1 | /* |
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2 | * libcaca Colour ASCII-Art library |
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3 | * Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org> |
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4 | * All Rights Reserved |
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5 | * |
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6 | * $Id: triangle.c 3912 2009-11-16 13:14:32Z jylam $ |
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7 | * |
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8 | * This library is free software. It comes without any warranty, to |
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9 | * the extent permitted by applicable law. You can redistribute it |
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10 | * and/or modify it under the terms of the Do What The Fuck You Want |
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11 | * To Public License, Version 2, as published by Sam Hocevar. See |
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12 | * http://sam.zoy.org/wtfpl/COPYING for more details. |
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13 | */ |
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14 | |
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15 | /* |
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16 | * This file contains triangle drawing functions, both filled and outline. |
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17 | */ |
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18 | |
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19 | #include "config.h" |
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20 | |
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21 | #if !defined(__KERNEL__) |
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22 | # include <stdlib.h> |
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23 | #endif |
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24 | |
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25 | #include "caca.h" |
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26 | #include "caca_internals.h" |
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27 | |
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28 | /** \brief Draw a triangle on the canvas using the given character. |
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29 | * |
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30 | * This function never fails. |
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31 | * |
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32 | * \param cv The handle to the libcaca canvas. |
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33 | * \param x1 X coordinate of the first point. |
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34 | * \param y1 Y coordinate of the first point. |
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35 | * \param x2 X coordinate of the second point. |
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36 | * \param y2 Y coordinate of the second point. |
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37 | * \param x3 X coordinate of the third point. |
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38 | * \param y3 Y coordinate of the third point. |
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39 | * \param ch UTF-32 character to be used to draw the triangle outline. |
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40 | * \return This function always returns 0. |
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41 | */ |
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42 | int caca_draw_triangle(caca_canvas_t *cv, int x1, int y1, int x2, int y2, |
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43 | int x3, int y3, uint32_t ch) |
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44 | { |
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45 | caca_draw_line(cv, x1, y1, x2, y2, ch); |
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46 | caca_draw_line(cv, x2, y2, x3, y3, ch); |
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47 | caca_draw_line(cv, x3, y3, x1, y1, ch); |
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48 | |
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49 | return 0; |
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50 | } |
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51 | |
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52 | /** \brief Draw a thin triangle on the canvas. |
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53 | * |
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54 | * This function never fails. |
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55 | * |
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56 | * \param cv The handle to the libcaca canvas. |
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57 | * \param x1 X coordinate of the first point. |
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58 | * \param y1 Y coordinate of the first point. |
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59 | * \param x2 X coordinate of the second point. |
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60 | * \param y2 Y coordinate of the second point. |
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61 | * \param x3 X coordinate of the third point. |
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62 | * \param y3 Y coordinate of the third point. |
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63 | * \return This function always returns 0. |
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64 | */ |
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65 | int caca_draw_thin_triangle(caca_canvas_t *cv, int x1, int y1, |
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66 | int x2, int y2, int x3, int y3) |
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67 | { |
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68 | caca_draw_thin_line(cv, x1, y1, x2, y2); |
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69 | caca_draw_thin_line(cv, x2, y2, x3, y3); |
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70 | caca_draw_thin_line(cv, x3, y3, x1, y1); |
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71 | |
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72 | return 0; |
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73 | } |
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74 | |
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75 | /** \brief Fill a triangle on the canvas using the given character. |
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76 | * |
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77 | * This function never fails. |
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78 | * |
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79 | * \param cv The handle to the libcaca canvas. |
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80 | * \param x1 X coordinate of the first point. |
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81 | * \param y1 Y coordinate of the first point. |
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82 | * \param x2 X coordinate of the second point. |
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83 | * \param y2 Y coordinate of the second point. |
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84 | * \param x3 X coordinate of the third point. |
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85 | * \param y3 Y coordinate of the third point. |
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86 | * \param ch UTF-32 character to be used to fill the triangle. |
