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244 行
15 KiB
244 行
15 KiB
// ------------------------------------------------------------------
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// PCF Filtering Tent Functions
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// ------------------------------------------------------------------
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// Assuming a isoceles right angled triangle of height "triangleHeight" (as drawn below).
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// This function return the area of the triangle above the first texel.
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//
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// |\ <-- 45 degree slop isosceles right angled triangle
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// | \
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// ---- <-- length of this side is "triangleHeight"
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// _ _ _ _ <-- texels
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real SampleShadow_GetTriangleTexelArea(real triangleHeight)
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{
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return triangleHeight - 0.5;
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}
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// Assuming a isoceles triangle of 1.5 texels height and 3 texels wide lying on 4 texels.
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// This function return the area of the triangle above each of those texels.
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// | <-- offset from -0.5 to 0.5, 0 meaning triangle is exactly in the center
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// / \ <-- 45 degree slop isosceles triangle (ie tent projected in 2D)
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// / \
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// _ _ _ _ <-- texels
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// X Y Z W <-- result indices (in computedArea.xyzw and computedAreaUncut.xyzw)
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void SampleShadow_GetTexelAreas_Tent_3x3(real offset, out real4 computedArea, out real4 computedAreaUncut)
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{
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// Compute the exterior areas
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real offset01SquaredHalved = (offset + 0.5) * (offset + 0.5) * 0.5;
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computedAreaUncut.x = computedArea.x = offset01SquaredHalved - offset;
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computedAreaUncut.w = computedArea.w = offset01SquaredHalved;
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// Compute the middle areas
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// For Y : We find the area in Y of as if the left section of the isoceles triangle would
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// intersect the axis between Y and Z (ie where offset = 0).
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computedAreaUncut.y = SampleShadow_GetTriangleTexelArea(1.5 - offset);
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// This area is superior to the one we are looking for if (offset < 0) thus we need to
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// subtract the area of the triangle defined by (0,1.5-offset), (0,1.5+offset), (-offset,1.5).
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real clampedOffsetLeft = min(offset,0);
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real areaOfSmallLeftTriangle = clampedOffsetLeft * clampedOffsetLeft;
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computedArea.y = computedAreaUncut.y - areaOfSmallLeftTriangle;
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// We do the same for the Z but with the right part of the isoceles triangle
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computedAreaUncut.z = SampleShadow_GetTriangleTexelArea(1.5 + offset);
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real clampedOffsetRight = max(offset,0);
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real areaOfSmallRightTriangle = clampedOffsetRight * clampedOffsetRight;
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computedArea.z = computedAreaUncut.z - areaOfSmallRightTriangle;
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}
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// Assuming a isoceles triangle of 1.5 texels height and 3 texels wide lying on 4 texels.
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// This function return the weight of each texels area relative to the full triangle area.
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void SampleShadow_GetTexelWeights_Tent_3x3(real offset, out real4 computedWeight)
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{
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real4 dummy;
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SampleShadow_GetTexelAreas_Tent_3x3(offset, computedWeight, dummy);
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computedWeight *= 0.44444;//0.44 == 1/(the triangle area)
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}
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// Assuming a isoceles triangle of 2.5 texel height and 5 texels wide lying on 6 texels.
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// This function return the weight of each texels area relative to the full triangle area.
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// / \
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// _ _ _ _ _ _ <-- texels
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// 0 1 2 3 4 5 <-- computed area indices (in texelsWeights[])
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void SampleShadow_GetTexelWeights_Tent_5x5(real offset, out real3 texelsWeightsA, out real3 texelsWeightsB)
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{
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// See _UnityInternalGetAreaPerTexel_3TexelTriangleFilter for details.
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real4 computedArea_From3texelTriangle;
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real4 computedAreaUncut_From3texelTriangle;
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SampleShadow_GetTexelAreas_Tent_3x3(offset, computedArea_From3texelTriangle, computedAreaUncut_From3texelTriangle);
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// Triangle slope is 45 degree thus we can almost reuse the result of the 3 texel wide computation.
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// the 5 texel wide triangle can be seen as the 3 texel wide one but shifted up by one unit/texel.
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// 0.16 is 1/(the triangle area)
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texelsWeightsA.x = 0.16 * (computedArea_From3texelTriangle.x);
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texelsWeightsA.y = 0.16 * (computedAreaUncut_From3texelTriangle.y);
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texelsWeightsA.z = 0.16 * (computedArea_From3texelTriangle.y + 1);
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texelsWeightsB.x = 0.16 * (computedArea_From3texelTriangle.z + 1);
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texelsWeightsB.y = 0.16 * (computedAreaUncut_From3texelTriangle.z);
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texelsWeightsB.z = 0.16 * (computedArea_From3texelTriangle.w);
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}
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// Assuming a isoceles triangle of 3.5 texel height and 7 texels wide lying on 8 texels.
