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conic.c 8.3 KiB

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  1. /*
  2. * libcaca Colour ASCII-Art library
  3. * Copyright (c) 2002-2010 Sam Hocevar <sam@hocevar.net>
  4. * All Rights Reserved
  5. *
  6. * This library is free software. It comes without any warranty, to
  7. * the extent permitted by applicable law. You can redistribute it
  8. * and/or modify it under the terms of the Do What The Fuck You Want
  9. * To Public License, Version 2, as published by Sam Hocevar. See
  10. * http://sam.zoy.org/wtfpl/COPYING for more details.
  11. */
  12. /*
  13. * This file contains ellipse and circle drawing functions, both filled
  14. * and outline.
  15. */
  16. #include "config.h"
  17. #if !defined(__KERNEL__)
  18. # include <stdlib.h>
  19. #endif
  20. #include "caca.h"
  21. #include "caca_internals.h"
  22. static void ellipsepoints(caca_canvas_t *, int, int, int, int, uint32_t, int);
  23. /** \brief Draw a circle on the canvas using the given character.
  24. *
  25. * This function never fails.
  26. *
  27. * \param cv The handle to the libcaca canvas.
  28. * \param x Center X coordinate.
  29. * \param y Center Y coordinate.
  30. * \param r Circle radius.
  31. * \param ch UTF-32 character to be used to draw the circle outline.
  32. * \return This function always returns 0.
  33. */
  34. int caca_draw_circle(caca_canvas_t *cv, int x, int y, int r, uint32_t ch)
  35. {
  36. int test, dx, dy;
  37. /* Optimized Bresenham. Kick ass. */
  38. for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++)
  39. {
  40. ellipsepoints(cv, x, y, dx, dy, ch, 1);
  41. ellipsepoints(cv, x, y, dy, dx, ch, 1);
  42. test += test > 0 ? dx - dy-- : dx;
  43. }
  44. return 0;
  45. }
  46. /** \brief Fill an ellipse on the canvas using the given character.
  47. *
  48. * This function never fails.
  49. *
  50. * \param cv The handle to the libcaca canvas.
  51. * \param xo Center X coordinate.
  52. * \param yo Center Y coordinate.
  53. * \param a Ellipse X radius.
  54. * \param b Ellipse Y radius.
  55. * \param ch UTF-32 character to be used to fill the ellipse.
  56. * \return This function always returns 0.
  57. */
  58. int caca_fill_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b,
  59. uint32_t ch)
  60. {
  61. int d2;
  62. int x = 0;
  63. int y = b;
  64. int d1 = b*b - (a*a*b) + (a*a/4);
  65. while(a*a*y - a*a/2 > b*b*(x+1))
  66. {
  67. if(d1 < 0)
  68. {
  69. d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
  70. }
  71. else
  72. {
  73. d1 += b*b*(2*x*1) + a*a*(-2*y+2);
  74. caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
  75. caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
  76. y--;
  77. }
  78. x++;
  79. }
  80. caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
  81. caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
  82. d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
  83. while(y > 0)
  84. {
  85. if(d2 < 0)
  86. {
  87. d2 += b*b*(2*x+2) + a*a*(-2*y+3);
  88. x++;
  89. }
  90. else
  91. {
  92. d2 += a*a*(-2*y+3);
  93. }
  94. y--;
  95. caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
  96. caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
  97. }
  98. return 0;
  99. }
  100. /** \brief Draw an ellipse on the canvas using the given character.
  101. *
  102. * This function never fails.
  103. *
  104. * \param cv The handle to the libcaca canvas.
  105. * \param xo Center X coordinate.
  106. * \param yo Center Y coordinate.
  107. * \param a Ellipse X radius.
  108. * \param b Ellipse Y radius.
  109. * \param ch UTF-32 character to be used to draw the ellipse outline.
  110. * \return This function always returns 0.
  111. */
  112. int caca_draw_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b,
  113. uint32_t ch)
  114. {
  115. int d2;
  116. int x = 0;
  117. int y = b;
  118. int d1 = b*b - (a*a*b) + (a*a/4);
  119. ellipsepoints(cv, xo, yo, x, y, ch, 0);
  120. while(a*a*y - a*a/2 > b*b*(x+1))
  121. {
  122. if(d1 < 0)
  123. {
  124. d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
  125. }
  126. else
  127. {
  128. d1 += b*b*(2*x*1) + a*a*(-2*y+2);
  129. y--;
  130. }
  131. x++;
  132. ellipsepoints(cv, xo, yo, x, y, ch, 0);
  133. }
  134. d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
  135. while(y > 0)
  136. {
  137. if(d2 < 0)
  138. {
  139. d2 += b*b*(2*x+2) + a*a*(-2*y+3);
  140. x++;
  141. }
  142. else
  143. {
  144. d2 += a*a*(-2*y+3);
  145. }
  146. y--;
  147. ellipsepoints(cv, xo, yo, x, y, ch, 0);
  148. }
  149. return 0;
  150. }
  151. /** \brief Draw a thin ellipse on the canvas.
