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
FloatToInt(float a,int limit)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
SingleColourFit(ColourSet const * colours,int flags)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
Compress3(void * block)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
Compress4(void * block)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
ComputeEndPoints(SingleColourLookup const * const * lookups)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
173