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godotengine
GitHub Repository: godotengine/godot
 Path: blob/master/thirdparty/basis_universal/encoder/basisu_pvrtc1_4.cpp
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1
// basisu_pvrtc1_4.cpp

2
// Copyright (C) 2019-2024 Binomial LLC. All Rights Reserved.

3
//

4
// Licensed under the Apache License, Version 2.0 (the "License");

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// you may not use this file except in compliance with the License.

6
// You may obtain a copy of the License at

7
//

8
//    http://www.apache.org/licenses/LICENSE-2.0

9
//

10
// Unless required by applicable law or agreed to in writing, software

11
// distributed under the License is distributed on an "AS IS" BASIS,

12
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

13
// See the License for the specific language governing permissions and

14
// limitations under the License.

15
#include "basisu_pvrtc1_4.h"

16


17
namespace basisu

18
{

19
#if 0

20
	static const uint8_t g_pvrtc_5[32] = { 0,8,16,24,33,41,49,57,66,74,82,90,99,107,115,123,132,140,148,156,165,173,181,189,198,206,214,222,231,239,247,255 };

21
	static const uint8_t g_pvrtc_4[16] = { 0,16,33,49,66,82,99,115,140,156,173,189,206,222,239,255 };

22
	static const uint8_t g_pvrtc_3[8] = { 0,33,74,107,148,181,222,255 };

23
	static const uint8_t g_pvrtc_alpha[9] = { 0,34,68,102,136,170,204,238,255 };

24
#endif

25


26
	static const uint8_t g_pvrtc_5_nearest[256] = { 0,0,0,0,0,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,12,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15,16,16,16,16,16,16,16,16,16,17,17,17,17,17,17,17,17,18,18,18,18,18,18,18,18,19,19,19,19,19,19,19,19,20,20,20,20,20,20,20,20,20,21,21,21,21,21,21,21,21,22,22,22,22,22,22,22,22,23,23,23,23,23,23,23,23,24,24,24,24,24,24,24,24,24,25,25,25,25,25,25,25,25,26,26,26,26,26,26,26,26,27,27,27,27,27,27,27,27,28,28,28,28,28,28,28,28,28,29,29,29,29,29,29,29,29,30,30,30,30,30,30,30,30,31,31,31,31 };

27
	static const uint8_t g_pvrtc_4_nearest[256] = { 0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15 };

28
#if 0

29
	static const uint8_t g_pvrtc_3_nearest[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };

30
	static const uint8_t g_pvrtc_alpha_nearest[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8 };

31
#endif

32


33
#if 0

34
	static const uint8_t g_pvrtc_5_floor[256] =

35
	{

36
		0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,

37
		3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,

38
		7,7,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,11,11,11,11,11,11,

39
		11,11,11,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,14,14,14,14,14,14,14,14,15,15,15,15,15,

40
		15,15,15,15,16,16,16,16,16,16,16,16,17,17,17,17,17,17,17,17,18,18,18,18,18,18,18,18,19,19,19,19,

41
		19,19,19,19,19,20,20,20,20,20,20,20,20,21,21,21,21,21,21,21,21,22,22,22,22,22,22,22,22,23,23,23,

42
		23,23,23,23,23,23,24,24,24,24,24,24,24,24,25,25,25,25,25,25,25,25,26,26,26,26,26,26,26,26,27,27,

43
		27,27,27,27,27,27,27,28,28,28,28,28,28,28,28,29,29,29,29,29,29,29,29,30,30,30,30,30,30,30,30,31

44
	};

45


46
	static const uint8_t g_pvrtc_5_ceil[256] =

47
	{

48
		0,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,

49
		4,4,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,8,8,8,8,8,8,

50
		8,8,8,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,12,12,12,12,12,

51
		12,12,12,12,13,13,13,13,13,13,13,13,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15,16,16,16,16,

52
		16,16,16,16,16,17,17,17,17,17,17,17,17,18,18,18,18,18,18,18,18,19,19,19,19,19,19,19,19,20,20,20,

53
		20,20,20,20,20,20,21,21,21,21,21,21,21,21,22,22,22,22,22,22,22,22,23,23,23,23,23,23,23,23,24,24,

