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 current = b.textures['current_texture'];
  final history = b.textures['history_texture'];
  final velocity = b.textures['velocity_texture'];
  if (current == null || history == null || velocity == null) {
    return Vector4(1.0, 1.0, 1.0, 1.0);
  }
  final params = b.vec4('AccumulateInfo', 'params', Vector4.zero());
  final now = current.sample(v[0], v[1]);
  final motion = velocity.sample(v[0], v[1]);
  final thenU = v[0] - motion.x;
  final thenW = v[1] - motion.y;
  if (params.y < 0.5 ||
      thenU < 0.0 ||
      thenU > 1.0 ||
      thenW < 0.0 ||
      thenW > 1.0) {
    return now;
  }

  final lowest = now.clone();
  final highest = now.clone();
  for (var dy = -1; dy <= 1; dy++) {
    for (var dx = -1; dx <= 1; dx++) {
      final around = current.sample(
        v[0] + dx * params.z,
        v[1] + dy * params.w,
      );
      Vector4.min(lowest, around, lowest);
      Vector4.max(highest, around, highest);
    }
  }
  final past = history.sample(thenU, thenW);
  final clamped = Vector4(
    past.x.clamp(lowest.x, highest.x),
    past.y.clamp(lowest.y, highest.y),
    past.z.clamp(lowest.z, highest.z),
    past.w.clamp(lowest.w, highest.w),
  );
  return now + (clamped - now) * params.x;
}