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: line.c 1452 2006-12-11 15:48:46Z sam $ |
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7 | * |
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8 | * This library is free software. It commes 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 line and polyline drawing functions, with both thin |
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17 | * and thick styles. |
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18 | */ |
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19 | |
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20 | #include "config.h" |
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21 | #include "common.h" |
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22 | |
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23 | #if !defined(__KERNEL__) |
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24 | # include <stdlib.h> |
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25 | #endif |
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26 | |
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27 | #include "cucul.h" |
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28 | #include "cucul_internals.h" |
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29 | |
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30 | #if !defined(_DOXYGEN_SKIP_ME) |
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31 | struct line |
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32 | { |
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33 | int x1, y1; |
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34 | int x2, y2; |
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35 | uint32_t ch; |
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36 | void (*draw) (cucul_canvas_t *, struct line*); |
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37 | }; |
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38 | #endif |
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39 | |
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40 | static void clip_line(cucul_canvas_t*, struct line*); |
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41 | static uint8_t clip_bits(cucul_canvas_t*, int, int); |
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42 | static void draw_solid_line(cucul_canvas_t*, struct line*); |
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43 | static void draw_thin_line(cucul_canvas_t*, struct line*); |
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44 | |
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45 | /** \brief Draw a line on the canvas using the given character. |
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46 | * |
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47 | * This function never fails. |
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48 | * |
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49 | * \param cv The handle to the libcucul canvas. |
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50 | * \param x1 X coordinate of the first point. |
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51 | * \param y1 Y coordinate of the first point. |
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52 | * \param x2 X coordinate of the second point. |
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53 | * \param y2 Y coordinate of the second point. |
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54 | * \param ch UTF-32 character to be used to draw the line. |
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55 | * \return This function always returns 0. |
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56 | */ |
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57 | int cucul_draw_line(cucul_canvas_t *cv, int x1, int y1, int x2, int y2, |
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58 | unsigned long int ch) |
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59 | { |
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60 | struct line s; |
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61 | s.x1 = x1; |
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62 | s.y1 = y1; |
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63 | s.x2 = x2; |
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64 | s.y2 = y2; |
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65 | s.ch = ch; |
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66 | s.draw = draw_solid_line; |
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67 | clip_line(cv, &s); |
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68 | |
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69 | return 0; |
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70 | } |
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71 | |
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72 | /** \brief Draw a polyline. |
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73 | * |
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74 | * Draw a plyline on the canvas using the given character and coordinate |
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75 | * arrays. The first and last points are not connected, hence in order to |
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76 | * draw a polygon you need to specify the starting point at the end of the |
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77 | * list as well. |
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78 | * |
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79 | * This function never fails. |
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80 | * |
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81 | * \param cv The handle to the libcucul canvas. |
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82 | * \param x Array of X coordinates. Must have \p n + 1 elements. |
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83 | * \param y Array of Y coordinates. Must have \p n + 1 elements. |
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84 | * \param n Number of lines to draw. |
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85 | * \param ch UTF-32 character to be used to draw the lines. |
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86 | * \return This function always returns 0. |
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87 | */ |
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88 | int cucul_draw_polyline(cucul_canvas_t *cv, int const x[], int const y[], |
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89 | int n, unsigned long int ch) |
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90 | { |
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91 | int i; |
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92 | struct line s; |
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93 | s.ch = ch; |
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94 | s.draw = draw_solid_line; |
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95 | |
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96 | for(i = 0; i < n; i++) |
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97 | { |
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98 | s.x1 = x[i]; |
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99 | s.y1 = y[i]; |
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100 | s.x2 = x[i+1]; |
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101 | s.y2 = y[i+1]; |
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102 | clip_line(cv, &s); |
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103 | } |
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104 | |
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105 | return 0; |
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106 | } |
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107 | |
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108 | /** \brief Draw a thin line on the canvas, using ASCII art. |
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109 | * |
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110 | * This function never fails. |
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111 | * |
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112 | * \param cv The handle to the libcucul canvas. |
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113 | * \param x1 X coordinate of the first point. |
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114 | * \param y1 Y coordinate of the first point. |
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115 | * \param x2 X coordinate of the second point. |
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116 | * \param y2 Y coordinate of the second point. |
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117 | * \return This function always returns 0. |
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118 | */ |
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119 | int cucul_draw_thin_line(cucul_canvas_t *cv, int x1, int y1, int x2, int y2) |
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120 | { |
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121 | struct line s; |
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122 | s.x1 = x1; |
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123 | s.y1 = y1; |
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124 | s.x2 = x2; |
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125 | s.y2 = y2; |
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126 | s.draw = draw_thin_line; |
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127 | clip_line(cv, &s); |
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128 | |
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129 | return 0; |
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130 | } |
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131 | |
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132 | /** \brief Draw an ASCII art thin polyline. |
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133 | * |
