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 src = bloomSource(b);
  if (src == null) return Vector4(0.0, 0.0, 0.0, 1.0);
  final u = v[0];
  final w = v[1];

  Vector3 at(double dx, double dy) {
    final t = src.source.sample(u + dx * src.tx, w + dy * src.ty);
    return Vector3(t.x, t.y, t.z);
  }

  final a = at(-2, 2), bb = at(0, 2), cc = at(2, 2);
  final d = at(-2, 0), e = at(0, 0), f = at(2, 0);
  final g = at(-2, -2), h = at(0, -2), i = at(2, -2);
  final j = at(-1, 1), k = at(1, 1), l = at(-1, -1), m = at(1, -1);

  // The inner four boxes carry half the weight between them; the five outer
  // ones share the rest.
  final result = (j + k + l + m) * (0.5 * 0.25);
  result.add((a + bb + d + e) * (0.125 * 0.25));
  result.add((bb + cc + e + f) * (0.125 * 0.25));
  result.add((d + e + g + h) * (0.125 * 0.25));
  result.add((e + f + h + i) * (0.125 * 0.25));
  return Vector4(result.x, result.y, result.z, 1.0);
}