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1 /* ============================================================================
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2 * Freetype GL - A C OpenGL Freetype engine
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3 * Platform: Any
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4 * WWW: http://code.google.com/p/freetype-gl/
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5 * ----------------------------------------------------------------------------
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6 * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.
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7 *
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8 * Redistribution and use in source and binary forms, with or without
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9 * modification, are permitted provided that the following conditions are met:
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10 *
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11 * 1. Redistributions of source code must retain the above copyright notice,
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12 * this list of conditions and the following disclaimer.
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13 *
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14 * 2. Redistributions in binary form must reproduce the above copyright
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15 * notice, this list of conditions and the following disclaimer in the
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16 * documentation and/or other materials provided with the distribution.
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17 *
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18 * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''AS IS'' AND ANY EXPRESS OR
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19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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20 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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21 * EVENT SHALL NICOLAS P. ROUGIER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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22 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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28 *
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29 * The views and conclusions contained in the software and documentation are
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30 * those of the authors and should not be interpreted as representing official
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31 * policies, either expressed or implied, of Nicolas P. Rougier.
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32 * ============================================================================
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33 */
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34 #ifndef __TEXTURE_FONT_H__
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35 #define __TEXTURE_FONT_H__
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36
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37 #include <stdlib.h>
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38
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39 #ifdef __cplusplus
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40 extern "C" {
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41 #endif
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42
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43 #include "vector.h"
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44 #include "texture-atlas.h"
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45
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46 /**
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47 * @file texture-font.h
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48 * @author Nicolas Rougier (Nicolas.Rougier@inria.fr)
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49 *
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50 * @defgroup texture-font Texture font
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51 *
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52 * Texture font.
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53 *
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54 * Example Usage:
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55 * @code
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56 * #include "texture-font.h"
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57 *
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58 * int main( int arrgc, char *argv[] )
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59 * {
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60 * return 0;
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61 * }
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62 * @endcode
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63 *
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64 * @{
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65 */
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66
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67
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68
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69 /**
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70 * A structure that hold a kerning value relatively to a charcode.
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71 *
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72 * This structure cannot be used alone since the (necessary) right charcode is
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73 * implicitely held by the owner of this structure.
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74 */
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75 typedef struct
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76 {
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77 /**
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78 * Left character code in the kern pair.
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79 */
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80 wchar_t charcode;
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81
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82 /**
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83 * Kerning value (in fractional pixels).
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84 */
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85 float kerning;
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86
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87 } kerning_t;
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88
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89
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90
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91
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92 /*
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93 * Glyph metrics:
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94 * --------------
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95 *
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96 * xmin xmax
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97 * | |
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98 * |<-------- width -------->|
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99 * | |
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100 * | +-------------------------+----------------- ymax
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101 * | | ggggggggg ggggg | ^ ^
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102 * | | g:::::::::ggg::::g | | |
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103 * | | g:::::::::::::::::g | | |
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104 * | | g::::::ggggg::::::gg | | |
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105 * | | g:::::g g:::::g | | |
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106 * offset_x -|-------->| g:::::g g:::::g | offset_y |
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107 * | | g:::::g g:::::g | | |
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108 * | | g::::::g g:::::g | | |
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109 * | | g:::::::ggggg:::::g | | |
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110 * | | g::::::::::::::::g | | height
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111 * | | gg::::::::::::::g | | |
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112 * baseline ---*---------|---- gggggggg::::::g-----*-------- |
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113 * / | | g:::::g | |
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114 * origin | | gggggg g:::::g | |
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115 * | | g:::::gg gg:::::g | |
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116 * | | g::::::ggg:::::::g | |
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117 * | | gg:::::::::::::g | |
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118 * | | ggg::::::ggg | |
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119 * | | gggggg | v
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120 * | +-------------------------+----------------- ymin
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121 * | |
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122 * |------------- advance_x ---------->|
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123 */
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124
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125 /**
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126 * A structure that describe a glyph.