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134 | * Draw a thin polyline on the canvas using the given coordinate arrays and |
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135 | * with ASCII art. The first and last points are not connected, so in order |
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136 | * to draw a polygon you need to specify the starting point at the end of |
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137 | * the list as well. |
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138 | * |
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139 | * This function never fails. |
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140 | * |
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141 | * \param cv The handle to the libcucul canvas. |
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142 | * \param x Array of X coordinates. Must have \p n + 1 elements. |
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143 | * \param y Array of Y coordinates. Must have \p n + 1 elements. |
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144 | * \param n Number of lines to draw. |
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145 | * \return This function always returns 0. |
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146 | */ |
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147 | int cucul_draw_thin_polyline(cucul_canvas_t *cv, int const x[], int const y[], |
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148 | int n) |
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149 | { |
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150 | int i; |
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151 | struct line s; |
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152 | s.draw = draw_thin_line; |
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153 | |
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154 | for(i = 0; i < n; i++) |
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155 | { |
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156 | s.x1 = x[i]; |
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157 | s.y1 = y[i]; |
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158 | s.x2 = x[i+1]; |
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159 | s.y2 = y[i+1]; |
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160 | clip_line(cv, &s); |
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161 | } |
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162 | |
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163 | return 0; |
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164 | } |
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165 | |
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166 | /* |
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167 | * XXX: The following functions are local. |
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168 | */ |
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169 | |
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170 | /* Generic Cohen-Sutherland line clipping function. */ |
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171 | static void clip_line(cucul_canvas_t *cv, struct line* s) |
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172 | { |
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173 | uint8_t bits1, bits2; |
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174 | |
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175 | bits1 = clip_bits(cv, s->x1, s->y1); |
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176 | bits2 = clip_bits(cv, s->x2, s->y2); |
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177 | |
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178 | if(bits1 & bits2) |
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179 | return; |
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180 | |
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181 | if(bits1 == 0) |
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182 | { |
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183 | if(bits2 == 0) |
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184 | s->draw(cv, s); |
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185 | else |
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186 | { |
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187 | int tmp; |
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188 | tmp = s->x1; s->x1 = s->x2; s->x2 = tmp; |
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189 | tmp = s->y1; s->y1 = s->y2; s->y2 = tmp; |
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190 | clip_line(cv, s); |
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191 | } |
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192 | |
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193 | return; |
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194 | } |
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195 | |
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196 | if(bits1 & (1<<0)) |
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197 | { |
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198 | s->y1 = s->y2 - (s->x2 - 0) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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199 | s->x1 = 0; |
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200 | } |
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201 | else if(bits1 & (1<<1)) |
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202 | { |
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203 | int xmax = cv->width - 1; |
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204 | s->y1 = s->y2 - (s->x2 - xmax) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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205 | s->x1 = xmax; |
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206 | } |
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207 | else if(bits1 & (1<<2)) |
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208 | { |
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209 | s->x1 = s->x2 - (s->y2 - 0) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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210 | s->y1 = 0; |
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211 | } |
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212 | else if(bits1 & (1<<3)) |
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213 | { |
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214 | int ymax = cv->height - 1; |
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215 | s->x1 = s->x2 - (s->y2 - ymax) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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216 | s->y1 = ymax; |
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217 | } |
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218 | |
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219 | clip_line(cv, s); |
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220 | } |
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221 | |
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222 | /* Helper function for clip_line(). */ |
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223 | static uint8_t clip_bits(cucul_canvas_t *cv, int x, int y) |
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224 | { |
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225 | uint8_t b = 0; |
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226 | |
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227 | if(x < 0) |
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228 | b |= (1<<0); |
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229 | else if(x >= (int)cv->width) |
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230 | b |= (1<<1); |
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231 | |
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232 | if(y < 0) |
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233 | b |= (1<<2); |
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234 | else if(y >= (int)cv->height) |
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235 | b |= (1<<3); |
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236 | |
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237 | return b; |
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238 | } |
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239 | |
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240 | /* Solid line drawing function, using Bresenham's mid-point line |
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241 | * scan-conversion algorithm. */ |
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242 | static void draw_solid_line(cucul_canvas_t *cv, struct line* s) |
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243 | { |
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244 | int x1, y1, x2, y2; |
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245 | int dx, dy; |
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246 | int xinc, yinc; |
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247 | |
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248 | x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2; |
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249 | |
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250 | dx = abs(x2 - x1); |
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251 | dy = abs(y2 - y1); |
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252 | |
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253 | xinc = (x1 > x2) ? -1 : 1; |
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254 | yinc = (y1 > y2) ? -1 : 1; |
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255 | |
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256 | if(dx >= dy) |
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257 | { |
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258 | int dpr = dy << 1; |
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259 | int dpru = dpr - (dx << 1); |
