1 /* -*- Mode: C; tab-width: 4 -*- */
3 * braid --- random braids around a circle and then changes the color in
8 static const char sccsid[] = "@(#)braid.c 5.00 2000/11/01 xlockmore";
12 * Copyright (c) 1995 by John Neil.
14 * Permission to use, copy, modify, and distribute this software and its
15 * documentation for any purpose and without fee is hereby granted,
16 * provided that the above copyright notice appear in all copies and that
17 * both that copyright notice and this permission notice appear in
18 * supporting documentation.
20 * This file is provided AS IS with no warranties of any kind. The author
21 * shall have no liability with respect to the infringement of copyrights,
22 * trade secrets or any patents by this file or any part thereof. In no
23 * event will the author be liable for any lost revenue or profits or
24 * other special, indirect and consequential damages.
27 * 01-Nov-2000: Allocation checks
28 * 10-May-1997: Jamie Zawinski <jwz@jwz.org> compatible with xscreensaver
29 * 01-Sep-1995: color knotted components differently, J. Neil.
30 * 29-Aug-1995: Written. John Neil <neil@math.idbsu.edu>
35 # define DEFAULTS "*delay: 1000 \n" \
40 # define UNIFORM_COLORS
41 # define reshape_braid 0
42 # define braid_handle_event 0
43 # include "xlockmore.h"
45 #else /* STANDALONE */
47 # define ENTRYPOINT /**/
48 #endif /* STANDALONE */
52 ENTRYPOINT ModeSpecOpt braid_opts =
53 {0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
56 ModStruct braid_description =
57 {"braid", "init_braid", "draw_braid", "release_braid",
58 "refresh_braid", "init_braid", (char *) NULL, &braid_opts,
59 1000, 15, 100, 1, 64, 1.0, "",
60 "Shows random braids and knots", 0, NULL};
64 #if defined( COLORROUND ) && defined( COLORCOMP )
69 #if !defined( COLORROUND ) && !defined( COLORCOMP )
71 /* to color in a circular pattern use COLORROUND */
74 /* to color by component use COLORCOMP */
79 #define MAXLENGTH 50 /* the maximum length of a braid word */
80 #define MINLENGTH 8 /* the minimum length of a braid word */
81 #define MAXSTRANDS 15 /* the maximum number of strands in the braid */
82 #define MINSTRANDS 3 /* the minimum number of strands in the braid */
83 #define SPINRATE 12.0 /* the rate at which the colors spin */
85 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
86 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
90 int braidword[MAXLENGTH];
91 int components[MAXSTRANDS];
92 int startcomp[MAXLENGTH][MAXSTRANDS];
100 float top, bottom, left, right;
104 eraser_state *eraser;
108 static braidtype *braids = (braidtype *) NULL;
111 applyword(braidtype * braid, int string, int position)
116 for (i = position; i < braid->braidlength; i++) {
117 if (c == ABS(braid->braidword[i]))
119 else if (c == ABS(braid->braidword[i]) - 1)
122 for (i = 0; i < position; i++) {
123 if (c == ABS(braid->braidword[i]))
125 else if (c == ABS(braid->braidword[i]) - 1)
133 applywordto(braidtype * braid, int string, int position)
138 for (i = 0; i < position; i++) {
139 if (c == ABS(braid->braidword[i])) {
141 } else if (c == ABS(braid->braidword[i]) - 1) {
150 applywordbackto(braidtype * braid, int string, int position)
155 for (i = position - 1; i >= 0; i--) {
156 if (c == ABS(braid->braidword[i])) {
158 } else if (c == ABS(braid->braidword[i]) - 1) {
166 init_braid(ModeInfo * mi)
169 int used[MAXSTRANDS];
170 int i, count, comp, c;
173 if (braids == NULL) {
174 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
175 sizeof (braidtype))) == NULL)
178 braid = &braids[MI_SCREEN(mi)];
180 braid->center_x = MI_WIDTH(mi) / 2;
181 braid->center_y = MI_HEIGHT(mi) / 2;
184 /* jwz: go in the other direction sometimes. */
185 braid->color_direction = ((LRAND() & 1) ? 1 : -1);
191 min_length = (braid->center_x > braid->center_y) ?
