git.hungrycats.org Git - xscreensaver/blob - hacks/braid.c

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  * braid --- draws random color-cyling rotating braids around a circle.
   3  */
   4 #if !defined( lint ) && !defined( SABER )
   5 static const char sccsid[] = "@(#)braid.c       4.00 97/01/01 xlockmore";
   6 #endif
   7
   8 /*
   9  * Copyright (c) 1995 by John Neil.
  10  *
  11  * Permission to use, copy, modify, and distribute this software and its
  12  * documentation for any purpose and without fee is hereby granted,
  13  * provided that the above copyright notice appear in all copies and that
  14  * both that copyright notice and this permission notice appear in
  15  * supporting documentation.
  16  *
  17  * This file is provided AS IS with no warranties of any kind.  The author
  18  * shall have no liability with respect to the infringement of copyrights,
  19  * trade secrets or any patents by this file or any part thereof.  In no
  20  * event will the author be liable for any lost revenue or profits or
  21  * other special, indirect and consequential damages.
  22  *
  23  * Revision History:
  24  * 10-May-97: jwz@netscape.com: turned into a standalone program.
  25  * 01-Sep-95: color knotted components differently, J. Neil.
  26  * 29-Aug-95: Written.  John Neil <neil@math.idbsu.edu>
  27  */
  28
  29 #ifdef STANDALONE
  30 # define PROGCLASS                                      "Braid"
  31 # define HACK_INIT                                      init_braid
  32 # define HACK_DRAW                                      draw_braid
  33 # define braid_opts                                     xlockmore_opts
  34 # define DEFAULTS       "*count:                15    \n"                       \
  35                                         "*cycles:               100   \n"                       \
  36                                         "*delay:                1000  \n"                       \
  37                                         "*ncolors:              64    \n"
  38 # define UNIFORM_COLORS
  39 # include "xlockmore.h"                         /* from the xscreensaver distribution */
  40 #else  /* !STANDALONE */
  41 # include "xlock.h"                                     /* from the xlockmore distribution */
  42 #endif /* !STANDALONE */
  43
  44 ModeSpecOpt braid_opts = {
  45   0, NULL, 0, NULL, NULL };
  46
  47
  48 #if defined( COLORROUND ) && defined( COLORCOMP )
  49 #undef COLORROUND
  50 #undef COLORCOMP
  51 #endif
  52
  53 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  54 #if 0
  55 /* to color in a circular pattern use COLORROUND */
  56 #define COLORROUND
  57 #else
  58 /* to color by component use COLORCOMP */
  59 #define COLORCOMP
  60 #endif
  61 #endif
  62
  63 #define MAXLENGTH  50           /* the maximum length of a braid word */
  64 #define MINLENGTH  8            /* the minimum length of a braid word */
  65 #define MAXSTRANDS  15          /* the maximum number of strands in the braid */
  66 #define MINSTRANDS  3           /* the minimum number of strands in the braid */
  67 #define SPINRATE  12.0          /* the rate at which the colors spin */
  68
  69 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  70 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  71
  72 typedef struct {
  73         int         braidword[MAXLENGTH];
  74         int         components[MAXSTRANDS];
  75         int         startcomp[MAXLENGTH][MAXSTRANDS];
  76         int         nstrands;
  77         int         braidlength;
  78         float       startcolor;
  79         int         center_x;
  80         int         center_y;
  81         float       min_radius;
  82         float       max_radius;
  83         float       top, bottom, left, right;
  84         int         age;
  85     int         color_direction;
  86 } braidtype;
  87
  88 static braidtype *braids = NULL;
  89
  90 static int
  91 applyword(braidtype * braid, int string, int position)
  92 {
  93         int         i, c;
  94
  95         c = string;
  96         for (i = position; i < braid->braidlength; i++) {
  97                 if (c == ABS(braid->braidword[i]))
  98                         c--;
  99                 else if (c == ABS(braid->braidword[i]) - 1)
 100                         c++;
 101         }
 102         for (i = 0; i < position; i++) {
 103                 if (c == ABS(braid->braidword[i]))
 104                         c--;
 105                 else if (c == ABS(braid->braidword[i]) - 1)
 106                         c++;
 107         }
 108         return c;
 109 }
 110
 111 #if 0
 112 static int
 113 applywordto(braidtype * braid, int string, int position)
 114 {
 115         int         i, c;
 116
 117         c = string;
 118         for (i = 0; i < position; i++) {
 119                 if (c == ABS(braid->braidword[i])) {
 120                         c--;
