GPU accelerated maskeditor rendering (#6767)

## GPU accelerated brush engine for the mask editor

- Full GPU acceleration using TypeGPU and type-safe shaders
- Catmull-Rom Spline Smoothing
- arc-length equidistant resampling
- much improved performance, even for huge images
- photoshop like opacity clamping for brush strokes
- much improved soft brushes
- fallback to CPU fully implemented, much improved CPU rendering
features as well

### Tested Browsers
- Chrome (fully supported)
- Safari 26 (fully supported, prev versions CPU fallback)
- Firefox (CPU fallback, flags needed for full support)



https://github.com/user-attachments/assets/b7b5cb8a-2290-4a95-ae7d-180e11fccdb0



https://github.com/user-attachments/assets/4297aaa5-f249-499a-9b74-869677f1c73b



https://github.com/user-attachments/assets/602b4783-3e2b-489e-bcb9-70534bcaac5e

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6767-GPU-accelerated-maskeditor-rendering-2b16d73d3650818cb294e1fca03f6169)
by [Unito](https://www.unito.io)

package.json

@@ -75,6 +75,7 @@
     "@vitest/coverage-v8": "catalog:",
     "@vitest/ui": "catalog:",
     "@vue/test-utils": "catalog:",
+    "@webgpu/types": "catalog:",
     "cross-env": "catalog:",
     "eslint": "catalog:",
     "eslint-config-prettier": "catalog:",
@@ -112,6 +113,7 @@
     "typescript": "catalog:",
     "typescript-eslint": "catalog:",
     "unplugin-icons": "catalog:",
+    "unplugin-typegpu": "catalog:",
     "unplugin-vue-components": "catalog:",
     "uuid": "^11.1.0",
     "vite": "catalog:",
@@ -176,6 +178,7 @@
     "semver": "^7.7.2",
     "three": "^0.170.0",
     "tiptap-markdown": "^0.8.10",
+    "typegpu": "catalog:",
     "vue": "catalog:",
     "vue-i18n": "catalog:",
     "vue-router": "catalog:",

pnpm-lock.yaml

@@ -126,6 +126,9 @@ catalogs:
     '@vueuse/integrations':
       specifier: ^13.9.0
       version: 13.9.0
+    '@webgpu/types':
+      specifier: ^0.1.66
+      version: 0.1.66
     algoliasearch:
       specifier: ^5.21.0
       version: 5.21.0
@@ -246,6 +249,9 @@ catalogs:
     tw-animate-css:
       specifier: ^1.3.8
       version: 1.3.8
+    typegpu:
+      specifier: ^0.8.2
+      version: 0.8.2
     typescript:
       specifier: ^5.9.2
       version: 5.9.2
@@ -255,6 +261,9 @@ catalogs:
     unplugin-icons:
       specifier: ^0.22.0
       version: 0.22.0
+    unplugin-typegpu:
+      specifier: 0.8.0
+      version: 0.8.0
     unplugin-vue-components:
       specifier: ^0.28.0
       version: 0.28.0
@@ -464,6 +473,9 @@ importers:
       tiptap-markdown:
         specifier: ^0.8.10
         version: 0.8.10(@tiptap/core@2.10.4(@tiptap/pm@2.10.4))
+      typegpu:
+        specifier: 'catalog:'
+        version: 0.8.2
       vue:
         specifier: 'catalog:'
         version: 3.5.13(typescript@5.9.2)
@@ -561,6 +573,9 @@ importers:
       '@vue/test-utils':
         specifier: 'catalog:'
         version: 2.4.6
+      '@webgpu/types':
+        specifier: 'catalog:'
+        version: 0.1.66
       cross-env:
         specifier: 'catalog:'
         version: 10.1.0
@@ -672,6 +687,9 @@ importers:
       unplugin-icons:
         specifier: 'catalog:'
         version: 0.22.0(@vue/compiler-sfc@3.5.13)
+      unplugin-typegpu:
+        specifier: 'catalog:'
+        version: 0.8.0(typegpu@0.8.2)
       unplugin-vue-components:
         specifier: 'catalog:'
         version: 0.28.0(@babel/parser@7.28.4)(rollup@4.22.4)(vue@3.5.13(typescript@5.9.2))
@@ -1431,6 +1449,10 @@ packages:
     resolution: {integrity: sha512-Q/N6JNWvIvPnLDvjlE1OUBLPQHH6l3CltCEsHIujp45zQUSSh8K+gHnaEX45yAT1nyngnINhvWtzN+Nb9D8RAQ==}
     engines: {node: '>=6.9.0'}
 
+  '@babel/standalone@7.28.5':
+    resolution: {integrity: sha512-1DViPYJpRU50irpGMfLBQ9B4kyfQuL6X7SS7pwTeWeZX0mNkjzPi0XFqxCjSdddZXUQy4AhnQnnesA/ZHnvAdw==}
+    engines: {node: '>=6.9.0'}
+
   '@babel/template@7.27.2':
     resolution: {integrity: sha512-LPDZ85aEJyYSd18/DkjNh4/y1ntkE5KwUHWTiqgRxruuZL2F1yuHligVHLvcHY2vMHXttKFpJn6LwfI7cw7ODw==}
     engines: {node: '>=6.9.0'}
@@ -3790,8 +3812,8 @@ packages:
     peerDependencies:
       vue: ^3.5.0
 
-  '@webgpu/types@0.1.51':
+  '@webgpu/types@0.1.66':
-    resolution: {integrity: sha512-ktR3u64NPjwIViNCck+z9QeyN0iPkQCUOQ07ZCV1RzlkfP+olLTeEZ95O1QHS+v4w9vJeY9xj/uJuSphsHy5rQ==}
+    resolution: {integrity: sha512-YA2hLrwLpDsRueNDXIMqN9NTzD6bCDkuXbOSe0heS+f8YE8usA6Gbv1prj81pzVHrbaAma7zObnIC+I6/sXJgA==}
 
   '@xstate/fsm@1.6.5':
     resolution: {integrity: sha512-b5o1I6aLNeYlU/3CPlj/Z91ybk1gUsKT+5NAJI+2W4UjvS5KLG28K9v5UvNoFVjHV8PajVZ00RH3vnjyQO7ZAw==}
@@ -6038,6 +6060,10 @@ packages:
     resolution: {integrity: sha512-h5bgJWpxJNswbU7qCrV0tIKQCaS3blPDrqKWx+QxzuzL1zGUzij9XCWLrSLsJPu5t+eWA/ycetzYAO5IOMcWAQ==}
     hasBin: true
 
+  magic-string-ast@1.0.3:
+    resolution: {integrity: sha512-CvkkH1i81zl7mmb94DsRiFeG9V2fR2JeuK8yDgS8oiZSFa++wWLEgZ5ufEOyLHbvSbD1gTRKv9NdX69Rnvr9JA==}
+    engines: {node: '>=20.19.0'}
+
   magic-string@0.30.19:
     resolution: {integrity: sha512-2N21sPY9Ws53PZvsEpVtNuSW+ScYbQdp4b9qUaL+9QkHUrGFKo56Lg9Emg5s9V/qrtNBmiR01sYhUOwu3H+VOw==}
 
@@ -7411,6 +7437,14 @@ packages:
   tinybench@2.9.0:
     resolution: {integrity: sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==}
 
+  tinyest-for-wgsl@0.1.3:
+    resolution: {integrity: sha512-Wm5ADG1UyDxykf42S1gLYP4U9e1QP/TdtJeovQi6y68zttpiFLKqQGioHmPs9Mjysh7YMSAr/Lpuk0cD2MVdGA==}
+    engines: {node: '>=12.20.0'}
+
+  tinyest@0.1.2:
+    resolution: {integrity: sha512-aHRmouyowIq1P5jrTF+YK6pGX+WuvFtSCLbqk91yHnU3SWQRIcNIamZLM5XF6lLqB13AWz0PGPXRff2QGDsxIg==}
+    engines: {node: '>=12.20.0'}
+
   tinyexec@0.3.2:
     resolution: {integrity: sha512-KQQR9yN7R5+OSwaK0XQoj22pwHoTlgYqmUscPYoknOoWCWfj/5/ABTMRi69FrKU5ffPVh5QcFikpWJI/P1ocHA==}
 
@@ -7537,6 +7571,13 @@ packages:
     resolution: {integrity: sha512-3KS2b+kL7fsuk/eJZ7EQdnEmQoaho/r6KUef7hxvltNA5DR8NAUM+8wJMbJyZ4G9/7i3v5zPBIMN5aybAh2/Jg==}
     engines: {node: '>= 0.4'}
 
+  typed-binary@4.3.2:
+    resolution: {integrity: sha512-HT3pIBM2njCZUmeczDaQUUErGiM6GXFCqMsHegE12HCoBtvHCkfR10JJni0TeGOTnLilTd6YFyj+YhflqQDrDQ==}
+
+  typegpu@0.8.2:
+    resolution: {integrity: sha512-wkMJWhJE0pSkw2G/FesjqjbtHkREyOKu1Zmyj19xfmaX5+65YFwgfQNKSK8CxqN4kJkP7JFelLDJTSYY536TYg==}
+    engines: {node: '>=12.20.0'}
+
   typescript-eslint@8.44.0:
     resolution: {integrity: sha512-ib7mCkYuIzYonCq9XWF5XNw+fkj2zg629PSa9KNIQ47RXFF763S5BIX4wqz1+FLPogTZoiw8KmCiRPRa8bL3qw==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -7641,6 +7682,11 @@ packages:
       vue-template-es2015-compiler:
         optional: true
 
+  unplugin-typegpu@0.8.0:
+    resolution: {integrity: sha512-VJHdXSXGOkAx0WhwFczhVUjAI6HyDkrQXk20HnwyuzIE3FdqE5l9sJTCYZzoVGo3z8i/IA5TMHCDzzP0Bc97Cw==}
+    peerDependencies:
+      typegpu: ^0.8.0
+
   unplugin-vue-components@0.28.0:
     resolution: {integrity: sha512-jiTGtJ3JsRFBjgvyilfrX7yUoGKScFgbdNw+6p6kEXU+Spf/rhxzgvdfuMcvhCcLmflB/dY3pGQshYBVGOUx7Q==}
     engines: {node: '>=14'}
@@ -8969,6 +9015,8 @@ snapshots:
 
