rangefit.cc (5058B)
1 /* ----------------------------------------------------------------------------- 2 3 Copyright (c) 2006 Simon Brown si@sjbrown.co.uk 4 5 Permission is hereby granted, free of charge, to any person obtaining 6 a copy of this software and associated documentation files (the 7 "Software"), to deal in the Software without restriction, including 8 without limitation the rights to use, copy, modify, merge, publish, 9 distribute, sublicense, and/or sell copies of the Software, and to 10 permit persons to whom the Software is furnished to do so, subject to 11 the following conditions: 12 13 The above copyright notice and this permission notice shall be included 14 in all copies or substantial portions of the Software. 15 16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 17 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 23 24 -------------------------------------------------------------------------- */ 25 26 #include "rangefit.h" 27 #include "colourset.h" 28 #include "colourblock.h" 29 #include <cfloat> 30 31 namespace squish { 32 33 RangeFit::RangeFit( ColourSet const* colours, int flags, float* metric ) 34 : ColourFit( colours, flags ) 35 { 36 // initialise the metric (old perceptual = 0.2126f, 0.7152f, 0.0722f) 37 if( metric ) 38 m_metric = Vec3( metric[0], metric[1], metric[2] ); 39 else 40 m_metric = Vec3( 1.0f ); 41 42 // initialise the best error 43 m_besterror = FLT_MAX; 44 45 // cache some values 46 int const count = m_colours->GetCount(); 47 Vec3 const* values = m_colours->GetPoints(); 48 float const* weights = m_colours->GetWeights(); 49 50 // get the covariance matrix 51 Sym3x3 covariance = ComputeWeightedCovariance( count, values, weights ); 52 53 // compute the principle component 54 Vec3 principle = ComputePrincipleComponent( covariance ); 55 56 // get the min and max range as the codebook endpoints 57 Vec3 start( 0.0f ); 58 Vec3 end( 0.0f ); 59 if( count > 0 ) 60 { 61 float min, max; 62 63 // compute the range 64 start = end = values[0]; 65 min = max = Dot( values[0], principle ); 66 for( int i = 1; i < count; ++i ) 67 { 68 float val = Dot( values[i], principle ); 69 if( val < min ) 70 { 71 start = values[i]; 72 min = val; 73 } 74 else if( val > max ) 75 { 76 end = values[i]; 77 max = val; 78 } 79 } 80 } 81 82 // clamp the output to [0, 1] 83 Vec3 const one( 1.0f ); 84 Vec3 const zero( 0.0f ); 85 start = Min( one, Max( zero, start ) ); 86 end = Min( one, Max( zero, end ) ); 87 88 // clamp to the grid and save 89 Vec3 const grid( 31.0f, 63.0f, 31.0f ); 90 Vec3 const gridrcp( 1.0f/31.0f, 1.0f/63.0f, 1.0f/31.0f ); 91 Vec3 const half( 0.5f ); 92 m_start = Truncate( grid*start + half )*gridrcp; 93 m_end = Truncate( grid*end + half )*gridrcp; 94 } 95 96 void RangeFit::Compress3( void* block ) 97 { 98 // cache some values 99 int const count = m_colours->GetCount(); 100 Vec3 const* values = m_colours->GetPoints(); 101 102 // create a codebook 103 Vec3 codes[3]; 104 codes[0] = m_start; 105 codes[1] = m_end; 106 codes[2] = 0.5f*m_start + 0.5f*m_end; 107 108 // match each point to the closest code 109 u8 closest[16]; 110 float error = 0.0f; 111 for( int i = 0; i < count; ++i ) 112 { 113 // find the closest code 114 float dist = FLT_MAX; 115 int idx = 0; 116 for( int j = 0; j < 3; ++j ) 117 { 118 float d = LengthSquared( m_metric*( values[i] - codes[j] ) ); 119 if( d < dist ) 120 { 121 dist = d; 122 idx = j; 123 } 124 } 125 126 // save the index 127 closest[i] = ( u8 )idx; 128 129 // accumulate the error 130 error += dist; 131 } 132 133 // save this scheme if it wins 134 if( error < m_besterror ) 135 { 136 // remap the indices 137 u8 indices[16]; 138 m_colours->RemapIndices( closest, indices ); 139 140 // save the block 141 WriteColourBlock3( m_start, m_end, indices, block ); 142 143 // save the error 144 m_besterror = error; 145 } 146 } 147 148 void RangeFit::Compress4( void* block ) 149 { 150 // cache some values 151 int const count = m_colours->GetCount(); 152 Vec3 const* values = m_colours->GetPoints(); 153 154 // create a codebook 155 Vec3 codes[4]; 156 codes[0] = m_start; 157 codes[1] = m_end; 158 codes[2] = ( 2.0f/3.0f )*m_start + ( 1.0f/3.0f )*m_end; 159 codes[3] = ( 1.0f/3.0f )*m_start + ( 2.0f/3.0f )*m_end; 160 161 // match each point to the closest code 162 u8 closest[16]; 163 float error = 0.0f; 164 for( int i = 0; i < count; ++i ) 165 { 166 // find the closest code 167 float dist = FLT_MAX; 168 int idx = 0; 169 for( int j = 0; j < 4; ++j ) 170 { 171 float d = LengthSquared( m_metric*( values[i] - codes[j] ) ); 172 if( d < dist ) 173 { 174 dist = d; 175 idx = j; 176 } 177 } 178 179 // save the index 180 closest[i] = ( u8 )idx; 181 182 // accumulate the error 183 error += dist; 184 } 185 186 // save this scheme if it wins 187 if( error < m_besterror ) 188 { 189 // remap the indices 190 u8 indices[16]; 191 m_colours->RemapIndices( closest, indices ); 192 193 // save the block 194 WriteColourBlock4( m_start, m_end, indices, block ); 195 196 // save the error 197 m_besterror = error; 198 } 199 } 200 201 } // namespace squish