192 braid->center_y : braid->center_x;
193 braid->min_radius = min_length * 0.30;
194 braid->max_radius = min_length * 0.90;
196 if (MI_COUNT(mi) < MINSTRANDS)
197 braid->nstrands = MINSTRANDS;
199 braid->nstrands = INTRAND(MINSTRANDS,
200 MAX(MIN(MIN(MAXSTRANDS, MI_COUNT(mi)),
201 (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
202 braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
204 for (i = 0; i < braid->braidlength; i++) {
205 braid->braidword[i] =
206 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
208 while (braid->braidword[i] == -braid->braidword[i - 1])
209 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
212 while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
213 braid->braidword[braid->braidlength - 1] =
214 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
217 (void) memset((char *) used, 0, sizeof (used));
219 for (i = 0; i < braid->braidlength; i++)
220 used[ABS(braid->braidword[i])]++;
221 for (i = 0; i < braid->nstrands; i++)
222 count += (used[i] > 0) ? 1 : 0;
223 if (count < braid->nstrands - 1) {
224 braid->braidword[braid->braidlength] =
225 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
226 while (braid->braidword[braid->braidlength] ==
227 -braid->braidword[braid->braidlength - 1] &&
228 braid->braidword[0] == -braid->braidword[braid->braidlength])
229 braid->braidword[braid->braidlength] =
230 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
231 braid->braidlength++;
233 } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
235 braid->startcolor = (MI_NPIXELS(mi) > 2) ?
236 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
237 /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
240 (void) memset((char *) braid->components, 0, sizeof (braid->components));
243 braid->components[0] = 1;
247 i = applyword(braid, i, 0);
248 braid->components[i] = braid->components[comp];
251 for (i = 0; i < braid->nstrands; i++)
252 if (braid->components[i] == 0)
255 for (comp = 0; braid->components[comp] != 0; comp++);
256 braid->components[comp] = ++c;
260 braid->linewidth = MI_SIZE(mi);
262 if (braid->linewidth < 0)
263 braid->linewidth = NRAND(-braid->linewidth) + 1;
264 if (braid->linewidth * braid->linewidth * 8 > MIN(MI_WIDTH(mi), MI_HEIGHT(mi)))
265 braid->linewidth = MIN(1, (int) sqrt((double) MIN(MI_WIDTH(mi), MI_HEIGHT(mi)) / 8));
266 for (i = 0; i < braid->nstrands; i++)
267 if (!(braid->components[i] & 1))
268 braid->components[i] *= -1;
272 draw_braid(ModeInfo * mi)
274 Display *display = MI_DISPLAY(mi);
275 Window window = MI_WINDOW(mi);
276 int num_points = 500;
281 float x_1, y_1, x_2, y_2, r1, r2;
282 float color, color_use = 0.0, color_inc;
287 braid = &braids[MI_SCREEN(mi)];
291 braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
296 MI_IS_DRAWN(mi) = True;
297 XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
299 (braid->linewidth <= 3 ? CapButt : CapRound),
302 theta = (2.0 * M_PI) / (float) (braid->braidlength);
303 t_inc = (2.0 * M_PI) / (float) num_points;
304 color_inc = (float) MI_NPIXELS(mi) * braid->color_direction /
306 braid->startcolor += SPINRATE * color_inc;
307 if (((int) braid->startcolor) >= MI_NPIXELS(mi))
308 braid->startcolor = 0.0;
310 r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
312 color = braid->startcolor;
314 for (i = 0; i < braid->braidlength; i++) {
316 for (t = 0.0; t < theta; t += t_inc) {
319 if (((int) color) >= MI_NPIXELS(mi))
323 for (s = 0; s < braid->nstrands; s++) {
324 if (ABS(braid->braidword[i]) == s)
326 if (ABS(braid->braidword[i]) - 1 == s) {
329 if (MI_NPIXELS(mi) > 2) {
330 color_use = color + SPINRATE *
331 braid->components[applywordbackto(braid, s, i)] +
332 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
333 while (((int) color_use) >= MI_NPIXELS(mi))
334 color_use -= (float) MI_NPIXELS(mi);
335 while (((int) color_use) < 0)
336 color_use += (float) MI_NPIXELS(mi);