   '@babel/runtime@7.28.4': {}
 
+  '@babel/standalone@7.28.5': {}
+
   '@babel/template@7.27.2':
     dependencies:
       '@babel/code-frame': 7.27.1
@@ -11016,7 +11064,7 @@ snapshots:
       '@tweenjs/tween.js': 23.1.3
       '@types/stats.js': 0.17.3
       '@types/webxr': 0.5.20
-      '@webgpu/types': 0.1.51
+      '@webgpu/types': 0.1.66
       fflate: 0.8.2
       meshoptimizer: 0.18.1
 
@@ -11519,7 +11567,7 @@ snapshots:
     dependencies:
       vue: 3.5.13(typescript@5.9.2)
 
-  '@webgpu/types@0.1.51': {}
+  '@webgpu/types@0.1.66': {}
 
   '@xstate/fsm@1.6.5': {}
 
@@ -14000,6 +14048,10 @@ snapshots:
 
   lz-string@1.5.0: {}
 
+  magic-string-ast@1.0.3:
+    dependencies:
+      magic-string: 0.30.19
+
   magic-string@0.30.19:
     dependencies:
       '@jridgewell/sourcemap-codec': 1.5.5
@@ -15864,6 +15916,12 @@ snapshots:
 
   tinybench@2.9.0: {}
 
+  tinyest-for-wgsl@0.1.3:
+    dependencies:
+      tinyest: 0.1.2
+
+  tinyest@0.1.2: {}
+
   tinyexec@0.3.2: {}
 
   tinyexec@1.0.1: {}
@@ -15995,6 +16053,13 @@ snapshots:
       reflect.getprototypeof: 1.0.10
     optional: true
 
+  typed-binary@4.3.2: {}
+
+  typegpu@0.8.2:
+    dependencies:
+      tinyest: 0.1.2
+      typed-binary: 4.3.2
+
   typescript-eslint@8.44.0(eslint@9.35.0(jiti@2.4.2))(typescript@5.9.2):
     dependencies:
       '@typescript-eslint/eslint-plugin': 8.44.0(@typescript-eslint/parser@8.44.0(eslint@9.35.0(jiti@2.4.2))(typescript@5.9.2))(eslint@9.35.0(jiti@2.4.2))(typescript@5.9.2)
@@ -16090,6 +16155,19 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  unplugin-typegpu@0.8.0(typegpu@0.8.2):
+    dependencies:
+      '@babel/standalone': 7.28.5
+      defu: 6.1.4
+      estree-walker: 3.0.3
+      magic-string-ast: 1.0.3
+      pathe: 2.0.3
+      picomatch: 4.0.3
+      tinyest: 0.1.2
+      tinyest-for-wgsl: 0.1.3
+      typegpu: 0.8.2
+      unplugin: 2.3.5
+
   unplugin-vue-components@0.28.0(@babel/parser@7.28.4)(rollup@4.22.4)(vue@3.5.13(typescript@5.9.2)):
     dependencies:
       '@antfu/utils': 0.7.10

pnpm-workspace.yaml

@@ -43,6 +43,7 @@ catalog:
   '@vue/test-utils': ^2.4.6
   '@vueuse/core': ^11.0.0
   '@vueuse/integrations': ^13.9.0
+  '@webgpu/types': ^0.1.66
   algoliasearch: ^5.21.0
   axios: ^1.8.2
   cross-env: ^10.1.0
@@ -83,9 +84,11 @@ catalog:
   tailwindcss-primeui: ^0.6.1
   tsx: ^4.15.6
   tw-animate-css: ^1.3.8
+  typegpu: ^0.8.2
   typescript: ^5.9.2
   typescript-eslint: ^8.44.0
   unplugin-icons: ^0.22.0
+  unplugin-typegpu: 0.8.0
   unplugin-vue-components: ^0.28.0
   vite: ^5.4.19
   vite-plugin-dts: ^4.5.4

src/components/maskeditor/BrushCursor.vue

@@ -26,6 +26,10 @@
 <script setup lang="ts">
 import { computed } from 'vue'
 
+import {
+  getEffectiveBrushSize,
+  getEffectiveHardness
+} from '@/composables/maskeditor/brushUtils'
 import { BrushShape } from '@/extensions/core/maskeditor/types'
 import { useMaskEditorStore } from '@/stores/maskEditorStore'
 
@@ -36,11 +40,14 @@ const { containerRef } = defineProps<{
 const store = useMaskEditorStore()
 
 const brushOpacity = computed(() => {
-  return store.brushVisible ? '1' : '0'
+  return store.brushVisible ? 1 : 0
 })
 
 const brushRadius = computed(() => {
-  return store.brushSettings.size * store.zoomRatio
+  const size = store.brushSettings.size
+  const hardness = store.brushSettings.hardness
+  const effectiveSize = getEffectiveBrushSize(size, hardness)
+  return effectiveSize * store.zoomRatio
 })
 
 const brushSize = computed(() => {
@@ -78,19 +85,26 @@ const gradientVisible = computed(() => {
 })
 
 const gradientBackground = computed(() => {
+  const size = store.brushSettings.size
   const hardness = store.brushSettings.hardness
+  const effectiveSize = getEffectiveBrushSize(size, hardness)
+  const effectiveHardness = getEffectiveHardness(size, hardness, effectiveSize)
 
-  if (hardness === 1) {
+  if (effectiveHardness === 1) {
     return 'rgba(255, 0, 0, 0.5)'
   }
 
-  const midStop = hardness * 100
+  const midStop = effectiveHardness * 100
   const outerStop = 100
+  // Add an intermediate stop to approximate the squared falloff
+  // At 50% of the fade region, squared falloff is 0.25 (relative to max)
+  const fadeMidStop = midStop + (outerStop - midStop) * 0.5
 
   return `radial-gradient(
     circle,
     rgba(255, 0, 0, 0.5) 0%,
-    rgba(255, 0, 0, 0.25) ${midStop}%,
+    rgba(255, 0, 0, 0.5) ${midStop}%,
+    rgba(255, 0, 0, 0.125) ${fadeMidStop}%,
     rgba(255, 0, 0, 0) ${outerStop}%
   )`
 })

src/components/maskeditor/BrushSettingsPanel.vue

@@ -55,7 +55,7 @@
     <SliderControl
       :label="t('maskEditor.thickness')"
       :min="1"
-      :max="100"
+      :max="500"
       :step="1"
       :model-value="store.brushSettings.size"
       @update:model-value="onThicknessChange"
@@ -80,12 +80,12 @@
     />
 
     <SliderControl
-      :label="t('maskEditor.smoothingPrecision')"
+      label="Stepsize"
       :min="1"
       :max="100"
       :step="1"
-      :model-value="store.brushSettings.smoothingPrecision"
+      :model-value="store.brushSettings.stepSize"
-      @update:model-value="onSmoothingPrecisionChange"
+      @update:model-value="onStepSizeChange"
     />
   </div>
 </template>
@@ -119,8 +119,8 @@ const onHardnessChange = (value: number) => {
   store.setBrushHardness(value)
 }
 
-const onSmoothingPrecisionChange = (value: number) => {
+const onStepSizeChange = (value: number) => {
-  store.setBrushSmoothingPrecision(value)
+  store.setBrushStepSize(value)
 }
 
 const resetToDefault = () => {

src/components/maskeditor/MaskEditorContent.vue

@@ -12,19 +12,28 @@
     >
       <canvas
         ref="imgCanvasRef"
-        class="absolute top-0 left-0 w-full h-full"
+        class="absolute top-0 left-0 w-full h-full z-0"
         @contextmenu.prevent
       />
       <canvas
         ref="rgbCanvasRef"
-        class="absolute top-0 left-0 w-full h-full"
+        class="absolute top-0 left-0 w-full h-full z-10"
         @contextmenu.prevent
       />
       <canvas
         ref="maskCanvasRef"
-        class="absolute top-0 left-0 w-full h-full"
+        class="absolute top-0 left-0 w-full h-full z-30"
         @contextmenu.prevent
       />
+      <!-- GPU Preview Canvas -->
+      <canvas
+        ref="gpuCanvasRef"
+        class="absolute top-0 left-0 w-full h-full pointer-events-none"
+        :class="{
+          'z-20': store.activeLayer === 'rgb',
+          'z-40': store.activeLayer === 'mask'
+        }"
+      />
       <div ref="canvasBackgroundRef" class="bg-white w-full h-full" />
     </div>
 
@@ -87,6 +96,7 @@ const canvasContainerRef = ref<HTMLDivElement>()
 const imgCanvasRef = ref<HTMLCanvasElement>()
 const maskCanvasRef = ref<HTMLCanvasElement>()
 const rgbCanvasRef = ref<HTMLCanvasElement>()
+const gpuCanvasRef = ref<HTMLCanvasElement>()
 const canvasBackgroundRef = ref<HTMLDivElement>()
 
 const toolPanelRef = ref<InstanceType<typeof ToolPanel>>()
@@ -97,7 +107,7 @@ const initialized = ref(false)
 const keyboard = useKeyboard()
 const panZoom = usePanAndZoom()
 
-let toolManager: ReturnType<typeof useToolManager> | null = null
+const toolManager = useToolManager(keyboard, panZoom)
 
 let resizeObserver: ResizeObserver | null = null
 
@@ -135,8 +145,6 @@ const initUI = async () => {
   try {
     await loader.loadFromNode(node)
 
-    toolManager = useToolManager(keyboard, panZoom)
-
     const imageLoader = useImageLoader()
     const image = await imageLoader.loadImages()
 
@@ -149,6 +157,18 @@ const initUI = async () => {
 
     store.canvasHistory.saveInitialState()
 