54
		24,24,24,24,24,24,24,25,25,25,25,25,25,25,25,26,26,26,26,26,26,26,26,27,27,27,27,27,27,27,27,28,

55
		28,28,28,28,28,28,28,28,29,29,29,29,29,29,29,29,30,30,30,30,30,30,30,30,31,31,31,31,31,31,31,31

56
	};

57


58
	static const uint8_t g_pvrtc_4_floor[256] =

59
	{

60
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

61
		1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,

62
		3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,

63
		5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,

64
		7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,

65
		9,9,9,9,9,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,

66
		11,11,11,11,11,11,11,11,11,11,11,11,11,11,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,13,13,

67
		13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,15

68
	};

69


70
	static const uint8_t g_pvrtc_4_ceil[256] =

71
	{

72
		0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

73
		2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,

74
		4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,

75
		6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,

76
		8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,10,10,10,

77
		10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,12,12,

78
		12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,14,

79
		14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15

80
	};

81


82
	static const uint8_t g_pvrtc_3_floor[256] =

83
	{

84
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

85
		0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

86
		1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

87
		2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,

88
		3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,

89
		4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,

90
		5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,

91
		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7

92
	};

93


94
	static const uint8_t g_pvrtc_3_ceil[256] =

95
	{

96
		0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

97
		1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

98
		2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,

99
		3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,

100
		4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,

101
		5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,

102
		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,

103
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7

104
	};

105


106
	static const uint8_t g_pvrtc_alpha_floor[256] =

107
	{

108
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

109
		0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

110
		1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

111
		2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,

112
		3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,

113
		4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,

114
		5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

115
		6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8

116
	};

117


118
	static const uint8_t g_pvrtc_alpha_ceil[256] =

119
	{

120
		0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

121
		1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

122
		2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,

123
		3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,

124
		4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,

125
		5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

126
		6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

127
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8

128
	};

129
#endif

130


131
	uint32_t pvrtc4_swizzle_uv(uint32_t width, uint32_t height, uint32_t x, uint32_t y)

132
	{

133
		assert((x < width) && (y < height) && basisu::is_pow2(height) && basisu::is_pow2(width));

134
				

135
		uint32_t min_d = width, max_v = y;

136
		if (height < width)

137
		{

138
			min_d = height;

139
			max_v = x;

140
		}

141


142
		// Interleave the XY LSB's

143
		uint32_t shift_ofs = 0, swizzled = 0;

144
		for (uint32_t s_bit = 1, d_bit = 1; s_bit < min_d; s_bit <<= 1, d_bit <<= 2, ++shift_ofs)

145
		{

146
			if (y & s_bit) swizzled |= d_bit;

147
			if (x & s_bit) swizzled |= (2 * d_bit);

148
		}

149


150
		max_v >>= shift_ofs;

151
		

152
		// OR in the rest of the bits from the largest dimension

153
		swizzled |= (max_v << (2 * shift_ofs));

154


155
		return swizzled;

156
	}

157


158
	color_rgba pvrtc4_block::get_endpoint(uint32_t endpoint_index, bool unpack) const

159
	{

160
		assert(endpoint_index < 2);

161
		const uint32_t packed = m_endpoints >> (endpoint_index * 16);

162


163
		uint32_t r, g, b, a;

164
		if (packed & 0x8000)

165
		{

166
			// opaque 554 or 555

167
			if (!endpoint_index)

168
			{

169
				r = (packed >> 10) & 31;

170
				g = (packed >> 5) & 31;

171
				b = (packed >> 1) & 15;

172
					

173
				if (unpack)

174
				{

175
					b = (b << 1) | (b >> 3);

176
				}

177
			}

178
			else

179
			{

180
				r = (packed >> 10) & 31;

181
				g = (packed >> 5) & 31;

182
				b = packed & 31;

183
			}

184


185
			a = unpack ? 255 : 7;

186
		}

187
		else

188
		{

189
			// translucent 4433 or 4443

190
			if (!endpoint_index)

191
			{

192
				a = (packed >> 12) & 7;

193
				r = (packed >> 8) & 15;

194
				g = (packed >> 4) & 15;

195
				b = (packed >> 1) & 7;

196


197
				if (unpack)

198
				{

199
					a = (a << 1);

200
					a = (a << 4) | a;

201
						

202
					r = (r << 1) | (r >> 3);

