singlecolourfit.cc (4395B)
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 "singlecolourfit.h" 27 #include "colourset.h" 28 #include "colourblock.h" 29 30 namespace squish { 31 32 struct SourceBlock 33 { 34 u8 start; 35 u8 end; 36 u8 error; 37 }; 38 39 struct SingleColourLookup 40 { 41 SourceBlock sources[2]; 42 }; 43 44 #include "singlecolourlookup.inl" 45 46 static int FloatToInt( float a, int limit ) 47 { 48 // use ANSI round-to-zero behaviour to get round-to-nearest 49 int i = ( int )( a + 0.5f ); 50 51 // clamp to the limit 52 if( i < 0 ) 53 i = 0; 54 else if( i > limit ) 55 i = limit; 56 57 // done 58 return i; 59 } 60 61 SingleColourFit::SingleColourFit( ColourSet const* colours, int flags ) 62 : ColourFit( colours, flags ) 63 { 64 // grab the single colour 65 Vec3 const* values = m_colours->GetPoints(); 66 m_colour[0] = ( u8 )FloatToInt( 255.0f*values->X(), 255 ); 67 m_colour[1] = ( u8 )FloatToInt( 255.0f*values->Y(), 255 ); 68 m_colour[2] = ( u8 )FloatToInt( 255.0f*values->Z(), 255 ); 69 70 // initialise the best error 71 m_besterror = INT_MAX; 72 } 73 74 void SingleColourFit::Compress3( void* block ) 75 { 76 // build the table of lookups 77 SingleColourLookup const* const lookups[] = 78 { 79 lookup_5_3, 80 lookup_6_3, 81 lookup_5_3 82 }; 83 84 // find the best end-points and index 85 ComputeEndPoints( lookups ); 86 87 // build the block if we win 88 if( m_error < m_besterror ) 89 { 90 // remap the indices 91 u8 indices[16]; 92 m_colours->RemapIndices( &m_index, indices ); 93 94 // save the block 95 WriteColourBlock3( m_start, m_end, indices, block ); 96 97 // save the error 98 m_besterror = m_error; 99 } 100 } 101 102 void SingleColourFit::Compress4( void* block ) 103 { 104 // build the table of lookups 105 SingleColourLookup const* const lookups[] = 106 { 107 lookup_5_4, 108 lookup_6_4, 109 lookup_5_4 110 }; 111 112 // find the best end-points and index 113 ComputeEndPoints( lookups ); 114 115 // build the block if we win 116 if( m_error < m_besterror ) 117 { 118 // remap the indices 119 u8 indices[16]; 120 m_colours->RemapIndices( &m_index, indices ); 121 122 // save the block 123 WriteColourBlock4( m_start, m_end, indices, block ); 124 125 // save the error 126 m_besterror = m_error; 127 } 128 } 129 130 void SingleColourFit::ComputeEndPoints( SingleColourLookup const* const* lookups ) 131 { 132 // check each index combination (endpoint or intermediate) 133 m_error = INT_MAX; 134 for( int index = 0; index < 2; ++index ) 135 { 136 // check the error for this codebook index 137 SourceBlock const* sources[3]; 138 int error = 0; 139 for( int channel = 0; channel < 3; ++channel ) 140 { 141 // grab the lookup table and index for this channel 142 SingleColourLookup const* lookup = lookups[channel]; 143 int target = m_colour[channel]; 144 145 // store a pointer to the source for this channel 146 sources[channel] = lookup[target].sources + index; 147 148 // accumulate the error 149 int diff = sources[channel]->error; 150 error += diff*diff; 151 } 152 153 // keep it if the error is lower 154 if( error < m_error ) 155 { 156 m_start = Vec3( 157 ( float )sources[0]->start/31.0f, 158 ( float )sources[1]->start/63.0f, 159 ( float )sources[2]->start/31.0f 160 ); 161 m_end = Vec3( 162 ( float )sources[0]->end/31.0f, 163 ( float )sources[1]->end/63.0f, 164 ( float )sources[2]->end/31.0f 165 ); 166 m_index = ( u8 )( 2*index ); 167 m_error = error; 168 } 169 } 170 } 171 172 } // namespace squish