+    // Initialize GPU resources
+    if (toolManager.brushDrawing) {
+      await toolManager.brushDrawing.initGPUResources()
+      if (gpuCanvasRef.value && toolManager.brushDrawing.initPreviewCanvas) {
+        // Match preview canvas resolution to mask canvas
+        gpuCanvasRef.value.width = maskCanvasRef.value.width
+        gpuCanvasRef.value.height = maskCanvasRef.value.height
+
+        toolManager.brushDrawing.initPreviewCanvas(gpuCanvasRef.value)
+      }
+    }
+
     initialized.value = true
   } catch (error) {
     console.error('[MaskEditorContent] Initialization failed:', error)
@@ -172,7 +192,7 @@ onMounted(() => {
 })
 
 onBeforeUnmount(() => {
-  toolManager?.brushDrawing.saveBrushSettings()
+  toolManager.brushDrawing.saveBrushSettings()
 
   keyboard?.removeListeners()
 

src/components/maskeditor/dialog/TopBarHeader.vue

@@ -102,6 +102,7 @@ const onInvert = () => {
 
 const onClear = () => {
   canvasTools.clearMask()
+  store.triggerClear()
 }
 
 const handleSave = async () => {

src/composables/maskeditor/ShiftClick.test.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect } from 'vitest'
+import { resampleSegment } from './splineUtils'
+import type { Point } from '@/extensions/core/maskeditor/types'
+
+describe('Shift+Click Drawing Logic', () => {
+  it('should generate equidistant points across connected segments', () => {
+    const spacing = 4
+    let remainder = spacing // Simulate start point already painted
+    const outputPoints: Point[] = []
+
+    // Define points: A -> B -> C
+    // A(0,0) -> B(10,0) -> C(20,0)
+    // Total length 20. Spacing 4.
+    // Expected points at x = 4, 8, 12, 16, 20
+    const pA = { x: 0, y: 0 }
+    const pB = { x: 10, y: 0 }
+    const pC = { x: 20, y: 0 }
+
+    // Segment 1: A -> B
+    const result1 = resampleSegment([pA, pB], spacing, remainder)
+    outputPoints.push(...result1.points)
+    remainder = result1.remainder
+
+    // Verify intermediate state
+    // Length 10. Spacing 4. Start offset 4.
+    // Points at 4, 8. Next at 12.
+    // Remainder = 12 - 10 = 2.
+    expect(result1.points.length).toBe(2)
+    expect(result1.points[0].x).toBeCloseTo(4)
+    expect(result1.points[1].x).toBeCloseTo(8)
+    expect(remainder).toBeCloseTo(2)
+
+    // Segment 2: B -> C
+    const result2 = resampleSegment([pB, pC], spacing, remainder)
+    outputPoints.push(...result2.points)
+    remainder = result2.remainder
+
+    // Verify final state
+    // Start offset 2. Points at 2, 6, 10 (relative to B).
+    // Absolute x: 12, 16, 20.
+    expect(result2.points.length).toBe(3)
+    expect(result2.points[0].x).toBeCloseTo(12)
+    expect(result2.points[1].x).toBeCloseTo(16)
+    expect(result2.points[2].x).toBeCloseTo(20)
+
+    // Verify all distances
+    // Note: The first point is at distance `spacing` from start (0,0)
+    // Subsequent points are `spacing` apart.
+    let prevX = 0
+    for (const p of outputPoints) {
+      const dist = p.x - prevX
+      expect(dist).toBeCloseTo(spacing)
+      prevX = p.x
+    }
+  })
+
+  it('should handle segments shorter than spacing', () => {
+    const spacing = 10
+    let remainder = spacing // Simulate start point already painted
+
+    // A(0,0) -> B(5,0) -> C(15,0)
+    const pA = { x: 0, y: 0 }
+    const pB = { x: 5, y: 0 }
+    const pC = { x: 15, y: 0 }
+
+    // Segment 1: A -> B (Length 5)
+    // Spacing 10. No points should be generated.
+    // Remainder should be 5 (next point needs 5 more units).
+    const result1 = resampleSegment([pA, pB], spacing, remainder)
+    expect(result1.points.length).toBe(0)
+    expect(result1.remainder).toBeCloseTo(5)
+    remainder = result1.remainder
+
+    // Segment 2: B -> C (Length 10)
+    // Start offset 5. First point at 5 (relative to B).
+    // Absolute x = 10.
+    // Next point at 15 (relative to B). Segment ends at 10.
+    // Remainder = 15 - 10 = 5.
+    const result2 = resampleSegment([pB, pC], spacing, remainder)
+    expect(result2.points.length).toBe(1)
+    expect(result2.points[0].x).toBeCloseTo(10)
+    expect(result2.remainder).toBeCloseTo(5)
+  })
+})

src/composables/maskeditor/StrokeProcessor.test.ts

@@ -0,0 +1,108 @@
+import { describe, it, expect } from 'vitest'
+import { StrokeProcessor } from './StrokeProcessor'
+import type { Point } from '@/extensions/core/maskeditor/types'
+
+describe('StrokeProcessor', () => {
+  it('should generate equidistant points from irregular input', () => {
+    const spacing = 10
+    const processor = new StrokeProcessor(spacing)
+    const outputPoints: Point[] = []
+
+    // Simulate a horizontal line drawn with irregular speed
+    // Points: (0,0) -> (5,0) -> (25,0) -> (30,0) -> (100,0)
+    const inputPoints: Point[] = [
+      { x: 0, y: 0 },
+      { x: 5, y: 0 }, // dist 5
+      { x: 25, y: 0 }, // dist 20
+      { x: 30, y: 0 }, // dist 5
+      { x: 100, y: 0 } // dist 70
+    ]
+
+    for (const p of inputPoints) {
+      outputPoints.push(...processor.addPoint(p))
+    }
+    outputPoints.push(...processor.endStroke())
+
+    // Verify we have points
+    expect(outputPoints.length).toBeGreaterThan(0)
+
+    // Verify spacing
+    // Note: The first few points might be affected by the start condition,
+    // but the middle section should be perfectly spaced.
+    // Also, Catmull-Rom splines don't necessarily pass through control points in a straight line
+    // if the points are collinear, they should be straight.
+
+    // Let's check distances between consecutive points
+    const distances: number[] = []
+    for (let i = 1; i < outputPoints.length; i++) {
+      const dx = outputPoints[i].x - outputPoints[i - 1].x
+      const dy = outputPoints[i].y - outputPoints[i - 1].y
+      distances.push(Math.hypot(dx, dy))
+    }
+
+    // Check that distances are close to spacing
+    // We allow a small epsilon because of floating point and spline approximation
+    // Filter out the very last segment which might be shorter (remainder)
+    // But wait, our logic doesn't output the last point if it's not a full spacing step?
+    // resampleSegment outputs points at [start + spacing, start + 2*spacing, ...]
+    // It does NOT output the end point of the segment.
+    // So all distances between output points should be exactly `spacing`.
+    // EXCEPT possibly if the spline curvature makes the straight-line distance slightly different
+    // from the arc length. But for a straight line input, it should be exact.
+
+    // However, catmull-rom with collinear points IS a straight line.
+
+    // Let's log the distances for debugging if test fails
+    // console.log('Distances:', distances)
+
+    // All distances should be approximately equal to spacing
+    // We might have a gap between segments if the logic isn't perfect,
+    // but within a segment it's guaranteed by resampleSegment.
+    // The critical part is the transition between segments.
+
+    for (let i = 0; i < distances.length; i++) {
+      const d = distances[i]
+      if (Math.abs(d - spacing) > 0.5) {
+        console.log(
+          `Distance mismatch at index ${i}: ${d} (expected ${spacing})`
+        )
+        console.log(`Point ${i}:`, outputPoints[i])
+        console.log(`Point ${i + 1}:`, outputPoints[i + 1])
+      }
+      expect(d).toBeCloseTo(spacing, 1)
+    }
+  })
+
+  it('should handle a simple 3-point stroke', () => {
+    const spacing = 5
+    const processor = new StrokeProcessor(spacing)
+    const points: Point[] = []
+
+    points.push(...processor.addPoint({ x: 0, y: 0 }))
+    points.push(...processor.addPoint({ x: 10, y: 0 }))
+    points.push(...processor.addPoint({ x: 20, y: 0 }))
+    points.push(...processor.endStroke())
+
+    expect(points.length).toBeGreaterThan(0)
+
+    // Check distances
+    for (let i = 1; i < points.length; i++) {
+      const dx = points[i].x - points[i - 1].x
+      const dy = points[i].y - points[i - 1].y
+      const d = Math.hypot(dx, dy)
+      expect(d).toBeCloseTo(spacing, 1)
+    }
+  })
+
+  it('should handle a single point click', () => {
+    const spacing = 5
+    const processor = new StrokeProcessor(spacing)
+    const points: Point[] = []
+
+    points.push(...processor.addPoint({ x: 100, y: 100 }))
+    points.push(...processor.endStroke())
+
+    expect(points.length).toBe(1)
+    expect(points[0]).toEqual({ x: 100, y: 100 })
+  })
+})

src/composables/maskeditor/StrokeProcessor.ts

@@ -0,0 +1,115 @@
+import type { Point } from '@/extensions/core/maskeditor/types'
+import { catmullRomSpline, resampleSegment } from './splineUtils'
+
+export class StrokeProcessor {
+  private controlPoints: Point[] = []
+  private remainder: number = 0
+  private spacing: number
+  private isFirstPoint: boolean = true
+  private hasProcessedSegment: boolean = false
+
+  constructor(spacing: number) {
+    this.spacing = spacing
+  }
+
+  /**
+   * Adds a point to the stroke and returns any new equidistant points generated.
+   * Maintain a sliding window of 4 control points for spline generation
+   */
+  public addPoint(point: Point): Point[] {
+    // Initialize buffer with the first point
+    if (this.isFirstPoint) {
+      this.controlPoints.push(point) // p0: phantom start point
+      this.controlPoints.push(point) // p1: actual start point
+      this.isFirstPoint = false
+      return [] // Wait for more points to form a segment
+    }
+
+    this.controlPoints.push(point)
+
+    // Require 4 points for a spline segment
+    if (this.controlPoints.length < 4) {
+      return []
+    }
+
+    // Generate segment p1->p2
+    const p0 = this.controlPoints[0]
+    const p1 = this.controlPoints[1]
+    const p2 = this.controlPoints[2]
+    const p3 = this.controlPoints[3]
+
+    const newPoints = this.processSegment(p0, p1, p2, p3)
+
+    // Slide window
+    this.controlPoints.shift()
+
+    return newPoints
+  }
+
+  /**
+   * End stroke and flush remaining segments
+   */
+  public endStroke(): Point[] {
+    if (this.controlPoints.length < 2) {
+      // Insufficient points for a segment
+      return []
+    }
+
+    // Process remaining segments by duplicating the last point
+
+    const newPoints: Point[] = []
+
+    // Flush the buffer by processing the final segment
+
+    while (this.controlPoints.length >= 3) {
+      const p0 = this.controlPoints[0]
+      const p1 = this.controlPoints[1]
+      const p2 = this.controlPoints[2]
+      const p3 = p2 // Duplicate last point as phantom end
+
+      const points = this.processSegment(p0, p1, p2, p3)
+      newPoints.push(...points)
+
+      this.controlPoints.shift()
+    }
+
+    // Handle single point click
+    if (!this.hasProcessedSegment && this.controlPoints.length >= 2) {
+      // Process zero-length segment for single point
+      const p = this.controlPoints[1]
+      const points = this.processSegment(p, p, p, p)
+      newPoints.push(...points)
+    }
+
+    return newPoints
+  }
+
+  private processSegment(p0: Point, p1: Point, p2: Point, p3: Point): Point[] {
+    this.hasProcessedSegment = true
+    // Generate dense points for the segment
+    const densePoints: Point[] = []
+
+    // Adaptive sampling based on segment length
+    const dist = Math.hypot(p2.x - p1.x, p2.y - p1.y)
+    // Use 1 sample per pixel, but at least 5 samples to ensure smoothness for short segments
+    // and cap at a reasonable maximum if needed (though not strictly necessary with density)
+    const samples = Math.max(5, Math.ceil(dist))
+
+    for (let i = 0; i < samples; i++) {
+      const t = i / samples
+      densePoints.push(catmullRomSpline(p0, p1, p2, p3, t))
+    }
+    // Add segment end point
+    densePoints.push(p2)
+
+    // Resample points with carried-over remainder
+    const { points, remainder } = resampleSegment(
+      densePoints,
+      this.spacing,
+      this.remainder
+    )
+
+    this.remainder = remainder
+    return points
+  }
+}

