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comparison mupdf-source/thirdparty/freeglut/progs/demos/Fractals_random/fractals_random.c @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /* fractals_random.c */
2 /* This demo shows a single-buffering "freeglut" example. */
3
4 /*
5 * Program to draw a fractal by Michael Barnsley's stochastic algorithm.
6 * Algorithm:
7 * (1) Define the affine transformations (of the form r(i+1) = A r(i) + b )
8 * (2) Find the stationary point for the first transformation
9 * (3) To draw:
10 * - Pick a random integer between 1 and the number of transformations (inclusive)
11 * - Send the current point through the transformation to create the new current point
12 * - Plot the new current point
13 */
14
15 /*
16 * User Commands:
17 * PgUp, PgDn - increase/decrease scaling
18 * Arrow keys - translate viewing section
19 * r - reset view
20 * Escape - quit
21 */
22
23 #include <GL/freeglut.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <math.h>
28 #define FGH_PI 3.14159265358979323846
29 #ifdef _MSC_VER
30 /* DUMP MEMORY LEAKS */
31 #include <crtdbg.h>
32 #endif
33
34 typedef struct
35 {
36 double a00, a01, a10, a11 ; /* Transformation matrix */
37 double b0, b1 ; /* Constant vector added on */
38 double statx, staty ; /* Coordinates of the stationary point */
39 }
40 AffineTrans ;
41
42 /* Number of levels to draw the fractal */
43 static int num_levels = 0 ;
44
45 /* The definition of the fractal */
46 static int num_trans ;
47 static AffineTrans *affine ;
48
49 /* the window title */
50 char window_title [ 80 ] ;
51
52 /* The amount the view is translated */
53 double xwin = 0.0, ywin = 0.0 ;
54 double scale_factor = 1.0 ;
55
56 /* The current point */
57 double current_x = 0.0, current_y = 0.0 ;
58
59 /* Signals when a glClear is needed */
60 static GLboolean needClear = GL_TRUE;
61
62 static void draw_level ( int num, double m00, double m01, double m10, double m11, double n0, double n1 )
63 {
64 /* Draw a fractal transformed by "M", "N" as passed in */
65 int i ;
66
67 for ( i = 0; i < 10; i++ )
68 {
69 int random = ( rand( ) >> 10 ) % num_trans;
70 double new_x = affine[random].a00 * current_x + affine[random].a01 * current_y + affine[random].b0 ;
71 double new_y = affine[random].a10 * current_x + affine[random].a11 * current_y + affine[random].b1 ;
72
73 glVertex2d ( new_x, new_y ) ;
74 current_x = new_x ;
75 current_y = new_y ;
76 }
77 }
78
79 static void
80 Display(void)
81 {
82 if (needClear) {
83 glClear(GL_COLOR_BUFFER_BIT);
84 needClear = GL_FALSE;
85 }
86
87 /* the curve */
88 glPushMatrix();
89 glScaled(2.5, 2.5, 2.5);
90
91 glColor4f(0.0, 0.0, 0.0, 1.0);
92 glBegin ( GL_POINTS ) ;
93 draw_level ( num_levels, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0 );
94 glEnd () ;
95
96 glPopMatrix();
97
98 glFlush();
99 glutPostRedisplay(); /* Needed so that this function will be called again */
100 }
101
102 static void
103 Reshape(int width, int height)
104 {
105 float ar;
106 glViewport(0, 0, width, height);
107 glMatrixMode(GL_PROJECTION);
108 glLoadIdentity();
109 ar = (float) width / (float) height;
110 if( ar > 1 )
111 glFrustum(-ar, ar, -1.0, 1.0, 2.0, 100.0);
112 else
113 glFrustum(-1.0, 1.0, -1/ar, 1/ar, 2.0, 100.0);
114 glMatrixMode(GL_MODELVIEW);
115 glLoadIdentity();
116 xwin = -1.0 ;
117 ywin = 0.0 ;
118 glTranslated(xwin, ywin, -5.0);
119 needClear = GL_TRUE;
120 }
121
122 static void
123 Key(unsigned char key, int x, int y)
124 {
125 int changed_settings = 1;
126
127 switch (key) {
128 case 27: /* Escape key */
129 glutLeaveMainLoop ();
130 break;
131
132 case 'r' : case 'R' :
133 glMatrixMode(GL_MODELVIEW);
134 glLoadIdentity();
135 xwin = -1.0 ;
136 ywin = 0.0 ;