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// This function return the weight of each texels area relative to the full triangle area.
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// / \
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// _ _ _ _ _ _ _ _ <-- texels
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// 0 1 2 3 4 5 6 7 <-- computed area indices (in texelsWeights[])
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void SampleShadow_GetTexelWeights_Tent_7x7(real offset, out real4 texelsWeightsA, out real4 texelsWeightsB)
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{
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// See _UnityInternalGetAreaPerTexel_3TexelTriangleFilter for details.
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real4 computedArea_From3texelTriangle;
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real4 computedAreaUncut_From3texelTriangle;
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SampleShadow_GetTexelAreas_Tent_3x3(offset, computedArea_From3texelTriangle, computedAreaUncut_From3texelTriangle);
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// Triangle slope is 45 degree thus we can almost reuse the result of the 3 texel wide computation.
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// the 7 texel wide triangle can be seen as the 3 texel wide one but shifted up by two unit/texel.
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// 0.081632 is 1/(the triangle area)
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texelsWeightsA.x = 0.081632 * (computedArea_From3texelTriangle.x);
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texelsWeightsA.y = 0.081632 * (computedAreaUncut_From3texelTriangle.y);
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texelsWeightsA.z = 0.081632 * (computedAreaUncut_From3texelTriangle.y + 1);
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texelsWeightsA.w = 0.081632 * (computedArea_From3texelTriangle.y + 2);
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texelsWeightsB.x = 0.081632 * (computedArea_From3texelTriangle.z + 2);
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texelsWeightsB.y = 0.081632 * (computedAreaUncut_From3texelTriangle.z + 1);
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texelsWeightsB.z = 0.081632 * (computedAreaUncut_From3texelTriangle.z);
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texelsWeightsB.w = 0.081632 * (computedArea_From3texelTriangle.w);
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}
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// 3x3 Tent filter (45 degree sloped triangles in U and V)
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void SampleShadow_ComputeSamples_Tent_3x3(real4 shadowMapTexture_TexelSize, real2 coord, out real fetchesWeights[4], out real2 fetchesUV[4])
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{
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// tent base is 3x3 base thus covering from 9 to 12 texels, thus we need 4 bilinear PCF fetches
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real2 tentCenterInTexelSpace = coord.xy * shadowMapTexture_TexelSize.zw;
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real2 centerOfFetchesInTexelSpace = floor(tentCenterInTexelSpace + 0.5);
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real2 offsetFromTentCenterToCenterOfFetches = tentCenterInTexelSpace - centerOfFetchesInTexelSpace;
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// find the weight of each texel based
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real4 texelsWeightsU, texelsWeightsV;
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SampleShadow_GetTexelWeights_Tent_3x3(offsetFromTentCenterToCenterOfFetches.x, texelsWeightsU);
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SampleShadow_GetTexelWeights_Tent_3x3(offsetFromTentCenterToCenterOfFetches.y, texelsWeightsV);
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// each fetch will cover a group of 2x2 texels, the weight of each group is the sum of the weights of the texels
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real2 fetchesWeightsU = texelsWeightsU.xz + texelsWeightsU.yw;
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real2 fetchesWeightsV = texelsWeightsV.xz + texelsWeightsV.yw;
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// move the PCF bilinear fetches to respect texels weights
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real2 fetchesOffsetsU = texelsWeightsU.yw / fetchesWeightsU.xy + real2(-1.5,0.5);
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real2 fetchesOffsetsV = texelsWeightsV.yw / fetchesWeightsV.xy + real2(-1.5,0.5);
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fetchesOffsetsU *= shadowMapTexture_TexelSize.xx;
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fetchesOffsetsV *= shadowMapTexture_TexelSize.yy;
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real2 bilinearFetchOrigin = centerOfFetchesInTexelSpace * shadowMapTexture_TexelSize.xy;
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fetchesUV[0] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.x);
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fetchesUV[1] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.x);
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fetchesUV[2] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.y);
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fetchesUV[3] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.y);
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fetchesWeights[0] = fetchesWeightsU.x * fetchesWeightsV.x;
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fetchesWeights[1] = fetchesWeightsU.y * fetchesWeightsV.x;
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fetchesWeights[2] = fetchesWeightsU.x * fetchesWeightsV.y;
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fetchesWeights[3] = fetchesWeightsU.y * fetchesWeightsV.y;
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}
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// 5x5 Tent filter (45 degree sloped triangles in U and V)
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void SampleShadow_ComputeSamples_Tent_5x5(real4 shadowMapTexture_TexelSize, real2 coord, out real fetchesWeights[9], out real2 fetchesUV[9])
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{
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// tent base is 5x5 base thus covering from 25 to 36 texels, thus we need 9 bilinear PCF fetches
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real2 tentCenterInTexelSpace = coord.xy * shadowMapTexture_TexelSize.zw;
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real2 centerOfFetchesInTexelSpace = floor(tentCenterInTexelSpace + 0.5);
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real2 offsetFromTentCenterToCenterOfFetches = tentCenterInTexelSpace - centerOfFetchesInTexelSpace;
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// find the weight of each texel based on the area of a 45 degree slop tent above each of them.
