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 PROGCLASS "Braid"
36 #define HACK_INIT init_braid
37 #define HACK_DRAW draw_braid
38 #define braid_opts xlockmore_opts
39 #define DEFAULTS "*delay: 1000 \n" \
44 #define UNIFORM_COLORS
45 #include "xlockmore.h"
47 #else /* STANDALONE */
50 #endif /* STANDALONE */
54 ModeSpecOpt braid_opts =
55 {0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
58 ModStruct braid_description =
59 {"braid", "init_braid", "draw_braid", "release_braid",
60 "refresh_braid", "init_braid", (char *) NULL, &braid_opts,
61 1000, 15, 100, 1, 64, 1.0, "",
62 "Shows random braids and knots", 0, NULL};
66 #if defined( COLORROUND ) && defined( COLORCOMP )
71 #if !defined( COLORROUND ) && !defined( COLORCOMP )
73 /* to color in a circular pattern use COLORROUND */
76 /* to color by component use COLORCOMP */
81 #define MAXLENGTH 50 /* the maximum length of a braid word */
82 #define MINLENGTH 8 /* the minimum length of a braid word */
83 #define MAXSTRANDS 15 /* the maximum number of strands in the braid */
84 #define MINSTRANDS 3 /* the minimum number of strands in the braid */
85 #define SPINRATE 12.0 /* the rate at which the colors spin */
87 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
88 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
92 int braidword[MAXLENGTH];
93 int components[MAXSTRANDS];
94 int startcomp[MAXLENGTH][MAXSTRANDS];
102 float top, bottom, left, right;
107 static braidtype *braids = (braidtype *) NULL;
110 applyword(braidtype * braid, int string, int position)
115 for (i = position; i < braid->braidlength; i++) {
116 if (c == ABS(braid->braidword[i]))
118 else if (c == ABS(braid->braidword[i]) - 1)
121 for (i = 0; i < position; i++) {
122 if (c == ABS(braid->braidword[i]))
124 else if (c == ABS(braid->braidword[i]) - 1)
132 applywordto(braidtype * braid, int string, int position)
137 for (i = 0; i < position; i++) {
138 if (c == ABS(braid->braidword[i])) {
140 } else if (c == ABS(braid->braidword[i]) - 1) {
149 applywordbackto(braidtype * braid, int string, int position)
154 for (i = position - 1; i >= 0; i--) {
155 if (c == ABS(braid->braidword[i])) {
157 } else if (c == ABS(braid->braidword[i]) - 1) {
165 init_braid(ModeInfo * mi)
168 int used[MAXSTRANDS];
169 int i, count, comp, c;
172 if (braids == NULL) {
173 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
174 sizeof (braidtype))) == NULL)
177 braid = &braids[MI_SCREEN(mi)];
179 braid->center_x = MI_WIDTH(mi) / 2;
180 braid->center_y = MI_HEIGHT(mi) / 2;
183 /* jwz: go in the other direction sometimes. */
184 braid->color_direction = ((LRAND() & 1) ? 1 : -1);
188 min_length = (braid->center_x > braid->center_y) ?
189 braid->center_y : braid->center_x;
190 braid->min_radius = min_length * 0.30;
191 braid->max_radius = min_length * 0.90;
193 if (MI_COUNT(mi) < MINSTRANDS)
194 braid->nstrands = MINSTRANDS;
196 braid->nstrands = INTRAND(MINSTRANDS,
197 MAX(MIN(MIN(MAXSTRANDS, MI_COUNT(mi)),
198 (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
199 braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
201 for (i = 0; i < braid->braidlength; i++) {
202 braid->braidword[i] =
203 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
205 while (braid->braidword[i] == -braid->braidword[i - 1])
206 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
209 while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
210 braid->braidword[braid->braidlength - 1] =
211 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
214 (void) memset((char *) used, 0, sizeof (used));
216 for (i = 0; i < braid->braidlength; i++)
217 used[ABS(braid->braidword[i])]++;
218 for (i = 0; i < braid->nstrands; i++)
219 count += (used[i] > 0) ? 1 : 0;
220 if (count < braid->nstrands - 1) {
221 braid->braidword[braid->braidlength] =
222 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
223 while (braid->braidword[braid->braidlength] ==
224 -braid->braidword[braid->braidlength - 1] &&
225 braid->braidword[0] == -braid->braidword[braid->braidlength])
226 braid->braidword[braid->braidlength] =
227 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
228 braid->braidlength++;
230 } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
232 braid->startcolor = (MI_NPIXELS(mi) > 2) ?
