seeing through. Those are calibrated
+against how the community's TD step prints behave, not derived from first principles - TD is an
+empirical scale.
+
+How fast that happens is the single most useful fact about a stack, and `chroma_layers_to_opaque()`
+is it: a filament hides what is under it at about a tenth of its TD, so how many *layers* that takes
+depends entirely on how thick they are. TD 4 covers in two layers at 0.2 mm and in five at 0.08 mm.
+Below about two layers a band has no intermediate colours at all - the picture can only use the
+filament or not use it - which is why an otherwise sound stack prints as flat steps at a coarse
+layer height. The panel reports the number under the palette ramp, and warns when it falls below
+two, because nothing else makes it visible: the filaments look fine, the bands look long enough, and
+the result looks like the colour model is wrong when it is the layer height.
+
+How many of a picture's layers actually earn their place is a second question, and
+`chroma_distinct_levels()` answers it: a band eventually hides what is under it, and another layer of
+it then shows the colour the one below already showed. It is measured against the palette rather than
+against TD, because how long a band keeps paying depends on what is under it as much as on the
+filament - a light band over a dark one is finished in four or five layers, while a dark one over a
+light one goes on moving the colour perceptibly well past the depth at which it is nominally opaque,
+since the last few percent of light coming through still shifts a near-black colour. `Trim` shortens
+each band to its last layer that still changes anything.
+
+Beer-Lambert is also the only model that stays self-consistent applied per layer: transmittance
+multiplies, so a run of n layers of one filament passes `exp(-n h / d)` whether it is composited in
+one step or n, and the palette therefore does not depend on how the stack happens to be cut into
+bands. A unit test asserts exactly that. Compositing is done on linear light, because the quantity
+being attenuated is light rather than an sRGB code.
+
+The base is assumed opaque. That is what makes a column's colour depend only on the layers above it,
+and it is why the panel warns when the base is thin.
+
+## The solve
+
+`chroma_solve()` maps each pixel of the picture to the column height whose palette colour is
+closest to it, perceptually: both sides go to CIELAB and the match is a CIE76 distance. A 1-D
+palette of a few dozen entries makes the extra accuracy of CIEDE2000 hard to see and the cost of it
+easy to feel - several hundred million comparisons for a large picture - so the cheaper metric is
+the deliberate choice here, unlike the texture colour quantizer, which matches against a
+two-dimensional palette of filament mixes and uses a precomputed CIEDE2000 cube.
+
+Optional Floyd-Steinberg error diffusion, serpentine, trades the bands a photograph shows across a
+sky or a cheek for fine stipple. Off by default, since stipple is the artifact rather than the cure
+for flat-coloured artwork.
+
+Three things come back: the per-pixel layer count, the same thing as an 8-bit grayscale height map
+(0 at the base, 255 at the top of the stack), and the palette colours chosen, as an RGB image. The
+quantization belongs to the solve rather than to the displacement because the relief's steps have
+to land on layer boundaries, and a grey level is the only channel the displacement reads.
+
+The solve also reports the mean and worst colour difference it had to accept. That is the only
+honest answer to "will this stack reproduce my picture": under about 5 is a good match, over about
+15 means the filaments cannot reach the picture's colours and no number of layers will help.
+
+## How it attaches to a texture displacement layer
+
+A ChromaStack layer is an ordinary `TextureDisplacementLayer` whose height map is computed rather than
+imported:
+
+- `chroma_source` keeps the picture the user chose, so the solve can be redone whenever the stack,
+  the layer height or the picture changes;
+- `chroma` is the stack;
+- `image_data` - the same field every other layer uses - holds whatever the last solve produced.
+
+So everything downstream needs no changes at all and knows nothing about colour stacks. It also
+means the solve writes `depth_mm` (the relief is exactly as tall as the layers above the base) and
+pins `invert`, `midlevel` and `smoothing`: blurring a solved height map moves its steps off the
+layer boundaries they were solved for.
+
+Colour by filament swap and the layer's own `color_enabled` (one filament per triangle, via
+`mmu_segmentation_facets`) are mutually exclusive, and the panel enforces it. They are two
+different ways of colouring the same surface, and painting the relief per triangle would hide the
+very stack the heights were solved against.
+
+## The filament swaps
+
+`chroma_ranges()` turns the bands into Z bands in the object's own coordinates, merging any two
+adjacent bands that share a filament, since nothing is swapped between them. The panel writes them
+onto the object as `layer_config_ranges`, each range carrying `extruder` - which
+`apply_to_print_region_config()` spreads over every feature filament the range does not otherwise
+override, i.e. the whole band prints in that filament - and `layer_height`, both because the solve
+is only valid at the height it was run at and because `layer_height_profile_from_ranges()` reads
+that option without checking it is there.
+
+Height ranges rather than colour-change custom G-code: they are object-relative, so they survive
+the object being moved, they are saved in the project file, and they appear in the object list where
+the user can see and edit them. The cost is that an object can only have one set of them, so
+applying a stack replaces whatever ranges the object had, with a confirmation when it had any.
+
+`ObjectList::rebuild_layer_ranges()` mirrors them in the object tree without touching the
+selection - changing the selection while a gizmo is open tears the gizmo down under the user.
+
+## Geometry the model assumes
+
+A filament swap happens at one Z across the whole plate, and the relief grows along the painted
+surface's normal. The two agree only where that surface is horizontal, so:
+
+- the painted patch's height above the bottom of the object is what the base layer count has to
+  match, and the panel measures it from the patch and offers the number rather than leaving the user
+  to work it out;
+- a patch that is not flat in Z gets a warning, because its colours will only be right where it is
+  level. The relief itself is still computed, since a gently domed plaque is a legitimate thing to
+  print and only the user can judge how much error is acceptable.
+
+The model itself is the user's: the stack needs a slab of the base thickness with a face to paint,
+and nothing here creates or thickens geometry.
+
+## Seeing the colours
+
+The colours are blends of translucent filaments. No single filament makes them, so they cannot be
+expressed as the per-triangle filament assignment the 3D scene paints with, and there is nothing for
+the ordinary view to draw. They exist in two places: the sliced preview, which shows the filament
+bands as they print, and an overlay the gizmo draws over whatever surface is on screen.
+
+That overlay is a shader, `resources/shaders/*/chromastack.*`, and it reads the colour from each
+fragment's own **print Z** rather than from the height map or from anything in the mesh. A filament
+swap happens at one Z across the whole plate, so the layer a point sits in is what decides its
+colour whatever the picture says. Two things follow. A band edge lands exactly on the layer boundary
+however coarse the triangles are - a per-triangle colouring puts it wherever the mesh happens to
+have an edge. And it keeps working after a bake, when the relief is real geometry, the paint has
+been cleared and the height map is attached to nothing on screen; the overlay is built from the live
+preview's displaced mesh before a bake and from the volume's own mesh after one.
+
+The stack's colours reach the shader as a texture of one texel per printed layer, because a base can
+be several hundred layers and no uniform array holds that. The mesh carries nothing about the stack,
+so editing the stack costs a palette upload rather than a mesh rebuild.
+
+On top of the colour the shader tries to look like printed plastic, because a flat shaded colour
+reads as a rendering and the whole point of the overlay is judging a print:
+
+- the terminator is **wrapped** and the grazing angles **glow**, both scaled by the transmission
+  distance of the filament on top - filament translucent enough to be worth stacking scatters light
+  rather than reflecting it, and an opaque stack correctly gets neither;
+- the walls carry **layer lines**, a groove at every layer boundary that also modulates the
+  specular, so a wall glints in stripes as a printed one does. Terraces get none: a terrace is one
+  layer's top surface and has no lines to show.
+
+Both effects are driven by the fragment's height, so they are free of any texture or UV, and both
+fade out through `fwidth` once a pixel covers more than about half a layer - lines finer than a
+pixel are noise, and a colour read from one layer out of the dozen under a pixel flickers as the
+camera moves. The palette lookup slides off the texel centres over the same range so the linear
+filter averages the bands a pixel covers instead of picking one of them.
+
+The overlay is drawn pulled forward and without depth writes, the same pass the painted-colour
+overlay uses, since it is the same surface as whatever is underneath it.
+
+## What the panel shows
+
+The kind of a layer is the layer's own, chosen when it is added and fixed from then on: **Add layer**
+offers *Relief layer* or *ChromaStack picture*, and the card carries its kind as a chip. There is no
+panel-wide mode, so one object can hold a picture on its face and a knurl on its rim, and a card
+never shows a control that cannot do anything on it.
+
+What the two cards do not share:
+
+| Control | Relief card | ChromaStack card |
+| --- | --- | --- |
+| Depth | slider | the solve writes it; the card prints the result |
+| Tile size | repeats the pattern | **Picture size**, the same number named for what it does |
+| Midlevel, Smoothing, Invert, Edge fade | present | absent: each would move the steps off the layer boundaries |
+| Colors, Mix filaments, Denoise | one filament per triangle | absent: swaps are how this card colours |
+| Tile, tile method | present | absent: one copy, never tiled |
+| Blend | four modes | absent: it is the top layer and replaces what is under it |
+| Picture, prediction, stack, palette, match, Dither, Solve, Apply swaps | absent | present |
+
+A ChromaStack card has no grip and cannot be reordered: its colours come from swapping filament at a
+height, so anything printed above it would bury them. An object may hold only one, refused when the
+layer is added rather than when the swaps are applied, because the swaps are the object's own height
+ranges and there is one set of those.
+
+The card itself, top to bottom: what it is in one line, the picture and the predicted print side by
+side at the same size, the match figures, the base with the measurement from the painted face offered
+beside it, a row per band - swatch, filament, layer count, TD - the colours the stack reaches as a
+ramp, the totals, dither with the layer height it is solved against, and the two actions. Base and
+band counts are typed fields rather than sliders: a base is measured in hundreds of layers and a band
+in single digits, and dragging past the end of a slider's range is how a stack silently loses its
+backing.
+
+The ramp is computed from the stack alone, before any solve. It is what answers "can these filaments
+print this picture" without spending a solve to find out they cannot: a short or flat ramp means the
+filaments are too alike, or too opaque, to give the picture anything to work with.
+
+A per-slot flag records that the stack has been edited since the last solve, because a stale height
+map looks exactly like a good one.
@@ -1 +1 @@
-<?xml version="1.0" encoding="UTF-8"?><svg id="a" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 15 15"><rect x="7" y="12" width="1" height="1" style="fill:#fefefe;"/><path d="M4.5,5.5c0-1.71,1.43-3.09,3.16-3,1.62.08,2.84,1.54,2.84,3.17h0c0,.61-.25,1.2-.69,1.62l-2.31,2.24v.97" style="fill:none; stroke:#fefefe; stroke-linecap:round; stroke-linejoin:round;"/></svg>
+<?xml version="1.0" encoding="UTF-8"?><svg id="a" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 15 15"><rect x="1.5" y="3.5" width="12" height="8" rx="1" ry="1" style="fill:none; stroke:#fefefe; stroke-linecap:round; stroke-linejoin:round;"/><path d="M3,5h1v1h-1Z M5,5h1v1h-1Z M7,5h1v1h-1Z M9,5h1v1h-1Z M11,5h1v1h-1Z M4,7h1v1h-1Z M6,7h1v1h-1Z M8,7h1v1h-1Z M10,7h1v1h-1Z M5,9h5v1h-5Z" style="fill:#fefefe;"/></svg>
@@ -592,6 +592,10 @@
 			"name": "SUNLU PETG @base",
 			"sub_path": "filament/SUNLU/SUNLU PETG @base.json"
 		},
+		{
+			"name": "School House Spools PETG @base",
+			"sub_path": "filament/SchoolHouseSpools/School House Spools PETG @base.json"
+		},
 		{
 			"name": "eSUN PETG @base",
 			"sub_path": "filament/eSUN/eSUN PETG @base.json"
@@ -1096,6 +1100,10 @@
 			"name": "SUNLU Wood PLA @base",
 			"sub_path": "filament/SUNLU/SUNLU Wood PLA @base.json"
 		},
+		{
+			"name": "School House Spools PLA @base",
+			"sub_path": "filament/SchoolHouseSpools/School House Spools PLA @base.json"
+		},
 		{
 			"name": "Valment PLA @base",
 			"sub_path": "filament/Valment/Valment PLA @base.json"
@@ -2260,6 +2268,10 @@
 			"name": "SUNLU PETG @System",
 			"sub_path": "filament/SUNLU/SUNLU PETG @System.json"
 		},
+		{
+			"name": "School House Spools PETG @System",
+			"sub_path": "filament/SchoolHouseSpools/School House Spools PETG @System.json"
+		},
 		{
 			"name": "eSUN PETG @System",
 			"sub_path": "filament/eSUN/eSUN PETG @System.json"
@@ -3812,6 +3824,10 @@
 			"name": "SUNLU Wood PLA @System",
 			"sub_path": "filament/SUNLU/SUNLU Wood PLA @System.json"
 		},
+		{
+			"name": "School House Spools PLA @System",
+			"sub_path": "filament/SchoolHouseSpools/School House Spools PLA @System.json"
+		},
 		{
 			"name": "Valment PLA @System",
 			"sub_path": "filament/Valment/Valment PLA @System.json"
@@ -0,0 +1,18 @@
+{
+	"type": "filament",
+	"name": "School House Spools PETG @System",
+	"inherits": "School House Spools PETG @base",
+	"from": "system",
+	"setting_id": "RSu2orfhR8ktT36h",
+	"instantiation": "true",
+	"filament_max_volumetric_speed": [
+		"13"
+	],
+	"filament_long_retractions_when_cut": [
+		"1"
+	],
+	"filament_retraction_distances_when_cut": [
+		"18"
+	],
+	"compatible_printers": []
+}
@@ -0,0 +1,80 @@
+{
+	"type": "filament",
+	"name": "School House Spools PETG @base",
+	"inherits": "fdm_filament_pet",
+	"from": "system",
+	"filament_id": "OFnaCGQ9",
+	"instantiation": "false",
+	"cool_plate_temp": [
+		"0"
+	],
+	"cool_plate_temp_initial_layer": [
+		"0"
+	],
+	"eng_plate_temp": [
+		"70"
+	],
+	"eng_plate_temp_initial_layer": [
+		"70"
+	],
+	"fan_cooling_layer_time": [
+		"30"
+	],
+	"fan_max_speed": [
+		"40"
+	],
+	"fan_min_speed": [
+		"10"
+	],
+	"filament_cost": [
+		"16.00"
+	],
+	"filament_density": [
+		"1.25"
+	],
+	"filament_flow_ratio": [
+		"0.95"
+	],
+	"filament_max_volumetric_speed": [
+		"8"
+	],
+	"filament_multitool_ramming_flow": [
+		"8"
+	],
+	"filament_vendor": [
+		"School House Spools"
+	],
+	"hot_plate_temp": [
+		"70"
+	],
+	"hot_plate_temp_initial_layer": [
+		"70"
+	],
+	"nozzle_temperature": [
+		"252"
+	],
+	"nozzle_temperature_initial_layer": [
+		"252"
+	],
+	"nozzle_temperature_range_high": [
+		"270"
+	],
+	"nozzle_temperature_range_low": [
+		"230"
+	],
+	"overhang_fan_speed": [
+		"90"
+	],
+	"overhang_fan_threshold": [
+		"10%"
+	],
+	"slow_down_layer_time": [
+		"12"
+	],
+	"textured_plate_temp": [
+		"70"
+	],
+	"textured_plate_temp_initial_layer": [
+		"70"
+	]
+}
@@ -0,0 +1,18 @@
+{
+	"type": "filament",
+	"name": "School House Spools PLA @System",
+	"inherits": "School House Spools PLA @base",
+	"from": "system",
+	"setting_id": "3rHJk6SVAvFzyHI0",
+	"instantiation": "true",
+	"filament_max_volumetric_speed": [
+		"21"
+	],
+	"filament_long_retractions_when_cut": [
+		"1"
+	],
+	"filament_retraction_distances_when_cut": [
+		"18"
+	],
+	"compatible_printers": []
+}
@@ -0,0 +1,35 @@
+{
+	"type": "filament",
+	"name": "School House Spools PLA @base",
+	"inherits": "fdm_filament_pla",
+	"from": "system",
+	"filament_id": "OFHzwmT9",
+	"instantiation": "false",
+	"filament_cost": [
+		"17.00"
+	],
+	"filament_density": [
+		"1.26"
+	],
+	"filament_flow_ratio": [
+		"0.98"
+	],
+	"filament_max_volumetric_speed": [
+		"12"
+	],
+	"filament_vendor": [
+		"School House Spools"
+	],
+	"filament_scarf_seam_type": [
+		"none"
+	],
+	"filament_scarf_height": [
+		"10%"
+	],
+	"filament_scarf_gap": [
+		"0%"
+	],
+	"filament_scarf_length": [
+		"10"
+	]
+}
@@ -1,6 +1,6 @@
 {
 	"name": "RatRig",
-	"version": "02.04.00.06",
+	"version": "02.04.00.07",
 	"force_update": "0",
 	"description": "RatRig configurations",
 	"machine_model_list": [
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -107,7 +107,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -107,7 +107,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -107,7 +107,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -106,7 +106,7 @@
 	"z_hop": [
 		"0.2"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single] TOTAL_LAYER_COUNT={total_layer_count} X0={first_layer_print_min[0]} Y0={first_layer_print_min[1]} X1={first_layer_print_max[0]} Y1={first_layer_print_max[1]}",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n_ON_LAYER_CHANGE LAYER={layer_num + 1}",
 	"change_filament_gcode": "M600",
@@ -131,7 +131,7 @@
 	"bed_exclude_area": [
 		"0x0"
 	],
-	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single]",
+	"machine_start_gcode": "START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] EXTRUDER_OTHER_LAYER_TEMP=[nozzle_temperature] BED_TEMP=[bed_temperature_initial_layer_single]",
 	"machine_end_gcode": "END_PRINT",
 	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
 	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n",
@@ -0,0 +1,92 @@
+#version 110
+
+// What a ChromaStack print looks like, shaded per fragment.
+//
+// The colour is not a vertex attribute and not a texture on the surface: it is read from the
+// fragment's own height. A filament swap happens at one print Z across the whole plate, so the layer
+// a point sits in is what decides its colour - which means a band edge lands exactly on the layer
+// boundary however coarse the mesh is, and the same shader is right before a bake (on the preview's
+// displaced mesh) and after one (on the volume's own).
+//
+// On top of that it tries to look like printed plastic rather than like flat shaded colour: the
+// terminator is wrapped and the grazing angles glow, because filament translucent enough to be worth
+// stacking scatters light rather than reflecting it; and the walls carry layer lines, because that is
+// the first thing the eye uses to read a print as a print.
+
+#define INTENSITY_CORRECTION 0.6
+const vec3 LIGHT_TOP_DIR = vec3(-0.4574957, 0.4574957, 0.7624929);
+#define LIGHT_TOP_DIFFUSE    (0.8 * INTENSITY_CORRECTION)
+#define LIGHT_TOP_SPECULAR   (0.125 * INTENSITY_CORRECTION)
+#define LIGHT_TOP_SHININESS  20.0
+const vec3 LIGHT_FRONT_DIR = vec3(0.6985074, 0.1397015, 0.6985074);
+#define LIGHT_FRONT_DIFFUSE  (0.3 * INTENSITY_CORRECTION)
+#define INTENSITY_AMBIENT    0.3
+
+// The stack's colours, one texel per printed layer, bottom to top. A texture rather than a uniform
+// array because a base can be several hundred layers and no uniform array survives that.
+uniform sampler2D palette;
+uniform float     palette_size;  // texels in `palette`, i.e. the stack's total printed layers
+uniform float     base_z;        // world Z of the bottom of the object
+uniform float     layer_height;  // mm
+// How translucent the stack reads, 0 to 1, from the transmission distance of the filament on top.
+// It drives the wrap and the rim: an opaque stack should not glow.
+uniform float     translucency;
+uniform float     alpha;
+
+varying vec3  clipping_planes_dots;
+varying vec3  eye_normal;
+varying vec3  eye_position;
+varying vec3  world_normal;
+varying float world_z;
+
+void main()
+{
+    if (any(lessThan(clipping_planes_dots, vec3(0.0))))
+        discard;
+
+    float z_rel  = world_z - base_z;
+    float layers = max(z_rel / layer_height, 0.0);
+    // How much of a layer one pixel covers. Everything below is faded out as this grows: layer lines
+    // finer than a pixel are noise, and a colour read from one layer out of the dozen under a pixel
+    // flickers as the camera moves.
+    float px     = fwidth(layers);
+
+    // The layer this fragment sits in, 1-based. Up close that is an exact texel of the palette; once a
+    // pixel spans a layer or more it slides to a continuous coordinate so the linear filter averages
+    // the bands it covers instead of picking one of them at random.
+    float stepped = clamp(ceil(layers - 1.0e-4), 1.0, palette_size) - 0.5;
+    float smooth_ = clamp(layers, 0.5, palette_size - 0.5);
+    float u       = mix(stepped, smooth_, clamp(px - 0.5, 0.0, 1.0)) / palette_size;
+    vec3  albedo  = texture2D(palette, vec2(u, 0.5)).rgb;
+
+    vec3 N = normalize(eye_normal);
+    vec3 V = normalize(-eye_position);
+
+    // Layer lines, on the walls only: a terrace is one layer's top surface and has none to show. The
+    // groove runs round the part at every layer boundary, so it is a function of height alone.
+    float wall   = 1.0 - abs(world_normal.z);
+    float phase  = fract(layers);
+    float groove = smoothstep(0.0, 0.16, phase) * smoothstep(1.0, 0.84, phase);
+    groove       = mix(groove, 0.65, clamp(px * 1.5, 0.0, 1.0)); // fade to flat when too fine to resolve
+    float lines  = mix(1.0, 0.84 + 0.16 * groove, wall * 0.9);
+    albedo      *= lines;
+
+    // Diffuse, with a wrapped terminator: light entering translucent filament comes back out a little
+    // way round the curve, so the shaded side never goes as dark as an opaque surface's would.
+    float wrap    = 0.25 + 0.45 * translucency;
+    float ndotl   = dot(N, LIGHT_TOP_DIR);
+    float diffuse = max((ndotl + wrap) / (1.0 + wrap), 0.0) * LIGHT_TOP_DIFFUSE;
+    diffuse      += max((dot(N, LIGHT_FRONT_DIR) + wrap) / (1.0 + wrap), 0.0) * LIGHT_FRONT_DIFFUSE;
+
+    // Specular, strongest along a layer line, which is what makes a printed wall glint in stripes
+    // rather than evenly.
+    float spec = LIGHT_TOP_SPECULAR * pow(max(dot(V, reflect(-LIGHT_TOP_DIR, N)), 0.0), LIGHT_TOP_SHININESS);
+    spec      *= mix(1.0, 0.35 + 0.65 * groove, wall * 0.9);
+
+    // Scattering out of the edges: a translucent part lights up where it is seen at a grazing angle
+    // and where it is thin. Tinted by the filament, because what comes back out has been through it.
+    float rim = pow(1.0 - clamp(dot(N, V), 0.0, 1.0), 4.0);
+
+    vec3 color = albedo * (INTENSITY_AMBIENT + diffuse) + vec3(spec) + albedo * rim * translucency * 0.55;
+    gl_FragColor = vec4(color, alpha);
+}
@@ -0,0 +1,40 @@
+#version 110
+
+uniform mat4 view_model_matrix;
+uniform mat4 projection_matrix;
+uniform mat3 view_normal_matrix;
+uniform mat4 volume_world_matrix;
+// The volume's normal matrix in world space, so the fragment shader can tell a wall from a terrace -
+// which is what decides whether layer lines show at all.
+uniform mat3 world_normal_matrix;
+// Clipping plane, x = min z, y = max z (the FFF/SLA preview's top/bottom cut).
+uniform vec2 z_range;
+// Clipping plane, general orientation (the section view).
+uniform vec4 clipping_plane;
+
+// GLModel's P3N3 layout, which is what init_from(indexed_triangle_set) produces - this shader needs
+// nothing per vertex that the mesh does not already carry, because the colour comes from the
+// fragment's own height rather than from anything baked into the vertices.
+attribute vec3 v_position;
+attribute vec3 v_normal;
+
+varying vec3  clipping_planes_dots;
+varying vec3  eye_normal;
+varying vec3  eye_position;
+varying vec3  world_normal;
+varying float world_z;
+
+void main()
+{
+    vec4 model_pos = vec4(v_position, 1.0);
+    vec4 world_pos = volume_world_matrix * model_pos;
+    world_z        = world_pos.z;
+    world_normal   = normalize(world_normal_matrix * v_normal);
+    eye_normal     = normalize(view_normal_matrix * v_normal);
+
+    vec4 eye_pos = view_model_matrix * model_pos;
+    eye_position = eye_pos.xyz;
+    gl_Position  = projection_matrix * eye_pos;
+
+    clipping_planes_dots = vec3(dot(world_pos, clipping_plane), world_pos.z - z_range.x, z_range.y - world_pos.z);
+}
@@ -0,0 +1,94 @@
+#version 140
+
+// What a ChromaStack print looks like, shaded per fragment.
+//
+// The colour is not a vertex attribute and not a texture on the surface: it is read from the
+// fragment's own height. A filament swap happens at one print Z across the whole plate, so the layer
+// a point sits in is what decides its colour - which means a band edge lands exactly on the layer
+// boundary however coarse the mesh is, and the same shader is right before a bake (on the preview's
+// displaced mesh) and after one (on the volume's own).
+//
+// On top of that it tries to look like printed plastic rather than like flat shaded colour: the
+// terminator is wrapped and the grazing angles glow, because filament translucent enough to be worth
+// stacking scatters light rather than reflecting it; and the walls carry layer lines, because that is
+// the first thing the eye uses to read a print as a print.
+
+#define INTENSITY_CORRECTION 0.6
+const vec3 LIGHT_TOP_DIR = vec3(-0.4574957, 0.4574957, 0.7624929);
+#define LIGHT_TOP_DIFFUSE    (0.8 * INTENSITY_CORRECTION)
+#define LIGHT_TOP_SPECULAR   (0.125 * INTENSITY_CORRECTION)
+#define LIGHT_TOP_SHININESS  20.0
+const vec3 LIGHT_FRONT_DIR = vec3(0.6985074, 0.1397015, 0.6985074);
+#define LIGHT_FRONT_DIFFUSE  (0.3 * INTENSITY_CORRECTION)
+#define INTENSITY_AMBIENT    0.3
+
+// The stack's colours, one texel per printed layer, bottom to top. A texture rather than a uniform
+// array because a base can be several hundred layers and no uniform array survives that.
+uniform sampler2D palette;
+uniform float     palette_size;  // texels in `palette`, i.e. the stack's total printed layers
+uniform float     base_z;        // world Z of the bottom of the object
+uniform float     layer_height;  // mm
+// How translucent the stack reads, 0 to 1, from the transmission distance of the filament on top.
+// It drives the wrap and the rim: an opaque stack should not glow.
+uniform float     translucency;
+uniform float     alpha;
+
+in vec3  clipping_planes_dots;
+in vec3  eye_normal;
+in vec3  eye_position;
+in vec3  world_normal;
+in float world_z;
+
+out vec4 out_color;
+
+void main()
+{
+    if (any(lessThan(clipping_planes_dots, vec3(0.0))))
+        discard;
+
+    float z_rel  = world_z - base_z;
+    float layers = max(z_rel / layer_height, 0.0);
+    // How much of a layer one pixel covers. Everything below is faded out as this grows: layer lines
+    // finer than a pixel are noise, and a colour read from one layer out of the dozen under a pixel
+    // flickers as the camera moves.
+    float px     = fwidth(layers);
+
+    // The layer this fragment sits in, 1-based. Up close that is an exact texel of the palette; once a
+    // pixel spans a layer or more it slides to a continuous coordinate so the linear filter averages
+    // the bands it covers instead of picking one of them at random.
+    float stepped = clamp(ceil(layers - 1.0e-4), 1.0, palette_size) - 0.5;
+    float smooth_ = clamp(layers, 0.5, palette_size - 0.5);
+    float u       = mix(stepped, smooth_, clamp(px - 0.5, 0.0, 1.0)) / palette_size;
+    vec3  albedo  = texture(palette, vec2(u, 0.5)).rgb;
+
+    vec3 N = normalize(eye_normal);
+    vec3 V = normalize(-eye_position);
+
+    // Layer lines, on the walls only: a terrace is one layer's top surface and has none to show. The
+    // groove runs round the part at every layer boundary, so it is a function of height alone.
+    float wall   = 1.0 - abs(world_normal.z);
+    float phase  = fract(layers);
+    float groove = smoothstep(0.0, 0.16, phase) * smoothstep(1.0, 0.84, phase);
+    groove       = mix(groove, 0.65, clamp(px * 1.5, 0.0, 1.0)); // fade to flat when too fine to resolve
+    float lines  = mix(1.0, 0.84 + 0.16 * groove, wall * 0.9);
+    albedo      *= lines;
+
+    // Diffuse, with a wrapped terminator: light entering translucent filament comes back out a little
+    // way round the curve, so the shaded side never goes as dark as an opaque surface's would.
+    float wrap    = 0.25 + 0.45 * translucency;
+    float ndotl   = dot(N, LIGHT_TOP_DIR);
+    float diffuse = max((ndotl + wrap) / (1.0 + wrap), 0.0) * LIGHT_TOP_DIFFUSE;
+    diffuse      += max((dot(N, LIGHT_FRONT_DIR) + wrap) / (1.0 + wrap), 0.0) * LIGHT_FRONT_DIFFUSE;
+
+    // Specular, strongest along a layer line, which is what makes a printed wall glint in stripes
+    // rather than evenly.
+    float spec = LIGHT_TOP_SPECULAR * pow(max(dot(V, reflect(-LIGHT_TOP_DIR, N)), 0.0), LIGHT_TOP_SHININESS);
+    spec      *= mix(1.0, 0.35 + 0.65 * groove, wall * 0.9);
+
+    // Scattering out of the edges: a translucent part lights up where it is seen at a grazing angle
+    // and where it is thin. Tinted by the filament, because what comes back out has been through it.
+    float rim = pow(1.0 - clamp(dot(N, V), 0.0, 1.0), 4.0);
+
+    vec3 color = albedo * (INTENSITY_AMBIENT + diffuse) + vec3(spec) + albedo * rim * translucency * 0.55;
+    out_color  = vec4(color, alpha);
+}
@@ -0,0 +1,40 @@
+#version 140
+
+uniform mat4 view_model_matrix;
+uniform mat4 projection_matrix;
+uniform mat3 view_normal_matrix;
+uniform mat4 volume_world_matrix;
+// The volume's normal matrix in world space, so the fragment shader can tell a wall from a terrace -
+// which is what decides whether layer lines show at all.
+uniform mat3 world_normal_matrix;
+// Clipping plane, x = min z, y = max z (the FFF/SLA preview's top/bottom cut).
+uniform vec2 z_range;
+// Clipping plane, general orientation (the section view).
+uniform vec4 clipping_plane;
+
+// GLModel's P3N3 layout, which is what init_from(indexed_triangle_set) produces - this shader needs
+// nothing per vertex that the mesh does not already carry, because the colour comes from the
+// fragment's own height rather than from anything baked into the vertices.
+in vec3 v_position;
+in vec3 v_normal;
+
+out vec3  clipping_planes_dots;
+out vec3  eye_normal;
+out vec3  eye_position;
+out vec3  world_normal;
+out float world_z;
+
+void main()
+{
+    vec4 model_pos = vec4(v_position, 1.0);
+    vec4 world_pos = volume_world_matrix * model_pos;
+    world_z        = world_pos.z;
+    world_normal   = normalize(world_normal_matrix * v_normal);
+    eye_normal     = normalize(view_normal_matrix * v_normal);
+
+    vec4 eye_pos = view_model_matrix * model_pos;
+    eye_position = eye_pos.xyz;
+    gl_Position  = projection_matrix * eye_pos;
+
+    clipping_planes_dots = vec3(dot(world_pos, clipping_plane), world_pos.z - z_range.x, z_range.y - world_pos.z);
+}
@@ -18,7 +18,7 @@
  <script src="../js/plugin-config-ui.js"></script>
  <script src="./index.js"></script>
  <script src="./plugin-sort.js"></script>
-  <script src="../js/fuzzy-search.js"></script>
+  <script src="../../js/fuzzy-search.js"></script>
  <script src="./plugin-search.js"></script>
 </head>
 <body onLoad="OnInit()">
@@ -156,12 +156,16 @@ function SetCloudMode( bOn )

