feat(materials): texture channel packing (Phase 5 slice G)

CLAUDE.md

@@ -71,9 +71,12 @@ qtmesh scan ./assets --sarif report.sarif      # write SARIF report to file
 qtmesh scan ./assets --fix --dry-run           # preview auto-fixes
 qtmesh scan ./assets --include "*.fbx,*.glb"   # filter by extension
 qtmesh scan ./assets --fail-on warning         # exit 1 on warnings or errors
+qtmesh pack-textures --r ao.png --g rough.png --b metal.png -o orm.png  # pack 3 grayscale maps into RGB (Unity ORM)
+qtmesh pack-textures --r metal.png --g rough.png --bc 0 --no-alpha -o mr.png  # Unreal MR (constant blue)
+qtmesh pack-textures --r rough.png --invert-r -o gloss.png  # invert: roughness → glossiness
 ```
 
-CLI mode is activated by: (1) invoking via the `qtmesh` symlink, (2) passing `--cli`, or (3) using a recognized subcommand (`info`, `fix`, `convert`, `anim`, `validate`, `lod`, `pose`, `scan`, `material`) as the first argument. Use `--verbose` to see Ogre/engine debug output. Use `--no-telemetry` to permanently opt out of anonymous usage data collection.
+CLI mode is activated by: (1) invoking via the `qtmesh` symlink, (2) passing `--cli`, or (3) using a recognized subcommand (`info`, `fix`, `convert`, `anim`, `validate`, `lod`, `pose`, `scan`, `material`, `pack-textures`) as the first argument. Use `--verbose` to see Ogre/engine debug output. Use `--no-telemetry` to permanently opt out of anonymous usage data collection.
 
 If Xcode SDK is updated, clear CMake cache (`rm build_local/CMakeCache.txt`) and reconfigure.
 
@@ -159,6 +162,7 @@ Three singletons manage core state. All run on the main thread. Access via `Clas
 
 - **BatchExporter** (`src/BatchExporter.h/cpp`): Multi-file conversion wrapping CLIPipeline. Supports progress reporting.
 - **MaterialPresetLibrary** (`src/MaterialPresetLibrary.h/cpp`): QML_SINGLETON providing one-click material presets (Plastic, Metal, Wood, Glass, Unlit, Wireframe).
+- **TextureChannelPacker** (`src/TextureChannelPacker.h/cpp`, slice G): pure-data packer that takes 1-4 grayscale source images (or constants) and writes a single packed RGBA texture (PNG/TGA/JPG). Each output channel is sampled via Rec.601 luminance from its source image, with an optional invert flag (useful for roughness↔glossiness). Smaller sources are bilinear-scaled up to match the largest input. Surfaced via the `qtmesh pack-textures` CLI subcommand, the `pack_textures` MCP tool, and the "Pack Channels…" button in the Material Editor.
 
 ### MCP Server
 
@@ -171,7 +175,7 @@ Three singletons manage core state. All run on the main thread. Access via `Clas
 ### CLI Pipeline
 
 - **CLIPipeline** (`src/CLIPipeline.h/cpp`): Headless command-line interface for mesh operations. All static methods — entry point is `CLIPipeline::run(argc, argv)`.
-- Subcommands: `info`, `fix`, `convert`, `anim` (list/rename/merge), `validate`, `lod`, `pose`, `scan`.
+- Subcommands: `info`, `fix`, `convert`, `anim` (list/rename/merge), `validate`, `lod`, `pose`, `scan`, `material`, `pack-textures`.
 - Activated via `qtmesh` symlink (created at build time), `--cli` flag, or recognized subcommand as first arg.
 - Redirects stdout to stderr (Ogre/Qt noise) and writes CLI output to the original stdout fd. Uses `_exit()` to avoid Ogre static destructor crashes on macOS.
 - **AnimationMerger** (`src/AnimationMerger.h/cpp`): Public `renameAnimation()` static method used by both CLI and GUI for animation renaming.

qml/PropertiesPanel.qml

@@ -4,6 +4,7 @@ import QtQuick.Layouts
 import PropertiesPanel 1.0
 import AnimationControl 1.0
 import EditorMode 1.0
+import MaterialEditorQML 1.0
 
 Rectangle {
     id: root
@@ -1694,6 +1695,62 @@ Rectangle {
                     onClicked: PropertiesPanelController.triggerMaterialEditor()
                 }
             }
+
+            // Slice G: Texture Channel Packer — utility for combining
+            // grayscale source images into a single packed RGBA texture
+            // (e.g. ORM = AO+Roughness+Metallic). Lives in Mode Tools
+            // because it operates on PNG/TGA files on disk, not on the
+            // currently-selected submesh's TUS.
+            Rectangle {
+                width: Math.min(parent.width - 16, packLabel.implicitWidth + 16)
+                height: 26
+                radius: 3
+                color: packMa.containsMouse
+                    ? PropertiesPanelController.highlightColor
+                    : PropertiesPanelController.headerColor
+                border.color: PropertiesPanelController.borderColor
+                border.width: 1
+
+                Text {
+                    id: packLabel
+                    anchors.centerIn: parent
+                    text: "Pack Texture Channels…"
+                    color: PropertiesPanelController.textColor
+                    font.pixelSize: 11
+                }
+                MouseArea {
+                    id: packMa
+                    anchors.fill: parent
+                    hoverEnabled: true
+                    cursorShape: Qt.PointingHandCursor
+                    onClicked: root.openTextureChannelPackerDialog()
+                    ToolTip.visible: containsMouse
+                    ToolTip.delay: 500
+                    ToolTip.text: "Pack 1–4 grayscale source images into a single RGBA texture (e.g. Unity ORM = AO+Roughness+Metallic, Unreal MR)."
+                }
+            }
+        }
+    }
+
+    // The dialog is loaded by URL (rather than as a typed component)
+    // because the Properties Panel's QML engine doesn't have the
+    // MaterialEditorQML module's import path set up — only its singleton
+    // C++ type. Using a Loader with a qrc:// source bypasses module
+    // resolution while keeping the dialog as a top-level child so it
+    // overlays the viewport correctly.
+    Loader {
+        id: textureChannelPackerLoader
+        active: false
+        anchors.centerIn: parent
+        source: "qrc:/MaterialEditorQML/TextureChannelPackerDialog.qml"
+        onLoaded: if (item && item.open) item.open()
+    }
+
+    function openTextureChannelPackerDialog() {
+        if (!textureChannelPackerLoader.active) {
+            textureChannelPackerLoader.active = true
+        } else if (textureChannelPackerLoader.item) {
+            textureChannelPackerLoader.item.open()
         }
     }