Compute Boids: Sprite shader uses color

src/sample/computeBoids/sprite.wgsl

@@ -1,18 +1,35 @@
+struct VertexOutput {
+  @builtin(position) position : vec4<f32>,
+  @location(4) color : vec4<f32>,
+}
+
 @vertex
 fn vert_main(
   @location(0) a_particlePos : vec2<f32>,
   @location(1) a_particleVel : vec2<f32>,
   @location(2) a_pos : vec2<f32>
-) -> @builtin(position) vec4<f32> {
+) -> VertexOutput {
   let angle = -atan2(a_particleVel.x, a_particleVel.y);
   let pos = vec2(
     (a_pos.x * cos(angle)) - (a_pos.y * sin(angle)),
     (a_pos.x * sin(angle)) + (a_pos.y * cos(angle))
   );
-  return vec4(pos + a_particlePos, 0.0, 1.0);
+
+  var output : VertexOutput;
+  output.position = vec4(pos + a_particlePos, 0.0, 1.0);
+  output.color = vec4(
+    1.0 - sin(angle + 1.0) - a_particleVel.y,
+    pos.x * 100.0 - a_particleVel.y + 0.1,
+    a_particleVel.x + cos(angle + 0.5),
+    1.0);
+  return output;
 }
 
-@fragment
-fn frag_main() -> @location(0) vec4<f32> {
-  return vec4(1.0, 1.0, 1.0, 1.0);
+struct FragmentInput {
+  @location(4) color : vec3<f32>,
 }
+
+@fragment
+fn frag_main(@location(4) color : vec4<f32>) -> @location(0) vec4<f32> {
+  return color;
+}