/* ----------------------------------------------------------------------------- Copyright (c) 2006 Simon Brown si@sjbrown.co.uk Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. -------------------------------------------------------------------------- */ #include "rangefit.h" #include "colourset.h" #include "colourblock.h" #include <cfloat> namespace squish { RangeFit::RangeFit( ColourSet const* colours, int flags, float* metric ) : ColourFit( colours, flags ) { // initialise the metric (old perceptual = 0.2126f, 0.7152f, 0.0722f) if( metric ) m_metric = Vec3( metric[0], metric[1], metric[2] ); else m_metric = Vec3( 1.0f ); // initialise the best error m_besterror = FLT_MAX; // cache some values int const count = m_colours->GetCount(); Vec3 const* values = m_colours->GetPoints(); float const* weights = m_colours->GetWeights(); // get the covariance matrix Sym3x3 covariance = ComputeWeightedCovariance( count, values, weights ); // compute the principle component Vec3 principle = ComputePrincipleComponent( covariance ); // get the min and max range as the codebook endpoints Vec3 start( 0.0f ); Vec3 end( 0.0f ); if( count > 0 ) { float min, max; // compute the range start = end = values[0]; min = max = Dot( values[0], principle ); for( int i = 1; i < count; ++i ) { float val = Dot( values[i], principle ); if( val < min ) { start = values[i]; min = val; } else if( val > max ) { end = values[i]; max = val; } } } // clamp the output to [0, 1] Vec3 const one( 1.0f ); Vec3 const zero( 0.0f ); start = Min( one, Max( zero, start ) ); end = Min( one, Max( zero, end ) ); // clamp to the grid and save Vec3 const grid( 31.0f, 63.0f, 31.0f ); Vec3 const gridrcp( 1.0f/31.0f, 1.0f/63.0f, 1.0f/31.0f ); Vec3 const half( 0.5f ); m_start = Truncate( grid*start + half )*gridrcp; m_end = Truncate( grid*end + half )*gridrcp; } void RangeFit::Compress3( void* block ) { // cache some values int const count = m_colours->GetCount(); Vec3 const* values = m_colours->GetPoints(); // create a codebook Vec3 codes[3]; codes[0] = m_start; codes[1] = m_end; codes[2] = 0.5f*m_start + 0.5f*m_end; // match each point to the closest code u8 closest[16]; float error = 0.0f; for( int i = 0; i < count; ++i ) { // find the closest code float dist = FLT_MAX; int idx = 0; for( int j = 0; j < 3; ++j ) { float d = LengthSquared( m_metric*( values[i] - codes[j] ) ); if( d < dist ) { dist = d; idx = j; } } // save the index closest[i] = ( u8 )idx; // accumulate the error error += dist; } // save this scheme if it wins if( error < m_besterror ) { // remap the indices u8 indices[16]; m_colours->RemapIndices( closest, indices ); // save the block WriteColourBlock3( m_start, m_end, indices, block ); // save the error m_besterror = error; } } void RangeFit::Compress4( void* block ) { // cache some values int const count = m_colours->GetCount(); Vec3 const* values = m_colours->GetPoints(); // create a codebook Vec3 codes[4]; codes[0] = m_start; codes[1] = m_end; codes[2] = ( 2.0f/3.0f )*m_start + ( 1.0f/3.0f )*m_end; codes[3] = ( 1.0f/3.0f )*m_start + ( 2.0f/3.0f )*m_end; // match each point to the closest code u8 closest[16]; float error = 0.0f; for( int i = 0; i < count; ++i ) { // find the closest code float dist = FLT_MAX; int idx = 0; for( int j = 0; j < 4; ++j ) { float d = LengthSquared( m_metric*( values[i] - codes[j] ) ); if( d < dist ) { dist = d; idx = j; } } // save the index closest[i] = ( u8 )idx; // accumulate the error error += dist; } // save this scheme if it wins if( error < m_besterror ) { // remap the indices u8 indices[16]; m_colours->RemapIndices( closest, indices ); // save the block WriteColourBlock4( m_start, m_end, indices, block ); // save the error m_besterror = error; } } } // namespace squish