1 | /* |
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2 | * libcucul Canvas for ultrafast compositing of Unicode letters |
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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 2313 2008-04-23 21:24:34Z sam $ |
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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 "cucul.h" |
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26 | #include "cucul_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 libcucul 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 cucul_draw_triangle(cucul_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 | cucul_draw_line(cv, x1, y1, x2, y2, ch); |
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46 | cucul_draw_line(cv, x2, y2, x3, y3, ch); |
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47 | cucul_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 libcucul 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 cucul_draw_thin_triangle(cucul_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 | cucul_draw_thin_line(cv, x1, y1, x2, y2); |
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69 | cucul_draw_thin_line(cv, x2, y2, x3, y3); |
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70 | cucul_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 libcucul 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 cucul_fill_triangle(cucul_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 cucul_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 cucul_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 | cucul_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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