Fix issues

src/pipelines/diffusion/diffuse.wgsl

@@ -1,34 +1,28 @@
-struct VertexOutput {
-  @builtin(position) Position : vec4<f32>,
-  @location(0) fragUV : vec2<f32>,
-}
-
-@vertex
-fn vertex(@builtin(vertex_index) i : u32) -> VertexOutput {
-  var pos = array<vec2<f32>, 4>(
-    vec2(-1.0, 1.0),
-    vec2(-1.0, -1.0),
-    vec2(1.0, 1.0),
-    vec2(1.0, -1.0),
-  );
-
-  var output : VertexOutput;
-  output.Position = vec4<f32>(pos[i], 0.0, 1.0);
-  output.fragUV = output.Position.xy * 0.5 + 0.5;
-  return output;
-}
-
-
-@group(0) @binding(0) var mySampler: sampler;
-@group(0) @binding(1) var TargetTexture : texture_2d<f32>;
+struct Settings {
+  size : vec2<f32>,
+  diffusionRate : f32,
+  decayRate : f32,
+  deltaTime : f32,
+};
 
+@group(0) @binding(0) var<uniform> settings : Settings;
+@group(0) @binding(1) var Sampler: sampler;
+@group(0) @binding(2) var trailMap : texture_2d<f32>;
 
 @fragment
-fn fragment(@location(0) fragUV: vec2<f32>) -> @location(0) vec4<f32> {
-  // return vec4(1.0, 0.0, 0.0, 1.0);
-  return mix(
-    vec4(textureSample(TargetTexture, mySampler, fragUV).rgb, 0.1),
-    vec4(1.0, 1.0, 1.0, 1.0), 
-    0.01
+fn fragment(@location(0) uv: vec2<f32>) -> @location(0) vec4<f32> {
+  let current = textureSample(trailMap, Sampler, uv).rgb;
+
+  let neighbours: vec3<f32> = (
+      textureSample(trailMap, Sampler, uv + vec2<f32>(0, 1) / settings.size).rgb
+    + textureSample(trailMap, Sampler, uv + vec2<f32>(0, -1) / settings.size).rgb
+    + textureSample(trailMap, Sampler, uv + vec2<f32>(-1, 0) / settings.size).rgb
+    + textureSample(trailMap, Sampler, uv + vec2<f32>(1, 0) / settings.size).rgb
   );
+
+  return vec4(mix(
+    current,
+    neighbours / 4.0,
+    settings.diffusionRate
+  ) * (1.0 - settings.decayRate), 1.0);
 }