203
					g = (g << 1) | (g >> 3);

204
					b = (b << 2) | (b >> 1);

205
				}

206
			}

207
			else

208
			{

209
				a = (packed >> 12) & 7;

210
				r = (packed >> 8) & 15;

211
				g = (packed >> 4) & 15;

212
				b = packed & 15;

213


214
				if (unpack)

215
				{

216
					a = (a << 1);

217
					a = (a << 4) | a;

218


219
					r = (r << 1) | (r >> 3);

220
					g = (g << 1) | (g >> 3);

221
					b = (b << 1) | (b >> 3);

222
				}

223
			}

224
		}

225


226
		if (unpack)

227
		{

228
			r = (r << 3) | (r >> 2);

229
			g = (g << 3) | (g >> 2);

230
			b = (b << 3) | (b >> 2);

231
		}

232


233
		assert((r < 256) && (g < 256) && (b < 256) && (a < 256));

234


235
		return color_rgba(r, g, b, a);

236
	}

237


238
	color_rgba pvrtc4_block::get_endpoint_5554(uint32_t endpoint_index) const

239
	{

240
		assert(endpoint_index < 2);

241
		const uint32_t packed = m_endpoints >> (endpoint_index * 16);

242


243
		uint32_t r, g, b, a;

244
		if (packed & 0x8000)

245
		{

246
			// opaque 554 or 555

247
			if (!endpoint_index)

248
			{

249
				r = (packed >> 10) & 31;

250
				g = (packed >> 5) & 31;

251
				b = (packed >> 1) & 15;

252


253
				b = (b << 1) | (b >> 3);

254
			}

255
			else

256
			{

257
				r = (packed >> 10) & 31;

258
				g = (packed >> 5) & 31;

259
				b = packed & 31;

260
			}

261


262
			a = 15;

263
		}

264
		else

265
		{

266
			// translucent 4433 or 4443

267
			if (!endpoint_index)

268
			{

269
				a = (packed >> 12) & 7;

270
				r = (packed >> 8) & 15;

271
				g = (packed >> 4) & 15;

272
				b = (packed >> 1) & 7;

273


274
				a = a << 1;

275
						

276
				r = (r << 1) | (r >> 3);

277
				g = (g << 1) | (g >> 3);

278
				b = (b << 2) | (b >> 1);

279
			}

280
			else

281
			{

282
				a = (packed >> 12) & 7;

283
				r = (packed >> 8) & 15;

284
				g = (packed >> 4) & 15;

285
				b = packed & 15;

286


287
				a = a << 1;

288
						

289
				r = (r << 1) | (r >> 3);

290
				g = (g << 1) | (g >> 3);

291
				b = (b << 1) | (b >> 3);

292
			}

293
		}

294
						

295
		assert((r < 32) && (g < 32) && (b < 32) && (a < 16));

296


297
		return color_rgba(r, g, b, a);

298
	}

299


300
	bool pvrtc4_image::get_interpolated_colors(uint32_t x, uint32_t y, color_rgba* pColors) const

301
	{

302
		assert((x < m_width) && (y < m_height));

303


304
		int block_x0 = (static_cast<int>(x) - 2) >> 2;

305
		int block_x1 = block_x0 + 1;

306
		int block_y0 = (static_cast<int>(y) - 2) >> 2;

307
		int block_y1 = block_y0 + 1;

308
		

309
		block_x0 = posmod(block_x0, m_block_width);

310
		block_x1 = posmod(block_x1, m_block_width);

311
		block_y0 = posmod(block_y0, m_block_height);

312
		block_y1 = posmod(block_y1, m_block_height);

313
		

314
		pColors[0] = interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(0), m_blocks(block_x1, block_y0).get_endpoint_5554(0), m_blocks(block_x0, block_y1).get_endpoint_5554(0), m_blocks(block_x1, block_y1).get_endpoint_5554(0));

315
		pColors[3] = interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(1), m_blocks(block_x1, block_y0).get_endpoint_5554(1), m_blocks(block_x0, block_y1).get_endpoint_5554(1), m_blocks(block_x1, block_y1).get_endpoint_5554(1));

316


317
		if (get_block_uses_transparent_modulation(x >> 2, y >> 2))