src/composables/maskeditor/brushUtils.test.ts

@@ -0,0 +1,47 @@
+import { describe, it, expect } from 'vitest'
+import { getEffectiveBrushSize, getEffectiveHardness } from './brushUtils'
+
+describe('brushUtils', () => {
+  describe('getEffectiveBrushSize', () => {
+    it('should return original size when hardness is 1.0', () => {
+      const size = 100
+      const hardness = 1.0
+      expect(getEffectiveBrushSize(size, hardness)).toBe(100)
+    })
+
+    it('should return 1.5x size when hardness is 0.0', () => {
+      const size = 100
+      const hardness = 0.0
+      expect(getEffectiveBrushSize(size, hardness)).toBe(150)
+    })
+
+    it('should interpolate linearly', () => {
+      const size = 100
+      const hardness = 0.5
+      // Scale should be 1.0 + 0.5 * 0.5 = 1.25
+      expect(getEffectiveBrushSize(size, hardness)).toBe(125)
+    })
+  })
+
+  describe('getEffectiveHardness', () => {
+    it('should return same hardness if effective size matches size', () => {
+      const size = 100
+      const hardness = 0.8
+      const effectiveSize = 100
+      expect(getEffectiveHardness(size, hardness, effectiveSize)).toBe(0.8)
+    })
+
+    it('should scale hardness down as effective size increases', () => {
+      const size = 100
+      const hardness = 0.5
+      // Effective size at 0.5 hardness is 125
+      const effectiveSize = 125
+      // Hard core radius = 50. New hardness = 50 / 125 = 0.4
+      expect(getEffectiveHardness(size, hardness, effectiveSize)).toBe(0.4)
+    })
+
+    it('should return 0 if effective size is 0', () => {
+      expect(getEffectiveHardness(100, 0.5, 0)).toBe(0)
+    })
+  })
+})

src/composables/maskeditor/brushUtils.ts

@@ -0,0 +1,34 @@
+/**
+ * Calculates the effective brush size based on the base size and hardness.
+ * As hardness decreases, the effective size increases to allow for a softer falloff.
+ *
+ * @param size - The base radius of the brush
+ * @param hardness - The hardness of the brush (0.0 to 1.0)
+ * @returns The effective radius of the brush
+ */
+export function getEffectiveBrushSize(size: number, hardness: number): number {
+  // Scale factor for maximum softness
+  const MAX_SCALE = 1.5
+  const scale = 1.0 + (1.0 - hardness) * (MAX_SCALE - 1.0)
+  return size * scale
+}
+
+/**
+ * Calculates the effective hardness to maintain the visual "hard core" of the brush.
+ * Since the effective size is larger, we need to adjust the hardness value so that
+ * the inner hard circle remains at the same physical radius as the original size * hardness.
+ *
+ * @param size - The base radius of the brush
+ * @param hardness - The base hardness of the brush
+ * @param effectiveSize - The effective radius (calculated by getEffectiveBrushSize)
+ * @returns The adjusted hardness value (0.0 to 1.0)
+ */
+export function getEffectiveHardness(
+  size: number,
+  hardness: number,
+  effectiveSize: number
+): number {
+  if (effectiveSize <= 0) return 0
+  // Adjust hardness to maintain the physical radius of the hard core
+  return (size * hardness) / effectiveSize
+}