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87 | * \return This function always returns 0. |
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88 | */ |
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89 | int caca_fill_triangle(caca_canvas_t *cv, int x1, int y1, int x2, int y2, |
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90 | int x3, int y3, uint32_t ch) |
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91 | { |
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92 | int x, y, xmin, xmax, ymin, ymax; |
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93 | int xx1, xx2, xa, xb, sl21, sl31, sl32; |
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94 | |
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95 | /* Bubble-sort y1 <= y2 <= y3 */ |
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96 | if(y1 > y2) |
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97 | return caca_fill_triangle(cv, x2, y2, x1, y1, x3, y3, ch); |
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98 | |
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99 | if(y2 > y3) |
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100 | return caca_fill_triangle(cv, x1, y1, x3, y3, x2, y2, ch); |
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101 | |
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102 | /* Compute slopes and promote precision */ |
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103 | sl21 = (y2 == y1) ? 0 : (x2 - x1) * 0x10000 / (y2 - y1); |
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104 | sl31 = (y3 == y1) ? 0 : (x3 - x1) * 0x10000 / (y3 - y1); |
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105 | sl32 = (y3 == y2) ? 0 : (x3 - x2) * 0x10000 / (y3 - y2); |
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106 | |
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107 | x1 *= 0x10000; |
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108 | x2 *= 0x10000; |
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109 | x3 *= 0x10000; |
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110 | |
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111 | ymin = y1 < 0 ? 0 : y1; |
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112 | ymax = y3 + 1 < cv->height ? y3 + 1 : cv->height; |
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113 | |
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114 | if(ymin < y2) |
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115 | { |
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116 | xa = x1 + sl21 * (ymin - y1); |
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117 | xb = x1 + sl31 * (ymin - y1); |
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118 | } |
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119 | else if(ymin == y2) |
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120 | { |
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121 | xa = x2; |
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122 | xb = (y1 == y3) ? x3 : x1 + sl31 * (ymin - y1); |
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123 | } |
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124 | else /* (ymin > y2) */ |
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125 | { |
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126 | xa = x3 + sl32 * (ymin - y3); |
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127 | xb = x3 + sl31 * (ymin - y3); |
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128 | } |
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129 | |
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130 | /* Rasterize our triangle */ |
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131 | for(y = ymin; y < ymax; y++) |
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132 | { |
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133 | /* Rescale xa and xb, recentering the division */ |
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134 | if(xa < xb) |
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135 | { |
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136 | xx1 = (xa + 0x800) / 0x10000; |
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137 | xx2 = (xb + 0x801) / 0x10000; |
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138 | } |
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139 | else |
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140 | { |
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141 | xx1 = (xb + 0x800) / 0x10000; |
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142 | xx2 = (xa + 0x801) / 0x10000; |
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143 | } |
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144 | |
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145 | xmin = xx1 < 0 ? 0 : xx1; |
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146 | xmax = xx2 + 1 < cv->width ? xx2 + 1 : cv->width; |
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147 | |
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148 | for(x = xmin; x < xmax; x++) |
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149 | caca_put_char(cv, x, y, ch); |
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150 | |
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151 | xa += y < y2 ? sl21 : sl32; |
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152 | xb += sl31; |
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153 | } |
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154 | |
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155 | return 0; |
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156 | } |
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157 | |
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158 | /** \brief Fill a triangle on the canvas using an arbitrary-sized texture. |
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159 | * |
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160 | * This function fails if one or both the canvas are missing |
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161 | * |
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162 | * \param cv The handle to the libcaca canvas. |
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163 | * \param x1 X coordinate of the first point. |
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164 | * \param y1 Y coordinate of the first point. |
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165 | * \param x2 X coordinate of the second point. |
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166 | * \param y2 Y coordinate of the second point. |
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167 | * \param x3 X coordinate of the third point. |
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168 | * \param y3 Y coordinate of the third point. |
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169 | * \param u1 U texture coordinate of the first point. |
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170 | * \param v1 V texture coordinate of the first point. |
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171 | * \param u2 U texture coordinate of the second point. |
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172 | * \param v2 V texture coordinate of the second point. |
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173 | * \param u3 U texture coordinate of the third point. |
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174 | * \param v3 V texture coordinate of the third point. |
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175 | * \param tex The handle of the canvas texture. |