137 glTranslated(xwin, ywin, -5.0);
138 break ;
139
140 default:
141 changed_settings = 0;
142 break;
143 }
144 if (changed_settings)
145 needClear = GL_TRUE;
146 glutPostRedisplay();
147 }
148
149 static void
150 Special(int key, int x, int y)
151 {
152 int changed_settings = 1;
153
154 switch (key) {
155 case GLUT_KEY_UP :
156 glMatrixMode(GL_MODELVIEW);
157 ywin += 0.1 * scale_factor ;
158 glTranslated(0.0, 0.1 * scale_factor, 0.0);
159 break ;
160
161 case GLUT_KEY_DOWN :
162 glMatrixMode(GL_MODELVIEW);
163 ywin -= 0.1 * scale_factor ;
164 glTranslated(0.0, -0.1 * scale_factor, 0.0);
165 break ;
166
167 case GLUT_KEY_LEFT :
168 glMatrixMode(GL_MODELVIEW);
169 xwin -= 0.1 * scale_factor ;
170 glTranslated(-0.1 * scale_factor, 0.0, 0.0);
171 break ;
172
173 case GLUT_KEY_RIGHT :
174 glMatrixMode(GL_MODELVIEW);
175 xwin += 0.1 * scale_factor ;
176 glTranslated(0.1 * scale_factor, 0.0, 0.0);
177 break ;
178
179 case GLUT_KEY_PAGE_UP :
180 glMatrixMode(GL_MODELVIEW);
181 glTranslated ( -xwin, -ywin, 0.0 ) ;
182 glScaled(1.25, 1.25, 1.25);
183 glTranslated ( xwin, ywin, 0.0 ) ;
184 scale_factor *= 0.8 ;
185 break ;
186
187 case GLUT_KEY_PAGE_DOWN :
188 glMatrixMode(GL_MODELVIEW);
189 glTranslated ( -xwin, -ywin, 0.0 ) ;
190 glScaled(0.8, 0.8, 0.8);
191 glTranslated ( xwin, ywin, 0.0 ) ;
192 scale_factor *= 1.25 ;
193 break ;
194
195 default:
196 changed_settings = 0;
197 break;
198 }
199 if (changed_settings)
200 needClear = GL_TRUE;
201
202 glutPostRedisplay();
203 }
204
205
206 static int mouse_x = 0, mouse_y = 0 ;
207 static int button_down = GLUT_DOWN ;
208
209 static void
210 Mouse ( int button, int updown, int x, int y )
211 {
212 button_down = updown ;
213
214 if ( updown == GLUT_DOWN )
215 {
216 mouse_x = x ;
217 mouse_y = y ;
218 }
219 }
220
221 static void
222 MouseMotion ( int x, int y )
223 {
224 int window_width = glutGet ( GLUT_WINDOW_WIDTH ) ;
225 int window_height = glutGet ( GLUT_WINDOW_HEIGHT ) ;
226 int window_size = ( window_width < window_height ) ? window_width : window_height ;
227
228 double delta_x = 5.0 * (double)(x - mouse_x) / (double)(window_size) ;
229 double delta_y = 5.0 * (double)(y - mouse_y) / (double)(window_size) ;
230
231 xwin += delta_x * scale_factor ;
232 ywin -= delta_y * scale_factor ;
233 glMatrixMode ( GL_MODELVIEW ) ;
234 glTranslated ( delta_x * scale_factor, -delta_y * scale_factor, 0.0 ) ;
235
236 needClear = GL_TRUE;
237 glutPostRedisplay();
238
239 mouse_x = x ;
240 mouse_y = y ;
241 }
242
243 static void
244 MouseWheel ( int wheel_number, int direction, int x, int y )
245 {
246 double scale = ( direction > 0 ) ? 1.25 : 0.8 ;
247
248 glMatrixMode ( GL_MODELVIEW ) ;
249 glTranslated ( -xwin, -ywin, 0.0 ) ;
250 glScaled ( scale, scale, scale ) ;
251 glTranslated ( xwin, ywin, 0.0 ) ;
252 scale_factor /= scale ;
253
254 needClear = GL_TRUE;
255 glutPostRedisplay();
256 }
257
258
259 static void
260 checkedFGets ( char *s, int size, FILE *stream )
261 {
262 if ( fgets ( s, size, stream ) == NULL ) {
263 fprintf ( stderr, "fgets failed\n");
264 exit ( EXIT_FAILURE );
265 }
266 }
267
268
269 void readConfigFile ( char *fnme )
270 {
271 FILE *fptr = fopen ( fnme, "rt" ) ;
272 int i ;
273 char inputline [ 256 ] ;
274
275 if ( fptr )
276 {
277 /* Read a header line */
278 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
279
280 /* Read a comment line */
281 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
282
283 /* Read the window title */
284 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
285 /* We assume here that this line will not exceed 79 characters plus a
286 newline (window_title is 80 characters long). That'll cause a buffer
287 overflow. For a simple program like this, though, we're letting it
288 slide!