src/composables/maskeditor/gpu/GPUBrushRenderer.ts

@@ -0,0 +1,805 @@
+import * as d from 'typegpu/data'
+import { StrokePoint } from './gpuSchema'
+import {
+  brushFragment,
+  brushVertex,
+  blitShader,
+  compositeShader,
+  readbackShader
+} from './brushShaders'
+
+// ... (rest of the file)
+
+const QUAD_VERTS = new Float32Array([-1, -1, 1, -1, 1, 1, -1, 1])
+const QUAD_INDICES = new Uint16Array([0, 1, 2, 0, 2, 3])
+
+const UNIFORM_SIZE = 48 // Uniform buffer size aligned to 16 bytes
+const STROKE_STRIDE = d.sizeOf(StrokePoint) // 16
+const MAX_STROKES = 10000
+
+export class GPUBrushRenderer {
+  private device: GPUDevice
+
+  // Buffers
+  private quadVertexBuffer: GPUBuffer
+  private indexBuffer: GPUBuffer
+  private instanceBuffer: GPUBuffer
+  private uniformBuffer: GPUBuffer
+
+  // Pipelines
+  private renderPipeline: GPURenderPipeline // Standard alpha blending pipeline
+  private accumulatePipeline: GPURenderPipeline // SourceOver blending pipeline for stroke accumulation
+  private blitPipeline: GPURenderPipeline
+  private compositePipeline: GPURenderPipeline // Composite pipeline that applies opacity
+  private compositePipelinePreview: GPURenderPipeline // Pipeline for rendering to the preview canvas
+  private erasePipeline: GPURenderPipeline // Pipeline for erasing (Destination Out)
+  private erasePipelinePreview: GPURenderPipeline // Eraser pipeline for the preview canvas
+  readbackPipeline: GPUComputePipeline // Compute pipeline for texture readback
+
+  // Bind Group Layouts
+  private uniformBindGroupLayout: GPUBindGroupLayout
+  private textureBindGroupLayout: GPUBindGroupLayout
+
+  // Shared Bind Groups
+  private mainUniformBindGroup: GPUBindGroup
+
+  // Textures
+  private currentStrokeTexture: GPUTexture | null = null
+  private currentStrokeView: GPUTextureView | null = null
+
+  // Cached Bind Groups
+  private compositeTextureBindGroup: GPUBindGroup | null = null
+  private previewTextureBindGroup: GPUBindGroup | null = null
+
+  // Removed separate uniform bind groups as we will use mainUniformBindGroup
+
+  private lastReadbackTexture: GPUTexture | null = null
+  private lastReadbackBuffer: GPUBuffer | null = null
+  private readbackBindGroup: GPUBindGroup | null = null
+
+  private lastBackgroundTexture: GPUTexture | null = null
+  private backgroundBindGroup: GPUBindGroup | null = null
+
+  constructor(
+    device: GPUDevice,
+    presentationFormat: GPUTextureFormat = 'rgba8unorm'
+  ) {
+    this.device = device
+
+    // --- 1. Initialize Buffers ---
+    this.quadVertexBuffer = device.createBuffer({
+      size: QUAD_VERTS.byteLength,
+      usage: GPUBufferUsage.VERTEX,
+      mappedAtCreation: true
+    })
+    new Float32Array(this.quadVertexBuffer.getMappedRange()).set(QUAD_VERTS)
+    this.quadVertexBuffer.unmap()
+
+    this.indexBuffer = device.createBuffer({
+      size: QUAD_INDICES.byteLength,
+      usage: GPUBufferUsage.INDEX,
+      mappedAtCreation: true
+    })
+    new Uint16Array(this.indexBuffer.getMappedRange()).set(QUAD_INDICES)
+    this.indexBuffer.unmap()
+
+    this.instanceBuffer = device.createBuffer({
+      size: MAX_STROKES * STROKE_STRIDE,
+      usage: GPUBufferUsage.VERTEX | GPUBufferUsage.COPY_DST
+    })
+
+    this.uniformBuffer = device.createBuffer({
+      size: UNIFORM_SIZE,
+      usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST
+    })
+
+    // --- 2. Brush Shader (Drawing) ---
+    const brushModuleV = device.createShaderModule({ code: brushVertex })
+    const brushModuleF = device.createShaderModule({ code: brushFragment })
+
+    // Create explicit bind group layouts
+    this.uniformBindGroupLayout = device.createBindGroupLayout({
+      entries: [
+        {
+          binding: 0,
+          visibility: GPUShaderStage.VERTEX | GPUShaderStage.FRAGMENT,
+          buffer: { type: 'uniform' }
+        }
+      ]
+    })
+
+    this.textureBindGroupLayout = device.createBindGroupLayout({
+      entries: [
+        {
+          binding: 0,
+          visibility: GPUShaderStage.FRAGMENT,
+          texture: {} // default is float, 2d
+        }
+      ]
+    })
+
+    this.mainUniformBindGroup = device.createBindGroup({
+      layout: this.uniformBindGroupLayout,
+      entries: [{ binding: 0, resource: { buffer: this.uniformBuffer } }]
+    })
+
+    const renderPipelineLayout = device.createPipelineLayout({
+      bindGroupLayouts: [this.uniformBindGroupLayout]
+    })
+
+    // Standard Render Pipeline (Alpha Blend)
+    this.renderPipeline = device.createRenderPipeline({
+      layout: renderPipelineLayout,
+      vertex: {
+        module: brushModuleV,
+        entryPoint: 'vs',
+        buffers: [
+          {
+            arrayStride: 8,
+            stepMode: 'vertex',
+            attributes: [{ shaderLocation: 0, offset: 0, format: 'float32x2' }] // Quad vertex attributes
+          },
+          {
+            arrayStride: 16,
+            stepMode: 'instance',
+            attributes: [
+              { shaderLocation: 1, offset: 0, format: 'float32x2' }, // Instance attributes: position
+              { shaderLocation: 2, offset: 8, format: 'float32' }, // size
+              { shaderLocation: 3, offset: 12, format: 'float32' } // pressure
+            ]
+          }
+        ]
+      },
+      fragment: {
+        module: brushModuleF,
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: 'rgba8unorm',
+            blend: {
+              color: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // Accumulate strokes using SourceOver blending to ensure smooth intersections.
+    this.accumulatePipeline = device.createRenderPipeline({
+      layout: renderPipelineLayout,
+      vertex: {
+        module: brushModuleV,
+        entryPoint: 'vs',
+        buffers: [
+          {
+            arrayStride: 8,
+            stepMode: 'vertex',
+            attributes: [{ shaderLocation: 0, offset: 0, format: 'float32x2' }]
+          },
+          {
+            arrayStride: 16,
+            stepMode: 'instance',
+            attributes: [
+              { shaderLocation: 1, offset: 0, format: 'float32x2' },
+              { shaderLocation: 2, offset: 8, format: 'float32' },
+              { shaderLocation: 3, offset: 12, format: 'float32' }
+            ]
+          }
+        ]
+      },
+      fragment: {
+        module: brushModuleF,
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: 'rgba8unorm',
+            blend: {
+              // Use SourceOver blending for smooth stroke intersections.
+              color: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // --- 3. Blit Pipeline (For Preview) ---
+    const blitPipelineLayout = device.createPipelineLayout({
+      bindGroupLayouts: [this.textureBindGroupLayout]
+    })
+
+    this.blitPipeline = device.createRenderPipeline({
+      layout: blitPipelineLayout,
+      vertex: {
+        module: device.createShaderModule({ code: blitShader }),
+        entryPoint: 'vs'
+      },
+      fragment: {
+        module: device.createShaderModule({ code: blitShader }),
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: presentationFormat, // Use the presentation format
+            blend: {
+              color: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // --- 4. Composite Pipeline ---
+
+    const compositePipelineLayout = device.createPipelineLayout({
+      bindGroupLayouts: [
+        this.textureBindGroupLayout,
+        this.uniformBindGroupLayout
+      ]
+    })
+
+    // Standard composite pipeline for offscreen textures
+    this.compositePipeline = device.createRenderPipeline({
+      layout: compositePipelineLayout,
+      vertex: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'vs'
+      },
+      fragment: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: 'rgba8unorm',
+            blend: {
+              color: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // Composite pipeline for the preview canvas
+    this.compositePipelinePreview = device.createRenderPipeline({
+      layout: compositePipelineLayout,
+      vertex: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'vs'
+      },
+      fragment: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: presentationFormat,
+            blend: {
+              color: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'one',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // --- 5. Erase Pipeline (Destination Out) ---
+    // Standard erase pipeline for offscreen textures
+    this.erasePipeline = device.createRenderPipeline({
+      layout: compositePipelineLayout,
+      vertex: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'vs'
+      },
+      fragment: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: 'rgba8unorm',
+            blend: {
+              color: {
+                srcFactor: 'zero',
+                dstFactor: 'one-minus-src-alpha', // dst * (1 - src_alpha)
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'zero',
+                dstFactor: 'one-minus-src-alpha', // dst_alpha * (1 - src_alpha)
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // Erase pipeline for the preview canvas
+    this.erasePipelinePreview = device.createRenderPipeline({
+      layout: compositePipelineLayout,
+      vertex: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'vs'
+      },
+      fragment: {
+        module: device.createShaderModule({ code: compositeShader }),
+        entryPoint: 'fs',
+        targets: [
+          {
+            format: presentationFormat,
+            blend: {
+              color: {
+                srcFactor: 'zero',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              },
+              alpha: {
+                srcFactor: 'zero',
+                dstFactor: 'one-minus-src-alpha',
+                operation: 'add'
+              }
+            }
+          }
+        ]
+      },
+      primitive: { topology: 'triangle-list' }
+    })
+
+    // --- 6. Readback Pipeline (Compute) ---
+    this.readbackPipeline = device.createComputePipeline({
+      layout: 'auto',
+      compute: {
+        module: device.createShaderModule({ code: readbackShader }),
+        entryPoint: 'main'
+      }
+    })
+  }
+
+  public prepareStroke(width: number, height: number) {
+    // Initialize or resize the accumulation texture
+    if (
+      !this.currentStrokeTexture ||
+      this.currentStrokeTexture.width !== width ||
+      this.currentStrokeTexture.height !== height
+    ) {
+      if (this.currentStrokeTexture) this.currentStrokeTexture.destroy()
+      this.currentStrokeTexture = this.device.createTexture({
+        size: [width, height],
+        format: 'rgba8unorm',
+        usage:
+          GPUTextureUsage.RENDER_ATTACHMENT |
+          GPUTextureUsage.TEXTURE_BINDING |
+          GPUTextureUsage.COPY_SRC
+      })
+      this.currentStrokeView = this.currentStrokeTexture.createView()
+
+      // Invalidate texture-dependent bind groups
+      this.compositeTextureBindGroup = null
+      this.previewTextureBindGroup = null
+      // Readback bind group might also be invalid if it was using the old texture
+      if (this.lastReadbackTexture === this.currentStrokeTexture) {
+        this.readbackBindGroup = null
+        this.lastReadbackTexture = null
+      }
