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 * colours,int flags)61 SingleColourFit::SingleColourFit( ColourSet * 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 m_error = INT_MAX;
73 }
74
Compress3(void * block)75 void SingleColourFit::Compress3( void* block )
76 {
77 // build the table of lookups
78 SingleColourLookup const* const lookups[] =
79 {
80 lookup_5_3,
81 lookup_6_3,
82 lookup_5_3
83 };
84
85 // find the best end-points and index
86 ComputeEndPoints( lookups );
87
88 // build the block if we win
89 if( m_error < m_besterror )
90 {
91 // remap the indices
92 u8 indices[16];
93 m_colours->RemapIndices( &m_index, indices );
94
95 // save the block
96 WriteColourBlock3( m_start, m_end, indices, block );
97
98 // save the error
99 m_besterror = m_error;
100 }
101 }
102
Compress4(void * block)103 void SingleColourFit::Compress4( void* block )
104 {
105 // build the table of lookups
106 SingleColourLookup const* const lookups[] =
107 {
108 lookup_5_4,
109 lookup_6_4,
110 lookup_5_4
111 };
112
113 // find the best end-points and index
114 ComputeEndPoints( lookups );
115
116 // build the block if we win
117 if( m_error < m_besterror )
118 {
119 // remap the indices
120 u8 indices[16];
121 m_colours->RemapIndices( &m_index, indices );
122
123 // save the block
124 WriteColourBlock4( m_start, m_end, indices, block );
125
126 // save the error
127 m_besterror = m_error;
128 }
129 }
130
ComputeEndPoints(SingleColourLookup const * const * lookups)131 void SingleColourFit::ComputeEndPoints( SingleColourLookup const* const* lookups )
132 {
133 // check each index combination (endpoint or intermediate)
134 m_error = INT_MAX;
135 for( int index = 0; index < 2; ++index )
136 {
137 // check the error for this codebook index
138 SourceBlock const* sources[3];
139 int error = 0;
140 for( int channel = 0; channel < 3; ++channel )
141 {
142 // grab the lookup table and index for this channel
143 SingleColourLookup const* lookup = lookups[channel];
144 int target = m_colour[channel];
145
146 // store a pointer to the source for this channel
147 sources[channel] = lookup[target].sources + index;
148
149 // accumulate the error
150 int diff = sources[channel]->error;
151 error += diff*diff;
152 }
153
154 // keep it if the error is lower
155 if( error < m_error )
156 {
157 m_start = Vec3(
158 ( float )sources[0]->start/31.0f,
159 ( float )sources[1]->start/63.0f,
160 ( float )sources[2]->start/31.0f
161 );
162 m_end = Vec3(
163 ( float )sources[0]->end/31.0f,
164 ( float )sources[1]->end/63.0f,
165 ( float )sources[2]->end/31.0f
166 );
167 m_index = ( u8 )( 2*index );
168 m_error = error;
169 }
170 }
171 }
172
173 } // namespace squish
174