 	m_CloudMode=bOn;
 	$("body").toggleClass("cloud-mode", bOn);
+
+	if( bOn )
+	{
+		$(".BtnItem").removeClass("BtnItemSelected");
+		$(".BtnShortcut").addClass("BtnItemSelected");
+	}
 }

 function GotoCloud()
 {
-	$(".BtnItem").removeClass("BtnItemSelected");
-	$(".BtnShortcut").addClass("BtnItemSelected");
 	SetCloudMode(true);
 	SendSimpleCommand("homepage_open_cloud");
 }
@@ -336,10 +336,10 @@ modules:
        sha256: 3d22d46c566b1761a0e15ea397589b3a5f36ac09b7c785382e6470156c04247f
        dest: external-packages/PNG

-      # libjpeg-turbo 3.0.1
+      # libjpeg-turbo 3.2.0
      - type: file
-        url: https://github.com/libjpeg-turbo/libjpeg-turbo/archive/refs/tags/3.0.1.zip
-        sha256: d6d99e693366bc03897677650e8b2dfa76b5d6c54e2c9e70c03f0af821b0a52f
+        url: https://github.com/libjpeg-turbo/libjpeg-turbo/archive/refs/tags/3.2.0.zip
+        sha256: 1b4c2cb6cba1ca5e53b9e85eeeab02154cab4b70894c96e97a9c747a26d19d63
        dest: external-packages/JPEG

      # Freetype 2.12.1
@@ -1,7 +1,7 @@
 #!/usr/bin/env sh

-# Work-around https://gitlab.gnome.org/GNOME/gnome-build-meta/-/issues/754
-grep -q org.freedesktop.Platform.GL.nvidia /.flatpak-info && export WEBKIT_DISABLE_DMABUF_RENDERER=1
+# WebKit's NVIDIA DMABUF workaround (gnome-build-meta#754) is applied by the
+# binary itself, gated on the runtime WebKitGTK version (src/OrcaSlicer.cpp).