318
		{

319
			for (uint32_t c = 0; c < 4; c++)

320
			{

321
				uint32_t m = (pColors[0][c] + pColors[3][c]) / 2;

322
				pColors[1][c] = static_cast<uint8_t>(m);

323
				pColors[2][c] = static_cast<uint8_t>(m);

324
			}

325
			pColors[2][3] = 0;

326
			return true;

327
		}

328


329
		for (uint32_t c = 0; c < 4; c++)

330
		{

331
			pColors[1][c] = static_cast<uint8_t>((pColors[0][c] * 5 + pColors[3][c] * 3) / 8);

332
			pColors[2][c] = static_cast<uint8_t>((pColors[0][c] * 3 + pColors[3][c] * 5) / 8);

333
		}

334


335
		return false;

336
	}

337
		

338
	color_rgba pvrtc4_image::get_pixel(uint32_t x, uint32_t y, uint32_t m) const

339
	{

340
		assert((x < m_width) && (y < m_height));

341


342
		int block_x0 = (static_cast<int>(x) - 2) >> 2;

343
		int block_x1 = block_x0 + 1;

344
		int block_y0 = (static_cast<int>(y) - 2) >> 2;

345
		int block_y1 = block_y0 + 1;

346
		

347
		block_x0 = posmod(block_x0, m_block_width);

348
		block_x1 = posmod(block_x1, m_block_width);

349
		block_y0 = posmod(block_y0, m_block_height);

350
		block_y1 = posmod(block_y1, m_block_height);

351
		

352
		if (get_block_uses_transparent_modulation(x >> 2, y >> 2))

353
		{

354
			if (m == 0)

355
				return interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(0), m_blocks(block_x1, block_y0).get_endpoint_5554(0), m_blocks(block_x0, block_y1).get_endpoint_5554(0), m_blocks(block_x1, block_y1).get_endpoint_5554(0));

356
			else if (m == 3)

357
				return interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(1), m_blocks(block_x1, block_y0).get_endpoint_5554(1), m_blocks(block_x0, block_y1).get_endpoint_5554(1), m_blocks(block_x1, block_y1).get_endpoint_5554(1));

358


359
			color_rgba l(interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(0), m_blocks(block_x1, block_y0).get_endpoint_5554(0), m_blocks(block_x0, block_y1).get_endpoint_5554(0), m_blocks(block_x1, block_y1).get_endpoint_5554(0)));

360
			color_rgba h(interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(1), m_blocks(block_x1, block_y0).get_endpoint_5554(1), m_blocks(block_x0, block_y1).get_endpoint_5554(1), m_blocks(block_x1, block_y1).get_endpoint_5554(1)));

361


362
			return color_rgba((l[0] + h[0]) / 2, (l[1] + h[1]) / 2, (l[2] + h[2]) / 2, (m == 2) ? 0 : (l[3] + h[3]) / 2);

363
		}

364
		else

365
		{

366
			if (m == 0)

367
				return interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(0), m_blocks(block_x1, block_y0).get_endpoint_5554(0), m_blocks(block_x0, block_y1).get_endpoint_5554(0), m_blocks(block_x1, block_y1).get_endpoint_5554(0));

368
			else if (m == 3)

369
				return interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(1), m_blocks(block_x1, block_y0).get_endpoint_5554(1), m_blocks(block_x0, block_y1).get_endpoint_5554(1), m_blocks(block_x1, block_y1).get_endpoint_5554(1));

370


371
			color_rgba l(interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(0), m_blocks(block_x1, block_y0).get_endpoint_5554(0), m_blocks(block_x0, block_y1).get_endpoint_5554(0), m_blocks(block_x1, block_y1).get_endpoint_5554(0)));

372
			color_rgba h(interpolate(x, y, m_blocks(block_x0, block_y0).get_endpoint_5554(1), m_blocks(block_x1, block_y0).get_endpoint_5554(1), m_blocks(block_x0, block_y1).get_endpoint_5554(1), m_blocks(block_x1, block_y1).get_endpoint_5554(1)));

373


374
			if (m == 2)

375
				return color_rgba((l[0] * 3 + h[0] * 5) / 8, (l[1] * 3 + h[1] * 5) / 8, (l[2] * 3 + h[2] * 5) / 8, (l[3] * 3 + h[3] * 5) / 8);

