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 "colourset.h"
27
28namespace squish {
29
30ColourSet::ColourSet( u8 const* rgba, int mask, int flags )
31 : m_count( 0 ),
32 m_transparent( false )
33{
34 // check the compression mode for dxt1
35 bool isDxt1 = ( ( flags & kDxt1 ) != 0 );
36 bool weightByAlpha = ( ( flags & kWeightColourByAlpha ) != 0 );
37
38 // create the minimal set
39 for( int i = 0; i < 16; ++i )
40 {
41 // check this pixel is enabled
42 int bit = 1 << i;
43 if( ( mask & bit ) == 0 )
44 {
45 m_remap[i] = -1;
46 continue;
47 }
48
49 // check for transparent pixels when using dxt1
50 if( isDxt1 && rgba[4*i + 3] < 128 )
51 {
52 m_remap[i] = -1;
53 m_transparent = true;
54 continue;
55 }
56
57 // loop over previous points for a match
58 for( int j = 0;; ++j )
59 {
60 // allocate a new point
61 if( j == i )
62 {
63 // normalise coordinates to [0,1]
64 float x = ( float )rgba[4*i] / 255.0f;
65 float y = ( float )rgba[4*i + 1] / 255.0f;
66 float z = ( float )rgba[4*i + 2] / 255.0f;
67
68 // ensure there is always non-zero weight even for zero alpha
69 float w = ( float )( rgba[4*i + 3] + 1 ) / 256.0f;
70
71 // add the point
72 m_points[m_count] = Vec3( x, y, z );
73 m_weights[m_count] = ( weightByAlpha ? w : 1.0f );
74 m_remap[i] = m_count;
75
76 // advance
77 ++m_count;
78 break;
79 }
80
81 // check for a match
82 int oldbit = 1 << j;
83 bool match = ( ( mask & oldbit ) != 0 )
84 && ( rgba[4*i] == rgba[4*j] )
85 && ( rgba[4*i + 1] == rgba[4*j + 1] )
86 && ( rgba[4*i + 2] == rgba[4*j + 2] )
87 && ( rgba[4*j + 3] >= 128 || !isDxt1 );
88 if( match )
89 {
90 // get the index of the match
91 int index = m_remap[j];
92
93 // ensure there is always non-zero weight even for zero alpha
94 float w = ( float )( rgba[4*i + 3] + 1 ) / 256.0f;
95
96 // map to this point and increase the weight
97 m_weights[index] += ( weightByAlpha ? w : 1.0f );
98 m_remap[i] = index;
99 break;
100 }
101 }
102 }
103
104 // square root the weights
105 for( int i = 0; i < m_count; ++i )
106 m_weights[i] = std::sqrt( m_weights[i] );
107}
108
109void ColourSet::RemapIndices( u8 const* source, u8* target ) const
110{
111 for( int i = 0; i < 16; ++i )
112 {
113 int j = m_remap[i];
114 if( j == -1 )
115 target[i] = 3;
116 else
117 target[i] = source[j];
118 }
119}
120
121} // namespace squish
122