+    }
+
+    // Clear the accumulation texture
+    const encoder = this.device.createCommandEncoder()
+    const pass = encoder.beginRenderPass({
+      colorAttachments: [
+        {
+          view: this.currentStrokeView!,
+          loadOp: 'clear',
+          clearValue: { r: 0, g: 0, b: 0, a: 0 },
+          storeOp: 'store'
+        }
+      ]
+    })
+    pass.end()
+    this.device.queue.submit([encoder.finish()])
+  }
+
+  public renderStrokeToAccumulator(
+    points: { x: number; y: number; pressure: number }[],
+    settings: {
+      size: number
+      opacity: number
+      hardness: number
+      color: [number, number, number]
+      width: number
+      height: number
+      brushShape: number
+    }
+  ) {
+    if (!this.currentStrokeView) return
+    // Render stroke using accumulation pipeline
+    this.renderStrokeInternal(
+      this.currentStrokeView,
+      this.accumulatePipeline,
+      points,
+      settings
+    )
+  }
+
+  public compositeStroke(
+    targetView: GPUTextureView,
+    settings: {
+      opacity: number
+      color: [number, number, number]
+      hardness: number // Required for uniform buffer layout
+      screenSize: [number, number]
+      brushShape: number
+      isErasing?: boolean
+    }
+  ) {
+    if (!this.currentStrokeTexture) return
+
+    // Update uniforms for the composite pass
+    const buffer = new ArrayBuffer(UNIFORM_SIZE)
+    const f32 = new Float32Array(buffer)
+    const u32 = new Uint32Array(buffer)
+
+    f32[0] = settings.color[0]
+    f32[1] = settings.color[1]
+    f32[2] = settings.color[2]
+    f32[3] = settings.opacity
+    f32[4] = settings.hardness
+    f32[5] = 0 // Padding
+    f32[6] = settings.screenSize[0]
+    f32[7] = settings.screenSize[1]
+    u32[8] = settings.brushShape // Brush shape: 0=Circle, 1=Square
+    this.device.queue.writeBuffer(this.uniformBuffer, 0, buffer)
+
+    const encoder = this.device.createCommandEncoder()
+
+    // Choose pipeline based on operation
+    const pipeline = settings.isErasing
+      ? this.erasePipeline
+      : this.compositePipeline
+
+    // 1. Texture Bind Group (Group 0)
+    if (!this.compositeTextureBindGroup) {
+      this.compositeTextureBindGroup = this.device.createBindGroup({
+        layout: this.textureBindGroupLayout,
+        entries: [
+          { binding: 0, resource: this.currentStrokeTexture.createView() }
+        ]
+      })
+    }
+
+    // 2. Uniform Bind Group (Group 1) - Use shared mainUniformBindGroup
+    // It is compatible because we used the same layout
+
+    const pass = encoder.beginRenderPass({
+      colorAttachments: [
+        {
+          view: targetView,
+          loadOp: 'load',
+          storeOp: 'store'
+        }
+      ]
+    })
+
+    pass.setPipeline(pipeline)
+    pass.setBindGroup(0, this.compositeTextureBindGroup)
+    pass.setBindGroup(1, this.mainUniformBindGroup)
+    pass.draw(3)
+    pass.end()
+
+    this.device.queue.submit([encoder.finish()])
+  }
+
+  // Direct rendering method
+  public renderStroke(
+    targetView: GPUTextureView,
+    points: { x: number; y: number; pressure: number }[],
+    settings: {
+      size: number
+      opacity: number
+      hardness: number
+      color: [number, number, number]
+      width: number
+      height: number
+      brushShape: number
+    }
+  ) {
+    this.renderStrokeInternal(targetView, this.renderPipeline, points, settings)
+  }
+
+  private renderStrokeInternal(
+    targetView: GPUTextureView,
+    pipeline: GPURenderPipeline,
+    points: { x: number; y: number; pressure: number }[],
+    settings: {
+      size: number
+      opacity: number
+      hardness: number
+      color: [number, number, number]
+      width: number
+      height: number
+      brushShape: number
+    }
+  ) {
+    if (points.length === 0) return
+
+    // 1. Update Uniforms
+    const buffer = new ArrayBuffer(UNIFORM_SIZE)
+    const f32 = new Float32Array(buffer)
+    const u32 = new Uint32Array(buffer)
+
+    f32[0] = settings.color[0]
+    f32[1] = settings.color[1]
+    f32[2] = settings.color[2]
+    f32[3] = settings.opacity
+    f32[4] = settings.hardness
+    f32[5] = 0 // Padding
+    f32[6] = settings.width
+    f32[7] = settings.height
+    u32[8] = settings.brushShape
+    this.device.queue.writeBuffer(this.uniformBuffer, 0, buffer)
+
+    // 2. Batch Rendering
+    let processedPoints = 0
+    while (processedPoints < points.length) {
+      const batchSize = Math.min(points.length - processedPoints, MAX_STROKES)
+      const iData = new Float32Array(batchSize * 4)
+
+      for (let i = 0; i < batchSize; i++) {
+        const p = points[processedPoints + i]
+        iData[i * 4 + 0] = p.x
+        iData[i * 4 + 1] = p.y
+        iData[i * 4 + 2] = settings.size
+        iData[i * 4 + 3] = p.pressure
+      }
+
+      this.device.queue.writeBuffer(this.instanceBuffer, 0, iData)
+
+      // 3. Render Pass
+      const encoder = this.device.createCommandEncoder()
+      const pass = encoder.beginRenderPass({
+        colorAttachments: [
+          {
+            view: targetView,
+            loadOp: 'load',
+            storeOp: 'store'
+          }
+        ]
+      })
+
+      pass.setPipeline(pipeline)
+      pass.setBindGroup(0, this.mainUniformBindGroup)
+      pass.setVertexBuffer(0, this.quadVertexBuffer)
+      pass.setVertexBuffer(1, this.instanceBuffer)
+      pass.setIndexBuffer(this.indexBuffer, 'uint16')
+      pass.drawIndexed(6, batchSize)
+      pass.end()
+
+      this.device.queue.submit([encoder.finish()])
+
+      processedPoints += batchSize
+    }
+  }
+
+  // Blit the accumulated stroke to the preview canvas
+  public blitToCanvas(
+    destinationCtx: GPUCanvasContext,
+    settings: {
+      opacity: number
+      color: [number, number, number]
+      hardness: number
+      screenSize: [number, number]
+      brushShape: number
+      isErasing?: boolean
+    },
+    backgroundTexture?: GPUTexture
+  ) {
+    const encoder = this.device.createCommandEncoder()
+    const destView = destinationCtx.getCurrentTexture().createView()
+
+    if (backgroundTexture) {
+      // Draw background texture to allow erasing effect on existing content
+      if (
+        this.lastBackgroundTexture !== backgroundTexture ||
+        !this.backgroundBindGroup
+      ) {
+        this.backgroundBindGroup = this.device.createBindGroup({
+          layout: this.textureBindGroupLayout,
+          entries: [{ binding: 0, resource: backgroundTexture.createView() }]
+        })
+        this.lastBackgroundTexture = backgroundTexture
+      }
+
+      const pass = encoder.beginRenderPass({
+        colorAttachments: [
+          {
+            view: destView,
+            loadOp: 'clear', // Clear attachment before drawing
+            clearValue: { r: 0, g: 0, b: 0, a: 0 },
+            storeOp: 'store'
+          }
+        ]
+      })
+      pass.setPipeline(this.blitPipeline)
+      pass.setBindGroup(0, this.backgroundBindGroup)
+      pass.draw(3)
+      pass.end()
+    } else {
+      // Clear the destination texture
+      const clearPass = encoder.beginRenderPass({
+        colorAttachments: [
+          {
+            view: destView,
+            loadOp: 'clear',
+            clearValue: { r: 0, g: 0, b: 0, a: 0 },
+            storeOp: 'store'
+          }
+        ]
+      })
+      clearPass.end()
+    }
+
+    // Draw the accumulated stroke
+    if (this.currentStrokeTexture) {
+      // Update uniforms for the preview pass
+      const buffer = new ArrayBuffer(UNIFORM_SIZE)
+      const f32 = new Float32Array(buffer)
+      const u32 = new Uint32Array(buffer)
+
+      f32[0] = settings.color[0]
+      f32[1] = settings.color[1]
+      f32[2] = settings.color[2]
+      f32[3] = settings.opacity
+      f32[4] = settings.hardness
+      f32[5] = 0 // Padding
+      f32[6] = settings.screenSize[0]
+      f32[7] = settings.screenSize[1]
+      u32[8] = settings.brushShape
+      this.device.queue.writeBuffer(this.uniformBuffer, 0, buffer)
+
+      // Select preview pipeline based on operation
+      const pipeline = settings.isErasing
+        ? this.erasePipelinePreview
+        : this.compositePipelinePreview
+
+      // 1. Texture Bind Group (Group 0)
+      if (!this.previewTextureBindGroup) {
+        this.previewTextureBindGroup = this.device.createBindGroup({
+          layout: this.textureBindGroupLayout,
+          entries: [
+            { binding: 0, resource: this.currentStrokeTexture.createView() }
+          ]
+        })
+      }
+
+      // 2. Uniform Bind Group (Group 1) - Use shared mainUniformBindGroup
+
+      const passStroke = encoder.beginRenderPass({
+        colorAttachments: [
+          {
+            view: destView,
+            loadOp: 'load', // Load the previous pass result
+            storeOp: 'store'
+          }
+        ]
+      })
+      passStroke.setPipeline(pipeline)
+      passStroke.setBindGroup(0, this.previewTextureBindGroup)
+      passStroke.setBindGroup(1, this.mainUniformBindGroup)
+      passStroke.draw(3)
+      passStroke.end()
+    }
+
+    this.device.queue.submit([encoder.finish()])
+  }
+
+  // Clear the preview canvas
+  public clearPreview(destinationCtx: GPUCanvasContext) {
+    const encoder = this.device.createCommandEncoder()
+    const pass = encoder.beginRenderPass({
+      colorAttachments: [
+        {
+          view: destinationCtx.getCurrentTexture().createView(),
+          loadOp: 'clear',
+          clearValue: { r: 0, g: 0, b: 0, a: 0 },
+          storeOp: 'store'
+        }
+      ]
+    })
+    pass.end()
+    this.device.queue.submit([encoder.finish()])
+  }
+
+  public prepareReadback(texture: GPUTexture, outputBuffer: GPUBuffer) {
+    if (
+      this.lastReadbackTexture !== texture ||
+      this.lastReadbackBuffer !== outputBuffer ||
+      !this.readbackBindGroup
+    ) {
+      this.readbackBindGroup = this.device.createBindGroup({
+        layout: this.readbackPipeline.getBindGroupLayout(0),
+        entries: [
+          { binding: 0, resource: texture.createView() },
+          { binding: 1, resource: { buffer: outputBuffer } }
+        ]
+      })
+      this.lastReadbackTexture = texture
+      this.lastReadbackBuffer = outputBuffer
+    }
+
+    const encoder = this.device.createCommandEncoder()
+    const pass = encoder.beginComputePass()
+    pass.setPipeline(this.readbackPipeline)
+    pass.setBindGroup(0, this.readbackBindGroup)
+
+    const width = texture.width
+    const height = texture.height
+    // Dispatch workgroups based on texture dimensions (8x8 block size)
+    pass.dispatchWorkgroups(Math.ceil(width / 8), Math.ceil(height / 8))
+    pass.end()
+
+    this.device.queue.submit([encoder.finish()])
+  }
+
+  public destroy() {
+    this.quadVertexBuffer.destroy()
+    this.indexBuffer.destroy()
+    this.instanceBuffer.destroy()
+    this.uniformBuffer.destroy()
+    if (this.currentStrokeTexture) this.currentStrokeTexture.destroy()
+
+    // Clear cached bind groups
+    this.compositeTextureBindGroup = null
+    this.previewTextureBindGroup = null
+    this.readbackBindGroup = null
+    this.backgroundBindGroup = null
+    this.lastReadbackTexture = null
+    this.lastReadbackBuffer = null
+    this.lastBackgroundTexture = null
+  }
+}