  152. *
  153. * This function never fails.
  154. *
  155. * \param cv The handle to the libcaca canvas.
  156. * \param xo Center X coordinate.
  157. * \param yo Center Y coordinate.
  158. * \param a Ellipse X radius.
  159. * \param b Ellipse Y radius.
  160. * \return This function always returns 0.
  161. */
  162. int caca_draw_thin_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b)
  163. {
  164. /* FIXME: this is not correct */
  165. int d2;
  166. int x = 0;
  167. int y = b;
  168. int d1 = b*b - (a*a*b) + (a*a/4);
  169. ellipsepoints(cv, xo, yo, x, y, '-', 1);
  170. while(a*a*y - a*a/2 > b*b*(x+1))
  171. {
  172. if(d1 < 0)
  173. {
  174. d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
  175. ellipsepoints(cv, xo, yo, x + 1, y, '0', 1);
  176. }
  177. else
  178. {
  179. d1 += b*b*(2*x*1) + a*a*(-2*y+2);
  180. y--;
  181. ellipsepoints(cv, xo, yo, x + 1, y, '1', 1);
  182. }
  183. x++;
  184. }
  185. d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
  186. while(y > 0)
  187. {
  188. if(d2 < 0)
  189. {
  190. d2 += b*b*(2*x+2) + a*a*(-2*y+3);
  191. x++;
  192. ellipsepoints(cv, xo, yo, x , y - 1, '2', 1);
  193. }
  194. else
  195. {
  196. d2 += a*a*(-2*y+3);
  197. ellipsepoints(cv, xo, yo, x , y - 1, '3', 1);
  198. }
  199. y--;
  200. }
  201. return 0;
  202. }
  203. static void ellipsepoints(caca_canvas_t *cv, int xo, int yo, int x, int y,
  204. uint32_t ch, int thin)
  205. {
  206. uint8_t b = 0;
  207. if(xo + x >= 0 && xo + x < (int)cv->width)
  208. b |= 0x1;
  209. if(xo - x >= 0 && xo - x < (int)cv->width)
  210. b |= 0x2;
  211. if(yo + y >= 0 && yo + y < (int)cv->height)
  212. b |= 0x4;
  213. if(yo - y >= 0 && yo - y < (int)cv->height)
  214. b |= 0x8;
  215. if((b & (0x1|0x4)) == (0x1|0x4)) {
  216. uint32_t c = ch;
  217. if(thin) {
  218. switch(c) {
  219. case '0':
  220. c = '-';
  221. break;
  222. case '1':
  223. c = ',';
  224. break;
  225. case '2':
  226. c = '/';
  227. break;
  228. case '3':
  229. c = '|';
  230. break;
  231. }
  232. }
  233. caca_put_char(cv, xo + x, yo + y, c);
  234. }
  235. if((b & (0x2|0x4)) == (0x2|0x4)) {
  236. uint32_t c = ch;
  237. if(thin) {
  238. switch(c) {
  239. case '0':
  240. c = '-';
  241. break;
  242. case '1':
  243. c = '.';
  244. break;
  245. case '2':
  246. c = '\\';
  247. break;
  248. case '3':
  249. c = '|';
  250. break;
  251. }
  252. }
  253. caca_put_char(cv, xo - x, yo + y, c);
  254. }
  255. if((b & (0x1|0x8)) == (0x1|0x8)) {
  256. uint32_t c = ch;
  257. if(thin) {
  258. switch(c) {
  259. case '0':
  260. c = '-';
  261. break;
  262. case '1':
  263. c = '`';
  264. break;
  265. case '2':
  266. c = '\\';
  267. break;
  268. case '3':
  269. c = '|';
  270. break;
  271. }
  272. }
  273. caca_put_char(cv, xo + x, yo - y, c);
  274. }
  275. if((b & (0x2|0x8)) == (0x2|0x8)) {
  276. uint32_t c = ch;
  277. if(thin) {
  278. switch(c) {
  279. case '0':
  280. c = '-';
  281. break;
  282. case '1':
  283. c = '\'';
  284. break;
  285. case '2':
  286. c = '/';
  287. break;
  288. case '3':
  289. c = '|';
  290. break;
  291. }
  292. }
  293. caca_put_char(cv, xo - x, yo - y, c);
  294. }
  295. }
  296. /*
  297. * XXX: The following functions are aliases.
  298. */
  299. int cucul_draw_circle(cucul_canvas_t *, int, int, int, uint32_t)
  300. CACA_ALIAS(caca_draw_circle);
  301. int cucul_draw_ellipse(cucul_canvas_t *, int, int, int, int, uint32_t)
  302. CACA_ALIAS(caca_draw_ellipse);
  303. int cucul_draw_thin_ellipse(cucul_canvas_t *, int, int, int, int)
  304. CACA_ALIAS(caca_draw_thin_ellipse);
  305. int cucul_fill_ellipse(cucul_canvas_t *, int, int, int, int, uint32_t)
  306. CACA_ALIAS(caca_fill_ellipse);