Question by OliverJackman · Aug 05, 2019 at 12:38 AM · shadows shader programming shaderlab

Is it possible to get shadows of each light in seperate channel ?

Hi , I'm looking for a way to get shadows of each light in the scene in separate channel in shader.

I toke a look in Lighting.cgisnc and AutoLight.cginc & UnityShadowLibrary.cgincand I think it's possible.

I need to mask a texture by shadows of different lights for example :

Masking Texture2D A with Point Light A Shadow
And Masking Texture2D B with Spot Light B Shadow

I saw shadows are generation to texture in UnityShadowLibrary or maybe I be wrong , I don't have good knowledge of shader writing.

But I understood a part of Shadow Mask Technique which I believe do the same thing , it will get each light shadow ( Up to 4 in RGBA ) and mix it with baked shadows in texture.

  if defined (SHADOWS_SHADOWMASK)
             #if defined(LIGHTMAP_ON)
                 fixed4 rawOcclusionMask = UNITY_SAMPLE_TEX2D(unity_ShadowMask, lightmapUV.xy);
             #else
                 fixed4 rawOcclusionMask = fixed4(1.0, 1.0, 1.0, 1.0);
                 #if UNITY_LIGHT_PROBE_PROXY_VOLUME
                     if (unity_ProbeVolumeParams.x == 1.0)
                         rawOcclusionMask = LPPV_SampleProbeOcclusion(worldPos);
                     else
                         rawOcclusionMask = UNITY_SAMPLE_TEX2D(unity_ShadowMask, lightmapUV.xy);
                 #else
                     rawOcclusionMask = UNITY_SAMPLE_TEX2D(unity_ShadowMask, lightmapUV.xy);
                 #endif
             #endif
             return saturate(dot(rawOcclusionMask, unity_OcclusionMaskSelector));
     
         #else

Please tell me is it possible and if yes , How can I reach that ?

Regards, Oliver

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