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compositeSourceOut: Exclusion Alpha Masking

Source Visibility Outside Destination Boundaries​

The source out composite operation performs exclusion masking where source color appears only in regions outside destination alpha coverage through complement multiplication.

sourceOut=src×(1−αdst)\text{sourceOut} = src \times (1 - \alpha_{dst})
Live Editor
const fragment = () => {
      const center = vec2(0.5, 0.5)
      const dist = uv.distance(center)
      const dstAlpha = smoothstep(0.4, 0.2, dist)
      const srcColor = vec3(0.1, 0.8, 0.6)
      const src = vec4(srcColor, 1)
      const dst = vec4(vec3(0), dstAlpha)
      return compositeSourceOutVec4(src, dst)
}