376
			else

377
				return color_rgba((l[0] * 5 + h[0] * 3) / 8, (l[1] * 5 + h[1] * 3) / 8, (l[2] * 5 + h[2] * 3) / 8, (l[3] * 5 + h[3] * 3) / 8);

378
		}

379
	}

380


381
	uint64_t pvrtc4_image::local_endpoint_optimization_opaque(uint32_t bx, uint32_t by, const image& orig_img, bool perceptual)

382
	{

383
		uint64_t initial_error = evaluate_1x1_endpoint_error(bx, by, orig_img, perceptual, false);

384
		if (!initial_error)

385
			return initial_error;

386


387
		vec3F c_avg_orig(0);

388


389
		for (int y = 0; y < 7; y++)

390
		{

391
			const uint32_t py = wrap_y(by * 4 + y - 1);

392
			for (uint32_t x = 0; x < 7; x++)

393
			{

394
				const uint32_t px = wrap_x(bx * 4 + x - 1);

395


396
				const color_rgba& c = orig_img(px, py);

397


398
				c_avg_orig[0] += c[0];

399
				c_avg_orig[1] += c[1];

400
				c_avg_orig[2] += c[2];

401
			}

402
		}

403


404
		c_avg_orig *= 1.0f / 49.0f;

405


406
		vec3F quant_colors[2];

407
		quant_colors[0].set(c_avg_orig);

408
		quant_colors[0] -= vec3F(.0125f);

409


410
		quant_colors[1].set(c_avg_orig);

411
		quant_colors[1] += vec3F(.0125f);

412


413
		float total_weight[2];

414


415
		bool success = true;

416


417
		for (uint32_t pass = 0; pass < 4; pass++)

418
		{

419
			vec3F new_colors[2] = { vec3F(0), vec3F(0) };

420
			memset(total_weight, 0, sizeof(total_weight));

421


422
			static const float s_weights[7][7] =

423
			{

424
				{ 1.000000f, 1.637089f, 2.080362f, 2.242640f, 2.080362f, 1.637089f, 1.000000f },

425
				{ 1.637089f, 2.414213f, 3.006572f, 3.242640f, 3.006572f, 2.414213f, 1.637089f },

426
				{ 2.080362f, 3.006572f, 3.828426f, 4.242640f, 3.828426f, 3.006572f, 2.080362f },

427
				{ 2.242640f, 3.242640f, 4.242640f, 5.000000f, 4.242640f, 3.242640f, 2.242640f },

428
				{ 2.080362f, 3.006572f, 3.828426f, 4.242640f, 3.828426f, 3.006572f, 2.080362f },

429
				{ 1.637089f, 2.414213f, 3.006572f, 3.242640f, 3.006572f, 2.414213f, 1.637089f },

430
				{ 1.000000f, 1.637089f, 2.080362f, 2.242640f, 2.080362f, 1.637089f, 1.000000f }

431
			};

432


433
			for (int y = 0; y < 7; y++)

434
			{

435
				const uint32_t py = wrap_y(by * 4 + y - 1);

436
				for (uint32_t x = 0; x < 7; x++)

437
				{

438
					const uint32_t px = wrap_x(bx * 4 + x - 1);

439


440
					const color_rgba& orig_c = orig_img(px, py);

441


442
					vec3F color(orig_c[0], orig_c[1], orig_c[2]);

443


444
					uint32_t c = quant_colors[0].squared_distance(color) > quant_colors[1].squared_distance(color);

445


446
					const float weight = s_weights[y][x];

447
					new_colors[c] += color * weight;

448


449
					total_weight[c] += weight;

450
				}

451
			}

452


453
			if (!total_weight[0] || !total_weight[1])

454
				success = false;

455


456
			quant_colors[0] = new_colors[0] / (float)total_weight[0];

457
			quant_colors[1] = new_colors[1] / (float)total_weight[1];

458
		}

459


460
		if (!success)

461
		{

462
			quant_colors[0] = c_avg_orig;

463
			quant_colors[1] = c_avg_orig;

464
		}

465


466
		vec4F colors[2] = { quant_colors[0], quant_colors[1] };

467


468
		colors[0] += vec3F(.5f);

