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- /* -----------------------------------------------------------------------------
- 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
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