 # Work-around https://github.com/bambulab/BambuStudio/issues/3440
 # Use LC_NUMERIC instead of LC_ALL to prevent decimal separator issues
@@ -163,6 +163,7 @@ using json = nlohmann::json;
 #include <X11/Xlib.h>
 #endif
 #include <unistd.h>
+#include "slic3r/GUI/Widgets/WebView.hpp"
 #endif

 #ifdef SLIC3R_GUI
@@ -1156,8 +1157,10 @@ int CLI::run(int argc, char **argv)
    // opt-in path. The ~2020-era WebKit2GTK XWayland compositor bug it
    // worked around appears fixed in WebKit2GTK >= 2.42; leaving it
    // unset preserves WebKit hardware acceleration on Device / Setup
-    // Wizard / login / store. The default path still applies it on
-    // XWayland sessions as a conservative fallback for older WebKit.
+    // Wizard / login / store. The default path applies it only where it
+    // forces GDK_BACKEND=x11 below (a build without EGL, so the app really
+    // runs through XWayland), and only when the linked WebKitGTK predates
+    // the fix (< 2.42), as a conservative fallback for older WebKit.
    // ------------------------------------------------------------------
    {
        const char* gdk_backend = ::getenv("GDK_BACKEND");
@@ -1165,6 +1168,14 @@ int CLI::run(int argc, char **argv)
        // honours the first backend in the comma-separated list).
        const bool x11_opt_in = gdk_backend && boost::starts_with(gdk_backend, "x11");

+        // NVIDIA's proprietary driver cannot back WebKitGTK's DMABUF renderer.
+        // Force the shared-memory transport, which keeps compositing and threaded
+        // scrolling; the second variable clears Debian/Ubuntu/openSUSE's isNVIDIA().
+        if (::access("/proc/driver/nvidia/version", F_OK) == 0 && WebView::SupportsForceSharedMemory()) {
+            ::setenv("WEBKIT_DMABUF_RENDERER_FORCE_SHM", "1", /* replace */ false);
+            ::setenv("WEBKIT_FORCE_DMABUF_RENDERER", "1", /* replace */ false);
+        }
+
        if (x11_opt_in) {
            // ===== X11 / XWayland (opted in via GDK_BACKEND=x11) =====
            BOOST_LOG_TRIVIAL(info) << "GDK_BACKEND=x11 detected; applying v2.3.2 X11/XWayland workarounds.";
@@ -1204,23 +1215,18 @@ int CLI::run(int argc, char **argv)
                if (wayland_env && *wayland_env) {
                    BOOST_LOG_TRIVIAL(warning) << "Wayland detected but wxWidgets has no EGL support (wxHAS_EGL is OFF). Forcing X11 backend.";
                    ::setenv("GDK_BACKEND", "x11", true);
+
+                    // GTK will use X11 in a Wayland session here, which is the
+                    // one default-path case that really runs through XWayland.
+                    // WebKit2GTK accelerated compositing could fail silently
+                    // there on releases before 2.42, so force it off. Disabling
+                    // it also turns off threaded scrolling, hence the gate.
+                    if (WebView::NeedsCompositingWorkaround())
+                        ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", /* replace */ false);
                }
            }
            #endif

