An example of using the stencil buffer to select specific pixels for processing in post processing effects in Unity.
This projects provides an example of how to discard pixels in a post processing effect using the stencil buffer.
In this example, the following steps are taken in the OnRenderImage event.
Pass #1: Write 0 to the stencil buffer
Pass #2: Write 1 to the stencil buffer if the roughness form the GBuffer is below a certain threashold
Pass #3: Apply an image effect where stencil buffer values are 0
Pass #4: Apply another image effect where stencil buffer values are 1
Thus, in this example, there are two image effetcs (each as a pass) in the shader
fixed4 FragmentMix1(Varyings input) : SV_Target
{
return lerp(tex2D(_MainTex, input.uv), fixed4(input.uv, .5, 1.), .5);
}
and
fixed4 FragmentMix2(Varyings input) : SV_Target
{
return lerp(tex2D(_MainTex, input.uv), 1. - fixed4(input.uv, .5, 1.), .5);
}
FragmentMix1 is applied when the roughness stored in the GBuffer is below a given threshold, and FragmentMix2 is applied otherwise.