469
		colors[1] += vec3F(.5f);

470
		color_rgba color_0((int)colors[0][0], (int)colors[0][1], (int)colors[0][2], 0);

471
		color_rgba color_1((int)colors[1][0], (int)colors[1][1], (int)colors[1][2], 0);

472


473
		pvrtc4_block cur_blocks[3][3];

474
		

475
		for (int y = -1; y <= 1; y++)

476
		{

477
			for (int x = -1; x <= 1; x++)

478
			{

479
				const uint32_t block_x = wrap_block_x(bx + x);

480
				const uint32_t block_y = wrap_block_y(by + y);

481
				cur_blocks[x + 1][y + 1] = m_blocks(block_x, block_y);

482
			}

483
		}

484


485
		color_rgba l1(0), h1(0);

486


487
		l1[0] = g_pvrtc_5_nearest[color_0[0]];

488
		h1[0] = g_pvrtc_5_nearest[color_1[0]];

489


490
		l1[1] = g_pvrtc_5_nearest[color_0[1]];

491
		h1[1] = g_pvrtc_5_nearest[color_1[1]];

492


493
		l1[2] = g_pvrtc_4_nearest[color_0[2]];

494
		h1[2] = g_pvrtc_5_nearest[color_0[2]];

495


496
		l1[3] = 0;

497
		h1[3] = 0;

498


499
		m_blocks(bx, by).set_endpoint_raw(0, l1, true);

500
		m_blocks(bx, by).set_endpoint_raw(1, h1, true);

501


502
		uint64_t e03_err_0 = remap_pixels_influenced_by_endpoint(bx, by, orig_img, perceptual, false);

503


504
		pvrtc4_block blocks0[3][3];

505
		for (int y = -1; y <= 1; y++)

506
		{

507
			for (int x = -1; x <= 1; x++)

508
			{

509
				const uint32_t block_x = wrap_block_x(bx + x);

510
				const uint32_t block_y = wrap_block_y(by + y);

511
				blocks0[x + 1][y + 1] = m_blocks(block_x, block_y);

512
			}

513
		}

514


515
		l1[0] = g_pvrtc_5_nearest[color_1[0]];

516
		h1[0] = g_pvrtc_5_nearest[color_0[0]];

517


518
		l1[1] = g_pvrtc_5_nearest[color_1[1]];

519
		h1[1] = g_pvrtc_5_nearest[color_0[1]];

520


521
		l1[2] = g_pvrtc_4_nearest[color_1[2]];

522
		h1[2] = g_pvrtc_5_nearest[color_0[2]];

523


524
		l1[3] = 0;

525
		h1[3] = 0;

526


527
		m_blocks(bx, by).set_endpoint_raw(0, l1, true);

528
		m_blocks(bx, by).set_endpoint_raw(1, h1, true);

529


530
		uint64_t e03_err_1 = remap_pixels_influenced_by_endpoint(bx, by, orig_img, perceptual, false);

531


532
		if (initial_error < basisu::minimum(e03_err_0, e03_err_1))

533
		{

534
			for (int y = -1; y <= 1; y++)

535
			{

536
				for (int x = -1; x <= 1; x++)

537
				{

538
					const uint32_t block_x = wrap_block_x(bx + x);

539
					const uint32_t block_y = wrap_block_y(by + y);

540
					m_blocks(block_x, block_y) = cur_blocks[x + 1][y + 1];

541
				}

542
			}

543
			return initial_error;

544
		}

545
		else if (e03_err_0 < e03_err_1)

546
		{

547
			for (int y = -1; y <= 1; y++)

548
			{

549
				for (int x = -1; x <= 1; x++)

550
				{

551
					const uint32_t block_x = wrap_block_x(bx + x);

552
					const uint32_t block_y = wrap_block_y(by + y);

553
					m_blocks(block_x, block_y) = blocks0[x + 1][y + 1];

554
				}

555
			}

556
			assert(e03_err_0 == evaluate_1x1_endpoint_error(bx, by, orig_img, perceptual, false));

557
			return e03_err_0;

558
		}

559


560
		assert(e03_err_1 == evaluate_1x1_endpoint_error(bx, by, orig_img, perceptual, false));

561
		return e03_err_1;

562
	}

563


564
} // basisu

565


566