53 lines
2.3 KiB
HLSL
53 lines
2.3 KiB
HLSL
#ifndef UNIVERSAL_PARALLAX_MAPPING_INCLUDED
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#define UNIVERSAL_PARALLAX_MAPPING_INCLUDED
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// Return view direction in tangent space, make sure tangentWS.w is already multiplied by GetOddNegativeScale()
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half3 GetViewDirectionTangentSpace(half4 tangentWS, half3 normalWS, half3 viewDirWS)
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{
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// must use interpolated tangent, bitangent and normal before they are normalized in the pixel shader.
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half3 unnormalizedNormalWS = normalWS;
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const half renormFactor = 1.0 / length(unnormalizedNormalWS);
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// use bitangent on the fly like in hdrp
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// IMPORTANT! If we ever support Flip on double sided materials ensure bitangent and tangent are NOT flipped.
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half crossSign = (tangentWS.w > 0.0 ? 1.0 : -1.0); // we do not need to multiple GetOddNegativeScale() here, as it is done in vertex shader
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half3 bitang = crossSign * cross(normalWS.xyz, tangentWS.xyz);
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half3 WorldSpaceNormal = renormFactor * normalWS.xyz; // we want a unit length Normal Vector node in shader graph
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// to preserve mikktspace compliance we use same scale renormFactor as was used on the normal.
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// This is explained in section 2.2 in "surface gradient based bump mapping framework"
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half3 WorldSpaceTangent = renormFactor * tangentWS.xyz;
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half3 WorldSpaceBiTangent = renormFactor * bitang;
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half3x3 tangentSpaceTransform = half3x3(WorldSpaceTangent, WorldSpaceBiTangent, WorldSpaceNormal);
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half3 viewDirTS = mul(tangentSpaceTransform, viewDirWS);
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return viewDirTS;
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}
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#ifndef BUILTIN_TARGET_API
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half2 ParallaxOffset1Step(half height, half amplitude, half3 viewDirTS)
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{
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height = height * amplitude - amplitude / 2.0;
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half3 v = normalize(viewDirTS);
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v.z += 0.42;
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return height * (v.xy / v.z);
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}
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#endif
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float2 ParallaxMapping(TEXTURE2D_PARAM(heightMap, sampler_heightMap), half3 viewDirTS, half scale, float2 uv)
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{
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half h = SAMPLE_TEXTURE2D(heightMap, sampler_heightMap, uv).g;
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float2 offset = ParallaxOffset1Step(h, scale, viewDirTS);
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return offset;
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}
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float2 ParallaxMappingChannel(TEXTURE2D_PARAM(heightMap, sampler_heightMap), half3 viewDirTS, half scale, float2 uv, int channel)
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{
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half h = SAMPLE_TEXTURE2D(heightMap, sampler_heightMap, uv)[channel];
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float2 offset = ParallaxOffset1Step(h, scale, viewDirTS);
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return offset;
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}
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#endif // UNIVERSAL_PARALLAX_MAPPING_INCLUDED
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