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176 | * \return This function return 0 if ok, -1 if canvas or texture are missing. |
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177 | */ |
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178 | int caca_fill_triangle_textured(caca_canvas_t *cv, |
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179 | int x1, int y1, |
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180 | int x2, int y2, |
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181 | int x3, int y3, |
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182 | float u1, float v1, |
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183 | float u2, float v2, |
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184 | float u3, float v3, |
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185 | caca_canvas_t *tex) |
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186 | { |
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187 | |
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188 | #define SWAP_F(a, b) {float c = a; a = b; b = c; } |
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189 | |
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190 | /* (very) Naive and |
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191 | * (very) float-based affine and |
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192 | * (very) non-clipped and |
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193 | * (very) non-corrected triangle mapper |
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194 | * |
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195 | * Accepts arbitrary texture sizes |
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196 | * Coordinates clamped to [0.0 - 1.0] (no repeat) |
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197 | */ |
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198 | if(!cv || !tex) return -1; |
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199 | |
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200 | /* Bubble-sort y1 <= y2 <= y3 */ |
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201 | if(y1 > y2) |
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202 | return caca_fill_triangle_textured(cv, |
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203 | x2, y2, x1, y1, x3, y3, |
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204 | u2, v2, u1, v1, u3, v3, |
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205 | tex); |
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206 | if(y2 > y3) |
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207 | return caca_fill_triangle_textured(cv, |
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208 | x1, y1, x3, y3, x2, y2, |
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209 | u1, v1, u3, v3, u2, v2, |
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210 | tex); |
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211 | |
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212 | |
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213 | /* Clip texture coordinates */ |
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214 | if(u1<0.0f) u1 = 0.0f; if(v1<0.0f) v1 = 0.0f; |
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215 | if(u2<0.0f) u2 = 0.0f; if(v2<0.0f) v2 = 0.0f; |
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216 | if(u3<0.0f) u3 = 0.0f; if(v3<0.0f) v3 = 0.0f; |
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217 | if(u1>1.0f) u1 = 1.0f; if(v1>1.0f) v1 = 1.0f; |
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218 | if(u2>1.0f) u2 = 1.0f; if(v2>1.0f) v2 = 1.0f; |
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219 | if(u3>1.0f) u3 = 1.0f; if(v3>1.0f) v3 = 1.0f; |
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220 | |
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221 | /* Convert relative tex coordinates to absolute */ |
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222 | int tw = caca_get_canvas_width(tex); |
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223 | int th = caca_get_canvas_height(tex); |
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224 | |
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225 | u1*=(float)tw; u2*=(float)tw; u3*=(float)tw; |
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226 | v1*=(float)th; v2*=(float)th; v3*=(float)th; |
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227 | |
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228 | int x, y; |
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229 | float y2y1 = y2-y1; |
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230 | float y3y1 = y3-y1; |
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231 | float y3y2 = y3-y2; |
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232 | |
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233 | /* Compute slopes, making sure we don't divide by zero */ |
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234 | /* (in this case, we don't need the value anyway) */ |
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235 | /* FIXME : only compute needed slopes */ |
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236 | float sl12 = ((float)x2 - x1) / (y2y1==0?1:y2y1); |
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237 | float sl13 = ((float)x3 - x1) / (y3y1==0?1:y3y1); |
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238 | float sl23 = ((float)x3 - x2) / (y3y2==0?1:y3y2); |
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239 | |
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240 | float usl12 = (u2 - u1) / (y2y1==0?1:y2y1); |
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241 | float usl13 = (u3 - u1) / (y3y1==0?1:y3y1); |
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242 | float usl23 = (u3 - u2) / (y3y2==0?1:y3y2); |
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243 | float vsl12 = (v2 - v1) / (y2y1==0?1:y2y1); |
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244 | float vsl13 = (v3 - v1) / (y3y1==0?1:y3y1); |
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245 | float vsl23 = (v3 - v2) / (y3y2==0?1:y3y2); |
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246 | |
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247 | float xa = (float) x1, xb = (float) x1; |
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248 | float ua = u1, ub = u1; |
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249 | float va = v1, vb = v1; |
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250 | float u, v; |
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251 | |
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252 | int s = 0; |
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253 | |
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254 | /* Top */ |
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255 | for(y = y1 ; y < y2; y++) |
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256 | { |
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257 | |
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258 | if(xb < xa) { |
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259 | SWAP_F(xb, xa); |
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260 | SWAP_F(sl13, sl12); |
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261 | SWAP_F(ua, ub); |
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262 | SWAP_F(va, vb); |
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263 | SWAP_F(usl13, usl12); |
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264 | SWAP_F(vsl13, vsl12); |
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265 | s=1; |
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266 | } |