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260 | int delta = dpr - dx; |
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261 | |
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262 | for(; dx>=0; dx--) |
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263 | { |
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264 | cucul_put_char(cv, x1, y1, s->ch); |
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265 | if(delta > 0) |
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266 | { |
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267 | x1 += xinc; |
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268 | y1 += yinc; |
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269 | delta += dpru; |
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270 | } |
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271 | else |
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272 | { |
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273 | x1 += xinc; |
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274 | delta += dpr; |
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275 | } |
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276 | } |
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277 | } |
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278 | else |
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279 | { |
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280 | int dpr = dx << 1; |
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281 | int dpru = dpr - (dy << 1); |
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282 | int delta = dpr - dy; |
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283 | |
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284 | for(; dy >= 0; dy--) |
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285 | { |
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286 | cucul_put_char(cv, x1, y1, s->ch); |
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287 | if(delta > 0) |
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288 | { |
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289 | x1 += xinc; |
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290 | y1 += yinc; |
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291 | delta += dpru; |
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292 | } |
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293 | else |
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294 | { |
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295 | y1 += yinc; |
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296 | delta += dpr; |
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297 | } |
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298 | } |
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299 | } |
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300 | } |
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301 | |
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302 | /* Thin line drawing function, using Bresenham's mid-point line |
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303 | * scan-conversion algorithm and ASCII art graphics. */ |
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304 | static void draw_thin_line(cucul_canvas_t *cv, struct line* s) |
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305 | { |
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306 | uint32_t charmapx[2], charmapy[2]; |
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307 | int x1, y1, x2, y2; |
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308 | int dx, dy; |
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309 | int yinc; |
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310 | |
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311 | if(s->x2 >= s->x1) |
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312 | { |
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313 | charmapx[0] = (s->y1 > s->y2) ? ',' : '`'; |
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314 | charmapx[1] = (s->y1 > s->y2) ? '\'' : '.'; |
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315 | x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2; |
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316 | } |
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317 | else |
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318 | { |
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319 | charmapx[0] = (s->y1 > s->y2) ? '`' : '.'; |
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320 | charmapx[1] = (s->y1 > s->y2) ? ',' : '\''; |
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321 | x2 = s->x1; y2 = s->y1; x1 = s->x2; y1 = s->y2; |
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322 | } |
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323 | |
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324 | dx = abs(x2 - x1); |
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325 | dy = abs(y2 - y1); |
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326 | |
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327 | if(y1 > y2) |
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328 | { |
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329 | charmapy[0] = ','; |
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330 | charmapy[1] = '\''; |
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331 | yinc = -1; |
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332 | } |
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333 | else |
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334 | { |
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335 | yinc = 1; |
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336 | charmapy[0] = '`'; |
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337 | charmapy[1] = '.'; |
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338 | } |
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339 | |
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340 | if(dx >= dy) |
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341 | { |
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342 | int dpr = dy << 1; |
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343 | int dpru = dpr - (dx << 1); |
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344 | int delta = dpr - dx; |
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345 | int prev = 0; |
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346 | |
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347 | for(; dx>=0; dx--) |
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348 | { |
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349 | if(delta > 0) |
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350 | { |
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351 | cucul_put_char(cv, x1, y1, charmapy[1]); |
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352 | x1++; |
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353 | y1 += yinc; |
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354 | delta += dpru; |
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355 | prev = 1; |
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356 | } |
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357 | else |
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358 | { |
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359 | if(prev) |
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360 | cucul_put_char(cv, x1, y1, charmapy[0]); |
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361 | else |
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362 | cucul_put_char(cv, x1, y1, '-'); |
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363 | x1++; |
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364 | delta += dpr; |
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365 | prev = 0; |
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366 | } |
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367 | } |
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368 | } |
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369 | else |
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370 | { |
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371 | int dpr = dx << 1; |
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372 | int dpru = dpr - (dy << 1); |
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373 | int delta = dpr - dy; |
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374 | |
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375 | for(; dy >= 0; dy--) |
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376 | { |
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377 | if(delta > 0) |
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378 | { |
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379 | cucul_put_char(cv, x1, y1, charmapx[0]); |
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380 | cucul_put_char(cv, x1 + 1, y1, charmapx[1]); |
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381 | x1++; |
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382 | y1 += yinc; |
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383 | delta += dpru; |
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384 | } |
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385 | else |
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386 | { |
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387 | cucul_put_char(cv, x1, y1, '|'); |
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388 | y1 += yinc; |
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389 | delta += dpr; |
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390 | } |
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391 | } |
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392 | } |
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393 | } |
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394 | |
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