233 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
234 /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
237 (void) memset((char *) braid->components, 0, sizeof (braid->components));
240 braid->components[0] = 1;
244 i = applyword(braid, i, 0);
245 braid->components[i] = braid->components[comp];
248 for (i = 0; i < braid->nstrands; i++)
249 if (braid->components[i] == 0)
252 for (comp = 0; braid->components[comp] != 0; comp++);
253 braid->components[comp] = ++c;
257 braid->linewidth = MI_SIZE(mi);
259 if (braid->linewidth < 0)
260 braid->linewidth = NRAND(-braid->linewidth) + 1;
261 if (braid->linewidth * braid->linewidth * 8 > MIN(MI_WIDTH(mi), MI_HEIGHT(mi)))
262 braid->linewidth = MIN(1, (int) sqrt((double) MIN(MI_WIDTH(mi), MI_HEIGHT(mi)) / 8));
263 for (i = 0; i < braid->nstrands; i++)
264 if (!(braid->components[i] & 1))
265 braid->components[i] *= -1;
269 draw_braid(ModeInfo * mi)
271 Display *display = MI_DISPLAY(mi);
272 Window window = MI_WINDOW(mi);
273 int num_points = 500;
278 float x_1, y_1, x_2, y_2, r1, r2;
279 float color, color_use = 0.0, color_inc;
284 braid = &braids[MI_SCREEN(mi)];
286 MI_IS_DRAWN(mi) = True;
287 XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
289 (braid->linewidth <= 3 ? CapButt : CapRound),
292 theta = (2.0 * M_PI) / (float) (braid->braidlength);
293 t_inc = (2.0 * M_PI) / (float) num_points;
294 color_inc = (float) MI_NPIXELS(mi) * braid->color_direction /
296 braid->startcolor += SPINRATE * color_inc;
297 if (((int) braid->startcolor) >= MI_NPIXELS(mi))
298 braid->startcolor = 0.0;
300 r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
302 color = braid->startcolor;
304 for (i = 0; i < braid->braidlength; i++) {
306 for (t = 0.0; t < theta; t += t_inc) {
309 if (((int) color) >= MI_NPIXELS(mi))
313 for (s = 0; s < braid->nstrands; s++) {
314 if (ABS(braid->braidword[i]) == s)
316 if (ABS(braid->braidword[i]) - 1 == s) {
319 if (MI_NPIXELS(mi) > 2) {
320 color_use = color + SPINRATE *
321 braid->components[applywordbackto(braid, s, i)] +
322 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
323 while (((int) color_use) >= MI_NPIXELS(mi))
324 color_use -= (float) MI_NPIXELS(mi);
325 while (((int) color_use) < 0)
326 color_use += (float) MI_NPIXELS(mi);
330 if (MI_NPIXELS(mi) > 2) {
331 color_use += SPINRATE * color_inc;
332 while (((int) color_use) >= MI_NPIXELS(mi))
333 color_use -= (float) MI_NPIXELS(mi);
336 r1 = braid->min_radius + r_diff * (float) (s);
337 r2 = braid->min_radius + r_diff * (float) (s + 1);
338 if (braid->braidword[i] > 0 ||
339 (FABSF(t - theta / 2.0) > theta / 7.0)) {
340 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
341 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
342 COSF(t + psi) + braid->center_x;
343 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
344 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
345 SINF(t + psi) + braid->center_y;
346 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
347 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
348 COSF(t + t_inc + psi) + braid->center_x;
349 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
350 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
351 SINF(t + t_inc + psi) + braid->center_y;
352 if (MI_NPIXELS(mi) > 2)
353 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
355 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
357 XDrawLine(display, window, MI_GC(mi),
358 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
361 if (MI_NPIXELS(mi) > 2) {
362 color_use = color + SPINRATE *
363 braid->components[applywordbackto(braid, s + 1, i)] +
364 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
365 while (((int) color_use) >= MI_NPIXELS(mi))
366 color_use -= (float) MI_NPIXELS(mi);
367 while (((int) color_use) < 0)
368 color_use += (float) MI_NPIXELS(mi);
371 if (braid->braidword[i] < 0 ||
372 (FABSF(t - theta / 2.0) > theta / 7.0)) {
373 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
374 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
375 COSF(t + psi) + braid->center_x;
376 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
377 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
378 SINF(t + psi) + braid->center_y;
379 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
380 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
381 COSF(t + t_inc + psi) + braid->center_x;
382 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
383 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
384 SINF(t + t_inc + psi) + braid->center_y;
385 if (MI_NPIXELS(mi) > 2)
386 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
388 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
390 XDrawLine(display, window, MI_GC(mi),
391 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
396 if (MI_NPIXELS(mi) > 2) {
397 color_use = color + SPINRATE *
398 braid->components[applywordbackto(braid, s, i)] +
399 (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
400 while (((int) color_use) >= MI_NPIXELS(mi))
401 color_use -= (float) MI_NPIXELS(mi);
402 while (((int) color_use) < 0)
403 color_use += (float) MI_NPIXELS(mi);
407 if (MI_NPIXELS(mi) > 2) {
408 color_use += SPINRATE * color_inc;
409 while (((int) color_use) >= MI_NPIXELS(mi))
410 color_use -= (float) MI_NPIXELS(mi);
413 r1 = braid->min_radius + r_diff * (float) (s);
414 x_1 = r1 * COSF(t + psi) + braid->center_x;
415 y_1 = r1 * SINF(t + psi) + braid->center_y;
416 x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
417 y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
418 if (MI_NPIXELS(mi) > 2)
419 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
421 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
423 XDrawLine(display, window, MI_GC(mi),
424 (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
429 XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
431 if (++braid->age > MI_CYCLES(mi)) {
433 erase_full_window(MI_DISPLAY(mi), MI_WINDOW(mi));
440 release_braid(ModeInfo * mi)
442 if (braids != NULL) {
443 (void) free((void *) braids);
444 braids = (braidtype *) NULL;
449 refresh_braid(ModeInfo * mi)
454 #endif /* MODE_braid */