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comparison src/video/SDL_rect.c @ 2997:e4f025078c1c

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indent
author Sam Lantinga <slouken@libsdl.org>
date Sun, 04 Jan 2009 23:41:09 +0000
parents 7563b99e9a49
children f3d7226a8dfd
comparison
equal deleted inserted replaced
2996:972a69e47cd9 2997:e4f025078c1c
182 *Y2 = recty2; 182 *Y2 = recty2;
183 } 183 }
184 return SDL_TRUE; 184 return SDL_TRUE;
185 } 185 }
186 186
187 else 187 else {
188 { 188 /* The task of clipping a line with finite slope ratios in a fixed-
189 /* The task of clipping a line with finite slope ratios in a fixed- 189 * precision coordinate space is not as immediately simple as it is
190 * precision coordinate space is not as immediately simple as it is 190 * with coordinates of arbitrary precision. If the ratio of slopes
191 * with coordinates of arbitrary precision. If the ratio of slopes 191 * between the input line segment and the result line segment is not
192 * between the input line segment and the result line segment is not 192 * a whole number, you have in fact *moved* the line segment a bit,
193 * a whole number, you have in fact *moved* the line segment a bit, 193 * and there can be no avoiding it without more precision
194 * and there can be no avoiding it without more precision 194 */
195 */ 195 int *x_result_[] = { X1, X2, NULL }, **x_result = x_result_;
196 int *x_result_[] = {X1, X2, NULL}, **x_result = x_result_; 196 int *y_result_[] = { Y1, Y2, NULL }, **y_result = y_result_;
197 int *y_result_[] = {Y1, Y2, NULL}, **y_result = y_result_;
198 SDL_bool intersection = SDL_FALSE; 197 SDL_bool intersection = SDL_FALSE;
199 double b, m, left, right, bottom, top; 198 double b, m, left, right, bottom, top;
200 int xl, xh, yl, yh; 199 int xl, xh, yl, yh;
201 200
202 /* solve mx+b line formula */ 201 /* solve mx+b line formula */
203 m = (double)(y1-y2) / (double)(x1-x2); 202 m = (double) (y1 - y2) / (double) (x1 - x2);
204 b = y2 - m * (double) x2; 203 b = y2 - m * (double) x2;
205 204
206 /* find some linear intersections */ 205 /* find some linear intersections */
207 left = (m * (double) rectx1) + b; 206 left = (m * (double) rectx1) + b;
208 right = (m * (double) rectx2) + b; 207 right = (m * (double) rectx2) + b;
230 /* check for a point that's entirely inside the rect */ 229 /* check for a point that's entirely inside the rect */
231 if (RISING(rectx1, x1, rectx2) && RISING(recty1, y1, recty2)) { 230 if (RISING(rectx1, x1, rectx2) && RISING(recty1, y1, recty2)) {
232 x_result++; 231 x_result++;
233 y_result++; 232 y_result++;
234 intersection = SDL_TRUE; 233 intersection = SDL_TRUE;
235 } else /* it was determined earlier that *both* end-points are not contained */ 234 } else
236 235 /* it was determined earlier that *both* end-points are not contained */
237 if (RISING(rectx1, x2, rectx2) && RISING(recty1, y2, recty2)) { 236 if (RISING(rectx1, x2, rectx2) && RISING(recty1, y2, recty2)) {
238 **(x_result++) = x2; 237 **(x_result++) = x2;
239 **(y_result++) = y2; 238 **(y_result++) = y2;
240 intersection = SDL_TRUE; 239 intersection = SDL_TRUE;
241 } 240 }
244 **(x_result++) = rectx1; 243 **(x_result++) = rectx1;
245 **(y_result++) = (int) left; 244 **(y_result++) = (int) left;
246 intersection = SDL_TRUE; 245 intersection = SDL_TRUE;
247 } 246 }
248 247
249 if (*x_result == NULL) return intersection; 248 if (*x_result == NULL)
249 return intersection;
250 if (RISING(recty1, right, recty2) && RISING(xl, rectx2, xh)) { 250 if (RISING(recty1, right, recty2) && RISING(xl, rectx2, xh)) {
251 **(x_result++) = rectx2; 251 **(x_result++) = rectx2;
252 **(y_result++) = (int) right; 252 **(y_result++) = (int) right;
253 intersection = SDL_TRUE; 253 intersection = SDL_TRUE;
254 } 254 }
255 255
256 if (*x_result == NULL) return intersection; 256 if (*x_result == NULL)
257 return intersection;
257 if (RISING(rectx1, top, rectx2) && RISING(yl, recty1, yh)) { 258 if (RISING(rectx1, top, rectx2) && RISING(yl, recty1, yh)) {
258 **(x_result++) = (int) top; 259 **(x_result++) = (int) top;
259 **(y_result++) = recty1; 260 **(y_result++) = recty1;
260 intersection = SDL_TRUE; 261 intersection = SDL_TRUE;
261 } 262 }
262 263
263 if (*x_result == NULL) return intersection; 264 if (*x_result == NULL)
265 return intersection;
264 if (RISING(rectx1, bottom, rectx2) && RISING(yl, recty2, yh)) { 266 if (RISING(rectx1, bottom, rectx2) && RISING(yl, recty2, yh)) {
265 **(x_result++) = (int) bottom; 267 **(x_result++) = (int) bottom;
266 **(y_result++) = recty2; 268 **(y_result++) = recty2;
267 intersection = SDL_TRUE; 269 intersection = SDL_TRUE;
268 } 270 }