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real3 texelsWeightsU_A, texelsWeightsU_B;
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real3 texelsWeightsV_A, texelsWeightsV_B;
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SampleShadow_GetTexelWeights_Tent_5x5(offsetFromTentCenterToCenterOfFetches.x, texelsWeightsU_A, texelsWeightsU_B);
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SampleShadow_GetTexelWeights_Tent_5x5(offsetFromTentCenterToCenterOfFetches.y, texelsWeightsV_A, texelsWeightsV_B);
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// each fetch will cover a group of 2x2 texels, the weight of each group is the sum of the weights of the texels
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real3 fetchesWeightsU = real3(texelsWeightsU_A.xz, texelsWeightsU_B.y) + real3(texelsWeightsU_A.y, texelsWeightsU_B.xz);
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real3 fetchesWeightsV = real3(texelsWeightsV_A.xz, texelsWeightsV_B.y) + real3(texelsWeightsV_A.y, texelsWeightsV_B.xz);
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// move the PCF bilinear fetches to respect texels weights
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real3 fetchesOffsetsU = real3(texelsWeightsU_A.y, texelsWeightsU_B.xz) / fetchesWeightsU.xyz + real3(-2.5,-0.5,1.5);
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real3 fetchesOffsetsV = real3(texelsWeightsV_A.y, texelsWeightsV_B.xz) / fetchesWeightsV.xyz + real3(-2.5,-0.5,1.5);
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fetchesOffsetsU *= shadowMapTexture_TexelSize.xxx;
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fetchesOffsetsV *= shadowMapTexture_TexelSize.yyy;
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real2 bilinearFetchOrigin = centerOfFetchesInTexelSpace * shadowMapTexture_TexelSize.xy;
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fetchesUV[0] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.x);
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fetchesUV[1] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.x);
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fetchesUV[2] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.x);
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fetchesUV[3] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.y);
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fetchesUV[4] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.y);
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fetchesUV[5] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.y);
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fetchesUV[6] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.z);
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fetchesUV[7] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.z);
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fetchesUV[8] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.z);
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fetchesWeights[0] = fetchesWeightsU.x * fetchesWeightsV.x;
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fetchesWeights[1] = fetchesWeightsU.y * fetchesWeightsV.x;
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fetchesWeights[2] = fetchesWeightsU.z * fetchesWeightsV.x;
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fetchesWeights[3] = fetchesWeightsU.x * fetchesWeightsV.y;
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fetchesWeights[4] = fetchesWeightsU.y * fetchesWeightsV.y;
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fetchesWeights[5] = fetchesWeightsU.z * fetchesWeightsV.y;
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fetchesWeights[6] = fetchesWeightsU.x * fetchesWeightsV.z;
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fetchesWeights[7] = fetchesWeightsU.y * fetchesWeightsV.z;
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fetchesWeights[8] = fetchesWeightsU.z * fetchesWeightsV.z;
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}
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// 7x7 Tent filter (45 degree sloped triangles in U and V)
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void SampleShadow_ComputeSamples_Tent_7x7(real4 shadowMapTexture_TexelSize, real2 coord, out real fetchesWeights[16], out real2 fetchesUV[16])
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{
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// tent base is 7x7 base thus covering from 49 to 64 texels, thus we need 16 bilinear PCF fetches
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real2 tentCenterInTexelSpace = coord.xy * shadowMapTexture_TexelSize.zw;
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real2 centerOfFetchesInTexelSpace = floor(tentCenterInTexelSpace + 0.5);
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real2 offsetFromTentCenterToCenterOfFetches = tentCenterInTexelSpace - centerOfFetchesInTexelSpace;
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// find the weight of each texel based on the area of a 45 degree slop tent above each of them.