src/composables/maskeditor/gpu/brushShaders.ts

@@ -0,0 +1,171 @@
+import tgpu from 'typegpu'
+import * as d from 'typegpu/data'
+import { BrushUniforms } from './gpuSchema'
+
+const VertexOutput = d.struct({
+  position: d.builtin.position,
+  localUV: d.location(0, d.vec2f),
+  color: d.location(1, d.vec3f),
+  opacity: d.location(2, d.f32),
+  hardness: d.location(3, d.f32)
+})
+
+const brushVertexTemplate = `
+@group(0) @binding(0) var<uniform> globals: BrushUniforms;
+
+@vertex
+fn vs(
+  @location(0) quadPos: vec2<f32>,
+  @location(1) pos: vec2<f32>,
+  @location(2) size: f32,
+  @location(3) pressure: f32
+) -> VertexOutput {
+  // Convert diameter to radius
+  let radius = size * pressure;
+  let pixelPos = pos + (quadPos * radius);
+  
+  // Convert pixel coordinates to Normalized Device Coordinates (NDC)
+  let ndcX = (pixelPos.x / globals.screenSize.x) * 2.0 - 1.0;
+  let ndcY = 1.0 - ((pixelPos.y / globals.screenSize.y) * 2.0);  // Flip Y axis for WebGPU coordinate system
+
+  return VertexOutput(
+    vec4<f32>(ndcX, ndcY, 0.0, 1.0),
+    quadPos,
+    globals.brushColor,
+    pressure * globals.brushOpacity,
+    globals.hardness
+  );
+}
+`
+
+export const brushVertex = tgpu.resolve({
+  template: brushVertexTemplate,
+  externals: {
+    BrushUniforms,
+    VertexOutput
+  }
+})
+
+const brushFragmentTemplate = `
+@group(0) @binding(0) var<uniform> globals: BrushUniforms;
+
+@fragment
+fn fs(v: VertexOutput) -> @location(0) vec4<f32> {
+  var dist: f32;
+  if (globals.brushShape == 1u) {
+    // Calculate Chebyshev distance for square shape
+    dist = max(abs(v.localUV.x), abs(v.localUV.y));
+  } else {
+    // Calculate Euclidean distance for circle shape
+    dist = length(v.localUV);
+  }
+
+  if (dist > 1.0) { discard; }
+
+  // Calculate alpha with hardness and anti-aliasing
+  let edgeWidth = fwidth(dist);
+  let startFade = min(v.hardness, 1.0 - edgeWidth * 2.0);
+  let linearAlpha = 1.0 - smoothstep(startFade, 1.0, dist);
+  // Apply quadratic falloff for smoother edges
+  let alphaShape = pow(linearAlpha, 2.0);
+  
+  // Return premultiplied alpha color
+  let alpha = alphaShape * v.opacity;
+  return vec4<f32>(v.color * alpha, alpha);
+}
+`
+
+export const brushFragment = tgpu.resolve({
+  template: brushFragmentTemplate,
+  externals: {
+    VertexOutput,
+    BrushUniforms
+  }
+})
+
+const blitShaderTemplate = `
+@vertex fn vs(@builtin(vertex_index) vIdx: u32) -> @builtin(position) vec4<f32> {
+  var pos = array<vec2<f32>, 3>(
+    vec2<f32>(-1.0, -1.0), vec2<f32>(3.0, -1.0), vec2<f32>(-1.0, 3.0)
+  );
+  return vec4<f32>(pos[vIdx], 0.0, 1.0);
+}
+
+@group(0) @binding(0) var myTexture: texture_2d<f32>;
+
+@fragment fn fs(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {
+  let c = textureLoad(myTexture, vec2<i32>(pos.xy), 0);
+  // Treat texture as premultiplied to prevent double-darkening on overlaps
+  return c;
+}
+`
+
+export const blitShader = tgpu.resolve({
+  template: blitShaderTemplate,
+  externals: {}
+})
+
+const compositeShaderTemplate = `
+@vertex fn vs(@builtin(vertex_index) vIdx: u32) -> @builtin(position) vec4<f32> {
+  var pos = array<vec2<f32>, 3>(
+    vec2<f32>(-1.0, -1.0), vec2<f32>(3.0, -1.0), vec2<f32>(-1.0, 3.0)
+  );
+  return vec4<f32>(pos[vIdx], 0.0, 1.0);
+}
+
+@group(0) @binding(0) var myTexture: texture_2d<f32>;
+@group(1) @binding(0) var<uniform> globals: BrushUniforms;
+
+@fragment fn fs(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {
+  let sampled = textureLoad(myTexture, vec2<i32>(pos.xy), 0);
+  // Apply global brush opacity to accumulated coverage
+  return sampled * globals.brushOpacity;
+}
+`
+
+export const compositeShader = tgpu.resolve({
+  template: compositeShaderTemplate,
+  externals: {
+    BrushUniforms
+  }
+})
+
+const readbackShaderTemplate = `
+@group(0) @binding(0) var inputTex: texture_2d<f32>;
+@group(0) @binding(1) var<storage, read_write> outputBuf: array<u32>;
+
+@compute @workgroup_size(8, 8)
+fn main(@builtin(global_invocation_id) id: vec3<u32>) {
+  let dims = textureDimensions(inputTex);
+  if (id.x >= dims.x || id.y >= dims.y) { return; }
+
+  let color = textureLoad(inputTex, vec2<i32>(id.xy), 0);
+  
+  var r = color.r;
+  var g = color.g;
+  var b = color.b;
+  let a = color.a;
+
+  if (a > 0.0) {
+    r = r / a;
+    g = g / a;
+    b = b / a;
+  }
+
+  let ir = u32(clamp(r * 255.0, 0.0, 255.0));
+  let ig = u32(clamp(g * 255.0, 0.0, 255.0));
+  let ib = u32(clamp(b * 255.0, 0.0, 255.0));
+  let ia = u32(clamp(a * 255.0, 0.0, 255.0));
+
+  // Pack RGBA channels into a single u32 (Little Endian)
+  let packed = ir | (ig << 8u) | (ib << 16u) | (ia << 24u);
+
+  let index = id.y * dims.x + id.x;
+  outputBuf[index] = packed;
+}
+`
+
+export const readbackShader = tgpu.resolve({
+  template: readbackShaderTemplate,
+  externals: {}
+})

src/composables/maskeditor/gpu/gpuSchema.ts

@@ -0,0 +1,17 @@
+import * as d from 'typegpu/data'
+
+// Global brush uniforms
+export const BrushUniforms = d.struct({
+  brushColor: d.vec3f,
+  brushOpacity: d.f32,
+  hardness: d.f32,
+  screenSize: d.vec2f,
+  brushShape: d.u32 // 0: Circle, 1: Square
+})
+
+// Per-point instance data
+export const StrokePoint = d.struct({
+  pos: d.location(0, d.vec2f), // Center position
+  size: d.location(1, d.f32), // Brush radius
+  pressure: d.location(2, d.f32) // Pressure value (0.0 - 1.0)
+})

src/composables/maskeditor/splineUtils.ts

@@ -0,0 +1,126 @@
+import type { Point } from '@/extensions/core/maskeditor/types'
+
+/**
+ * Evaluates a Catmull-Rom spline at parameter t between p1 and p2
+ * @param p0 Previous control point
+ * @param p1 Start point of the curve segment
+ * @param p2 End point of the curve segment
+ * @param p3 Next control point
+ * @param t Parameter in range [0, 1]
+ * @returns Interpolated point on the curve
+ */
+export function catmullRomSpline(
+  p0: Point,
+  p1: Point,
+  p2: Point,
+  p3: Point,
+  t: number
+): Point {
+  // Centripetal Catmull-Rom Spline (alpha = 0.5) to prevent loops and overshoots
+  const alpha = 0.5
+
+  const getT = (t: number, p0: Point, p1: Point) => {
+    const d = Math.hypot(p1.x - p0.x, p1.y - p0.y)
+    return t + Math.pow(d, alpha)
+  }
+
+  const t0 = 0
+  const t1 = getT(t0, p0, p1)
+  const t2 = getT(t1, p1, p2)
+  const t3 = getT(t2, p2, p3)
+
+  // Map normalized t to parameter range
+  const tInterp = t1 + (t2 - t1) * t
+
+  // Safe interpolation for coincident points
+  const interp = (
+    pA: Point,
+    pB: Point,
+    tA: number,
+    tB: number,
+    t: number
+  ): Point => {
+    if (Math.abs(tB - tA) < 0.0001) return pA
+    const k = (t - tA) / (tB - tA)
+    return add(mul(pA, 1 - k), mul(pB, k))
+  }
+
+  // Barry-Goldman pyramidal interpolation
+  const A1 = interp(p0, p1, t0, t1, tInterp)
+  const A2 = interp(p1, p2, t1, t2, tInterp)
+  const A3 = interp(p2, p3, t2, t3, tInterp)
+
+  const B1 = interp(A1, A2, t0, t2, tInterp)
+  const B2 = interp(A2, A3, t1, t3, tInterp)
+
+  const C = interp(B1, B2, t1, t2, tInterp)
+
+  return C
+}
+
+function add(p1: Point, p2: Point): Point {
+  return { x: p1.x + p2.x, y: p1.y + p2.y }
+}
+
+function mul(p: Point, s: number): Point {
+  return { x: p.x * s, y: p.y * s }
+}
+
+/**
+ * Resamples a curve segment with a starting offset (remainder from previous segment).
+ * Returns the resampled points and the new remainder distance.
+ *
+ * @param points Points defining the curve segment
+ * @param spacing Desired spacing between points
+ * @param startOffset Distance to travel before placing the first point (remainder)
+ * @returns Object containing points and new remainder
+ */
+export function resampleSegment(
+  points: Point[],
+  spacing: number,
+  startOffset: number
+): { points: Point[]; remainder: number } {
+  if (points.length === 0) return { points: [], remainder: startOffset }
+
+  const result: Point[] = []
+  let currentDist = 0
+  let nextSampleDist = startOffset
+
+  // Iterate through segment points
+  for (let i = 0; i < points.length - 1; i++) {
+    const p1 = points[i]
+    const p2 = points[i + 1]
+
+    const dx = p2.x - p1.x
+    const dy = p2.y - p1.y
+    const segmentLen = Math.hypot(dx, dy)
+
+    // Handle zero-length segments
+    if (segmentLen < 0.0001) {
+      while (nextSampleDist <= currentDist) {
+        result.push(p1)
+        nextSampleDist += spacing
+      }
+      continue
+    }
+
+    // Generate samples within the segment
+    while (nextSampleDist <= currentDist + segmentLen) {
+      const t = (nextSampleDist - currentDist) / segmentLen
+
+      // Interpolate
+      const x = p1.x + t * dx
+      const y = p1.y + t * dy
+      result.push({ x, y })
+
+      nextSampleDist += spacing
+    }
+
+    currentDist += segmentLen
+  }
+
+  // Calculate remainder distance for the next segment
+  const remainder = nextSampleDist - currentDist
+
+  return { points: result, remainder }
+}

src/composables/maskeditor/useCanvasHistory.ts

@@ -4,7 +4,9 @@ import { useMaskEditorStore } from '@/stores/maskEditorStore'
 export function useCanvasHistory(maxStates = 20) {
   const store = useMaskEditorStore()
 
-  const states = ref<{ mask: ImageData; rgb: ImageData }[]>([])
+  const states = ref<
+    { mask: ImageData | ImageBitmap; rgb: ImageData | ImageBitmap }[]
+  >([])
   const currentStateIndex = ref(-1)
   const initialized = ref(false)
 
@@ -53,7 +55,10 @@ export function useCanvasHistory(maxStates = 20) {
     initialized.value = true
   }
 
-  const saveState = () => {
+  const saveState = (
+    providedMaskData?: ImageData | ImageBitmap,
+    providedRgbData?: ImageData | ImageBitmap
+  ) => {
     const maskCtx = store.maskCtx
     const rgbCtx = store.rgbCtx
     const maskCanvas = store.maskCanvas
@@ -68,23 +73,32 @@ export function useCanvasHistory(maxStates = 20) {
 
     states.value = states.value.slice(0, currentStateIndex.value + 1)
 
-    const maskState = maskCtx.getImageData(
+    let maskState: ImageData | ImageBitmap
-      0,
+    let rgbState: ImageData | ImageBitmap
-      0,
+
-      maskCanvas.width,
+    if (providedMaskData && providedRgbData) {
-      maskCanvas.height
+      maskState = providedMaskData
-    )
+      rgbState = providedRgbData
-    const rgbState = rgbCtx.getImageData(
+    } else {
-      0,
+      maskState = maskCtx.getImageData(
-      0,
+        0,
-      rgbCanvas.width,
+        0,
-      rgbCanvas.height
+        maskCanvas.width,
-    )
+        maskCanvas.height
+      )
+      rgbState = rgbCtx.getImageData(0, 0, rgbCanvas.width, rgbCanvas.height)
+    }
+
     states.value.push({ mask: maskState, rgb: rgbState })
     currentStateIndex.value++
 
     if (states.value.length > maxStates) {
-      states.value.shift()
+      const removed = states.value.shift()
+      // Cleanup ImageBitmaps to avoid memory leaks
+      if (removed) {
+        if (removed.mask instanceof ImageBitmap) removed.mask.close()
+        if (removed.rgb instanceof ImageBitmap) removed.rgb.close()
+      }
       currentStateIndex.value--
     }
   }
@@ -109,16 +123,35 @@ export function useCanvasHistory(maxStates = 20) {
     restoreState(states.value[currentStateIndex.value])
   }
 
