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 | * This library is free software; you can redistribute it and/or |
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7 | * modify it under the terms of the GNU Lesser General Public |
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8 | * License as published by the Free Software Foundation; either |
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9 | * version 2 of the License, or (at your option) any later version. |
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10 | * |
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11 | * This library is distributed in the hope that it will be useful, |
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 | * Lesser General Public License for more details. |
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15 | * |
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16 | * You should have received a copy of the GNU Lesser General Public |
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17 | * License along with this library; if not, write to the Free Software |
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18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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19 | * 02111-1307 USA |
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20 | */ |
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21 | |
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22 | /** \file conic.c |
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23 | * \version \$Id: conic.c 205 2003-11-22 12:45:25Z sam $ |
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24 | * \author Sam Hocevar <sam@zoy.org> |
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25 | * \brief Ellipse and circle drawing functions |
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26 | * |
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27 | * This file contains ellipse and circle drawing functions, both filled |
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28 | * and outline. |
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29 | */ |
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30 | |
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31 | #include "config.h" |
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32 | |
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33 | #ifdef HAVE_INTTYPES_H |
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34 | # include <inttypes.h> |
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35 | #else |
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36 | typedef unsigned char uint8_t; |
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37 | #endif |
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38 | |
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39 | #include <stdlib.h> |
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40 | |
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41 | #include "caca.h" |
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42 | #include "caca_internals.h" |
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43 | |
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44 | static void ellipsepoints(int, int, int, int, char); |
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45 | |
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46 | void caca_draw_circle(int x, int y, int r, char c) |
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47 | { |
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48 | int test, dx, dy; |
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49 | |
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50 | /* Optimized Bresenham. Kick ass. */ |
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51 | for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++) |
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52 | { |
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53 | ellipsepoints(x, y, dx, dy, c); |
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54 | ellipsepoints(x, y, dy, dx, c); |
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55 | |
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56 | test += test > 0 ? dx - dy-- : dx; |
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57 | } |
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58 | } |
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59 | |
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60 | void caca_fill_ellipse(int xo, int yo, int a, int b, char c) |
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61 | { |
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62 | int d2; |
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63 | int x = 0; |
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64 | int y = b; |
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65 | int d1 = b*b - (a*a*b) + (a*a/4); |
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66 | |
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67 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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68 | { |
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69 | if(d1 < 0) |
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70 | { |
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71 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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72 | } |
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73 | else |
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74 | { |
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75 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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76 | caca_draw_line(xo - x, yo - y, xo + x, yo - y, c); |
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77 | caca_draw_line(xo - x, yo + y, xo + x, yo + y, c); |
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78 | y--; |
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79 | } |
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80 | x++; |
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81 | } |
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82 | |
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83 | caca_draw_line(xo - x, yo - y, xo + x, yo - y, c); |
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84 | caca_draw_line(xo - x, yo + y, xo + x, yo + y, c); |
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85 | |
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86 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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87 | while(y > 0) |
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88 | { |
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89 | if(d2 < 0) |
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90 | { |
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91 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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92 | x++; |
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93 | } |
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94 | else |
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95 | { |
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96 | d2 += a*a*(-2*y+3); |
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97 | } |
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98 | |
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99 | y--; |
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100 | caca_draw_line(xo - x, yo - y, xo + x, yo - y, c); |
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101 | caca_draw_line(xo - x, yo + y, xo + x, yo + y, c); |
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102 | } |
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103 | } |
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104 | |
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105 | void caca_draw_ellipse(int xo, int yo, int a, int b, char c) |
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106 | { |
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107 | int d2; |
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108 | int x = 0; |
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109 | int y = b; |
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110 | int d1 = b*b - (a*a*b) + (a*a/4); |
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111 | |
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112 | ellipsepoints(xo, yo, x, y, c); |
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113 | |
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114 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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115 | { |
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116 | if(d1 < 0) |
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117 | { |
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118 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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119 | } |
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120 | else |
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121 | { |
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122 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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123 | y--; |
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124 | } |
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125 | x++; |
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126 | ellipsepoints(xo, yo, x, y, c); |
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127 | } |
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128 | |
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129 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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130 | while(y > 0) |
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131 | { |
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132 | if(d2 < 0) |
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133 | { |
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134 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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135 | x++; |
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136 | } |
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137 | else |
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138 | { |
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139 | d2 += a*a*(-2*y+3); |
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140 | } |
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141 | |
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142 | y--; |
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143 | ellipsepoints(xo, yo, x, y, c); |
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144 | } |
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145 | } |
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146 | |
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147 | void caca_draw_thin_ellipse(int xo, int yo, int a, int b) |
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148 | { |
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149 | /* FIXME: this is not correct */ |
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150 | int d2; |
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151 | int x = 0; |
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152 | int y = b; |
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153 | int d1 = b*b - (a*a*b) + (a*a/4); |
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154 | |
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155 | ellipsepoints(xo, yo, x, y, '-'); |
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156 | |
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157 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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158 | { |
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159 | if(d1 < 0) |
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160 | { |
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161 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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162 | } |
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163 | else |
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164 | { |
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165 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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166 | y--; |
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167 | } |
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168 | x++; |
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169 | ellipsepoints(xo, yo, x, y, '-'); |
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170 | } |
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171 | |
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172 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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173 | while(y > 0) |
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174 | { |
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175 | if(d2 < 0) |
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176 | { |
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177 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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178 | x++; |
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179 | } |
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180 | else |
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181 | { |
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182 | d2 += a*a*(-2*y+3); |
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183 | } |
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184 | |
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185 | y--; |
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186 | ellipsepoints(xo, yo, x, y, '|'); |
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187 | } |
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188 | } |
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189 | |
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190 | static void ellipsepoints(int xo, int yo, int x, int y, char c) |
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191 | { |
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192 | uint8_t b = 0; |
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193 | |
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194 | if(xo + x >= 0 && xo + x < (int)caca_get_width()) |
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195 | b |= 0x1; |
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196 | if(xo - x >= 0 && xo - x < (int)caca_get_width()) |
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197 | b |= 0x2; |
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198 | if(yo + y >= 0 && yo + y < (int)caca_get_height()) |
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199 | b |= 0x4; |
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200 | if(yo - y >= 0 && yo - y < (int)caca_get_height()) |
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201 | b |= 0x8; |
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202 | |
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203 | if((b & (0x1|0x4)) == (0x1|0x4)) |
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204 | caca_putchar(xo + x, yo + y, c); |
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205 | |
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206 | if((b & (0x2|0x4)) == (0x2|0x4)) |
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207 | caca_putchar(xo - x, yo + y, c); |
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208 | |
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209 | if((b & (0x1|0x8)) == (0x1|0x8)) |
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210 | caca_putchar(xo + x, yo - y, c); |
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211 | |
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212 | if((b & (0x2|0x8)) == (0x2|0x8)) |
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213 | caca_putchar(xo - x, yo - y, c); |
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214 | } |
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215 | |
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