1 | /* |
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2 | * libcaca ASCII-Art library |
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3 | * Copyright (c) 2002, 2003 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 185 2003-11-16 00:33:35Z sam $ |
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7 | * |
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8 | * This program is free software; you can redistribute it and/or modify |
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9 | * it under the terms of the GNU General Public License as published by |
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10 | * the Free Software Foundation; either version 2 of the License, or |
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11 | * (at your option) any later version. |
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12 | * |
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13 | * This program is distributed in the hope that it will be useful, |
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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16 | * GNU General Public License for more details. |
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17 | * |
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18 | * You should have received a copy of the GNU General Public License |
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19 | * along with this program; if not, write to the Free Software |
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20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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21 | */ |
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22 | |
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23 | #include "config.h" |
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24 | |
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25 | #ifdef HAVE_INTTYPES_H |
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26 | # include <inttypes.h> |
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27 | #else |
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28 | typedef unsigned char uint8_t; |
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29 | #endif |
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30 | |
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31 | #include <stdlib.h> |
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32 | |
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33 | #include "caca.h" |
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34 | #include "caca_internals.h" |
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35 | |
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36 | struct line |
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37 | { |
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38 | int x1, y1; |
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39 | int x2, y2; |
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40 | char c; |
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41 | void (*draw) (struct line*); |
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42 | }; |
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43 | |
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44 | static void clip_line(struct line*); |
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45 | static uint8_t clip_bits(int, int); |
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46 | static void draw_solid_line(struct line*); |
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47 | static void draw_thin_line(struct line*); |
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48 | |
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49 | /** |
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50 | * \brief Draw a line on the screen using the given character. |
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51 | * |
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52 | * \param x1 X coordinate of the first point. |
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53 | * \param y1 Y coordinate of the first point. |
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54 | * \param x2 X coordinate of the second point. |
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55 | * \param y2 Y coordinate of the second point. |
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56 | * \param c Character to draw the line with. |
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57 | * \return nothing |
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58 | */ |
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59 | void caca_draw_line(int x1, int y1, int x2, int y2, char c) |
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60 | { |
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61 | struct line s; |
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62 | s.x1 = x1; |
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63 | s.y1 = y1; |
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64 | s.x2 = x2; |
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65 | s.y2 = y2; |
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66 | s.c = c; |
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67 | s.draw = draw_solid_line; |
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68 | clip_line(&s); |
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69 | } |
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70 | |
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71 | void caca_draw_polyline(const int x[], const int y[], int n, char c) |
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72 | { |
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73 | int i; |
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74 | struct line s; |
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75 | s.c = c; |
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76 | s.draw = draw_solid_line; |
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77 | |
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78 | for(i = 0; i < n; i++) |
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79 | { |
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80 | s.x1 = x[i]; |
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81 | s.y1 = y[i]; |
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82 | s.x2 = x[i+1]; |
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83 | s.y2 = y[i+1]; |
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84 | clip_line(&s); |
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85 | } |
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86 | } |
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87 | |
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88 | /** |
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89 | * \brief Draw a thin line on the screen, using ASCII art. |
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90 | * |
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91 | * \param x1 X coordinate of the first point. |
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92 | * \param y1 Y coordinate of the first point. |
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93 | * \param x2 X coordinate of the second point. |
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94 | * \param y2 Y coordinate of the second point. |
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95 | * \return nothing |
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96 | */ |
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97 | void caca_draw_thin_line(int x1, int y1, int x2, int y2) |
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98 | { |
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99 | struct line s; |
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100 | s.x1 = x1; |
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101 | s.y1 = y1; |
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102 | s.x2 = x2; |
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103 | s.y2 = y2; |
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104 | s.draw = draw_thin_line; |
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105 | clip_line(&s); |
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106 | } |
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107 | |
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108 | void caca_draw_thin_polyline(const int x[], const int y[], int n) |
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109 | { |
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110 | int i; |
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111 | struct line s; |
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112 | s.draw = draw_thin_line; |
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113 | |
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114 | for(i = 0; i < n; i++) |
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115 | { |
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116 | s.x1 = x[i]; |
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117 | s.y1 = y[i]; |
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118 | s.x2 = x[i+1]; |
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119 | s.y2 = y[i+1]; |
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120 | clip_line(&s); |
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121 | } |
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122 | } |