289 */
290 sscanf ( inputline, "%[a-zA-Z0-9!@#$%^&*()+=/\\_-\" ]", window_title ) ;
291
292 /* Read a comment line */
293 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
294
295 /* Read the number of affine transformations */
296 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
297 sscanf ( inputline, "%d", &num_trans ) ;
298
299 affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
300
301 /* Read a comment line */
302 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
303
304 for ( i = 0; i < num_trans; i++ )
305 {
306 /* Read an affine transformation definition */
307 checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
308 sscanf ( inputline, "%lf %lf %lf %lf %lf %lf", &affine[i].a00, &affine[i].a01,
309 &affine[i].a10, &affine[i].a11, &affine[i].b0, &affine[i].b1 ) ;
310 }
311 }
312 else /* No data file, set a default */
313 {
314 printf ( "ERROR opening file <%s>\n", fnme ) ;
315 strcpy ( window_title, "Koch Snowflake" ) ;
316 num_trans = 4 ;
317 affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
318 affine[0].a00 = 1/3. ; affine[0].a01 = 0.00 ; affine[0].a10 = 0.00 ; affine[0].a11 = 1/3. ;
319 affine[0].b0 = 0.0 ; affine[0].b1 = 0.0 ;
320
321 affine[1].a00 = 1/6. ; affine[1].a01 = -1/3.*sin(FGH_PI/3.) ; affine[1].a10 = 1/3.*sin(FGH_PI/3.) ; affine[1].a11 = 1/6. ;
322 affine[1].b0 = 1/3. ; affine[1].b1 = 0.0 ;
323
324 affine[2].a00 = 1/6. ; affine[2].a01 = -1/3.*sin(-FGH_PI/3.) ; affine[2].a10 = 1/3.*sin(-FGH_PI/3.) ; affine[2].a11 = 1/6. ;
325 affine[2].b0 = 0.5 ; affine[2].b1 = sqrt(3)/6. ;
326
327 affine[3].a00 = 1/3. ; affine[3].a01 = 0.00 ; affine[3].a10 = 0.00 ; affine[3].a11 = 1/3. ;
328 affine[3].b0 = 2/3. ; affine[3].b1 = 0.0 ;
329 }
330
331 for ( i = 0; i < num_trans; i++ )
332 {
333 double m00, m01, m10, m11 ; /* Matrix "I" minus "A" */
334 double determ ; /* Determinant of this matrix */
335
336 /* Calculate the stationary point */
337
338 m00 = 1.0 - affine[i].a00 ;
339 m01 = - affine[i].a01 ;
340 m10 = - affine[i].a10 ;
341 m11 = 1.0 - affine[i].a11 ;
342
343 determ = m00 * m11 - m01 * m10 ;
344
345 if ( fabs ( determ ) > 1.e-6 )
346 {
347 affine[i].statx = ( m11 * affine[i].b0 - m01 * affine[i].b1 ) / determ ;
348 affine[i].staty = ( -m10 * affine[i].b0 + m00 * affine[i].b1 ) / determ ;
349 }
350 else
351 affine[i].statx = affine[i].staty = 0.0 ;
352 }
353 }
354
355 int
356 main(int argc, char *argv[])
357 {
358 glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE );
359
360 glutInitWindowSize(500, 250);
361 glutInitWindowPosition ( 140, 140 ) ;
362 glutInit(&argc, argv);
363
364 if ( argc > 1 )
365 readConfigFile ( argv[1] ) ;
366 else
367 readConfigFile ( "fractals.dat" ) ;
368
369 glutCreateWindow( window_title );
370
371 glClearColor(1.0, 1.0, 1.0, 1.0);
372
373 glutReshapeFunc(Reshape);
374 glutKeyboardFunc(Key);
375 glutSpecialFunc(Special);
376 glutDisplayFunc(Display);
377 glutMouseFunc(Mouse);
378 glutMotionFunc(MouseMotion);
379 glutMouseWheelFunc(MouseWheel);
380
381 glutMainLoop();
382
383 printf ( "Back from the 'freeglut' main loop\n" ) ;
384
385 free ( affine ) ;
386
387 #ifdef _MSC_VER
388 /* DUMP MEMORY LEAK INFORMATION */
389 _CrtDumpMemoryLeaks () ;
390 #endif
391
392 return 0; /* ANSI C requires main to return int. */
393 }