-            // WebKit2GTK compositing can fail under XWayland on older
-            // WebKit releases. Disable it only when both DISPLAY and
-            // WAYLAND_DISPLAY are set (i.e. an XWayland session is in
-            // use). On pure X11 or native Wayland, compositing is left
-            // enabled so WebKit retains HW acceleration.
-            {
-                const char* display_env_wk = ::getenv("DISPLAY");
-                const char* wayland_env_wk = ::getenv("WAYLAND_DISPLAY");
-                if (display_env_wk && *display_env_wk && wayland_env_wk && *wayland_env_wk) {
-                    ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", /* replace */ false);
-                }
-            }
-
            // XInitThreads is needed before GStreamer may use Xlib. On
            // native Wayland without DISPLAY, GStreamer uses waylandsink
            // (no Xlib involved), so the call is skipped.
@@ -429,7 +429,8 @@ if [ "\$XDG_SESSION_TYPE" = "wayland" ] && [ "\$ZINK_DISABLE_OVERRIDE" != "1" ];
                export __EGL_VENDOR_LIBRARY_FILENAMES=/usr/share/glvnd/egl_vendor.d/50_mesa.json
                export MESA_LOADER_DRIVER_OVERRIDE=zink
                export GALLIUM_DRIVER=zink
-                export WEBKIT_DISABLE_DMABUF_RENDERER=1
+                # WebKit's NVIDIA DMABUF workaround is applied by the binary itself,
+                # gated on the runtime WebKitGTK version (src/OrcaSlicer.cpp).
            fi
        fi
    fi
@@ -327,6 +327,8 @@ set(lisbslic3r_sources
    Geometry/VoronoiUtils.cpp
    Geometry/VoronoiUtils.hpp
    Geometry/VoronoiVisualUtils.hpp
+    ChromaStack.cpp
+    ChromaStack.hpp
    IMEXArrange.cpp
    IMEXArrange.hpp
    IMEXHelpers.cpp
@@ -0,0 +1,394 @@
+#include "ChromaStack.hpp"
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+#include <limits>
+#include <cstdlib>
+#include <numeric>
+
+#include <tbb/blocked_range.h>
+#include <tbb/parallel_for.h>
+
+#include <miniz.h>
+
+namespace Slic3r {
+
+// How many e-folding lengths of absorption count as "the colour beneath no longer shows". Three
+// passes 5% of the light, which is about where the eye stops seeing what is under a layer.
+static constexpr float OPAQUE_EFOLDS = 3.f;
+
+// TD is a filament property, so a zero or negative value in a preset is a data error rather than a
+// request for an infinitely opaque filament. Clamp instead: below this the filament is opaque at a
+// single layer anyway.
+static constexpr float TD_MIN_MM = 0.05f;
+static constexpr float TD_MAX_MM = 100.f;
+
+static float srgb_to_linear(float c)
+{
+    return c <= 0.04045f ? c / 12.92f : std::pow((c + 0.055f) / 1.055f, 2.4f);
+}
+
+static float linear_to_srgb(float c)
+{
+    return c <= 0.0031308f ? c * 12.92f : 1.055f * std::pow(c, 1.f / 2.4f) - 0.055f;
+}
+
+// CIELAB under D65, from non-linear sRGB in [0, 1]. Only used for nearest-colour search, so the
+// absolute white point matters far less than both sides using the same one.
+struct Lab
+{
+    float l = 0.f, a = 0.f, b = 0.f;
+};
+
+static Lab srgb_to_lab(float r, float g, float b)
+{
+    const float rl = srgb_to_linear(r), gl = srgb_to_linear(g), bl = srgb_to_linear(b);
+    const float x = (0.4124f * rl + 0.3576f * gl + 0.1805f * bl) / 0.95047f;
+    const float y = (0.2126f * rl + 0.7152f * gl + 0.0722f * bl);
+    const float z = (0.0193f * rl + 0.1192f * gl + 0.9505f * bl) / 1.08883f;
+    auto        f = [](float t) {
+        return t > 0.008856f ? std::cbrt(t) : (7.787f * t + 16.f / 116.f);
+    };
+    const float fx = f(x), fy = f(y), fz = f(z);
+    return Lab{ 116.f * fy - 16.f, 500.f * (fx - fy), 200.f * (fy - fz) };
+}
+
+static float delta_e(const Lab &p, const Lab &q)
+{
+    const float dl = p.l - q.l, da = p.a - q.a, db = p.b - q.b;
+    return std::sqrt(dl * dl + da * da + db * db);
+}
+
+int ChromaStack::relief_layers() const
+{
+    int n = 0;
+    for (const ChromaBand &band : bands)
+        n += std::max(0, band.layers);
+    return n;
+}
+
+int ChromaStack::total_layers() const { return std::max(0, base_layers) + relief_layers(); }
+
+float ChromaStack::depth_mm() const { return float(relief_layers()) * layer_height_mm; }
+
+std::vector<ColorRGB> chroma_palette(const ChromaStack &stack)
+{
+    const int total = stack.total_layers();
+    // No bands means no picture and no filament to print the base in, whatever base_layers says.
+    if (total <= 0 || stack.bands.empty() || stack.layer_height_mm <= 0.f)
+        return {};
+
+    // The filament each printed layer is in, bottom-up: the base first, in the bottom band's filament,
+    // then the bands themselves.
+    std::vector<const ChromaFilament *> per_layer;
+    per_layer.reserve(size_t(total));
+    for (int i = 0; i < std::max(0, stack.base_layers); ++i)
+        per_layer.push_back(&stack.bands.front().filament);
+    for (const ChromaBand &band : stack.bands)
+        for (int i = 0; i < band.layers; ++i)
+            per_layer.push_back(&band.filament);
+
+    std::vector<ColorRGB> palette(size_t(total) + 1);
+
+    // Linear light, walking up from an opaque base: C_0 is the bottom layer's own colour, so a
+    // column one layer tall comes out exactly that colour however translucent the filament is.
+    std::array<float, 3> acc{ srgb_to_linear(per_layer.front()->color.r()), srgb_to_linear(per_layer.front()->color.g()),
+                              srgb_to_linear(per_layer.front()->color.b()) };
+    auto                 store = [&palette](size_t k, const std::array<float, 3> &lin) {
+        palette[k] = ColorRGB(std::clamp(linear_to_srgb(lin[0]), 0.f, 1.f), std::clamp(linear_to_srgb(lin[1]), 0.f, 1.f),
+                              std::clamp(linear_to_srgb(lin[2]), 0.f, 1.f));
+    };
+    store(0, acc);
+
+    for (int k = 1; k <= total; ++k) {
+        const ChromaFilament &f  = *per_layer[size_t(k - 1)];
+        const float             td = std::clamp(f.td_mm, TD_MIN_MM, TD_MAX_MM);
+        // The depth at which this filament hides what is behind it, turned into the e-folding length
+        // of its absorption; see CHROMA_TD_OPAQUE_FRACTION.
+        const float efold = CHROMA_TD_OPAQUE_FRACTION * td / OPAQUE_EFOLDS;
+        const float t     = std::exp(-stack.layer_height_mm / efold);
+        const std::array<float, 3> own{ srgb_to_linear(f.color.r()), srgb_to_linear(f.color.g()),
+                                        srgb_to_linear(f.color.b()) };
+        for (int c = 0; c < 3; ++c)
+            acc[size_t(c)] = (1.f - t) * own[size_t(c)] + t * acc[size_t(c)];
+        store(size_t(k), acc);
+    }
+    return palette;
+}
+
+ChromaSolve chroma_solve(const uint8_t *rgb, int width, int height, const ChromaStack &stack)
+{
+    ChromaSolve solve;
+    const int     total  = stack.total_layers();
+    const int     base   = std::max(0, stack.base_layers);
+    const int     relief = stack.relief_layers();
+    if (rgb == nullptr || width <= 0 || height <= 0 || relief <= 0 || relief > CHROMA_MAX_RELIEF_LAYERS)
+        return solve;
+
+    const std::vector<ColorRGB> palette = chroma_palette(stack);
+    if (int(palette.size()) != total + 1)
+        return solve;
+
+    // Only the heights the solver may choose: base (nothing of the relief printed) up to total.
+    const int               choices = relief + 1;
+    const size_t                        choice_count = size_t(choices);
+    std::vector<Lab>                    choice_lab(choice_count);
+    std::vector<std::array<uint8_t, 3>> choice_rgb(choice_count);
+    for (int i = 0; i < choices; ++i) {
+        const ColorRGB &c = palette[size_t(base + i)];
+        choice_lab[size_t(i)] = srgb_to_lab(c.r(), c.g(), c.b());
+        choice_rgb[size_t(i)] = { uint8_t(std::lround(c.r() * 255.f)), uint8_t(std::lround(c.g() * 255.f)),
+                                  uint8_t(std::lround(c.b() * 255.f)) };
+    }
+
+    const size_t count = size_t(width) * size_t(height);
+    solve.width        = width;
+    solve.height       = height;
+    solve.levels.resize(count);
+    solve.grey.resize(count);
+    solve.preview.resize(count * 3);
+
+    std::vector<float> errors(count, 0.f);
+
+    auto pick = [&](float r, float g, float b, float &out_error) {
+        const Lab target = srgb_to_lab(std::clamp(r, 0.f, 1.f), std::clamp(g, 0.f, 1.f), std::clamp(b, 0.f, 1.f));
+        int       best   = 0;
+        float     best_d = std::numeric_limits<float>::max();
+        for (int i = 0; i < choices; ++i) {
+            const float d = delta_e(target, choice_lab[size_t(i)]);
+            if (d < best_d) {
+                best_d = d;
+                best   = i;
+            }
+        }
+        out_error = best_d;
+        return best;
+    };
+
+    // The grey level a chosen height is written as. Rounded to the nearest of 256 levels, which for
+    // any practical layer budget (a few dozen) maps every height to its own level exactly - the
+    // relief's steps stay on layer boundaries, which is the whole point of quantizing here.
+    auto grey_of = [relief](int choice) {
+        return uint8_t(std::lround(255.0 * double(choice) / double(relief)));
+    };
+
+    auto write = [&](size_t px, int choice, float err) {
+        solve.levels[px]        = uint16_t(base + choice);
+        solve.grey[px]          = grey_of(choice);
+        solve.preview[px * 3]     = choice_rgb[size_t(choice)][0];
+        solve.preview[px * 3 + 1] = choice_rgb[size_t(choice)][1];
+        solve.preview[px * 3 + 2] = choice_rgb[size_t(choice)][2];
+        errors[px]              = err;
+    };
+
+    if (stack.dither) {
+        // Floyd-Steinberg, serpentine so the error does not drift consistently to one side. The
+        // diffusion buffer holds the two rows the kernel reaches, in sRGB - which is where the
+        // artifact being traded away lives, and what every reference implementation diffuses in.
+        const size_t                      row_len = size_t(width);
+        std::vector<std::array<float, 3>> row(row_len), next(row_len);
+        for (int x = 0; x < width; ++x) {
+            const uint8_t *src = rgb + size_t(x) * 3;
+            row[size_t(x)]     = { src[0] / 255.f, src[1] / 255.f, src[2] / 255.f };
+        }
+        for (int y = 0; y < height; ++y) {
+            if (y + 1 < height)
+                for (int x = 0; x < width; ++x) {
+                    const uint8_t *src = rgb + (size_t(y + 1) * size_t(width) + size_t(x)) * 3;
+                    next[size_t(x)]    = { src[0] / 255.f, src[1] / 255.f, src[2] / 255.f };
+                }
+            const bool ltr = (y % 2) == 0;
+            for (int i = 0; i < width; ++i) {
+                const int    x  = ltr ? i : width - 1 - i;
+                const size_t px = size_t(y) * size_t(width) + size_t(x);
+                float        err = 0.f;
+                const int    choice = pick(row[size_t(x)][0], row[size_t(x)][1], row[size_t(x)][2], err);
+                write(px, choice, err);
+
+                std::array<float, 3> residual{};
+                for (int c = 0; c < 3; ++c)
+                    residual[size_t(c)] = row[size_t(x)][size_t(c)] - choice_rgb[size_t(choice)][size_t(c)] / 255.f;
+
+                const int  ahead = ltr ? x + 1 : x - 1;
+                const int  back  = ltr ? x - 1 : x + 1;
+                auto spread = [&](std::vector<std::array<float, 3>> &dst, int at, float w) {
+                    if (at < 0 || at >= width)
+                        return;
+                    for (int c = 0; c < 3; ++c)
+                        dst[size_t(at)][size_t(c)] += residual[size_t(c)] * w;
+                };
+                spread(row, ahead, 7.f / 16.f);
+                if (y + 1 < height) {
+                    spread(next, back, 3.f / 16.f);
+                    spread(next, x, 5.f / 16.f);
+                    spread(next, ahead, 1.f / 16.f);
+                }
+            }
+            row.swap(next);
+        }
+    } else {
+        tbb::parallel_for(tbb::blocked_range<int>(0, height), [&](const tbb::blocked_range<int> &range) {
+            for (int y = range.begin(); y < range.end(); ++y)
+                for (int x = 0; x < width; ++x) {
+                    const size_t   px  = size_t(y) * size_t(width) + size_t(x);
+                    const uint8_t *src = rgb + px * 3;
+                    float          err = 0.f;
+                    write(px, pick(src[0] / 255.f, src[1] / 255.f, src[2] / 255.f, err), err);
+                }
+        });
+    }
+
+    solve.mean_delta_e = count == 0 ? 0. : std::accumulate(errors.begin(), errors.end(), 0.) / double(count);
+    solve.max_delta_e  = errors.empty() ? 0. : double(*std::max_element(errors.begin(), errors.end()));
+    return solve;
+}
+
+float chroma_layers_to_opaque(float td_mm, float layer_height_mm)
+{
+    if (layer_height_mm <= 0.f)
+        return 0.f;
+    return CHROMA_TD_OPAQUE_FRACTION * std::clamp(td_mm, TD_MIN_MM, TD_MAX_MM) / layer_height_mm;
+}
+
+// Below about one dE two colours are the same colour to the eye. Half of that is the threshold for
+// "this layer changed something", so a step has to be comfortably invisible before a layer is called
+// wasted.
+static constexpr float VISIBLE_DE = 0.5f;
+
+static float step_delta_e(const ColorRGB &a, const ColorRGB &b)
+{
+    return delta_e(srgb_to_lab(a.r(), a.g(), a.b()), srgb_to_lab(b.r(), b.g(), b.b()));
+}
+
+int chroma_distinct_levels(const ChromaStack &stack)
+{
+    const std::vector<ColorRGB> palette = chroma_palette(stack);
+    const int                   base    = std::max(0, stack.base_layers);
+    if (int(palette.size()) <= base + 1)
+        return 0;
+    int n = 0;
+    for (size_t i = size_t(base) + 1; i < palette.size(); ++i)
+        if (step_delta_e(palette[i - 1], palette[i]) > VISIBLE_DE)
+            ++n;
+    return n;
+}
+
+void chroma_trim_bands(ChromaStack &stack)
+{
+    // Walked over the stack's own palette rather than over the filaments' TD, because how fast a band
+    // runs out of anything to say depends on what is under it as much as on the filament. A light band
+    // over a dark one is finished in four or five layers; a dark one over a light one goes on paying
+    // for many more, long past the depth at which it is nominally opaque, because the last few percent
+    // of light coming through still moves a near-black colour perceptibly.
+    const std::vector<ColorRGB> palette = chroma_palette(stack);
+    if (palette.empty())
+        return;
+    int layer = std::max(0, stack.base_layers); // palette index of the layer under the band being looked at
+    for (ChromaBand &band : stack.bands) {
+        int keep = 1;
+        for (int i = 1; i <= band.layers; ++i) {
+            const size_t cur = size_t(layer) + size_t(i);
+            if (cur >= palette.size())
+                break;
+            if (step_delta_e(palette[cur - 1], palette[cur]) > VISIBLE_DE)
+                keep = i; // the last layer of this band that still changes the colour
+        }
+        layer += band.layers;
+        band.layers = std::clamp(keep, 1, band.layers);
+    }
+}
+
+int chroma_level_at(const ChromaStack &stack, double z_mm)
+{
+    const int total = stack.total_layers();
+    if (total <= 0 || stack.layer_height_mm <= 0.f)
+        return 0;
+    // Layer k occupies ((k-1)h, k h], so a point inside it rounds up. The epsilon keeps a surface
+    // sitting exactly on a layer boundary in the layer that printed it rather than in the one above,
+    // which is the difference between a terrace showing its own colour and showing the next band's.
+    const int k = int(std::ceil(z_mm / double(stack.layer_height_mm) - 1e-6));
+    return std::clamp(k, 1, total);
+}
+
+std::vector<unsigned char> chroma_encode_height_png(const ChromaSolve &solve)
+{
+    if (solve.empty())
+        return {};
+    size_t      size = 0;
+    void       *png  = tdefl_write_image_to_png_file_in_memory_ex(solve.grey.data(), solve.width, solve.height, 1, &size,
+                                                                  MZ_DEFAULT_LEVEL, MZ_FALSE);
+    if (png == nullptr || size == 0)
+        return {};
+    const unsigned char       *bytes = static_cast<const unsigned char *>(png);
+    std::vector<unsigned char> out(bytes, bytes + size);
+    mz_free(png);
+    return out;
+}
+
+std::vector<ChromaRange> chroma_ranges(const ChromaStack &stack, double z_bottom)
+{
+    std::vector<ChromaRange> out;
+    if (stack.layer_height_mm <= 0.f)
+        return out;
+    // The layer height is stored as a float, like every other dimension of a texture displacement
+    // layer, so multiplying it up leaves noise in the last few digits - 5 layers of 0.1 mm come out as
+    // 0.5000000074. The slicer derives its own layer boundaries from the print config in double
+    // precision and lands on 0.5 exactly, and a boundary that misses it by any amount is a boundary a
+    // layer can fall on the wrong side of. Rounding to the nanometre removes the noise without
+    // disturbing any layer height a profile can express.
+    const auto snap = [](double z) { return std::round(z * 1e6) / 1e6; };
+
+    // The base is printed in the bottom band's filament - it is what is loaded when the print starts -
+    // so it extends that band's range down to the first layer instead of being a swap of its own.
+    int  layer = std::max(0, stack.base_layers);
+    bool first = true;
+    for (const ChromaBand &band : stack.bands) {
+        if (band.layers <= 0)
+            continue;
+        const double z_min = snap(z_bottom + (first ? 0. : double(layer) * double(stack.layer_height_mm)));
+        first = false;
+        layer += band.layers;
+        const double z_max = snap(z_bottom + double(layer) * double(stack.layer_height_mm));
+        if (!out.empty() && out.back().filament == band.filament.filament)
+            out.back().z_max = z_max; // no swap happens here, so it is one range
+        else
+            out.push_back(ChromaRange{ z_min, z_max, band.filament.filament });
+    }
+    return out;
+}
+
+ChromaStack chroma_default_stack(const std::vector<ChromaFilament> &filaments, float layer_height_mm,
+                                     int base_layers, int relief_layers)
+{
+    ChromaStack stack;
+    stack.layer_height_mm = layer_height_mm > 0.f ? layer_height_mm : 0.08f;
+    stack.base_layers     = std::max(0, base_layers);
+    if (filaments.empty() || relief_layers <= 0)
+        return stack;
+
+    std::vector<ChromaFilament> ordered = filaments;
+    std::stable_sort(ordered.begin(), ordered.end(), [](const ChromaFilament &a, const ChromaFilament &b) {
+        // Relative luminance of the linear colour: the perceptual order, so a saturated yellow
+        // counts as light and a saturated blue as dark, which a plain r+g+b sum gets wrong.
+        auto lum = [](const ColorRGB &c) {
+            return 0.2126f * srgb_to_linear(c.r()) + 0.7152f * srgb_to_linear(c.g()) + 0.0722f * srgb_to_linear(c.b());
+        };
+        return lum(a.color) > lum(b.color);
+    });
+
+    const int count = int(ordered.size());
+    int       left  = relief_layers;
+    for (int i = 0; i < count; ++i) {
+        // Spread the remainder over the first bands rather than piling it onto the last one.
+        const int share = left / (count - i) + ((left % (count - i)) > 0 ? 1 : 0);
+        ChromaBand band;
+        band.filament = ordered[size_t(i)];
+        band.layers   = std::max(1, share);
+        left -= share;
+        stack.bands.push_back(band);
+    }
+    return stack;
+}
+
+} // namespace Slic3r
@@ -0,0 +1,286 @@
+#ifndef slic3r_ChromaStack_hpp_
+#define slic3r_ChromaStack_hpp_
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include <cereal/cereal.hpp>
+#include <cereal/types/vector.hpp>
+
+#include "Color.hpp"
+
+namespace Slic3r {
+
+// ChromaStack-style colour printing: a picture is reproduced on a single face by stacking thin layers
+// of a few filaments, swapping filament at fixed layer boundaries, and varying the *height* of each
+// pixel's column. Where the column is low, the layers above it are missing and the filament below
+// shows; where it is high, the topmost filament covers everything beneath it. Because filament is
+// translucent, a column that stops part-way through a run shows a blend of that run's filament and
+// what is under it, which is what gives far more colours than there are filaments loaded.
+//
+// So there are only two things to compute, and they are both here:
+//  - the *palette*: the colour the stack shows at every possible column height (chroma_palette());
+//  - the *height map*: per pixel, the column height whose palette colour is closest to the picture
+//    (chroma_solve()).
+//
+// Everything else is machinery that already exists. The height map is handed to a texture
+// displacement layer as its height texture, so the existing projection/preview/bake pipeline turns
+// it into real geometry (see TextureDisplacement.hpp), and the filament swaps are handed to the
+// object's height ranges (ModelObject::layer_config_ranges), which is the slicer's own way of
+// saying "print this Z band with that filament".
+
+// The depth of filament that blocks essentially all the light behind it, as a fraction of the
+// filament's transmission distance (TD).
+//
+// TD's scale is empirical, not physical: its values run from about 1
+// for an opaque filament to 10 and above for a nearly clear one, and the community's calibration
+// prints (the "seashell" step test) read a TD off the step where the colour beneath stops showing.
+// That step is about a tenth of the TD number, which is the only thing this constant encodes - a
+// filament of TD 2 stops hiding what is under it at roughly 0.2 mm, i.e. after two or three layers,
+// while one of TD 8 needs most of a millimetre. The model below turns that into a per-layer
+// transmittance; see chroma_palette().
+static constexpr float CHROMA_TD_OPAQUE_FRACTION = 0.1f;
+
+// What a fresh stack gets above the base. Twenty-four layers is about two millimetres at a fine layer
+// height: enough steps for a continuous tonal ramp, and still a print that finishes in an evening.
+static constexpr int CHROMA_DEFAULT_RELIEF_LAYERS = 24;
+
+// The most picture layers the solve can express. A column's height above the base is stored as one
+// byte per pixel in the 8-bit grayscale height map the displacement reads, so beyond this two
+// different heights would have to share a grey level and the relief's steps would stop landing on
+// layer boundaries - which is the one thing the quantization exists to guarantee.
+//
+// It bounds the bands, not the stack: the base is whatever the model already is under the painted
+// face, often hundreds of layers on a tall part, and nothing about it is quantized into the height
+// map. As a limit on the picture it is not one in practice - 255 layers is 20 mm of relief at
+// 0.08 mm, far past where a picture gains anything.
+static constexpr int CHROMA_MAX_RELIEF_LAYERS = 255;
+
+// The most filament changes one stack may hold. Every band is a swap the printer has to make, so this is
+// a limit on patience rather than on the model; the palette itself is bounded by the layer count.
+static constexpr size_t CHROMA_MAX_BANDS = 16;
+
+// One filament as the colour model sees it: what colour it is, and how far light gets into it.
+struct ChromaFilament
+{
+    // 0-based index into the project's filaments, which is what a height range's `extruder` option
+    // (1-based) is written from. -1 for a filament that is not loaded, which the GUI refuses to
+    // solve with rather than silently printing in the wrong colour.
+    int      filament = -1;
+    ColorRGB color;
+    // The filament preset's own name, so the panel can say which filament this is. Six similar greys
+    // are six identical swatches and six identical numbers otherwise. Stored rather than looked up on
+    // demand because a stack outlives the project's filament list - a preset can be swapped out from
+    // under a saved stack, and then the name is the only record of what it was solved against.
+    std::string name;
+    // Transmission distance, mm, as the filament preset reports it
+    // (`filament_transmission_distance`). Clamped to a sane range when the palette is built: zero
+    // would make a layer infinitely opaque and a negative value is meaningless.
+    float    td_mm = 4.f;
+
+    template<class Archive> void serialize(Archive &ar)
+    {
+        float r = color.r(), g = color.g(), b = color.b();
+        ar(filament, r, g, b, td_mm, name);
+        color = ColorRGB(r, g, b);
+    }
+};
+
+// A run of consecutive layers printed in one filament. The stack is a list of these, bottom-up, so
+// a band boundary is exactly where the print pauses and the filament is changed.
+struct ChromaBand
+{
+    ChromaFilament filament;
+    int              layers = 1;
+
+    template<class Archive> void serialize(Archive &ar) { ar(filament, layers); }
+};
+
+// The whole recipe: which filaments, in which order, how thick a layer is, and how much of the
+// bottom is solid backing rather than picture.
+struct ChromaStack
+{
+    std::vector<ChromaBand> bands; // bottom-up; bands.front() is the one the base is printed in
+
+    // The print's layer height, mm. Taken from the print profile rather than chosen here - a stack
+    // solved against 0.08 mm layers prints as the wrong picture at 0.2 mm, so the GUI re-solves when
+    // the profile's layer height changes.
+    float layer_height_mm = 0.08f;
+
+    // Layers of solid backing under the picture: everything the model already is below the painted
+    // face. Not part of any band - the bands are the picture - but printed in the bottom band's
+    // filament, since that is what is loaded when the print starts.
+    //
+    // Keeping it out of the bands is what lets it be what it really is: a measurement of the model,
+    // often a hundred layers or more, while a band is a handful. Folding the two together put a
+    // three-digit number on a slider meant for single digits and made "how thick is the backing" and
+    // "how many layers does the first filament get" the same control, which they are not.
+    //
+    // The colour model treats the base as opaque. That is what makes a column's colour depend only on
+    // the layers above it, and why the panel warns about a base thin enough to let the plate show
+    // through.
+    int  base_layers = 4;
+
+    // Whether `base_layers` follows the model or was typed in. It follows by default, and it should:
+    // the painted face is wherever the geometry puts it, and a base that disagrees with it shifts
+    // every colour in the picture - the stack ends up anchored at the bottom of the part instead of
+    // under the face, so the picture's whole range is squeezed into the first few millimetres and
+    // everything above it clamps to the top band.
+    //
+    // It cannot be measured once and left: a layer is created, and its picture chosen, before there
+    // is any paint to measure, and the face moves again whenever the part is scaled or the layer
+    // height changes. So the panel re-measures it every frame while this is set.
+    bool base_auto = true;
+
+    // Spread the quantization error into neighbouring pixels (Floyd-Steinberg, serpentine) instead
+    // of rounding each pixel to its nearest palette colour on its own. A palette of twenty or thirty
+    // colours has to cover a photograph's whole range, so plain rounding leaves visible bands across
+    // a sky or a cheek; diffusing the error trades them for fine stipple, which at a tenth of a
+    // millimetre per pixel reads as the intermediate colour. Off for flat-coloured artwork, where
+    // stipple is the artifact rather than the cure.
+    bool dither = false;
+
+    // Total printed layers, base included: what the tallest column is.
+    int  total_layers() const;
+    // Layers the picture is built from, i.e. the bands' own total above the base.
+    int  relief_layers() const;
+    // The relief's height in mm, which is the `depth_mm` of the texture displacement layer the
+    // height map is handed to.
+    float depth_mm() const;
+    bool  empty() const { return bands.empty(); }
+
+    template<class Archive> void serialize(Archive &ar) { ar(bands, layer_height_mm, base_layers, dither, base_auto); }
+};
+
+// The colour the stack shows at every column height: entry k is a column of exactly k printed
+// layers, so the vector has total_layers() + 1 entries.
+//
+// The model is Beer-Lambert absorption, layer by layer. A layer of thickness h in a filament of
+// transmission distance TD passes
+//
+//     T = exp(-h / (CHROMA_TD_OPAQUE_FRACTION * TD / 3))
+//
+// of the light coming from under it and shows its own colour with the rest, so
+//
+//     C_k = (1 - T_k) * c_k + T_k * C_(k-1)
+//
+// walking up from an opaque base, C_0 = c_1. The divisor is what makes "opaque at
+// CHROMA_TD_OPAQUE_FRACTION * TD" true: three e-folding lengths pass 5% of the light, which is
+// where the colour beneath stops being visible to the eye.
+//
+// Beer-Lambert is not just the physically honest choice here, it is the only one that stays
+// consistent when applied per layer: transmittance multiplies, so a run of n layers of one filament
+// passes exp(-n h / d) whether it is composited in one step or n, and the palette does not depend on
+// how the stack happens to be cut into bands.
+//
+// Compositing is done on linear light and the entries are converted back to sRGB, because the
+// quantity being attenuated is light, not an sRGB code.
+std::vector<ColorRGB> chroma_palette(const ChromaStack &stack);
+
+// What chroma_solve() produced.
+struct ChromaSolve
+{
+    int width  = 0;
+    int height = 0;
+
+    // Per pixel, row-major and top-to-bottom like DecodedHeightTexture: the column's printed layer
+    // count, between base_layers and total_layers(). Sixteen bits because it counts from the build
+    // plate, and the base alone can be several hundred layers on a tall part.
+    std::vector<uint16_t> levels;
+    // The same thing as the 8-bit grayscale height map the displacement samples: 0 at base_layers,
+    // 255 at total_layers(). This is what gets encoded as a PNG into the layer's `image_data`, which
+    // is why the solve has to be the thing that owns the quantization - the relief's steps have to
+    // land on layer boundaries, and a grey level is the only channel the displacement reads.
+    std::vector<uint8_t> grey;
+    // Per pixel RGB: the palette colour the solve chose, i.e. what the print is predicted to look
+    // like. Shown in the panel next to the source picture, since the 3D view can only show the
+    // relief - the colours do not exist until the print swaps filament.
+    std::vector<uint8_t> preview;
+
+    // How far the prediction landed from the picture, as a mean and worst-case CIE76 dE over all
+    // pixels. The panel reports it because it is the only honest answer to "will this stack
+    // reproduce my image": under about 5 is a good match, over about 15 means the filaments cannot
+    // reach the picture's colours and no amount of layers will fix it.
+    double mean_delta_e = 0.;
+    double max_delta_e  = 0.;
+
+    bool empty() const { return width <= 0 || height <= 0 || levels.empty(); }
+};
+
+// Solves `rgb` (width * height * 3 bytes, row-major, top-to-bottom) against the stack's palette.
+// An empty stack, a zero-sized image or a stack with no relief layers gives an empty result.
+ChromaSolve chroma_solve(const uint8_t *rgb, int width, int height, const ChromaStack &stack);
+
+// How many layers of this filament it takes to hide what is under it, at this layer height. The
+// single most useful number about a stack and the one nothing else makes visible: it is what decides
+// whether a band is a gradient or a step.
+//
+// A filament hides what is behind it at about CHROMA_TD_OPAQUE_FRACTION of its TD (see
+// chroma_palette()), so this is that depth in layers. Below two the band has no intermediate colours
+// at all - the picture can only use the filament or not use it - which is what a coarse layer height
+// does to an otherwise good stack: TD 4 at 0.2 mm covers in two layers, the same filament at 0.08 mm
+// in five.
+float chroma_layers_to_opaque(float td_mm, float layer_height_mm);
+
+// How many of the picture's layers actually change the colour.
+//
+// A band eventually stops saying anything: once it hides what is under it, another layer of it shows
+// the colour the one below already showed. Those layers still cost print time and still take up
+// relief height, and nothing about the stack makes them visible - the band looks like ten layers of
+// gradient and is, say, five of gradient and five of flat.
+//
+// Measured against the palette rather than against TD, because how long a band keeps paying depends
+// on what is under it as much as on the filament: a light band over a dark one is finished in four or
+// five layers, while a dark one over a light one goes on moving the colour perceptibly well past the
+// depth at which it is nominally opaque.
+int chroma_distinct_levels(const ChromaStack &stack);
+
+// Shortens every band to its last layer that still changes the colour. Bands already shorter than
+// that are left alone: they are still inside their fade, where every layer counts.
+void chroma_trim_bands(ChromaStack &stack);
+
+// The printed layer a point `z_mm` above the bottom of the object falls in: 1-based, clamped to the
+// stack, 0 for a stack that prints nothing. Pair it with chroma_palette() to get the colour shown
+// there.
+//
+// This, rather than the height map, is what decides the colour a surface shows. A filament swap
+// happens at one print Z across the whole plate, so every surface crossing that height changes colour
+// whatever the picture says - the terraces of the relief, the walls between them, and the sides of the
+// model alike. Colouring a preview this way is therefore not an approximation of the print; it is what
+// the print does, and it keeps working after the relief has been baked into the mesh and the height
+// map is no longer attached to anything on screen.
+int chroma_level_at(const ChromaStack &stack, double z_mm);
+
+// The solve's height map as an 8-bit grayscale PNG, ready to be stored in a
+// TextureDisplacementLayer's `image_data`.
+std::vector<unsigned char> chroma_encode_height_png(const ChromaSolve &solve);
+
+// One filament swap as an object height range: the Z band, in the object's own coordinates (0 at its
+// bottom), that prints in `filament` (0-based).
+struct ChromaRange
+{
+    double z_min = 0.;
+    double z_max = 0.;
+    int    filament = -1;
+};
+
+// The stack's bands as height ranges, in object coordinates, starting at `z_bottom` (which is 0 for
+// a stack whose base starts at the object's first layer). Bands printed in the same filament as the
+// band below are merged, so a stack that repeats a filament does not produce a pointless swap.
+std::vector<ChromaRange> chroma_ranges(const ChromaStack &stack, double z_bottom = 0.);
+
+// A starting point for a stack: the given filaments, lightest at the bottom, each with an equal
+// share of `relief_layers` on top of `base_layers`.
+//
+// Light-to-dark is the convention filament-painting guides teach, and it is not arbitrary: a dark
+// filament over a light one reads as a midtone at one or two layers and as the dark colour at four,
+// so putting the dark filaments last is what buys the long tonal ramp. The reverse order gives a few
+// washed-out steps and then nothing.
+ChromaStack chroma_default_stack(const std::vector<ChromaFilament> &filaments, float layer_height_mm,
+                                     int base_layers, int relief_layers);
+
+} // namespace Slic3r
+
+#endif // slic3r_ChromaStack_hpp_
@@ -432,27 +432,36 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)