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267 | |
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268 | float tus = (ub - ua) / (xb - xa); |
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269 | float tvs = (vb - va) / (xb - xa); |
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270 | v = va; u = ua; |
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271 | |
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272 | /* scanline */ |
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273 | for(x = xa ; x < xb; x++) |
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274 | { |
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275 | u+=tus; |
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276 | v+=tvs; |
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277 | /* FIXME: use caca_get_canvas_attrs / caca_get_canvas_chars */ |
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278 | uint32_t attr = caca_get_attr(tex, u, v); |
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279 | uint32_t c = caca_get_char(tex, u, v); |
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280 | caca_set_attr(cv, attr); |
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281 | caca_put_char(cv, x, y, c); |
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282 | } |
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283 | |
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284 | xa+=sl13; |
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285 | xb+=sl12; |
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286 | |
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287 | ua+=usl13; va+=vsl13; |
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288 | ub+=usl12; vb+=vsl12; |
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289 | } |
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290 | |
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291 | if(s) |
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292 | { |
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293 | SWAP_F(xb, xa); |
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294 | SWAP_F(sl13, sl12); |
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295 | SWAP_F(ua, ub); |
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296 | SWAP_F(va, vb); |
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297 | SWAP_F(usl13, usl12); |
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298 | SWAP_F(vsl13, vsl12); |
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299 | } |
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300 | |
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301 | |
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302 | /* Bottom */ |
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303 | xb = (float) x2; |
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304 | |
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305 | /* These variables are set by 'top' routine |
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306 | * and are in an incorrect state if we only draw the bottom part |
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307 | */ |
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308 | if(y1 == y2) { |
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309 | ua = u1; |
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310 | ub = u2; |
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311 | va = v1; |
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312 | vb = v2; |
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313 | } |
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314 | |
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315 | for(y = y2 ; y < y3; y++) |
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316 | { |
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317 | if(xb <= xa) |
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318 | { |
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319 | SWAP_F(xb, xa); |
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320 | SWAP_F(sl13, sl23); |
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321 | SWAP_F(ua, ub); |
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322 | SWAP_F(va, vb); |
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323 | SWAP_F(usl13, usl23); |
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324 | SWAP_F(vsl13, vsl23); |
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325 | } |
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326 | |
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327 | float tus = (ub - ua) / ((float)xb - xa); |
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328 | float tvs = (vb - va) / ((float)xb - xa); |
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329 | u = ua; v = va; |
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330 | |
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331 | /* scanline */ |
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332 | for(x = xa ; x < xb; x++) |
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333 | { |
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334 | u+=tus; |
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335 | v+=tvs; |
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336 | /* FIXME, can be heavily optimised */ |
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337 | uint32_t attr = caca_get_attr(tex, u, v); |
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338 | uint32_t c = caca_get_char(tex, u, v); |
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339 | caca_set_attr(cv, attr); |
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340 | caca_put_char(cv, x, y, c); |
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341 | } |
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342 | |
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343 | xa+=sl13; |
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344 | xb+=sl23; |
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345 | |
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346 | ua+=usl13; va+=vsl13; |
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347 | ub+=usl23; vb+=vsl23; |
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348 | } |
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349 | |
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350 | return 0; |
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351 | } |
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352 | |
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353 | |
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354 | /* |
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355 | * XXX: The following functions are aliases. |
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356 | */ |
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357 | |
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358 | int cucul_draw_triangle(cucul_canvas_t *, int, int, int, int, int, |
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359 | int, uint32_t) CACA_ALIAS(caca_draw_triangle); |
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360 | int cucul_draw_thin_triangle(cucul_canvas_t *, int, int, int, int, |
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361 | int, int) CACA_ALIAS(caca_draw_thin_triangle); |
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362 | int cucul_fill_triangle(cucul_canvas_t *, int, int, int, int, int, |
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363 | int, uint32_t) CACA_ALIAS(caca_fill_triangle); |
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364 | |
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