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123 | |
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124 | /* |
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125 | * XXX: The following functions are local. |
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126 | */ |
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127 | |
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128 | /** |
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129 | * \brief Generic Cohen-Sutherland line clipping function. |
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130 | * |
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131 | * \param s a line structure |
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132 | * \return nothing |
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133 | */ |
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134 | static void clip_line(struct line* s) |
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135 | { |
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136 | uint8_t bits1, bits2; |
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137 | |
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138 | bits1 = clip_bits(s->x1, s->y1); |
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139 | bits2 = clip_bits(s->x2, s->y2); |
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140 | |
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141 | if(bits1 & bits2) |
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142 | return; |
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143 | |
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144 | if(bits1 == 0) |
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145 | { |
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146 | if(bits2 == 0) |
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147 | s->draw(s); |
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148 | else |
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149 | { |
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150 | int tmp; |
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151 | tmp = s->x1; s->x1 = s->x2; s->x2 = tmp; |
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152 | tmp = s->y1; s->y1 = s->y2; s->y2 = tmp; |
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153 | clip_line(s); |
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154 | } |
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155 | |
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156 | return; |
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157 | } |
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158 | |
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159 | if(bits1 & (1<<0)) |
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160 | { |
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161 | s->y1 = s->y2 - (s->x2 - 0) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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162 | s->x1 = 0; |
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163 | } |
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164 | else if(bits1 & (1<<1)) |
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165 | { |
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166 | int xmax = caca_get_width() - 1; |
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167 | s->y1 = s->y2 - (s->x2 - xmax) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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168 | s->x1 = xmax; |
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169 | } |
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170 | else if(bits1 & (1<<2)) |
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171 | { |
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172 | s->x1 = s->x2 - (s->y2 - 0) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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173 | s->y1 = 0; |
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174 | } |
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175 | else if(bits1 & (1<<3)) |
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176 | { |
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177 | int ymax = caca_get_height() - 1; |
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178 | s->x1 = s->x2 - (s->y2 - ymax) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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179 | s->y1 = ymax; |
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180 | } |
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181 | |
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182 | clip_line(s); |
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183 | } |
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184 | |
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185 | /** |
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186 | * \brief Helper function for clip_line(). |
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187 | * |
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188 | * \param x X coordinate of the point. |
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189 | * \param y Y coordinate of the point. |
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190 | * \return b The clipping bits for the given point. |
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191 | */ |
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192 | static uint8_t clip_bits(int x, int y) |
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193 | { |
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194 | uint8_t b = 0; |
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195 | |
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196 | if(x < 0) |
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197 | b |= (1<<0); |
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198 | else if(x >= caca_get_width()) |
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199 | b |= (1<<1); |
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200 | |
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201 | if(y < 0) |
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202 | b |= (1<<2); |
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203 | else if(y >= caca_get_height()) |
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204 | b |= (1<<3); |
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205 | |
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206 | return b; |
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207 | } |
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208 | |
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209 | /** |
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210 | * \brief Solid line drawing function, using Bresenham's mid-point line |
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211 | * scan-conversion algorithm. |
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212 | * |
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213 | * \param s a line structure |
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214 | * \return nothing |
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215 | */ |
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216 | static void draw_solid_line(struct line* s) |
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217 | { |
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218 | int x1, y1, x2, y2; |
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219 | int dx, dy; |
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220 | int xinc, yinc; |
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221 | |
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222 | x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2; |
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223 | |
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224 | dx = abs(x2 - x1); |
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225 | dy = abs(y2 - y1); |
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226 | |
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227 | xinc = (x1 > x2) ? -1 : 1; |
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228 | yinc = (y1 > y2) ? -1 : 1; |
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229 | |
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230 | if(dx >= dy) |
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231 | { |
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232 | int dpr = dy << 1; |
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233 | int dpru = dpr - (dx << 1); |
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234 | int delta = dpr - dx; |
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235 | |
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236 | for(; dx>=0; dx--) |
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237 | { |
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238 | caca_putchar(x1, y1, s->c); |
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239 | if(delta > 0) |
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240 | { |
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241 | x1 += xinc; |
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242 | y1 += yinc; |
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243 | delta += dpru; |
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244 | } |
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245 | else |