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real4 texelsWeightsU_A, texelsWeightsU_B;
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real4 texelsWeightsV_A, texelsWeightsV_B;
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SampleShadow_GetTexelWeights_Tent_7x7(offsetFromTentCenterToCenterOfFetches.x, texelsWeightsU_A, texelsWeightsU_B);
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SampleShadow_GetTexelWeights_Tent_7x7(offsetFromTentCenterToCenterOfFetches.y, texelsWeightsV_A, texelsWeightsV_B);
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// each fetch will cover a group of 2x2 texels, the weight of each group is the sum of the weights of the texels
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real4 fetchesWeightsU = real4(texelsWeightsU_A.xz, texelsWeightsU_B.xz) + real4(texelsWeightsU_A.yw, texelsWeightsU_B.yw);
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real4 fetchesWeightsV = real4(texelsWeightsV_A.xz, texelsWeightsV_B.xz) + real4(texelsWeightsV_A.yw, texelsWeightsV_B.yw);
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// move the PCF bilinear fetches to respect texels weights
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real4 fetchesOffsetsU = real4(texelsWeightsU_A.yw, texelsWeightsU_B.yw) / fetchesWeightsU.xyzw + real4(-3.5,-1.5,0.5,2.5);
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real4 fetchesOffsetsV = real4(texelsWeightsV_A.yw, texelsWeightsV_B.yw) / fetchesWeightsV.xyzw + real4(-3.5,-1.5,0.5,2.5);
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fetchesOffsetsU *= shadowMapTexture_TexelSize.xxxx;
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fetchesOffsetsV *= shadowMapTexture_TexelSize.yyyy;
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real2 bilinearFetchOrigin = centerOfFetchesInTexelSpace * shadowMapTexture_TexelSize.xy;
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fetchesUV[0] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.x);
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fetchesUV[1] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.x);
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fetchesUV[2] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.x);
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fetchesUV[3] = bilinearFetchOrigin + real2(fetchesOffsetsU.w, fetchesOffsetsV.x);
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fetchesUV[4] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.y);
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fetchesUV[5] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.y);
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fetchesUV[6] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.y);
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fetchesUV[7] = bilinearFetchOrigin + real2(fetchesOffsetsU.w, fetchesOffsetsV.y);
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fetchesUV[8] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.z);
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fetchesUV[9] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.z);
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fetchesUV[10] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.z);
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fetchesUV[11] = bilinearFetchOrigin + real2(fetchesOffsetsU.w, fetchesOffsetsV.z);
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fetchesUV[12] = bilinearFetchOrigin + real2(fetchesOffsetsU.x, fetchesOffsetsV.w);
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fetchesUV[13] = bilinearFetchOrigin + real2(fetchesOffsetsU.y, fetchesOffsetsV.w);
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fetchesUV[14] = bilinearFetchOrigin + real2(fetchesOffsetsU.z, fetchesOffsetsV.w);
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fetchesUV[15] = bilinearFetchOrigin + real2(fetchesOffsetsU.w, fetchesOffsetsV.w);
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fetchesWeights[0] = fetchesWeightsU.x * fetchesWeightsV.x;
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fetchesWeights[1] = fetchesWeightsU.y * fetchesWeightsV.x;
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fetchesWeights[2] = fetchesWeightsU.z * fetchesWeightsV.x;
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fetchesWeights[3] = fetchesWeightsU.w * fetchesWeightsV.x;
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fetchesWeights[4] = fetchesWeightsU.x * fetchesWeightsV.y;
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fetchesWeights[5] = fetchesWeightsU.y * fetchesWeightsV.y;
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fetchesWeights[6] = fetchesWeightsU.z * fetchesWeightsV.y;
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fetchesWeights[7] = fetchesWeightsU.w * fetchesWeightsV.y;
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fetchesWeights[8] = fetchesWeightsU.x * fetchesWeightsV.z;
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fetchesWeights[9] = fetchesWeightsU.y * fetchesWeightsV.z;
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fetchesWeights[10] = fetchesWeightsU.z * fetchesWeightsV.z;
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fetchesWeights[11] = fetchesWeightsU.w * fetchesWeightsV.z;
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fetchesWeights[12] = fetchesWeightsU.x * fetchesWeightsV.w;
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fetchesWeights[13] = fetchesWeightsU.y * fetchesWeightsV.w;
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fetchesWeights[14] = fetchesWeightsU.z * fetchesWeightsV.w;
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fetchesWeights[15] = fetchesWeightsU.w * fetchesWeightsV.w;
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}
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