mirror of
https://github.com/maxartz15/VolumetricLighting.git
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43 lines
1.5 KiB
Plaintext
43 lines
1.5 KiB
Plaintext
// Based on 'Volumetric fog: Unified, compute shader based solution to atmospheric scattering, ACM Siggraph 2014'
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// https://bartwronski.com/publications/
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#pragma kernel CSMain
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#define VOLUME_DEPTH 128.0
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Texture3D _VolumeInject;
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RWTexture3D<float4> _VolumeScatter;
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float4 ScatterStep(float3 accumulatedLight, float accumulatedTransmittance, float3 sliceLight, float sliceDensity)
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{
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sliceDensity = max(sliceDensity, 0.000001);
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float sliceTransmittance = exp(-sliceDensity / VOLUME_DEPTH);
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// Seb Hillaire's improved transmission by calculating an integral over slice depth instead of
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// constant per slice value. Light still constant per slice, but that's acceptable. See slide 28 of
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// Physically-based & Unified Volumetric Rendering in Frostbite
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// http://www.frostbite.com/2015/08/physically-based-unified-volumetric-rendering-in-frostbite/
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float3 sliceLightIntegral = sliceLight * (1.0 - sliceTransmittance) / sliceDensity;
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accumulatedLight += sliceLightIntegral * accumulatedTransmittance;
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accumulatedTransmittance *= sliceTransmittance;
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return float4(accumulatedLight, accumulatedTransmittance);
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}
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[numthreads(32, 2, 1)]
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void CSMain (uint3 id : SV_DispatchThreadID)
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{
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// Store transmission in .a, as opposed to density in _VolumeInject
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float4 accum = float4(0, 0, 0, 1);
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uint3 pos = uint3(id.xy, 0);
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uint steps = VOLUME_DEPTH;
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for(uint z = 0; z < steps; z++)
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{
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pos.z = z;
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float4 slice = _VolumeInject[pos];
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accum = ScatterStep(accum.rgb, accum.a, slice.rgb, slice.a);
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_VolumeScatter[pos] = accum;
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}
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}
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