Clean up

src/pipelines/eraser/eraser-agent-pipeline.ts

@@ -14,6 +14,7 @@ export class EraserAgentPipeline {
   private readonly pipeline: GPUComputePipeline;
   private readonly uniforms: GPUBuffer;
   private readonly uniformValues = new Float32Array(EraserAgentPipeline.UNIFORM_COUNT);
+  private readonly uniformUintValues = new Uint32Array(this.uniformValues.buffer);
   private readonly uniformCache = createCachedFloat32BufferWrite(
     EraserAgentPipeline.UNIFORM_COUNT
   );
@@ -93,7 +94,7 @@ export class EraserAgentPipeline {
     this.activeSegmentCount = this.pendingSegmentCount;
     this.pendingSegmentCount = 0;
 
-    this.uniformValues[0] = agentCount;
+    this.uniformUintValues[0] = Math.max(0, Math.floor(agentCount));
     this.uniformValues[1] = eraserMaskAlphaThreshold;
     this.uniformValues[2] = 0;
     this.uniformValues[3] = 0;

src/pipelines/eraser/eraser-agent.wgsl

@@ -1,5 +1,5 @@
 struct Settings {
-  agentCount: f32,
+  agentCount: u32,
   eraserMaskAlphaThreshold: f32,
   padding1: f32,
   padding2: f32,
@@ -15,7 +15,7 @@ fn main(
 ) {
   let id = get_id(global_id, num_workgroups);
 
-  if id >= u32(settings.agentCount) {
+  if id >= settings.agentCount {
     return;
   }
 
@@ -32,7 +32,7 @@ fn main(
   );
   let maskSample = textureLoad(eraserMask, maskPosition, 0);
 
-  if maskSample.a < settings.eraserMaskAlphaThreshold {
+  if maskSample.r < settings.eraserMaskAlphaThreshold {
     agents[id].colorIndex = -1.0;
   }
 }

src/pipelines/eraser/eraser-texture-pipeline.ts

@@ -64,7 +64,12 @@ export class EraserTexturePipeline {
     });
 
     const shaderModule = smartCompile(device, CommonState.shaderCode, shader);
-    this.combinedPipeline = this.createPipeline(shaderModule, 'fragmentCombined', 4);
+    this.combinedPipeline = this.createPipeline(shaderModule, 'fragmentCombined', [
+      'r8unorm',
+      'rgba16float',
+      'rgba16float',
+      'rgba16float',
+    ]);
 
     this.uniforms = this.device.createBuffer({
       size: EraserTexturePipeline.UNIFORM_COUNT * Float32Array.BYTES_PER_ELEMENT,
@@ -119,7 +124,7 @@ export class EraserTexturePipeline {
     this.uniformValues[3] = eraserClearGreen;
     this.uniformValues[4] = eraserClearBlue;
     this.uniformValues[5] = eraserClearAlpha;
-    this.uniformValues[6] = 0;
+    this.uniformValues[6] = eraserRadius;
     this.uniformValues[7] = 0;
     writeFloat32BufferIfChanged(
       this.device,
@@ -225,7 +230,7 @@ export class EraserTexturePipeline {
   private createPipeline(
     shaderModule: GPUShaderModule,
     fragmentEntryPoint: string,
-    colorTargetCount: number
+    targetFormats: Array<GPUTextureFormat>
   ): GPURenderPipeline {
     return this.device.createRenderPipeline({
       layout: this.device.createPipelineLayout({
@@ -258,9 +263,7 @@ export class EraserTexturePipeline {
       fragment: {
         module: shaderModule,
         entryPoint: fragmentEntryPoint,
-        targets: Array.from({ length: colorTargetCount }, () => ({
-          format: 'rgba16float' as const,
-        })),
+        targets: targetFormats.map((format) => ({ format })),
       },
       primitive: {
         topology: 'triangle-list',

src/pipelines/eraser/eraser-texture.wgsl

@@ -5,7 +5,7 @@ struct Settings {
   clearGreen: f32,
   clearBlue: f32,
   clearAlpha: f32,
-  padding0: f32,
+  eraserRadius: f32,
   padding1: f32,
 };
 