340 if (MI_NPIXELS(mi) > 2) {
341 color_use += SPINRATE * color_inc;
342 while (((int) color_use) >= MI_NPIXELS(mi))
343 color_use -= (float) MI_NPIXELS(mi);
346 r1 = braid->min_radius + r_diff * (float) (s);
347 r2 = braid->min_radius + r_diff * (float) (s + 1);
348 if (braid->braidword[i] > 0 ||
349 (FABSF(t - theta / 2.0) > theta / 7.0)) {
350 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
351 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
352 COSF(t + psi) + braid->center_x;
353 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
354 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
355 SINF(t + psi) + braid->center_y;
356 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
357 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
358 COSF(t + t_inc + psi) + braid->center_x;
359 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
360 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
361 SINF(t + t_inc + psi) + braid->center_y;
362 if (MI_NPIXELS(mi) > 2)
363 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
365 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
367 XDrawLine(display, window, MI_GC(mi),
368 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
371 if (MI_NPIXELS(mi) > 2) {
372 color_use = color + SPINRATE *
373 braid->components[applywordbackto(braid, s + 1, i)] +
374 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
375 while (((int) color_use) >= MI_NPIXELS(mi))
376 color_use -= (float) MI_NPIXELS(mi);
377 while (((int) color_use) < 0)
378 color_use += (float) MI_NPIXELS(mi);
381 if (braid->braidword[i] < 0 ||
382 (FABSF(t - theta / 2.0) > theta / 7.0)) {
383 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
384 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
385 COSF(t + psi) + braid->center_x;
386 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
387 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
388 SINF(t + psi) + braid->center_y;
389 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
390 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
391 COSF(t + t_inc + psi) + braid->center_x;
392 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
393 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
394 SINF(t + t_inc + psi) + braid->center_y;
395 if (MI_NPIXELS(mi) > 2)
396 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
398 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
400 XDrawLine(display, window, MI_GC(mi),
401 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
406 if (MI_NPIXELS(mi) > 2) {
407 color_use = color + SPINRATE *
408 braid->components[applywordbackto(braid, s, i)] +
409 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
410 while (((int) color_use) >= MI_NPIXELS(mi))
411 color_use -= (float) MI_NPIXELS(mi);
412 while (((int) color_use) < 0)
413 color_use += (float) MI_NPIXELS(mi);
417 if (MI_NPIXELS(mi) > 2) {
418 color_use += SPINRATE * color_inc;
419 while (((int) color_use) >= MI_NPIXELS(mi))
420 color_use -= (float) MI_NPIXELS(mi);
423 r1 = braid->min_radius + r_diff * (float) (s);
424 x_1 = r1 * COSF(t + psi) + braid->center_x;
425 y_1 = r1 * SINF(t + psi) + braid->center_y;
426 x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
427 y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
428 if (MI_NPIXELS(mi) > 2)
429 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
431 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
433 XDrawLine(display, window, MI_GC(mi),
434 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
439 XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
441 if (++braid->age > MI_CYCLES(mi)) {
443 braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
450 release_braid(ModeInfo * mi)
452 if (braids != NULL) {
453 (void) free((void *) braids);
454 braids = (braidtype *) NULL;
459 refresh_braid(ModeInfo * mi)
464 XSCREENSAVER_MODULE ("Braid", braid)
466 #endif /* MODE_braid */