    std::string OozePrevention::pre_toolchange(GCode& gcodegen)
    {
-        std::string gcode;
-
        unsigned int extruder_id = gcodegen.writer().filament()->id();
-        const auto& filament_idle_temp = gcodegen.config().idle_temperature;
-        if (filament_idle_temp.get_at(extruder_id) == 0) {
-            // There is no idle temperature defined in filament settings.
-            // Use the delta value from print config.
-            if (gcodegen.config().standby_temperature_delta.value != 0) {
-                // we assume that heating is always slower than cooling, so no need to block
-                gcode += gcodegen.writer().set_temperature
-                (this->_get_temp(gcodegen) + gcodegen.config().standby_temperature_delta.value, false, extruder_id);
-                gcode.pop_back();
-                gcode += " ;cooldown\n"; // this is a marker for GCodeProcessor, so it can supress the commands when needed
-            }
-        } else {
-            // Use the value from filament settings. That one is absolute, not delta.
-            gcode += gcodegen.writer().set_temperature(filament_idle_temp.get_at(extruder_id), false, extruder_id);
-            gcode.pop_back();
-            gcode += " ;cooldown\n"; // this is a marker for GCodeProcessor, so it can supress the commands when needed
+
+        // Check if this tool will ever be used again in this print.
+        bool is_last_use = false;
+        if (gcodegen.m_print != nullptr && !gcodegen.m_print->tool_ordering().empty()) {
+            coordf_t current_z        = gcodegen.layer() ? gcodegen.layer()->print_z : gcodegen.writer().get_position().z();
+            const auto& tool_ordering = gcodegen.m_print->tool_ordering();
+            const auto& cfg           = gcodegen.config();
+            const int heater          = imex_physical_heater_for(cfg.is_imex.value, cfg.physical_extruder_map, int(extruder_id));
+            is_last_use               = tool_ordering.is_last_extrusion_layer(current_z, extruder_id);
+            for (unsigned int f : tool_ordering.all_extruders())
+                if (is_last_use && imex_physical_heater_for(cfg.is_imex.value, cfg.physical_extruder_map, int(f)) == heater)
+                    is_last_use = tool_ordering.is_last_extrusion_layer(current_z, f);
        }

+        int temp = 0;
+        if (!is_last_use) {
+            const auto& filament_idle_temp = gcodegen.config().idle_temperature;
+            if (filament_idle_temp.get_at(extruder_id) == 0) {
+                if (gcodegen.config().standby_temperature_delta.value == 0)
+                    return std::string();
+                temp = this->_get_temp(gcodegen) + gcodegen.config().standby_temperature_delta.value;
+            } else {
+                temp = filament_idle_temp.get_at(extruder_id);
+            }
+        }
+
+        std::string gcode = gcodegen.writer().set_temperature(temp, false, extruder_id);
+        gcode.pop_back();
+        gcode += " ;cooldown\n"; // this is a marker for GCodeProcessor, so it can supress the commands when needed
        return gcode;
    }

@@ -1004,6 +1004,7 @@ protected:
        size_t                                                  num_objects,
        size_t                                                  num_islands);

+    friend class OozePrevention;
    friend class Wipe;
    friend class WipeTowerIntegration;
    friend class PressureEqualizer;
@@ -1276,6 +1276,13 @@ void ToolOrdering::collect_extruder_statistics(bool prime_multi_material)
        sort_remove_duplicates(m_all_printing_extruders);
    }

+    m_last_layer_per_extruder.clear();
+    for (const LayerTools& lt : m_layer_tools) {
+        for (unsigned int ext : lt.extruders) {
+            m_last_layer_per_extruder[ext] = lt.print_z;
+        }
+    }
+
    if (prime_multi_material && ! m_all_printing_extruders.empty()) {
        // Reorder m_all_printing_extruders in the sequence they will be primed, the last one will be m_first_printing_extruder.
        // Then set m_first_printing_extruder to the 1st extruder primed.
@@ -3664,5 +3671,11 @@ int WipingExtrusions::get_support_interface_extruder_overrides(const PrintObject
    return -1;
 }

-
+bool ToolOrdering::is_last_extrusion_layer(coordf_t print_z, unsigned int extruder_id) const
+{
+    auto it = m_last_layer_per_extruder.find(extruder_id);
+    if (it == m_last_layer_per_extruder.end())
+        return true;
+    return print_z >= it->second - EPSILON;
+}
 } // namespace Slic3r
@@ -370,6 +370,7 @@ public:
                                                  std::vector<int> & initial_filaments);

    bool                has_non_support_filament(const PrintConfig &config);
+    bool                is_last_extrusion_layer(coordf_t print_z, unsigned int extruder_id) const;

 private:
    void				initialize_layers(std::vector<coordf_t> &zs);
@@ -413,6 +414,8 @@ private:
    // which keeps every legacy per-object code path bit-identical (loops over an empty map are
    // no-ops; downstream emission falls through to the per-object branch).
    std::map<unsigned int, std::map<LayerTools::MixedSubLayerGroup::VolumeKey, std::vector<size_t>>> m_gradient_volume_layers;
+    // Map: extruder_id -> print_z (z coordinate) of the last layer it is used on
+    std::map<unsigned int, coordf_t> m_last_layer_per_extruder;
    const PrintObject*         m_print_object_ptr = nullptr;
    Print*                     m_print;
    bool                       m_sorted = false;
@@ -211,6 +211,35 @@ bool decode_colored_png(const ReadBuf &in_buf, ImageColorscale &out_img)
    return decode_colored_png(stream, out_img);
 }

+bool is_decodable_8bit_png(const ReadBuf &pngbuf)
+{
+    static const constexpr int PNG_SIG_BYTES = 8;
+
+    struct ReadBufStream stream{pngbuf};
+    std::vector<png_byte> sig(PNG_SIG_BYTES, 0);
+    stream.read(sig.data(), PNG_SIG_BYTES);
+    if (!png_check_sig(sig.data(), PNG_SIG_BYTES))
+        return false;
+
+    PNGDescr dsc;
+    dsc.png = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+    if (!dsc.png)
+        return false;
+    dsc.info = png_create_info_struct(dsc.png);
+    if (!dsc.info)
+        return false;
+
+    if (!png_read_header_guarded(dsc.png, dsc.info, &stream, PNG_SIG_BYTES))
+        return false;
+
+    const size_t color_type = png_get_color_type(dsc.png, dsc.info);
+    const size_t bit_depth  = png_get_bit_depth(dsc.png, dsc.info);
+    const bool   grey       = color_type == PNG_COLOR_TYPE_GRAY;
+    const bool   colour     = color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_RGB_ALPHA;
+    return png_get_image_width(dsc.png, dsc.info) > 0 && png_get_image_height(dsc.png, dsc.info) > 0 &&
+           bit_depth == 8 && (grey || colour);
+}
+

 // Down to earth function to store a packed RGB image to file. Mostly useful for debugging purposes.
 // Based on https://www.lemoda.net/c/write-png/
@@ -50,6 +50,9 @@ struct ReadBuf { const void *buf = nullptr; const size_t sz = 0; };

 bool is_png(const ReadBuf &pngbuf);

+// True if decode_png() or decode_colored_png() would accept these bytes, judged from the header alone.
+bool is_decodable_8bit_png(const ReadBuf &pngbuf);
+
 struct ReadBufStream: public IStream {
    const ReadBuf &rbuf_ref;
    size_t pos = 0;
@@ -1489,7 +1489,7 @@ static std::vector<std::string> s_Preset_print_options{
 static std::vector<std::string> s_Preset_filament_options {/*"filament_colour", */ "default_filament_colour", "required_nozzle_HRC", "filament_diameter", "pellet_flow_coefficient", "volumetric_speed_coefficients", "filament_type",
                                                          "filament_soluble", "filament_is_support", "filament_printable", "filament_extruder_compatibility",
    "filament_max_volumetric_speed", "filament_adaptive_volumetric_speed",
-    "filament_flow_ratio", "filament_density", "filament_adhesiveness_category", "filament_cost", "filament_minimal_purge_on_wipe_tower",
+    "filament_flow_ratio", "filament_density", "filament_transmission_distance", "filament_adhesiveness_category", "filament_cost", "filament_minimal_purge_on_wipe_tower",
    "filament_tower_interface_pre_extrusion_dist", "filament_tower_interface_pre_extrusion_length", "filament_tower_ironing_area", "filament_tower_interface_purge_volume",
    "filament_tower_interface_print_temp",
    "nozzle_temperature", "nozzle_temperature_initial_layer",
@@ -228,6 +228,7 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
        "filament_diameter",
         "volumetric_speed_coefficients",
        "filament_density",
+        "filament_transmission_distance",
        "filament_cost",
        "filament_notes",
        "outer_wall_acceleration",
@@ -3440,6 +3440,20 @@ void PrintConfigDef::init_fff_params()
    def->mode = comAdvanced;
    def->set_default_value(new ConfigOptionFloats { 0. });