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127 */
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128 typedef struct
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129 {
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130 /**
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131 * Wide character this glyph represents
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132 */
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133 wchar_t charcode;
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134
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135 /**
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136 * Glyph id (used for display lists)
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137 */
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138 unsigned int id;
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139
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140 /**
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141 * Glyph's width in pixels.
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142 */
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143 size_t width;
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144
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145 /**
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146 * Glyph's height in pixels.
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147 */
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148 size_t height;
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149
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150 /**
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151 * Glyph's left bearing expressed in integer pixels.
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152 */
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153 int offset_x;
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154
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155 /**
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156 * Glyphs's top bearing expressed in integer pixels.
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157 *
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158 * Remember that this is the distance from the baseline to the top-most
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159 * glyph scanline, upwards y coordinates being positive.
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160 */
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161 int offset_y;
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162
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163 /**
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164 * For horizontal text layouts, this is the horizontal distance (in
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165 * fractional pixels) used to increment the pen position when the glyph is
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166 * drawn as part of a string of text.
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167 */
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168 float advance_x;
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169
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170 /**
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171 * For vertical text layouts, this is the vertical distance (in fractional
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172 * pixels) used to increment the pen position when the glyph is drawn as
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173 * part of a string of text.
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174 */
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175 float advance_y;
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176
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177 /**
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178 * First normalized texture coordinate (x) of top-left corner
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179 */
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180 float s0;
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181
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182 /**
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183 * Second normalized texture coordinate (y) of top-left corner
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184 */
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185 float t0;
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186
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187 /**
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188 * First normalized texture coordinate (x) of bottom-right corner
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189 */
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190 float s1;
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191
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192 /**
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193 * Second normalized texture coordinate (y) of bottom-right corner
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194 */
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195 float t1;
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196
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197 /**
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198 * A vector of kerning pairs relative to this glyph.
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199 */
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200 vector_t * kerning;
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201
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202 /**
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203 * Glyph outline type (0 = None, 1 = line, 2 = inner, 3 = outer)
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204 */
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205 int outline_type;
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206
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207 /**
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208 * Glyph outline thickness
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209 */
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210 float outline_thickness;
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211
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212 } texture_glyph_t;
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213
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214
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215
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216 /**
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217 * Texture font structure.
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218 */
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219 typedef struct
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220 {
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221 /**
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222 * Vector of glyphs contained in this font.
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223 */
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224 vector_t * glyphs;
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225
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226 /**
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227 * Atlas structure to store glyphs data.
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228 */
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229 texture_atlas_t * atlas;
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230
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231 /**
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232 * Font filename
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233 */
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234 char * filename;
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235
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236 /**
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237 * Font size
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238 */
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239 float size;
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240
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241 /**
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242 * Whether to use autohint when rendering font
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243 */
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244 int hinting;
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245
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246 /**
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247 * Outline type (0 = None, 1 = line, 2 = inner, 3 = outer)
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248 */
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249 int outline_type;
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250
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251 /**
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252 * Outline thickness
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253 */
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254 float outline_thickness;
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255
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256 /**
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257 * Whether to use our own lcd filter.
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258 */
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259 int filtering;
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260
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261 /**
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262 * Whether to use kerning if available
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263 */
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264 int kerning;
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265
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266 /**
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267 * LCD filter weights
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268 */
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269 unsigned char lcd_weights[5];
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270
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271 /**
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272 * This field is simply used to compute a default line spacing (i.e., the
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273 * baseline-to-baseline distance) when writing text with this font. Note
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274 * that it usually is larger than the sum of the ascender and descender
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275 * taken as absolute values. There is also no guarantee that no glyphs
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276 * extend above or below subsequent baselines when using this distance.