-  const restoreState = (state: { mask: ImageData; rgb: ImageData }) => {
+  const restoreState = (state: {
+    mask: ImageData | ImageBitmap
+    rgb: ImageData | ImageBitmap
+  }) => {
     const maskCtx = store.maskCtx
     const rgbCtx = store.rgbCtx
     if (!maskCtx || !rgbCtx) return
 
-    maskCtx.putImageData(state.mask, 0, 0)
+    if (state.mask instanceof ImageBitmap) {
-    rgbCtx.putImageData(state.rgb, 0, 0)
+      maskCtx.clearRect(0, 0, state.mask.width, state.mask.height)
+      maskCtx.drawImage(state.mask, 0, 0)
+    } else {
+      maskCtx.putImageData(state.mask, 0, 0)
+    }
+
+    if (state.rgb instanceof ImageBitmap) {
+      rgbCtx.clearRect(0, 0, state.rgb.width, state.rgb.height)
+      rgbCtx.drawImage(state.rgb, 0, 0)
+    } else {
+      rgbCtx.putImageData(state.rgb, 0, 0)
+    }
   }
 
   const clearStates = () => {
+    // Cleanup bitmaps
+    states.value.forEach((state) => {
+      if (state.mask instanceof ImageBitmap) state.mask.close()
+      if (state.rgb instanceof ImageBitmap) state.rgb.close()
+    })
     states.value = []
     currentStateIndex.value = -1
     initialized.value = false
@@ -127,6 +160,7 @@ export function useCanvasHistory(maxStates = 20) {
   return {
     canUndo,
     canRedo,
+    currentStateIndex,
     saveInitialState,
     saveState,
     undo,

src/composables/maskeditor/useMaskEditorLoader.ts

@@ -80,21 +80,64 @@ export function useMaskEditorLoader() {
     try {
       validateNode(node)
 
-      const nodeImageUrl = getNodeImageUrl(node)
+      let nodeImageUrl = getNodeImageUrl(node)
 
-      const nodeImageRef = parseImageRef(nodeImageUrl)
+      let nodeImageRef = parseImageRef(nodeImageUrl)
 
       let widgetFilename: string | undefined
       if (node.widgets) {
         const imageWidget = node.widgets.find((w) => w.name === 'image')
-        if (
+        if (imageWidget) {
-          imageWidget &&
+          if (typeof imageWidget.value === 'string') {
-          typeof imageWidget.value === 'object' &&
+            widgetFilename = imageWidget.value
-          imageWidget.value &&
+          } else if (
-          'filename' in imageWidget.value &&
+            typeof imageWidget.value === 'object' &&
-          typeof imageWidget.value.filename === 'string'
+            imageWidget.value &&
-        ) {
+            'filename' in imageWidget.value &&
-          widgetFilename = imageWidget.value.filename
+            typeof imageWidget.value.filename === 'string'
+          ) {
+            widgetFilename = imageWidget.value.filename
+          }
+        }
+      }
+
+      // If we have a widget filename, we should prioritize it over the node image
+      // because the node image might be stale (e.g. from a previous save)
+      // while the widget value reflects the current selection.
+      if (widgetFilename) {
+        try {
+          // Parse the widget value which might be in format "subfolder/filename [type]" or just "filename"
+          let filename = widgetFilename
+          let subfolder: string | undefined = undefined
+          let type: string | undefined = 'input' // Default to input for widget values
+
+          // Check for type in brackets at the end
+          const typeMatch = filename.match(/ \[([^\]]+)\]$/)
+          if (typeMatch) {
+            type = typeMatch[1]
+            filename = filename.substring(
+              0,
+              filename.length - typeMatch[0].length
+            )
+          }
+
+          // Check for subfolder (forward slash separator)
+          const lastSlashIndex = filename.lastIndexOf('/')
+          if (lastSlashIndex !== -1) {
+            subfolder = filename.substring(0, lastSlashIndex)
+            filename = filename.substring(lastSlashIndex + 1)
+          }
+
+          nodeImageRef = {
+            filename,
+            type,
+            subfolder
+          }
+
+          // We also need to update nodeImageUrl to match this new ref so subsequent logic works
+          nodeImageUrl = mkFileUrl({ ref: nodeImageRef })
+        } catch (e) {
+          console.warn('Failed to parse widget filename as ref', e)
         }
       }
 

src/extensions/core/maskeditor/types.ts

@@ -61,5 +61,5 @@ export interface Brush {
   size: number
   opacity: number
   hardness: number
-  smoothingPrecision: number
+  stepSize: number
 }

src/stores/maskEditorStore.ts

@@ -22,7 +22,7 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
     size: 10,
     opacity: 0.7,
     hardness: 1,
-    smoothingPrecision: 10
+    stepSize: 10
   })
 
   const maskBlendMode = ref<MaskBlendMode>(MaskBlendMode.Black)
@@ -50,6 +50,7 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
   const panOffset = ref<Offset>({ x: 0, y: 0 })
   const cursorPoint = ref<Point>({ x: 0, y: 0 })
   const resetZoomTrigger = ref<number>(0)
+  const clearTrigger = ref<number>(0)
 
   const maskCanvas = ref<HTMLCanvasElement | null>(null)
   const maskCtx = ref<CanvasRenderingContext2D | null>(null)
@@ -70,6 +71,8 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
 
   const canvasHistory = useCanvasHistory(20)
 
+  const tgpuRoot = ref<any>(null)
+
   watch(maskCanvas, (canvas) => {
     if (canvas) {
       maskCtx.value = canvas.getContext('2d', { willReadFrequently: true })
@@ -110,7 +113,7 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
   })
 
   function setBrushSize(size: number): void {
-    brushSettings.value.size = _.clamp(size, 1, 100)
+    brushSettings.value.size = _.clamp(size, 1, 500)
   }
 
   function setBrushOpacity(opacity: number): void {
@@ -121,8 +124,8 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
     brushSettings.value.hardness = _.clamp(hardness, 0, 1)
   }
 
-  function setBrushSmoothingPrecision(precision: number): void {
+  function setBrushStepSize(step: number): void {
-    brushSettings.value.smoothingPrecision = _.clamp(precision, 1, 100)
+    brushSettings.value.stepSize = _.clamp(step, 1, 100)
   }
 
   function resetBrushToDefault(): void {
@@ -130,7 +133,7 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
     brushSettings.value.size = 20
     brushSettings.value.opacity = 1
     brushSettings.value.hardness = 1
-    brushSettings.value.smoothingPrecision = 60
+    brushSettings.value.stepSize = 5
   }
 
   function setPaintBucketTolerance(tolerance: number): void {
@@ -169,6 +172,10 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
     resetZoomTrigger.value++
   }
 
+  function triggerClear(): void {
+    clearTrigger.value++
+  }
+
   function setMaskOpacity(opacity: number): void {
     maskOpacity.value = _.clamp(opacity, 0, 1)
   }
@@ -179,7 +186,7 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
       size: 10,
       opacity: 0.7,
       hardness: 1,
-      smoothingPrecision: 10
+      stepSize: 5
     }
     maskBlendMode.value = MaskBlendMode.Black
     activeLayer.value = 'mask'
@@ -243,10 +250,12 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
 
     canvasHistory,
 
+    tgpuRoot,
+
     setBrushSize,
     setBrushOpacity,
     setBrushHardness,
-    setBrushSmoothingPrecision,
+    setBrushStepSize,
     resetBrushToDefault,
     setPaintBucketTolerance,
     setFillOpacity,
@@ -257,6 +266,8 @@ export const useMaskEditorStore = defineStore('maskEditor', () => {
     setPanOffset,
     setCursorPoint,
     resetZoom,
+    triggerClear,
+    clearTrigger,
     setMaskOpacity,
     resetState
   }

tests-ui/tests/composables/maskeditor/useCanvasHistory.test.ts

@@ -18,6 +18,19 @@ vi.mock('@/stores/maskEditorStore', () => ({
   useMaskEditorStore: vi.fn(() => mockStore)
 }))
 
+// Mock ImageBitmap for test environment
+if (typeof globalThis.ImageBitmap === 'undefined') {
+  globalThis.ImageBitmap = class ImageBitmap {
+    width: number
+    height: number
+    constructor(width = 100, height = 100) {
+      this.width = width
+      this.height = height
+    }
+    close() {}
+  } as any
+}
+
 describe('useCanvasHistory', () => {
   beforeEach(() => {
     vi.clearAllMocks()
@@ -42,12 +55,16 @@ describe('useCanvasHistory', () => {
 
     mockMaskCtx = {
       getImageData: vi.fn(() => createMockImageData()),
-      putImageData: vi.fn()
+      putImageData: vi.fn(),
+      clearRect: vi.fn(),
+      drawImage: vi.fn()
     }
 
     mockRgbCtx = {
       getImageData: vi.fn(() => createMockImageData()),
-      putImageData: vi.fn()
+      putImageData: vi.fn(),
+      clearRect: vi.fn(),
+      drawImage: vi.fn()
     }
 
     mockMaskCanvas = {

tsconfig.json

@@ -45,7 +45,8 @@
       "./node_modules"
     ],
     "types": [
-      "vitest/globals"
+      "vitest/globals",
+      "@webgpu/types"
     ],
     "outDir": "./dist",
     "rootDir": "./"

vite.config.mts

@@ -10,6 +10,7 @@ import { FileSystemIconLoader } from 'unplugin-icons/loaders'
 import IconsResolver from 'unplugin-icons/resolver'
 import Icons from 'unplugin-icons/vite'
 import Components from 'unplugin-vue-components/vite'
+import typegpuPlugin from 'unplugin-typegpu/vite'
 import { defineConfig } from 'vite'
 import type { ProxyOptions, UserConfig } from 'vite'
 import { createHtmlPlugin } from 'vite-plugin-html'
@@ -231,6 +232,7 @@ export default defineConfig({
       ? [vueDevTools(), vue(), createHtmlPlugin({})]
       : [vue()]),
     tailwindcss(),
+    typegpuPlugin({}),
     comfyAPIPlugin(IS_DEV),
     // Twitter/Open Graph meta tags plugin (cloud distribution only)
     {