1 | /* |
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2 | * libee 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 102 2003-11-09 18:10:44Z 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 | #include <inttypes.h> |
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26 | #include <stdlib.h> |
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27 | |
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28 | #include "ee.h" |
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29 | |
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30 | struct line |
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31 | { |
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32 | int x1, y1; |
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33 | int x2, y2; |
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34 | char c; |
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35 | void (*draw) (struct line*); |
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36 | }; |
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37 | |
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38 | static void clip_line(struct line*); |
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39 | static uint8_t clip_bits(int, int); |
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40 | static void draw_solid_line(struct line*); |
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41 | |
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42 | void ee_draw_line(int x1, int y1, int x2, int y2, char c) |
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43 | { |
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44 | struct line s; |
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45 | s.x1 = x1; |
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46 | s.y1 = y1; |
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47 | s.x2 = x2; |
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48 | s.y2 = y2; |
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49 | s.c = c; |
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50 | s.draw = draw_solid_line; |
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51 | clip_line(&s); |
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52 | } |
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53 | |
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54 | static void clip_line(struct line* s) |
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55 | { |
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56 | uint8_t bits1, bits2; |
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57 | |
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58 | bits1 = clip_bits(s->x1, s->y1); |
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59 | bits2 = clip_bits(s->x2, s->y2); |
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60 | |
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61 | if(bits1 & bits2) |
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62 | return; |
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63 | |
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64 | if(bits1 == 0) |
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65 | { |
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66 | if(bits2 == 0) |
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67 | s->draw(s); |
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68 | else |
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69 | { |
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70 | int tmp; |
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71 | tmp = s->x1; s->x1 = s->x2; s->x2 = tmp; |
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72 | tmp = s->y1; s->y1 = s->y2; s->y2 = tmp; |
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73 | clip_line(s); |
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74 | } |
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75 | |
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76 | return; |
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77 | } |
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78 | |
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79 | if(bits1 & (1<<0)) |
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80 | { |
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81 | s->y1 = s->y2 - (s->x2 - 0) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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82 | s->x1 = 0; |
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83 | } |
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84 | else if( bits1 & (1<<1) ) |
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85 | { |
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86 | int xmax = ee_get_width() - 1; |
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87 | s->y1 = s->y2 - (s->x2 - xmax) * (s->y2 - s->y1) / (s->x2 - s->x1); |
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88 | s->x1 = xmax; |
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89 | } |
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90 | else if( bits1 & (1<<2) ) |
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91 | { |
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92 | s->x1 = s->x2 - (s->y2 - 0) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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93 | s->y1 = 0; |
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94 | } |
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95 | else if( bits1 & (1<<3) ) |
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96 | { |
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97 | int ymax = ee_get_height() - 1; |
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98 | s->x1 = s->x2 - (s->y2 - ymax) * (s->x2 - s->x1) / (s->y2 - s->y1); |
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99 | s->y1 = ymax; |
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100 | } |
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101 | |
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102 | clip_line(s); |
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103 | } |
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104 | |
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105 | static uint8_t clip_bits(int x, int y) |
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106 | { |
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107 | uint8_t b = 0; |
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108 | |
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109 | if(x < 0) |
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110 | b |= (1<<0); |
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111 | else if(x >= ee_get_width()) |
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112 | b |= (1<<1); |
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113 | |
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114 | if(y < 0) |
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115 | b |= (1<<2); |
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116 | else if(y >= ee_get_height()) |
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117 | b |= (1<<3); |
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118 | |
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119 | return b; |
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120 | } |
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121 | |
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122 | static void draw_solid_line(struct line* s) |
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123 | { |
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124 | int x1 = s->x1; |
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125 | int y1 = s->y1; |
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126 | int x2 = s->x2; |
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127 | int y2 = s->y2; |
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128 | |
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129 | int dx = abs(x2-x1); |
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130 | int dy = abs(y2-y1); |
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131 | |
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132 | int xinc, yinc; |
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133 | |
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134 | xinc = (x1 > x2) ? -1 : 1; |
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135 | yinc = (y1 > y2) ? -1 : 1; |
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136 | |
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137 | if(dx >= dy) |
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138 | { |
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139 | int dpr = dy << 1; |
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140 | int dpru = dpr - (dx << 1); |
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141 | int delta = dpr - dx; |
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142 | |
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143 | for(; dx>=0; dx--) |
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144 | { |
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145 | ee_goto(x1, y1); |
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146 | ee_putchar(s->c); |
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147 | if(delta > 0) |
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148 | { |
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149 | x1 += xinc; |
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150 | y1 += yinc; |
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151 | delta += dpru; |
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152 | } |
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153 | else |
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154 | { |
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155 | x1 += xinc; |
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156 | delta += dpr; |
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157 | } |
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158 | } |
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159 | } |
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160 | else |
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161 | { |
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162 | int dpr = dx << 1; |
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163 | int dpru = dpr - (dy << 1); |
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164 | int delta = dpr - dy; |
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165 | |
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166 | for(; dy >= 0; dy--) |
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167 | { |
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168 | ee_goto(x1, y1); |
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169 | ee_putchar(s->c); |
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170 | if(delta > 0) |
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171 | { |
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172 | x1 += xinc; |
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173 | y1 += yinc; |
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174 | delta += dpru; |
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175 | } |
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176 | else |
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177 | { |
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178 | y1 += yinc; |
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179 | delta += dpr; |
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180 | } |
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181 | } |
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182 | } |
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183 | } |
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184 | |
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