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: conic.c 982 2006-05-25 20:01:10Z sam $ |
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7 | * |
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8 | * This library is free software; you can redistribute it and/or |
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9 | * modify it under the terms of the Do What The Fuck You Want To |
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10 | * Public License, Version 2, as published by Sam Hocevar. See |
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11 | * http://sam.zoy.org/wtfpl/COPYING for more details. |
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12 | */ |
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13 | |
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14 | /* |
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15 | * This file contains ellipse and circle drawing functions, both filled |
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16 | * 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 | #include "common.h" |
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21 | |
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22 | #if !defined(__KERNEL__) |
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23 | # include <stdlib.h> |
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24 | #endif |
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25 | |
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26 | #include "cucul.h" |
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27 | #include "cucul_internals.h" |
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28 | |
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29 | static void ellipsepoints(cucul_canvas_t *, int, int, int, int, uint32_t); |
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30 | |
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31 | /** \brief Draw a circle on the canvas using the given character. |
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32 | * |
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33 | * This function never fails. |
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34 | * |
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35 | * \param cv The handle to the libcucul canvas. |
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36 | * \param x Center X coordinate. |
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37 | * \param y Center Y coordinate. |
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38 | * \param r Circle radius. |
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39 | * \param str UTF-8 string representing the character that should be used |
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40 | * to draw the circle outline. |
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41 | * \return This function always returns 0. |
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42 | */ |
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43 | int cucul_draw_circle(cucul_canvas_t *cv, int x, int y, int r, char const *str) |
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44 | { |
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45 | int test, dx, dy; |
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46 | uint32_t ch = cucul_utf8_to_utf32(str, NULL); |
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47 | |
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48 | /* Optimized Bresenham. Kick ass. */ |
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49 | for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++) |
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50 | { |
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51 | ellipsepoints(cv, x, y, dx, dy, ch); |
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52 | ellipsepoints(cv, x, y, dy, dx, ch); |
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53 | |
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54 | test += test > 0 ? dx - dy-- : dx; |
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55 | } |
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56 | |
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57 | return 0; |
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58 | } |
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59 | |
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60 | /** \brief Fill an ellipse on the canvas using the given character. |
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61 | * |
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62 | * This function never fails. |
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63 | * |
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64 | * \param cv The handle to the libcucul canvas. |
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65 | * \param xo Center X coordinate. |
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66 | * \param yo Center Y coordinate. |
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67 | * \param a Ellipse X radius. |
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68 | * \param b Ellipse Y radius. |
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69 | * \param str UTF-8 string representing the character that should be used |
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70 | * to fill the ellipse. |
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71 | * \return This function always returns 0. |
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72 | */ |
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73 | int cucul_fill_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b, |
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74 | char const *str) |
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75 | { |
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76 | int d2; |
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77 | int x = 0; |
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78 | int y = b; |
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79 | int d1 = b*b - (a*a*b) + (a*a/4); |
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80 | |
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81 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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82 | { |
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83 | if(d1 < 0) |
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84 | { |
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85 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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86 | } |
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87 | else |
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88 | { |
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89 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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90 | cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str); |
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91 | cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str); |
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92 | y--; |
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93 | } |
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94 | x++; |
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95 | } |
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96 | |
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97 | cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str); |
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98 | cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str); |
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99 | |
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100 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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101 | while(y > 0) |
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102 | { |
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103 | if(d2 < 0) |
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104 | { |
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105 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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106 | x++; |
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107 | } |
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108 | else |
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109 | { |
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110 | d2 += a*a*(-2*y+3); |
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111 | } |
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112 | |
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113 | y--; |
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114 | cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str); |
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115 | cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str); |
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116 | } |
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117 | |
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118 | return 0; |
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119 | } |
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120 | |
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121 | /** \brief Draw an ellipse on the canvas using the given character. |
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122 | * |
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123 | * This function never fails. |
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124 | * |
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125 | * \param cv The handle to the libcucul canvas. |
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126 | * \param xo Center X coordinate. |
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127 | * \param yo Center Y coordinate. |
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128 | * \param a Ellipse X radius. |
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129 | * \param b Ellipse Y radius. |
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130 | * \param str UTF-8 string representing the character that should be used |
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131 | * to draw the ellipse outline. |