@@ -15,7 +15,8 @@ struct VertexOutput {
   @builtin(position) position: vec4<f32>,
   @location(0) screenPosition: vec2<f32>,
   @location(1) @interpolate(flat) start: vec2<f32>,
-  @location(2) @interpolate(flat) end: vec2<f32>
+  @location(2) @interpolate(flat) direction: vec2<f32>,
+  @location(3) @interpolate(flat) inverseLengthSquared: f32,
 }
 
 struct EraserTextureTargets {
@@ -37,19 +38,26 @@ fn vertex(
   @location(0) start: vec2<f32>,
   @location(1) end: vec2<f32>
 ) -> VertexOutput {
-  let screenPosition = segment_vertex_position(vertexIndex, start, end, sqrt(settings.eraserRadiusSquared));
+  let direction = end - start;
+  let denominator = dot(direction, direction);
+  var inverseLengthSquared = 0.0;
+  if denominator > settings.lineDistanceEpsilon {
+    inverseLengthSquared = 1.0 / denominator;
+  }
+  let screenPosition = segment_vertex_position(vertexIndex, start, end, settings.eraserRadius);
   let uv = screenPosition / state.size;
   let position = vec2(uv.x * 2.0 - 1.0, 1.0 - uv.y * 2.0);
-  return VertexOutput(vec4(position, 0.0, 1.0), screenPosition, start, end);
+  return VertexOutput(vec4(position, 0.0, 1.0), screenPosition, start, direction, inverseLengthSquared);
 }
 
 @fragment
 fn fragment(
   @location(0) screenPosition: vec2<f32>,
   @location(1) @interpolate(flat) start: vec2<f32>,
-  @location(2) @interpolate(flat) end: vec2<f32>
+  @location(2) @interpolate(flat) direction: vec2<f32>,
+  @location(3) @interpolate(flat) inverseLengthSquared: f32
 ) -> @location(0) vec4<f32> {
-  if shouldDiscardEraserFragment(screenPosition, start, end) {
+  if shouldDiscardEraserFragment(screenPosition, start, direction, inverseLengthSquared) {
     discard;
   }
 
@@ -60,9 +68,10 @@ fn fragment(
 fn fragmentMrt(
   @location(0) screenPosition: vec2<f32>,
   @location(1) @interpolate(flat) start: vec2<f32>,
-  @location(2) @interpolate(flat) end: vec2<f32>
+  @location(2) @interpolate(flat) direction: vec2<f32>,
+  @location(3) @interpolate(flat) inverseLengthSquared: f32
 ) -> EraserTextureTargets {
-  if shouldDiscardEraserFragment(screenPosition, start, end) {
+  if shouldDiscardEraserFragment(screenPosition, start, direction, inverseLengthSquared) {
     discard;
   }
 
@@ -74,14 +83,19 @@ fn fragmentMrt(
 fn fragmentCombined(
   @location(0) screenPosition: vec2<f32>,
   @location(1) @interpolate(flat) start: vec2<f32>,
-  @location(2) @interpolate(flat) end: vec2<f32>
+  @location(2) @interpolate(flat) direction: vec2<f32>,
+  @location(3) @interpolate(flat) inverseLengthSquared: f32
 ) -> EraserCombinedTargets {
-  if shouldDiscardEraserFragment(screenPosition, start, end) {
+  if shouldDiscardEraserFragment(screenPosition, start, direction, inverseLengthSquared) {
     discard;
   }
 
   let cleared = getEraserClearValue();
-  return EraserCombinedTargets(cleared, cleared, cleared, cleared);
+  return EraserCombinedTargets(getEraserMaskValue(), cleared, cleared, cleared);
+}
+
+fn getEraserMaskValue() -> vec4<f32> {
+  return vec4<f32>(settings.clearAlpha, 0.0, 0.0, 1.0);
 }
 
 fn getEraserClearValue() -> vec4<f32> {
@@ -96,21 +110,25 @@ fn getEraserClearValue() -> vec4<f32> {
 fn shouldDiscardEraserFragment(
   screenPosition: vec2<f32>,
   start: vec2<f32>,
-  end: vec2<f32>
+  direction: vec2<f32>,
+  inverseLengthSquared: f32
 ) -> bool {
-  return distanceSquaredFromLine(screenPosition, start, end) > settings.eraserRadiusSquared;
+  return distanceSquaredFromLine(screenPosition, start, direction, inverseLengthSquared) > settings.eraserRadiusSquared;
 }
 
-fn distanceSquaredFromLine(position: vec2<f32>, start: vec2<f32>, end: vec2<f32>) -> f32 {
+fn distanceSquaredFromLine(
+  position: vec2<f32>,
+  start: vec2<f32>,
+  direction: vec2<f32>,
+  inverseLengthSquared: f32
+) -> f32 {
   let pa = position - start;
-  let direction = end - start;
-  let denominator = dot(direction, direction);
 
-  if denominator <= settings.lineDistanceEpsilon {
+  if inverseLengthSquared <= 0.0 {
     return dot(pa, pa);
   }
 
-  let q = clamp(dot(pa, direction) / denominator, 0.0, 1.0);
+  let q = clamp(dot(pa, direction) * inverseLengthSquared, 0.0, 1.0);
   let nearestOffset = pa - direction * q;
   return dot(nearestOffset, nearestOffset);
 }