,

src/pipelines/eraser/eraser-agent.wgsl

@@ -1,14 +1,12 @@
 struct Settings {
-  eraserRadius: f32,
-  segmentCount: f32,
   agentCount: f32,
-  eraserRadiusSquared: f32,
+  padding0: f32,
+  padding1: f32,
+  padding2: f32,
 };
 
-const MAX_SEGMENT_COUNT = 384u;
-
 @group(1) @binding(0) var<uniform> settings: Settings;
-@group(1) @binding(2) var<storage, read> segments: array<vec4<f32>>;
+@group(1) @binding(2) var eraserMask: texture_2d<f32>;
 
 @compute @workgroup_size(64)
 fn main(
@@ -26,38 +24,16 @@ fn main(
     return;
   }
 
-  for (var i = 0u; i < MAX_SEGMENT_COUNT; i++) {
-    if i >= u32(settings.segmentCount) {
-      break;
-    }
+  let maskSize = vec2<i32>(textureDimensions(eraserMask));
+  let maskPosition = clamp(
+    vec2<i32>(agent.position),
+    vec2<i32>(0, 0),
+    maskSize - vec2<i32>(1, 1)
+  );
+  let maskSample = textureLoad(eraserMask, maskPosition, 0);
 
-    let segment = segments[i];
-    let distanceSquared = distanceSquaredFromLine(
-      agent.position,
-      segment.xy,
-      segment.zw
-    );
-
-    if distanceSquared <= settings.eraserRadiusSquared {
-      agent.position = vec2<f32>(-1.0, -1.0);
-      agent.targetPosition = vec2<f32>(-1.0, -1.0);
-      agent.colorIndex = -1.0;
-      agents[id] = agent;
-      return;
-    }
+  if maskSample.a < 0.5 {
+    agent.colorIndex = -1.0;
+    agents[id] = agent;
   }
 }
-
-fn distanceSquaredFromLine(position: vec2<f32>, start: vec2<f32>, end: vec2<f32>) -> f32 {
-  let pa = position - start;
-  let direction = end - start;
-  let denominator = dot(direction, direction);
-
-  if denominator <= 0.0001 {
-    return dot(pa, pa);
-  }
-
-  let q = clamp(dot(pa, direction) / denominator, 0.0, 1.0);
-  let nearestOffset = pa - direction * q;
-  return dot(nearestOffset, nearestOffset);
-}