run method

@override Vector4? run(Float32List v, ShaderBindings b, FragmentContext c)

Returns linear RGBA for attachment zero. Null discards the fragment.

Implementation

@override
Vector4? run(Float32List v, ShaderBindings b, FragmentContext c) {
  final accumulation = b.textures['accumulation_texture'];
  final revealage = b.textures['revealage_texture'];
  // Nothing bound covers nothing, which source-over leaves alone.
  if (accumulation == null || revealage == null) return Vector4.zero();
  final sum = accumulation.sample(v[0], v[1]);
  final coverage = 1.0 - revealage.sample(v[0], v[1]).x;
  final weight = sum.w.clamp(1e-5, 65504.0);
  return Vector4(
    math.min(sum.x, 65504.0) / weight * coverage,
    math.min(sum.y, 65504.0) / weight * coverage,
    math.min(sum.z, 65504.0) / weight * coverage,
    coverage,
  );
}