+    def = this->add("filament_transmission_distance", coFloats);
+    def->label = L("Transmission distance");
+    def->tooltip = L("How deep light gets into this filament, in millimetres, also called its "
+                     "transmission distance or TD. About 1 for an opaque filament, 4 to 7 for a usefully "
+                     "translucent one, 8 and above for a nearly clear one. Used only to predict the "
+                     "colours of a ChromaStack in the texture displacement tool; it has no effect on "
+                     "slicing. Measure it with a step test print, or take a published value for the "
+                     "filament.");
+    def->sidetext = L("mm");
+    def->min = 0;
+    def->max = 100;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloats { 4. });
+
    def = this->add("filament_type", coStrings);
    def->label = L("Type");
    def->tooltip = L("Filament material type");
@@ -1709,6 +1709,9 @@ PRINT_CONFIG_CLASS_DEFINE(
    ((ConfigOptionStrings,             volumetric_speed_coefficients))
    ((ConfigOptionInts,              filament_adhesiveness_category))
    ((ConfigOptionFloats,              filament_density))
+    // Transmission distance: how deep light gets into this filament. Not used by
+    // slicing - it is the colour model of a ChromaStack stack (see ChromaStack.hpp).
+    ((ConfigOptionFloats,              filament_transmission_distance))
    ((ConfigOptionStrings,             filament_type))
    ((ConfigOptionBools,               filament_soluble))
    ((ConfigOptionStrings,             filament_ids))
@@ -858,11 +858,10 @@ void PrintObject::contour_z()
    BOOST_LOG_TRIVIAL(debug) << "Contouring in parallel - start";

    TriangleMesh mesh = this->m_model_object->raw_mesh();
-    if (m_model_object->instances.size() != 1) {
-        throw RuntimeError("ContourZ: unexpected number of instances");
-    }
-
-    ModelInstance *inst = m_model_object->instances.front();
+    // A PrintObject groups the instances that share their whole transformation but the XY shift: an
+    // instance rotated, scaled or mirrored differently is a PrintObject of its own. So the first
+    // instance stands for all of them.
+    const ModelInstance *inst = m_instances.front().model_instance;
    Point                    center_offset = this->center_offset();
    Geometry::Transformation trans = inst->get_transformation();

@@ -283,7 +283,7 @@ bool height_texture_has_color(const TextureDisplacementLayer &layer)
    return decode_height_texture(layer).has_color();
 }

-DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer)
+DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer, bool keep_decoded)
 {
    DecodedHeightTexture result;
    if (layer.empty())
@@ -351,13 +351,15 @@ DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer
                }
        }

-        std::lock_guard<std::mutex> lock(g_decoded_texture_cache.mutex);
-        // Opportunistically drop entries for image_data that no longer exists anywhere, so the
-        // cache doesn't grow without bound across many add/remove-texture cycles in a long session.
-        auto &entries = g_decoded_texture_cache.entries;
-        for (auto it = entries.begin(); it != entries.end();)
-            it = it->second.first.expired() ? entries.erase(it) : std::next(it);
-        entries[key] = { std::weak_ptr<const std::vector<unsigned char>>(layer.image_data), result };
+        if (keep_decoded) {
+            std::lock_guard<std::mutex> lock(g_decoded_texture_cache.mutex);
+            // Opportunistically drop entries for image_data that no longer exists anywhere, so the
+            // cache doesn't grow without bound across many add/remove-texture cycles in a long session.
+            auto &entries = g_decoded_texture_cache.entries;
+            for (auto it = entries.begin(); it != entries.end();)
+                it = it->second.first.expired() ? entries.erase(it) : std::next(it);
+            entries[key] = { std::weak_ptr<const std::vector<unsigned char>>(layer.image_data), result };
+        }
    }

    // The image-adjustment panel's live edits, on top of the decode and before the smoothing. Before,
@@ -18,6 +18,7 @@

 #include <array>

+#include "ChromaStack.hpp"
 #include "Point.hpp"
 #include "TriangleSelector.hpp"

@@ -353,16 +354,33 @@ struct TextureDisplacementLayer
    // for the boundary to be drawn on.
    bool color_enabled = false;

+    // ChromaStack (see ChromaStack.hpp): when set, `image_data` is not a texture the user picked but the
+    // height map chroma_solve() computed, so that the whole displacement pipeline - preview, UV
+    // editor, bake - goes on reading one grayscale height map and needs to know nothing about colour
+    // stacks. The picture it was solved from is kept here instead, because the solve has to be redone
+    // whenever the stack, the print's layer height or the picture itself changes.
+    //
+    // A ChromaStack layer gets its colour from filament swaps at fixed Z, which is what `chroma`
+    // records and what the object's height ranges carry out. That is a different mechanism from
+    // `color_enabled` (per-triangle filament assignment), and the two are mutually exclusive: the
+    // panel turns colour off on a ChromaStack layer, since painting the relief in one filament per
+    // triangle would hide the very stack the heights were solved against.
+    bool                                        chroma_enabled = false;
+    ChromaStack                               chroma;
+    std::shared_ptr<std::vector<unsigned char>> chroma_source;
+
    bool empty() const { return !image_data || image_data->empty(); }

    template<class Archive> void save(Archive &ar) const
    {
        std::string blob = image_data ? std::string(image_data->begin(), image_data->end()) : std::string();
+        std::string source = chroma_source ? std::string(chroma_source->begin(), chroma_source->end()) : std::string();
        ar(slot, name, path, path_in_3mf, blob, depth_mm, tiling_scale, rotation_deg, offset, invert, tile_enabled,
           static_cast<int>(tile_method), static_cast<int>(projection_method), lscm_seam_angle_deg, islands,
           static_cast<int>(blend_mode), midlevel, island_padding_mm, lscm_seam_edges, view_project_right,
           view_project_up, smoothing, edge_smoothing, edge_smoothing_amount, auto_connect_islands, island_groups,
-           lscm_uv_overrides, view_project_projective, view_project_matrix, color_enabled);
+           lscm_uv_overrides, view_project_projective, view_project_matrix, color_enabled, chroma_enabled, chroma,
+           source);
    }
    template<class Archive> void load(Archive &ar)
    {
@@ -370,12 +388,14 @@ struct TextureDisplacementLayer
        int         tile_method_int       = 0;
        int         projection_method_int = 0;
        int         blend_mode_int        = 0;
+        std::string source;
        ar(slot, name, path, path_in_3mf, blob, depth_mm, tiling_scale, rotation_deg, offset, invert, tile_enabled,
           tile_method_int, projection_method_int, lscm_seam_angle_deg, islands, blend_mode_int, midlevel,
           island_padding_mm, lscm_seam_edges, view_project_right, view_project_up, smoothing, edge_smoothing,
           edge_smoothing_amount, auto_connect_islands, island_groups, lscm_uv_overrides, view_project_projective,
-           view_project_matrix, color_enabled);
+           view_project_matrix, color_enabled, chroma_enabled, chroma, source);
        image_data        = blob.empty() ? nullptr : std::make_shared<std::vector<unsigned char>>(blob.begin(), blob.end());
+        chroma_source   = source.empty() ? nullptr : std::make_shared<std::vector<unsigned char>>(source.begin(), source.end());
        tile_method       = static_cast<TextureTileMethod>(tile_method_int);
        projection_method = static_cast<TextureProjectionMethod>(projection_method_int);
        blend_mode        = static_cast<TextureBlendMode>(blend_mode_int);
@@ -599,8 +619,9 @@ DecodedHeightTexture downscale_height_texture(const DecodedHeightTexture &src, i
 // colour PNGs are accepted; for a colour source the height is its luminance, using the same
 // coefficients wxImage::ConvertToGreyscale() uses, so a texture imported as colour displaces exactly
 // as it did when the importer flattened it to grey on the way in. Returns an empty
-// DecodedHeightTexture if image_data is empty or is not a PNG at all.
-DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer);
+// DecodedHeightTexture if image_data is empty or is not a PNG at all. keep_decoded = false leaves the
+// result out of the decode cache, for one-off reads such as a picker thumbnail that must not hold full-size pixels.
+DecodedHeightTexture decode_height_texture(const TextureDisplacementLayer &layer, bool keep_decoded = true);

 // decode_height_texture(layer).has_color(), answered from the decode cache rather than from a copy of the
 // texture - cheap enough to ask every frame. Smoothing does not change it, so the raw decode is what is read.
@@ -842,6 +842,13 @@ void load_string_file(const boost::filesystem::path& p, std::string& str);

 bool check_layer_id_pattern(const std::string& pattern, int layer_id);

+// On Windows, return an equivalent path carrying the extended-length ("\\?\" / "\\?\UNC\")
+// prefix so the Win32 APIs accept it past MAX_PATH even when LongPathsEnabled is off. The path
+// is made absolute and lexically normalized first, because the prefix disables normalisation.
+// A path that is already extended (or a device path) is returned unchanged; on other platforms,
+// or when an absolute path cannot be formed, the input is returned unchanged.
+boost::filesystem::path extended_path(const boost::filesystem::path& path);
+
 } // namespace Slic3r

 #if WIN32
@@ -17,6 +17,7 @@

 #if defined(_MSC_VER) || defined(__MINGW64__)
 #include "boost/nowide/cstdio.hpp"
+#include "boost/nowide/convert.hpp"
 #endif

 #include "I18N.hpp"
@@ -62,7 +63,11 @@ bool open_zip(mz_zip_archive *zip, const char *fname, bool isread)

    FILE *f = nullptr;
 #if defined(_MSC_VER) || defined(__MINGW64__)
-    f = boost::nowide::fopen(fname, mode);
+    // fname is UTF-8 (the nowide contract). Route it through the shared extended-path helper so an
+    // archive stored past MAX_PATH opens even with LongPathsEnabled off.
+    const std::wstring wide_path = boost::nowide::widen(fname);
+    const std::string  extended  = boost::nowide::narrow(Slic3r::extended_path(boost::filesystem::path(wide_path)).wstring());
+    f = boost::nowide::fopen(extended.c_str(), mode);
 #elif defined(__GNUC__) && defined(_LARGEFILE64_SOURCE)
    f = fopen64(fname, mode);
 #else
@@ -101,6 +106,14 @@ bool close_zip(mz_zip_archive *zip, bool isread)
    }
    return ret;
 }
+
+#ifdef WIN32
+// mz_file_write_func writing an extracted entry into an already-open FILE*.
+size_t mz_write_to_cfile(void *opaque, mz_uint64 /*file_ofs*/, const void *buffer, size_t size)
+{
+    return std::fwrite(buffer, 1, size, static_cast<FILE *>(opaque));
+}
+#endif
 }

 bool open_zip_reader(mz_zip_archive *zip, const std::string &fname)
@@ -116,6 +129,36 @@ bool open_zip_writer(mz_zip_archive *zip, const std::string &fname)
 bool close_zip_reader(mz_zip_archive *zip) { return close_zip(zip, true); }
 bool close_zip_writer(mz_zip_archive *zip) { return close_zip(zip, false); }

+bool extract_zip_entry_to_file(mz_zip_archive *zip, mz_uint file_index, const boost::filesystem::path &dest_path)
+{
+    if (!zip)
+        return false;
+#ifdef WIN32
+    // Open the destination ourselves with a Windows extended-length path: miniz's narrow
+    // extract_to_file cannot be relied on past MAX_PATH with LongPathsEnabled off, and its wide
+    // variant takes a plain (unprefixed) path and a text-mode stream. This keeps the write binary.
+    FILE *file = ::_wfopen(Slic3r::extended_path(dest_path).wstring().c_str(), L"wb");
+    if (!file) {
+        zip->m_last_error = MZ_ZIP_FILE_OPEN_FAILED;
+        return false;
+    }
+
+    const bool written = mz_zip_reader_extract_to_callback(zip, file_index, mz_write_to_cfile, file, 0) != 0;
+    const bool closed  = std::fclose(file) == 0;
+    if (!written || !closed) {
+        if (written && !closed)
+            zip->m_last_error = MZ_ZIP_FILE_CLOSE_FAILED;
+        // Drop the partial entry rather than leave a truncated file behind.
+        boost::system::error_code ec;
+        boost::filesystem::remove(Slic3r::extended_path(dest_path), ec);
+        return false;
+    }
+    return true;
+#else
+    return mz_zip_reader_extract_to_file(zip, file_index, dest_path.string().c_str(), 0) != 0;
+#endif
+}
+
 std::string decode_archive_entry_path(mz_zip_archive *zip, const mz_zip_archive_file_stat &stat)
 {
    if (stat.m_is_utf8)
@@ -156,10 +199,13 @@ bool extract_archive_confined(const std::string &zip_path_utf8, const std::strin
        }
        const std::string dest_file = dest_dir + "/" + stat.m_filename;
        try {
+            // Use the extended-length form for every filesystem call so entries under a destination
+            // past MAX_PATH are created even with LongPathsEnabled off.
+            const boost::filesystem::path dest_path(dest_file);
+            const boost::filesystem::path io_dest = extended_path(dest_path);
            if (stat.m_is_directory) {
-                const boost::filesystem::path dest_path(dest_file);
-                if (!boost::filesystem::exists(dest_path))
-                    boost::filesystem::create_directories(dest_path);
+                if (!boost::filesystem::exists(io_dest))
+                    boost::filesystem::create_directories(io_dest);
                continue;
            }
            if (stat.m_uncomp_size == 0) {
@@ -167,10 +213,9 @@ bool extract_archive_confined(const std::string &zip_path_utf8, const std::strin
                continue;
            }
            // Replace a symlink at the destination rather than writing through it.
-            const boost::filesystem::path dest_path(dest_file);
-            if (boost::filesystem::is_symlink(boost::filesystem::symlink_status(dest_path)))
-                boost::filesystem::remove(dest_path);
-            if (!mz_zip_reader_extract_to_file(&archive, stat.m_file_index, dest_file.c_str(), 0)) {
+            if (boost::filesystem::is_symlink(boost::filesystem::symlink_status(io_dest)))
+                boost::filesystem::remove(io_dest);
+            if (!extract_zip_entry_to_file(&archive, stat.m_file_index, dest_path)) {
                BOOST_LOG_TRIVIAL(error) << "Unzip: extract file " << stat.m_filename << " to dest " << dest_file << " failed";
                close_zip_reader(&archive);
                return false;
@@ -1,6 +1,7 @@
 #ifndef MINIZ_EXTENSION_HPP
 #define MINIZ_EXTENSION_HPP

+#include <boost/filesystem/path.hpp>
 #include <string>
 #include <miniz.h>

@@ -13,6 +14,10 @@ bool close_zip_writer(mz_zip_archive *zip);
 std::string decode_archive_entry_path(mz_zip_archive *zip, const mz_zip_archive_file_stat &stat);
 // Extracts every entry of the archive under dest_dir. Nothing is written if any entry would resolve outside dest_dir.
 bool extract_archive_confined(const std::string &zip_path_utf8, const std::string &dest_dir);
+// Extracts one entry into dest_path, binary-safe and overwriting. On Windows the destination is
+// opened through an extended-length path so it works past MAX_PATH even with LongPathsEnabled off;
+// a partial file is removed if the write fails. False for a directory/unsupported entry or on error.
+bool extract_zip_entry_to_file(mz_zip_archive *zip, mz_uint file_index, const boost::filesystem::path &dest_path);

 class MZ_Archive {
 public:
@@ -2254,5 +2254,45 @@ bool check_layer_id_pattern(const std::string& pattern, int layer_id){
    return mod >= 0 && mod < count;
 }