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277 */
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278 float height;
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279
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280 /**
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281 * This field is the distance that must be placed between two lines of
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282 * text. The baseline-to-baseline distance should be computed as:
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283 * ascender - descender + linegap
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284 */
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285 float linegap;
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286
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287 /**
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288 * The ascender is the vertical distance from the horizontal baseline to
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289 * the highest 'character' coordinate in a font face. Unfortunately, font
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290 * formats define the ascender differently. For some, it represents the
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291 * ascent of all capital latin characters (without accents), for others it
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292 * is the ascent of the highest accented character, and finally, other
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293 * formats define it as being equal to bbox.yMax.
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294 */
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295 float ascender;
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296
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297 /**
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298 * The descender is the vertical distance from the horizontal baseline to
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299 * the lowest 'character' coordinate in a font face. Unfortunately, font
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300 * formats define the descender differently. For some, it represents the
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301 * descent of all capital latin characters (without accents), for others it
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302 * is the ascent of the lowest accented character, and finally, other
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303 * formats define it as being equal to bbox.yMin. This field is negative
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304 * for values below the baseline.
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305 */
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306 float descender;
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307
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308 /**
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309 * The position of the underline line for this face. It is the center of
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310 * the underlining stem. Only relevant for scalable formats.
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311 */
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312 float underline_position;
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313
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314 /**
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315 * The thickness of the underline for this face. Only relevant for scalable
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316 * formats.
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317 */
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318 float underline_thickness;
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319
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320 } texture_font_t;
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321
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322
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323
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324 /**
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325 * This function creates a new texture font from given filename and size. The
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326 * texture atlas is used to store glyph on demand. Note the depth of the atlas
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327 * will determine if the font is rendered as alpha channel only (depth = 1) or
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328 * RGB (depth = 3) that correspond to subpixel rendering (if available on your
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329 * freetype implementation).
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330 *
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331 * @param atlas A texture atlas
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332 * @param filename A font filename
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333 * @param size Size of font to be created (in points)
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334 *
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335 * @return A new empty font (no glyph inside yet)
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336 *
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337 */
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338 texture_font_t *
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339 texture_font_new( texture_atlas_t * atlas,
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340 const char * filename,
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341 const float size );
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342
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343
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344 /**
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345 * Delete a texture font. Note that this does not delete the glyph from the
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346 * texture atlas.
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347 *
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348 * @param self a valid texture font
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349 */
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350 void
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351 texture_font_delete( texture_font_t * self );
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352
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353
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354 /**
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355 * Request a new glyph from the font. If it has not been created yet, it will
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356 * be.
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357 *
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358 * @param self A valid texture font
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359 * @param charcode Character codepoint to be loaded.
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360 *
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361 * @return A pointer on the new glyph or 0 if the texture atlas is not big
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362 * enough
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363 *
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364 */
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365 texture_glyph_t *
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366 texture_font_get_glyph( texture_font_t * self,
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367 wchar_t charcode );
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368
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369
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370 /**
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371 * Request the loading of several glyphs at once.
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372 *
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373 * @param self a valid texture font
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374 * @param charcodes character codepoints to be loaded.
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375 *
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376 * @return Number of missed glyph if the texture is not big enough to hold
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377 * every glyphs.
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378 */
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379 size_t
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380 texture_font_load_glyphs( texture_font_t * self,
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381 const wchar_t * charcodes );
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382
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383 /**
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384 * Get the kerning between two horizontal glyphs.
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385 *
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386 * @param self a valid texture glyph
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387 * @param charcode codepoint of the peceding glyph
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388 *
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389 * @return x kerning value
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390 */
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391 float
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392 texture_glyph_get_kerning( const texture_glyph_t * self,
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393 const wchar_t charcode );
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394
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395
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396 /**
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397 * Creates a new empty glyph
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398 *
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399 * @return a new empty glyph (not valid)
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400 */
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401 texture_glyph_t *
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402 texture_glyph_new( void );
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403
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404 /** @} */
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405
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406
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407 #ifdef __cplusplus
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408 }
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409 #endif
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410
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411 #endif /* __TEXTURE_FONT_H__ */
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412
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