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132 | * \return This function always returns 0. |
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133 | */ |
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134 | int cucul_draw_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b, |
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135 | char const *str) |
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136 | { |
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137 | int d2; |
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138 | int x = 0; |
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139 | int y = b; |
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140 | int d1 = b*b - (a*a*b) + (a*a/4); |
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141 | uint32_t ch = cucul_utf8_to_utf32(str, NULL); |
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142 | |
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143 | ellipsepoints(cv, xo, yo, x, y, ch); |
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144 | |
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145 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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146 | { |
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147 | if(d1 < 0) |
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148 | { |
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149 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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150 | } |
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151 | else |
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152 | { |
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153 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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154 | y--; |
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155 | } |
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156 | x++; |
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157 | ellipsepoints(cv, xo, yo, x, y, ch); |
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158 | } |
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159 | |
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160 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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161 | while(y > 0) |
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162 | { |
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163 | if(d2 < 0) |
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164 | { |
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165 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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166 | x++; |
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167 | } |
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168 | else |
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169 | { |
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170 | d2 += a*a*(-2*y+3); |
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171 | } |
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172 | |
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173 | y--; |
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174 | ellipsepoints(cv, xo, yo, x, y, ch); |
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175 | } |
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176 | |
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177 | return 0; |
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178 | } |
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179 | |
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180 | /** \brief Draw a thin ellipse on the canvas. |
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181 | * |
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182 | * This function never fails. |
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183 | * |
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184 | * \param cv The handle to the libcucul canvas. |
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185 | * \param xo Center X coordinate. |
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186 | * \param yo Center Y coordinate. |
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187 | * \param a Ellipse X radius. |
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188 | * \param b Ellipse Y radius. |
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189 | * \return This function always returns 0. |
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190 | */ |
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191 | int cucul_draw_thin_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b) |
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192 | { |
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193 | /* FIXME: this is not correct */ |
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194 | int d2; |
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195 | int x = 0; |
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196 | int y = b; |
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197 | int d1 = b*b - (a*a*b) + (a*a/4); |
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198 | |
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199 | ellipsepoints(cv, xo, yo, x, y, '-'); |
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200 | |
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201 | while(a*a*y - a*a/2 > b*b*(x+1)) |
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202 | { |
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203 | if(d1 < 0) |
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204 | { |
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205 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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206 | } |
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207 | else |
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208 | { |
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209 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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210 | y--; |
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211 | } |
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212 | x++; |
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213 | ellipsepoints(cv, xo, yo, x, y, '-'); |
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214 | } |
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215 | |
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216 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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217 | while(y > 0) |
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218 | { |
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219 | if(d2 < 0) |
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220 | { |
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221 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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222 | x++; |
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223 | } |
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224 | else |
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225 | { |
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226 | d2 += a*a*(-2*y+3); |
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227 | } |
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228 | |
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229 | y--; |
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230 | ellipsepoints(cv, xo, yo, x, y, '|'); |
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231 | } |
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232 | |
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233 | return 0; |
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234 | } |
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235 | |
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236 | static void ellipsepoints(cucul_canvas_t *cv, int xo, int yo, int x, int y, |
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237 | uint32_t ch) |
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238 | { |
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239 | uint8_t b = 0; |
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240 | |
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241 | if(xo + x >= 0 && xo + x < (int)cv->width) |
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242 | b |= 0x1; |
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243 | if(xo - x >= 0 && xo - x < (int)cv->width) |
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244 | b |= 0x2; |
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245 | if(yo + y >= 0 && yo + y < (int)cv->height) |
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246 | b |= 0x4; |
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247 | if(yo - y >= 0 && yo - y < (int)cv->height) |
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248 | b |= 0x8; |
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249 | |
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250 | if((b & (0x1|0x4)) == (0x1|0x4)) |
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251 | cucul_putchar(cv, xo + x, yo + y, ch); |
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252 | |
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253 | if((b & (0x2|0x4)) == (0x2|0x4)) |
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254 | cucul_putchar(cv, xo - x, yo + y, ch); |
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255 | |
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256 | if((b & (0x1|0x8)) == (0x1|0x8)) |
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257 | cucul_putchar(cv, xo + x, yo - y, ch); |
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258 | |
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259 | if((b & (0x2|0x8)) == (0x2|0x8)) |
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260 | cucul_putchar(cv, xo - x, yo - y, ch); |
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261 | } |
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262 | |
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