+boost::filesystem::path extended_path(const boost::filesystem::path& path) {
+#ifdef WIN32
+    namespace fs = boost::filesystem;
+
+    // Already extended, or an explicit device path (which is not subject to MAX_PATH and must not
+    // be absolutized or normalized): leave it alone.
+    {
+        fs::path prefix_candidate = path;
+        const std::wstring native = prefix_candidate.make_preferred().wstring();
+        if (native.rfind(L"\\\\?\\", 0) == 0 || native.rfind(L"\\\\.\\", 0) == 0)
+            return fs::path(native);
+    }
+
+    fs::path absolute = path;
+    if (!absolute.is_absolute()) {
+        boost::system::error_code ec;
+        absolute = fs::absolute(absolute, ec);
+        if (ec)
+            return path; // can't form a valid prefixed path from a relative one
+    }
+
+    // A trailing separator is redundant to the Win32 APIs, but lexically_normal() would rewrite it
+    // as a "." element, which the "\\?\" prefix (normalisation off) takes literally. Drop it first.
+    while (absolute.has_relative_path() && absolute.filename() == ".")
+        absolute = absolute.parent_path();
+
+    // The "\\?\" prefix turns off Win32 normalisation, so do it here first.
+    absolute = absolute.lexically_normal();
+
+    // Extended paths only recognize backslash separators.
+    const std::wstring native = absolute.make_preferred().wstring();
+    if (native.empty())
+        return path;
+    if (native.rfind(L"\\\\", 0) == 0)
+        return fs::path(L"\\\\?\\UNC\\" + native.substr(2)); // \\server\share\... -> \\?\UNC\server\share\...
+    return fs::path(L"\\\\?\\" + native);                    // C:\dir\... -> \\?\C:\dir\...
+#else
+    return path;
+#endif
+}

 }; // namespace Slic3r
@@ -222,6 +222,7 @@ set(SLIC3R_GUI_SOURCES
    GUI/Gizmos/GLGizmoUtils.hpp
    GUI/GLCanvas3D.cpp
    GUI/GLCanvas3D.hpp
+    GUI/SequentialPrintClearance.hpp
    GUI/GLModel.cpp
    GUI/GLModel.hpp
    GUI/GLSelectionRectangle.cpp
@@ -689,6 +690,8 @@ set(SLIC3R_GUI_SOURCES
    plugin/host/PluginHostUi.hpp
    plugin/host/PluginPages.cpp
    plugin/host/PluginPages.hpp
+    plugin/host/PluginResourceTextures.cpp
+    plugin/host/PluginResourceTextures.hpp
    plugin/CloudPluginService.cpp
    plugin/CloudPluginService.hpp
    plugin/PluginFsUtils.cpp
@@ -712,6 +715,9 @@ set(SLIC3R_GUI_SOURCES
    plugin/pluginTypes/pages/PagesPluginCapability.hpp
    plugin/pluginTypes/pages/PagesPluginCapability.cpp
    plugin/pluginTypes/pages/PagesPluginCapabilityTrampoline.hpp
+    plugin/pluginTypes/resourceTexture/ResourceTexturePluginCapability.hpp
+    plugin/pluginTypes/resourceTexture/ResourceTexturePluginCapability.cpp
+    plugin/pluginTypes/resourceTexture/ResourceTexturePluginCapabilityTrampoline.hpp
    plugin/pluginTypes/script/ScriptPluginCapability.hpp
    plugin/pluginTypes/script/ScriptPluginCapability.cpp
    plugin/pluginTypes/script/ScriptPluginCapabilityTrampoline.hpp
@@ -85,6 +85,96 @@ static std::string float_to_string_with_precision(float value, int precision = 3
    return stream.str();
 }

+static std::string colour_to_ams_string(const wxColour& color)
+{
+    char col_buf[10];
+    sprintf(col_buf, "%02X%02X%02X%02X", (int)color.Red(), (int)color.Green(), (int)color.Blue(), (int)color.Alpha());
+    return col_buf;
+}
+
+static wxColour mix_colour(const wxColour& left, const wxColour& right, double ratio)
+{
+    ratio = std::max(0.0, std::min(1.0, ratio));
+    auto mix_channel = [ratio](unsigned char l, unsigned char r) {
+        return static_cast<unsigned char>(std::round(l + (r - l) * ratio));
+    };
+    return wxColour(mix_channel(left.Red(), right.Red()),
+                    mix_channel(left.Green(), right.Green()),
+                    mix_channel(left.Blue(), right.Blue()),
+                    mix_channel(left.Alpha(), right.Alpha()));
+}
+
+static std::vector<ColorPickerPopup::ColorItem> collect_ams_color_items(DevFilaSystem* fila_system)
+{
+    std::vector<ColorPickerPopup::ColorItem> items;
+    if (!fila_system) return items;
+
+    for (const auto& ams_pair : fila_system->GetAmsList()) {
+        DevAms* ams = ams_pair.second;
+        if (!ams) continue;
+
+        for (const auto& tray_pair : ams->GetTrays()) {
+            DevAmsTray* tray = tray_pair.second;
+            if (!tray || !tray->is_tray_info_ready()) continue;
+
+            ColorPickerPopup::ColorItem item;
+            for (const std::string& col : tray->cols) {
+                item.colors.emplace_back(DevAmsTray::decode_color(col));
+            }
+            if (item.colors.empty() && !tray->color.empty()) {
+                item.colors.emplace_back(DevAmsTray::decode_color(tray->color));
+            }
+            if (item.colors.empty()) continue;
+
+            item.ctype = item.colors.size() > 1 ? tray->ctype : 2;
+            items.emplace_back(std::move(item));
+        }
+    }
+
+    return items;
+}
+
+static std::vector<ColorPickerPopup::ColorItem> collect_preset_color_items(const std::string& filament_id)
+{
+    std::vector<ColorPickerPopup::ColorItem> items;
+    if (filament_id.empty()) return items;
+
+    auto* clr_query = GUI::wxGetApp().get_filament_color_code_query();
+    if (!clr_query) return items;
+
+    auto* agent = wxGetApp().getAgent();
+    const std::string catalog_id = agent ? agent->from_orca_filament_id(filament_id) : filament_id;
+    FilamentColorCodes* color_codes = clr_query->GetFilaInfoMap(wxString::FromUTF8(catalog_id));
+    if (!color_codes || !color_codes->GetFilamentColor2CodeMap()) return items;
+
+    std::set<std::string> seen;
+    for (const auto& color_pair : *color_codes->GetFilamentColor2CodeMap()) {
+        const FilamentColor& fila_color = color_pair.first;
+        FilamentColorCode* color_code = color_pair.second;
+        if (!color_code || fila_color.GetColors().empty()) continue;
+
+        ColorPickerPopup::ColorItem item;
+        item.ctype = fila_color.ColorCount() < 2 ? 2 :
+            (fila_color.m_color_type == FilamentColor::ColorType::GRADIENT_CLR ? 0 : 1);
+        item.name = color_code->GetFilaColorName();
+
+        std::string key = std::to_string(item.ctype);
+        for (const wxColour& color : fila_color.GetColors()) {
+            item.colors.emplace_back(color);
+            char rgba[9];
+            std::snprintf(rgba, sizeof(rgba), "%02X%02X%02X%02X",
+                static_cast<unsigned>(color.Red()), static_cast<unsigned>(color.Green()),
+                static_cast<unsigned>(color.Blue()), static_cast<unsigned>(color.Alpha()));
+            key += "|" + std::string(rgba);
+        }
+
+        if (item.colors.empty() || !seen.insert(key).second) continue;
+        items.emplace_back(std::move(item));
+    }
+
+    return items;
+}
+
 AMSMaterialsSetting::AMSMaterialsSetting(wxWindow *parent, wxWindowID id)
    : DPIDialog(parent, id, _L("AMS Materials Setting"), wxDefaultPosition, wxDefaultSize, wxCAPTION | wxCLOSE_BOX)
    , m_color_picker_popup(ColorPickerPopup(this))
@@ -740,8 +830,19 @@ void AMSMaterialsSetting::on_select_ok(wxCommandEvent &event)
    nozzle_temp_min.ToLong(&nozzle_temp_min_int);
    nozzle_temp_max.ToLong(&nozzle_temp_max_int);
    wxColour color = m_clr_picker->m_colour;
-    char col_buf[10];
-    sprintf(col_buf, "%02X%02X%02X%02X", (int)color.Red(), (int)color.Green(), (int)color.Blue(), (int)color.Alpha());
+    std::string tray_color = colour_to_ams_string(color);
+    std::vector<std::string> tray_colors;
+    int tray_ctype = 2;
+    // Only firmware advertising fun2[23] receives the manual multi-color fields.
+    if (obj->is_support_filament_manual_multi_color) {
+        for (const wxColour& selected_color : m_clr_picker->m_cols) {
+            tray_colors.emplace_back(colour_to_ams_string(selected_color));
+        }
+        if (tray_colors.empty()) {
+            tray_colors.emplace_back(tray_color);
+        }
+        tray_ctype = tray_colors.size() > 1 ? m_clr_picker->ctype : 2;
+    }

    if (ams_filament_id.empty() || nozzle_temp_min.empty() || nozzle_temp_max.empty() || m_filament_type.empty()) {
        BOOST_LOG_TRIVIAL(trace) << "Invalid Setting id";
@@ -760,13 +861,33 @@ void AMSMaterialsSetting::on_select_ok(wxCommandEvent &event)
                            << ", tray_info_idx (filament_id) = " << ams_filament_id
                            << ", setting_id = " << ams_setting_id
                            << ", tray_type = " << m_filament_type
-                            << ", tray_color = " << col_buf
+                            << ", tray_color = " << tray_color
                            << ", nozzle_temp_min = " << nozzle_temp_min_int
                            << ", nozzle_temp_max = " << nozzle_temp_max_int;

    // set filament
    if (m_is_third) {
-        obj->command_ams_filament_settings(ams_id, slot_id, ams_filament_id, ams_setting_id, std::string(col_buf), m_filament_type, nozzle_temp_min_int, nozzle_temp_max_int);
+        obj->command_ams_filament_settings(ams_id, slot_id, ams_filament_id, ams_setting_id, tray_color, m_filament_type, nozzle_temp_min_int, nozzle_temp_max_int,
+                                           tray_colors, tray_ctype);
+
+        // Refresh the edited tray immediately while its MQTT acknowledgement is pending.
+        DevAmsTray* tray = nullptr;
+        if (is_virtual_tray()) {
+            for (auto& virtual_tray : obj->vt_slot) {
+                if (virtual_tray.id == std::to_string(ams_id)) {
+                    tray = &virtual_tray;
+                    break;
+                }
+            }
+        } else {
+            tray = obj->GetFilaSystem()->GetAmsTray(std::to_string(ams_id), std::to_string(slot_id));
+        }
+        if (tray) {
+            tray->color = tray_color;
+            tray->cols = tray_colors;
+            tray->ctype = tray_ctype;
+            tray->set_hold_count();
+        }
    }

    //reset param
@@ -923,8 +1044,15 @@ void AMSMaterialsSetting::set_ctype(int ctype)

 void AMSMaterialsSetting::on_picker_color(wxCommandEvent& event)
 {
-    unsigned int color_num  = event.GetInt();
-    set_color(wxColour(color_num>>24&0xFF, color_num>>16&0xFF, color_num>>8&0xFF, color_num&0xFF));
+    std::vector<wxColour> colors = m_color_picker_popup.get_selected_colours();
+    if (colors.empty()) {
+        unsigned int color_num = event.GetInt();
+        colors.emplace_back(color_num >> 24 & 0xFF, color_num >> 16 & 0xFF, color_num >> 8 & 0xFF, color_num & 0xFF);
+    }
+
+    set_ctype(m_color_picker_popup.get_selected_ctype());
+    set_color(colors.front());
+    set_colors(colors);
 }

 void AMSMaterialsSetting::on_clr_picker(wxMouseEvent &event)
@@ -939,14 +1067,12 @@ void AMSMaterialsSetting::on_clr_picker(wxMouseEvent &event)
        }
    }

-    std::vector<wxColour> ams_colors;
-    obj->GetFilaSystem()->CollectAmsColors(ams_colors);
-
+    m_color_picker_popup.set_ams_colours(collect_ams_color_items(obj->GetFilaSystem().get()));
+    m_color_picker_popup.set_preset_colours(collect_preset_color_items(ams_filament_id));
+    m_color_picker_popup.set_def_colour(m_clr_picker->m_colour, m_clr_picker->m_cols, m_clr_picker->ctype);
    wxPoint img_pos = m_clr_picker->ClientToScreen(wxPoint(0, 0));
    wxPoint popup_pos(img_pos.x - m_color_picker_popup.GetSize().x - FromDIP(95), img_pos.y - FromDIP(65));
    m_color_picker_popup.Position(popup_pos, wxSize(0, 0));
-    m_color_picker_popup.set_ams_colours(ams_colors);
-    m_color_picker_popup.set_def_colour(m_clr_picker->m_colour);
    m_color_picker_popup.Popup();
 }

@@ -1735,7 +1861,46 @@ void ColorPicker::doRender(wxDC& dc)
    auto radius = m_show_full ? size.x / 2 - FromDIP(1) : size.x / 2;
    if (m_selected) radius -= FromDIP(1);

-    if (alpha == 0) {
+    if (m_show_full && m_cols.size() > 1) {
+        if (ctype == 0) {
+            const double center_x = size.x / 2.0;
+            const double center_y = size.y / 2.0;
+            const double draw_radius = radius;
+            dc.SetPen(*wxTRANSPARENT_PEN);
+            for (int x = 0; x < size.x; ++x) {
+                const double dx = x + 0.5 - center_x;
+                if (std::abs(dx) > draw_radius) continue;
+
+                const double half_height = std::sqrt(std::max(0.0, draw_radius * draw_radius - dx * dx));
+                const int top = std::max(0, static_cast<int>(std::ceil(center_y - half_height)));
+                const int bottom = std::min(size.y - 1, static_cast<int>(std::floor(center_y + half_height)));
+                const double pos = size.x > 1 ? static_cast<double>(x) / (size.x - 1) : 0.0;
+                const double scaled = pos * (m_cols.size() - 1);
+                const size_t idx = std::min(static_cast<size_t>(scaled), m_cols.size() - 2);
+                const double ratio = scaled - idx;
+
+                if (top <= bottom) {
+                    dc.SetBrush(wxBrush(mix_colour(m_cols[idx], m_cols[idx + 1], ratio)));
+                    dc.DrawRectangle(x, top, 1, bottom - top + 1);
+                }
+            }
+        }
+        else {
+            float ev_angle = 360.0 / m_cols.size();
+            const float overlap = 2.0f;
+            wxPoint center(size.x / 2, size.y / 2);
+            dc.SetPen(*wxTRANSPARENT_PEN);
+            dc.SetBrush(wxBrush(m_cols.front()));
+            dc.DrawCircle(center.x, center.y, radius);
+            for (int i = 0; i < m_cols.size(); i++) {
+                dc.SetBrush(m_cols[i]);
+                float startAngle = 270.0f + i * ev_angle;
+                float endAngle = startAngle + ev_angle;
+                dc.DrawEllipticArc(center.x - radius, center.y - radius, 2 * radius, 2 * radius, startAngle - overlap, endAngle + overlap);
+            }
+        }
+    }
+    else if (alpha == 0) {
        wxSize bmp_size = m_bitmap_transparent_def.GetBmpSize();
        int center_x = (size.x - bmp_size.x) / 2;
        int center_y = (size.y - bmp_size.y) / 2;
@@ -1777,52 +1942,6 @@ void ColorPicker::doRender(wxDC& dc)
        dc.SetPen(wxPen(wxColour("#6B6B6B")));
        dc.SetBrush(*wxTRANSPARENT_BRUSH);
        dc.DrawCircle(size.x / 2, size.y / 2, radius);
-
-        if (m_cols.size() > 1) {
-            if (ctype == 0) {
-                int left = FromDIP(0);
-                float total_width = size.x;
-                int gwidth = std::round(total_width / (m_cols.size() - 1));
-
-                for (int i = 0; i < m_cols.size() - 1; i++) {
-
-                    if ((left + gwidth) > (size.x)) {
-                        gwidth = size.x - left;
-                    }
-
-                    auto rect = wxRect(left, 0, gwidth, size.y);
-                    dc.GradientFillLinear(rect, m_cols[i], m_cols[i + 1], wxEAST);
-                    left += gwidth;
-                }
-                if (wxGetApp().dark_mode()) {
-                    dc.DrawBitmap(m_bitmap_border_dark, wxPoint(0, 0));
-                }
-                else {
-                    dc.DrawBitmap(m_bitmap_border, wxPoint(0, 0));
-                }
-            }
-            else {
-                float ev_angle = 360.0 / m_cols.size();
-                float startAngle = 270.0;
-                float endAngle = 270.0;
-                dc.SetPen(*wxTRANSPARENT_PEN);
-                for (int i = 0; i < m_cols.size(); i++) {
-                    dc.SetBrush(m_cols[i]);
-                    endAngle += ev_angle;
-                    endAngle = endAngle > 360.0 ? endAngle - 360.0 : endAngle;
-                    wxPoint center(size.x / 2, size.y / 2);
-                    dc.DrawEllipticArc(center.x - radius, center.y - radius, 2 * radius, 2 * radius, startAngle, endAngle);
-                    startAngle += ev_angle;
-                    startAngle = startAngle > 360.0 ? startAngle - 360.0 : startAngle;
-                }
-                if (wxGetApp().dark_mode()) {
-                    dc.DrawBitmap(m_bitmap_border_dark, wxPoint(0, 0));
-                }
-                else {
-                    dc.DrawBitmap(m_bitmap_border, wxPoint(0, 0));
-                }
-            }
-        }
    }

    if (m_is_empty) {
@@ -1891,19 +2010,21 @@ ColorPickerPopup::ColorPickerPopup(wxWindow* parent)
    m_ams_fg_sizer->SetNonFlexibleGrowMode(wxFLEX_GROWMODE_SPECIFIED);

