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91 行
2.7 KiB
91 行
2.7 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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#ifdef LEFT_HAND_COORDINATES
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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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#ifdef LEFT_HAND_COORDINATES
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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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