46 lines
1.8 KiB
Plaintext
46 lines
1.8 KiB
Plaintext
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Texture2D<float> In_BaseMaskTex;
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Texture2D<float> In_HeightTex;
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Texture2D<float> RemapTex;
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RWTexture2D<float> OutputTex;
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float EffectStrength;
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float4 TerrainDimensions;
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int RemapTexRes;
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float4 TextureResolution;
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#define EPSILON TextureResolution.z
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#define TERRAIN_ASPECT_SCALE TextureResolution.w
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#define TWO_OVER_PI 0.6366197723675f
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float3 gradient(uint2 id, uint2 offset) {
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uint upY = max(0, id.y - offset.y);
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uint downY = min((uint)TextureResolution.y, id.y + offset.y);
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uint rightX = max(0, id.x - offset.x);
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uint leftX = min((uint)TextureResolution.x, id.x + offset.x);
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float dzdx = ((In_HeightTex[uint2(rightX, upY)] + 2 * In_HeightTex[uint2(rightX, id.y)] + In_HeightTex[uint2(rightX, downY)]) -
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(In_HeightTex[uint2(leftX, upY)] + 2 * In_HeightTex[uint2(leftX, id.y)] + In_HeightTex[uint2(leftX, downY)])) / 8.0f * TerrainDimensions.y * TextureResolution.x / TerrainDimensions.x;
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float dzdy = ((In_HeightTex[uint2(leftX, downY)] + 2 * In_HeightTex[uint2(id.x, downY)] + In_HeightTex[uint2(rightX, downY)]) -
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(In_HeightTex[uint2(leftX, upY)] + 2 * In_HeightTex[uint2(id.x, upY)] + In_HeightTex[uint2(rightX, upY)])) / 8.0f * TerrainDimensions.y * TextureResolution.x / TerrainDimensions.z;
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float mag = length(float2(dzdx, dzdy)); // "steepness"
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return float3(dzdx / mag, dzdy / mag, mag * TERRAIN_ASPECT_SCALE);
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}
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#pragma kernel GradientMultiply
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[numthreads(1, 1, 1)]
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void GradientMultiply(uint3 id : SV_DispatchThreadID)
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{
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uint2 offset = uint2(EPSILON, EPSILON);
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float3 g = gradient(id.xy, offset);
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float angle = saturate(TWO_OVER_PI * atan2(g.z, EPSILON * TextureResolution.x));
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uint remapIdx = (uint)(angle * (float)(RemapTexRes - 1));
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float remappedGradient = RemapTex[uint2(remapIdx, 0)];
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OutputTex[id.xy] = lerp(1.0f, remappedGradient, EffectStrength) * In_BaseMaskTex[id.xy];
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}
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