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34 lines
1.1 KiB
34 lines
1.1 KiB
#ifndef UNIVERSAL_SPEEDTREE_UTILITY |
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#define UNIVERSAL_SPEEDTREE_UTILITY |
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uint2 ComputeFadeMaskSeed(float3 V, uint2 positionSS) |
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{ |
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uint2 fadeMaskSeed; |
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// Is this a reasonable quality gate? |
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#if defined(SHADER_QUALITY_HIGH) |
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if (IsPerspectiveProjection()) |
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{ |
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// Start with the world-space direction V. It is independent from the orientation of the camera, |
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// and only depends on the position of the camera and the position of the fragment. |
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// Now, project and transform it into [-1, 1]. |
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float2 pv = PackNormalOctQuadEncode(V); |
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// Rescale it to account for the resolution of the screen. |
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pv *= _ScreenParams.xy; |
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// The camera only sees a small portion of the sphere, limited by hFoV and vFoV. |
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// Therefore, we must rescale again (before quantization), roughly, by 1/tan(FoV/2). |
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pv *= UNITY_MATRIX_P._m00_m11; |
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// Truncate and quantize. |
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fadeMaskSeed = asuint((int2)pv); |
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} |
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else |
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#endif |
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{ |
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// Can't use the view direction, it is the same across the entire screen. |
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fadeMaskSeed = positionSS; |
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} |
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return fadeMaskSeed; |
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} |
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#endif
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