    //other
-    wxFlexGridSizer* fg_sizer;
-    fg_sizer = new wxFlexGridSizer(0, 8, 0, 0);
-    fg_sizer->SetFlexibleDirection(wxBOTH);
-    fg_sizer->SetNonFlexibleGrowMode(wxFLEX_GROWMODE_SPECIFIED);
+    m_other_fg_sizer = new wxFlexGridSizer(0, 8, 0, 0);
+    m_other_fg_sizer->SetFlexibleDirection(wxBOTH);
+    m_other_fg_sizer->SetNonFlexibleGrowMode(wxFLEX_GROWMODE_SPECIFIED);


    for (wxColour col : m_def_colors) {
        auto cp = new ColorPicker(m_def_color_box, wxID_ANY, wxDefaultPosition, wxDefaultSize);
        cp->set_color(col);
+        cp->set_colors({col});
+        cp->ctype = 2;
        cp->set_selected(false);
        cp->SetBackgroundColour(StateColor::darkModeColorFor(wxColour(238,238,238)));
        m_color_pickers.push_back(cp);
-        fg_sizer->Add(cp, 0, wxALL, FromDIP(3));
+        m_default_color_pickers.push_back(cp);
+        m_other_fg_sizer->Add(cp, 0, wxALL, FromDIP(3));
        cp->Bind(wxEVT_LEFT_DOWN, [this, cp](auto& e) {
            set_def_colour(cp->m_colour);

@@ -1970,7 +2091,7 @@ ColorPickerPopup::ColorPickerPopup(wxWindow* parent)
    m_sizer_box->Add(m_sizer_ams, 1, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
    m_sizer_box->Add(m_ams_fg_sizer, 0, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
    m_sizer_box->Add(m_sizer_other, 1, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
-    m_sizer_box->Add(fg_sizer, 0, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
+    m_sizer_box->Add(m_other_fg_sizer, 0, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
    m_sizer_box->Add(m_sizer_custom, 0, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(10));
    m_sizer_box->Add(m_custom_cp, 0, wxEXPAND|wxLEFT|wxRIGHT, FromDIP(16));
    m_sizer_box->Add(0, 0, 0, wxTOP, FromDIP(10));
@@ -1981,7 +2102,7 @@ ColorPickerPopup::ColorPickerPopup(wxWindow* parent)
    m_def_color_box->Fit();

    m_sizer_main->Add(m_def_color_box, 0, wxALL | wxEXPAND, 10);
-    SetSizer(m_sizer_main);
+    SetSizerAndFit(m_sizer_main);
    Layout();
    Fit();

@@ -2019,13 +2140,15 @@ void ColorPickerPopup::on_custom_clr_picker(wxMouseEvent& /*event*/)
    wxPostEvent(GetParent(), evt);
 }

-void ColorPickerPopup::set_ams_colours(std::vector<wxColour> ams)
+void ColorPickerPopup::set_ams_colours(const std::vector<ColorItem>& ams)
 {
+    m_ams_fg_sizer->Clear(false);
    if (m_ams_color_pickers.size() > 0) {
        for (ColorPicker* col_pick:m_ams_color_pickers) {

            std::vector<ColorPicker*>::iterator iter = find(m_color_pickers.begin(), m_color_pickers.end(), col_pick);
            if (iter != m_color_pickers.end()) {
+                col_pick->Hide();
                col_pick->Destroy();
                m_color_pickers.erase(iter);
            }
@@ -2035,17 +2158,22 @@ void ColorPickerPopup::set_ams_colours(std::vector<wxColour> ams)
    }


-    m_ams_colors = ams;
-    for (wxColour col : m_ams_colors) {
+    m_ams_color_items = ams;
+    for (const ColorItem& item : m_ams_color_items) {
+        if (item.colors.empty()) continue;
+
        auto cp = new ColorPicker(m_def_color_box, wxID_ANY, wxDefaultPosition, wxDefaultSize);
-        cp->set_color(col);
+        cp->set_color(item.colors.front());
+        cp->set_colors(item.colors);
+        cp->ctype = item.colors.size() > 1 ? item.ctype : 2;
+        cp->set_show_full(true);
        cp->set_selected(false);
        cp->SetBackgroundColour(StateColor::darkModeColorFor(wxColour(238,238,238)));
        m_color_pickers.push_back(cp);
        m_ams_color_pickers.push_back(cp);
        m_ams_fg_sizer->Add(cp, 0, wxALL, FromDIP(3));
        cp->Bind(wxEVT_LEFT_DOWN, [this, cp](auto& e) {
-            set_def_colour(cp->m_colour);
+            set_def_colour(cp->m_colour, cp->m_cols, cp->ctype);

            wxCommandEvent evt(EVT_SELECTED_COLOR);
            unsigned long g_col = ((cp->m_colour.Red() & 0xff) << 24) + ((cp->m_colour.Green() & 0xff) << 16) + ((cp->m_colour.Blue() & 0xff) << 8) + (cp->m_colour.Alpha() & 0xff);
@@ -2058,9 +2186,68 @@ void ColorPickerPopup::set_ams_colours(std::vector<wxColour> ams)
    Fit();
 }

-void ColorPickerPopup::set_def_colour(wxColour col)
+void ColorPickerPopup::set_preset_colours(const std::vector<ColorItem>& preset_colors)
+{
+    m_other_fg_sizer->Clear(false);
+    if (!m_preset_color_pickers.empty()) {
+        for (ColorPicker* col_pick : m_preset_color_pickers) {
+            auto iter = std::find(m_color_pickers.begin(), m_color_pickers.end(), col_pick);
+            if (iter != m_color_pickers.end()) {
+                col_pick->Hide();
+                col_pick->Destroy();
+                m_color_pickers.erase(iter);
+            }
+        }
+        m_preset_color_pickers.clear();
+    }
+
+    for (const ColorItem& item : preset_colors) {
+        if (item.colors.empty()) continue;
+
+        auto cp = new ColorPicker(m_def_color_box, wxID_ANY, wxDefaultPosition, wxDefaultSize);
+        cp->set_color(item.colors.front());
+        cp->set_colors(item.colors);
+        cp->ctype = item.colors.size() > 1 ? item.ctype : 2;
+        cp->set_show_full(true);
+        cp->set_selected(false);
+        cp->SetBackgroundColour(StateColor::darkModeColorFor(wxColour(238,238,238)));
+        if (!item.name.empty()) {
+            cp->SetToolTip(item.name);
+        }
+
+        m_color_pickers.push_back(cp);
+        m_preset_color_pickers.push_back(cp);
+        cp->Bind(wxEVT_LEFT_DOWN, [this, cp](auto& e) {
+            set_def_colour(cp->m_colour, cp->m_cols, cp->ctype);
+
+            wxCommandEvent evt(EVT_SELECTED_COLOR);
+            unsigned long g_col = ((cp->m_colour.Red() & 0xff) << 24) + ((cp->m_colour.Green() & 0xff) << 16) + ((cp->m_colour.Blue() & 0xff) << 8) + (cp->m_colour.Alpha() & 0xff);
+            evt.SetInt(g_col);
+            wxPostEvent(GetParent(), evt);
+        });
+    }
+
+    const bool show_default_colours = m_preset_color_pickers.empty();
+    for (ColorPicker* cp : m_default_color_pickers) {
+        cp->Show(show_default_colours);
+    }
+    for (ColorPicker* cp : (show_default_colours ? m_default_color_pickers : m_preset_color_pickers)) {
+        m_other_fg_sizer->Add(cp, 0, wxALL, FromDIP(3));
+    }
+
+    m_other_fg_sizer->Layout();
+    Layout();
+    Fit();
+}
+
+void ColorPickerPopup::set_def_colour(wxColour col, std::vector<wxColour> cols, int ctype)
 {
    m_def_col = col;
+    if (cols.empty()) {
+        cols.push_back(col);
+    }
+    m_def_cols = cols;
+    m_def_ctype = m_def_cols.size() > 1 ? ctype : 2;

    for (ColorPicker* cp : m_color_pickers) {
        if (cp->m_selected) {
@@ -2069,7 +2256,8 @@ void ColorPickerPopup::set_def_colour(wxColour col)
    }

    for (ColorPicker* cp : m_color_pickers) {
-        if (cp->m_colour == m_def_col) {
+        if (!cp->IsShown()) continue;
+        if (cp->ctype == m_def_ctype && cp->m_cols == m_def_cols) {
            cp->set_selected(true);
            break;
        }
@@ -82,14 +82,22 @@ public:
 class ColorPickerPopup : public PopupWindow
 {
 public:
+    struct ColorItem
+    {
+        std::vector<wxColour> colors;
+        int                   ctype = 2;
+        wxString              name;
+    };
+
    ScalableBitmap m_ts_bitmap_custom;
    wxStaticBitmap* m_ts_stbitmap_custom;
    StaticBox* m_custom_cp;
    StaticBox* m_def_color_box;
    wxFlexGridSizer* m_ams_fg_sizer;
+    wxFlexGridSizer* m_other_fg_sizer;
    wxColour m_def_col;
    std::vector<wxColour> m_def_colors;
-    std::vector<wxColour> m_ams_colors;
+    std::vector<ColorItem> m_ams_color_items;
    std::vector<ColorPicker*> m_color_pickers;
    std::vector<ColorPicker*> m_ams_color_pickers;

@@ -97,13 +105,20 @@ public:
    ColorPickerPopup(wxWindow* parent);
    ~ColorPickerPopup() {};
    void on_custom_clr_picker(wxMouseEvent& event);
-    void set_ams_colours(std::vector<wxColour> ams);
-    void set_def_colour(wxColour col);
+    void set_ams_colours(const std::vector<ColorItem>& ams);
+    void set_preset_colours(const std::vector<ColorItem>& preset_colors);
+    void set_def_colour(wxColour col, std::vector<wxColour> cols = {}, int ctype = 2);
+    const std::vector<wxColour>& get_selected_colours() const { return m_def_cols; }
+    int get_selected_ctype() const { return m_def_ctype; }
    void paintEvent(wxPaintEvent& evt);
    virtual void OnDismiss() wxOVERRIDE;
    virtual bool ProcessLeftDown(wxMouseEvent& event) wxOVERRIDE;

-public:
+private:
+    std::vector<ColorPicker*> m_default_color_pickers;
+    std::vector<ColorPicker*> m_preset_color_pickers;
+    std::vector<wxColour> m_def_cols;
+    int m_def_ctype = 2;
 };


@@ -747,7 +747,9 @@ Print::ApplyStatus BackgroundSlicingProcess::apply(const Model& model, const Dyn

    // Orca: prevent resetting under gcode viewer mode
    if (invalidated != PrintBase::APPLY_STATUS_UNCHANGED) {
-        const auto plater = GUI::wxGetApp().mainframe->m_plater;
+        // Use the app’s plater accessor instead of going through mainframe, otherwise anything during startup that reaches apply() 
+        // (loading presets, config or input files, e.g. from the CLI) therefore dereferences a null `mainframe` and crashes.
+        const auto plater = GUI::wxGetApp().plater();
        if (plater && plater->only_gcode_mode()) {
            invalidated = PrintBase::APPLY_STATUS_UNCHANGED;
        }
@@ -1798,7 +1798,8 @@ int MachineObject::command_ams_calibrate(int ams_id)
    return command_with_dialog(m_agent->command_ams_calibrate(get_dev_id(), ams_id, MachineObject::m_sequence_id++, is_lan_mode_printer()));
 }

-int MachineObject::command_ams_filament_settings(int ams_id, int slot_id, std::string filament_id, std::string setting_id, std::string tray_color, std::string tray_type, int nozzle_temp_min, int nozzle_temp_max)
+int MachineObject::command_ams_filament_settings(int ams_id, int slot_id, std::string filament_id, std::string setting_id, std::string tray_color, std::string tray_type,
+                                                 int nozzle_temp_min, int nozzle_temp_max, const std::vector<std::string>& tray_colors, int tray_ctype)
 {
    int tag_tray_id = 0;
    int tag_ams_id  = ams_id;
@@ -1827,6 +1828,10 @@ int MachineObject::command_ams_filament_settings(int ams_id, int slot_id, std::s
    j["print"]["nozzle_temp_min"]   = nozzle_temp_min;
    j["print"]["nozzle_temp_max"]   = nozzle_temp_max;
    j["print"]["tray_type"]         = tray_type;
+    if (!tray_colors.empty()) {
+        j["print"]["cols"]  = tray_colors;
+        j["print"]["ctype"] = tray_ctype;
+    }

    return this->publish_json(j);
 }
@@ -5478,6 +5483,7 @@ void MachineObject::parse_new_info(json print)
        is_support_pa_mode = (get_flag_bits_no_border(fun2, 3) == 1);
        is_support_remote_dry = (get_flag_bits_no_border(fun2, 5) == 1);
        is_support_check_track_switch_match_slice_printer = get_flag_bits_no_border(fun2, 19) == 1;
+        is_support_filament_manual_multi_color = (get_flag_bits_no_border(fun2, 23) == 1);

        if (DevPrinterConfigUtil::support_print_check_firmware_for_tpu_left(printer_type)) {
            m_firmware_support_print_tpu_left = get_flag_bits_no_border(fun2, 7) == 1;
@@ -674,6 +674,7 @@ public:
    bool is_support_remote_dry = false;
    bool is_support_check_track_switch_match_slice_printer{false};
    bool is_support_pa_mode{false};
+    bool is_support_filament_manual_multi_color{false};
    std::optional<bool> m_firmware_support_print_tpu_left;

    bool installed_upgrade_kit{false};
@@ -804,7 +805,7 @@ public:
    int command_ams_switch_filament(bool switch_filament);
    int command_ams_air_print_detect(bool air_print_detect);
    int command_ams_calibrate(int ams_id);
-    int command_ams_filament_settings(int ams_id, int slot_id, std::string filament_id, std::string setting_id, std::string tray_color, std::string tray_type, int nozzle_temp_min, int nozzle_temp_max);
+    int command_ams_filament_settings(int ams_id, int slot_id, std::string filament_id, std::string setting_id, std::string tray_color, std::string tray_type, int nozzle_temp_min, int nozzle_temp_max, const std::vector<std::string>& tray_colors = {}, int tray_ctype = 2);
    int command_ams_select_tray(std::string tray_id);
    int command_ams_refresh_rfid(int ams_id, int slot_id);
    int command_ams_control(std::string action);
@@ -96,7 +96,7 @@ void FilamentColorCodeQuery::LoadFromLocal()
                    const auto& fila_color_strs = json_data_item["fila_color"].get<std::vector<wxString>>();
                    for (const auto& color_str : fila_color_strs) {
                        if (color_str.size() > 3) /* Skip the value like "#0"*/{
-                            fila_color.m_colors.emplace(wxColour(color_str));
+                            fila_color.AddColor(wxColour(color_str));
                        }
                    }
                }
--- a/Show More
+++ b/Show More