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
31namespace squish {
32
33RangeFit::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
96void 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
148void 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
202