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90 行
2.9 KiB
90 行
2.9 KiB
#ifndef __CLUSTEREDUTILS_H__
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#define __CLUSTEREDUTILS_H__
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#ifndef FLT_EPSILON
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#define FLT_EPSILON 1.192092896e-07f
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#endif
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float GetScaleFromBase(float base)
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{
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const float C = (float)(1 << g_iLog2NumClusters);
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const float geomSeries = (1.0 - pow(base, C)) / (1 - base); // geometric series: sum_k=0^{C-1} base^k
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return geomSeries / (g_fFarPlane - g_fNearPlane);
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}
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int SnapToClusterIdxFlex(float z_in, float suggestedBase, bool logBasePerTile)
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{
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#if USE_LEFTHAND_CAMERASPACE
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float z = z_in;
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#else
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float z = -z_in;
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#endif
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float userscale = g_fClustScale;
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if (logBasePerTile)
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userscale = GetScaleFromBase(suggestedBase);
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// using the inverse of the geometric series
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const float dist = max(0, z - g_fNearPlane);
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return (int)clamp(log2(dist * userscale * (suggestedBase - 1.0f) + 1) / log2(suggestedBase), 0.0, (float)((1 << g_iLog2NumClusters) - 1));
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}
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int SnapToClusterIdx(float z_in, float suggestedBase)
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{
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#ifdef ENABLE_DEPTH_TEXTURE_BACKPLANE
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bool logBasePerTile = true; // resolved compile time
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#else
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bool logBasePerTile = false;
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#endif
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return SnapToClusterIdxFlex(z_in, suggestedBase, logBasePerTile);
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}
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float ClusterIdxToZFlex(int k, float suggestedBase, bool logBasePerTile)
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{
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float res;
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float userscale = g_fClustScale;
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if (logBasePerTile)
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userscale = GetScaleFromBase(suggestedBase);
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float dist = (pow(suggestedBase, (float)k) - 1.0) / (userscale * (suggestedBase - 1.0f));
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res = dist + g_fNearPlane;
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#if USE_LEFTHAND_CAMERASPACE
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return res;
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#else
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return -res;
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#endif
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}
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float ClusterIdxToZ(int k, float suggestedBase)
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{
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#ifdef ENABLE_DEPTH_TEXTURE_BACKPLANE
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bool logBasePerTile = true; // resolved compile time
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#else
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bool logBasePerTile = false;
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#endif
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return ClusterIdxToZFlex(k, suggestedBase, logBasePerTile);
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}
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// generate a log-base value such that half of the clusters are consumed from near plane to max. opaque depth of tile.
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float SuggestLogBase50(float tileFarPlane)
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{
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const float C = (float)(1 << g_iLog2NumClusters);
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float normDist = clamp((tileFarPlane - g_fNearPlane) / (g_fFarPlane - g_fNearPlane), FLT_EPSILON, 1.0);
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float suggested_base = pow((1.0 + sqrt(max(0.0, 1.0 - 4.0 * normDist * (1.0 - normDist)))) / (2.0 * normDist), 2.0 / C); //
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return max(g_fClustBase, suggested_base);
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}
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// generate a log-base value such that (approximately) a quarter of the clusters are consumed from near plane to max. opaque depth of tile.
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float SuggestLogBase25(float tileFarPlane)
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{
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const float C = (float)(1 << g_iLog2NumClusters);
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float normDist = clamp((tileFarPlane - g_fNearPlane) / (g_fFarPlane - g_fNearPlane), FLT_EPSILON, 1.0);
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float suggested_base = pow((1 / 2.3) * max(0.0, (0.8 / normDist) - 1), 4.0 / (C * 2)); // approximate inverse of d*x^4 + (-x) + (1-d) = 0 - d is normalized distance
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return max(g_fClustBase, suggested_base);
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}
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#endif
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