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246 | { |
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247 | x1 += xinc; |
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248 | delta += dpr; |
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249 | } |
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250 | } |
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251 | } |
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252 | else |
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253 | { |
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254 | int dpr = dx << 1; |
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255 | int dpru = dpr - (dy << 1); |
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256 | int delta = dpr - dy; |
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257 | |
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258 | for(; dy >= 0; dy--) |
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259 | { |
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260 | caca_putchar(x1, y1, s->c); |
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261 | if(delta > 0) |
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262 | { |
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263 | x1 += xinc; |
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264 | y1 += yinc; |
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265 | delta += dpru; |
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266 | } |
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267 | else |
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268 | { |
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269 | y1 += yinc; |
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270 | delta += dpr; |
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271 | } |
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272 | } |
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273 | } |
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274 | } |
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275 | |
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276 | /** |
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277 | * \brief Thin line drawing function, using Bresenham's mid-point line |
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278 | * scan-conversion algorithm and ASCII art graphics. |
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279 | * |
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280 | * \param s a line structure |
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281 | * \return nothing |
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282 | */ |
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283 | static void draw_thin_line(struct line* s) |
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284 | { |
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285 | char *charmapx, *charmapy; |
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286 | int x1, y1, x2, y2; |
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287 | int dx, dy; |
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288 | int yinc; |
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289 | |
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290 | if(s->x2 >= s->x1) |
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291 | { |
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292 | if(s->y1 > s->y2) |
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293 | charmapx = ",'"; |
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294 | else |
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295 | charmapx = "`."; |
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296 | x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2; |
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297 | } |
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298 | else |
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299 | { |
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300 | if(s->y1 > s->y2) |
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301 | charmapx = "`."; |
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302 | else |
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303 | charmapx = ",'"; |
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304 | x2 = s->x1; y2 = s->y1; x1 = s->x2; y1 = s->y2; |
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305 | } |
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306 | |
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307 | dx = abs(x2 - x1); |
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308 | dy = abs(y2 - y1); |
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309 | |
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310 | if(y1 > y2) |
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311 | { |
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312 | charmapy = ",'"; |
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313 | yinc = -1; |
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314 | } |
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315 | else |
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316 | { |
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317 | yinc = 1; |
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318 | charmapy = "`."; |
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319 | } |
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320 | |
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321 | if(dx >= dy) |
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322 | { |
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323 | int dpr = dy << 1; |
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324 | int dpru = dpr - (dx << 1); |
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325 | int delta = dpr - dx; |
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326 | int prev = 0; |
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327 | |
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328 | for(; dx>=0; dx--) |
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329 | { |
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330 | if(delta > 0) |
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331 | { |
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332 | caca_putchar(x1, y1, charmapy[1]); |
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333 | x1++; |
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334 | y1 += yinc; |
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335 | delta += dpru; |
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336 | prev = 1; |
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337 | } |
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338 | else |
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339 | { |
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340 | if(prev) |
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341 | caca_putchar(x1, y1, charmapy[0]); |
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342 | else |
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343 | caca_putchar(x1, y1, '-'); |
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344 | x1++; |
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345 | delta += dpr; |
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346 | prev = 0; |
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347 | } |
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348 | } |
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349 | } |
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350 | else |
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351 | { |
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352 | int dpr = dx << 1; |
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353 | int dpru = dpr - (dy << 1); |
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354 | int delta = dpr - dy; |
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355 | |
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356 | for(; dy >= 0; dy--) |
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357 | { |
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358 | if(delta > 0) |
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359 | { |
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360 | caca_putchar(x1, y1, charmapx[0]); |
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361 | caca_putchar(x1 + 1, y1, charmapx[1]); |
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362 | x1++; |
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363 | y1 += yinc; |
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364 | delta += dpru; |
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365 | } |
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366 | else |
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367 | { |
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368 | caca_putchar(x1, y1, '|'); |
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369 | y1 += yinc; |
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370 | delta += dpr; |
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371 | } |
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372 | } |
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373 | } |
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374 | } |
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375 | |
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