 121                 } else if (c == ABS(braid->braidword[i]) - 1) {
 122                         c++;
 123                 }
 124         }
 125         return c;
 126 }
 127 #endif
 128
 129 static int
 130 applywordbackto(braidtype * braid, int string, int position)
 131 {
 132         int         i, c;
 133
 134         c = string;
 135         for (i = position - 1; i >= 0; i--) {
 136                 if (c == ABS(braid->braidword[i])) {
 137                         c--;
 138                 } else if (c == ABS(braid->braidword[i]) - 1) {
 139                         c++;
 140                 }
 141         }
 142         return c;
 143 }
 144
 145 void
 146 init_braid(ModeInfo * mi)
 147 {
 148         Display    *display = MI_DISPLAY(mi);
 149         braidtype  *braid;
 150         int         used[MAXSTRANDS];
 151         int         i, count, comp, c;
 152         float       min_length;
 153
 154         if (braids == NULL) {
 155                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 156                                                 sizeof (braidtype))) == NULL)
 157                         return;
 158         }
 159         braid = &braids[MI_SCREEN(mi)];
 160
 161         braid->center_x = MI_WIN_WIDTH(mi) / 2;
 162         braid->center_y = MI_WIN_HEIGHT(mi) / 2;
 163         braid->age = 0;
 164
 165         /* jwz: go in the other direction sometimes. */
 166         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 167
 168         XClearWindow(display, MI_WINDOW(mi));
 169
 170         min_length = (braid->center_x > braid->center_y) ?
 171                 braid->center_y : braid->center_x;
 172         braid->min_radius = min_length * 0.30;
 173         braid->max_radius = min_length * 0.90;
 174
 175         if (MI_BATCHCOUNT(mi) < MINSTRANDS)
 176                 braid->nstrands = MINSTRANDS;
 177         else
 178                 braid->nstrands = INTRAND(MINSTRANDS,
 179                                   MAX(MIN(MIN(MAXSTRANDS, MI_BATCHCOUNT(mi)),
 180                                           (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
 181         braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
 182
 183         for (i = 0; i < braid->braidlength; i++) {
 184                 braid->braidword[i] =
 185                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 186                 if (i > 0)
 187                         while (braid->braidword[i] == -braid->braidword[i - 1])
 188                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 189         }
 190
 191         while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
 192                 braid->braidword[braid->braidlength - 1] =
 193                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 194
 195         do {
 196                 (void) memset((char *) used, 0, sizeof (used));
 197                 count = 0;
 198                 for (i = 0; i < braid->braidlength; i++)
 199                         used[ABS(braid->braidword[i])]++;
 200                 for (i = 0; i < braid->nstrands; i++)
 201                         count += (used[i] > 0) ? 1 : 0;
 202                 if (count < braid->nstrands - 1) {
 203                         braid->braidword[braid->braidlength] =
 204                                 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 205                         while (braid->braidword[braid->braidlength] ==
 206                                -braid->braidword[braid->braidlength - 1] &&
 207                                braid->braidword[0] == -braid->braidword[braid->braidlength])
 208                                 braid->braidword[braid->braidlength] =
 209                                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 210                         braid->braidlength++;
 211                 }
 212         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 213
 214         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 215                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 216         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 217            JoinRound); */
 218
 219         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 220         c = 1;
 221         comp = 0;
 222         braid->components[0] = 1;
 223         do {
 224                 i = comp;
 225                 do {
 226                         i = applyword(braid, i, 0);
 227                         braid->components[i] = braid->components[comp];
 228                 } while (i != comp);
 229                 count = 0;
 230                 for (i = 0; i < braid->nstrands; i++)
 231                         if (braid->components[i] == 0)
 232                                 count++;
 233                 if (count > 0) {
 234                         for (comp = 0; braid->components[comp] != 0; comp++);
 235                         braid->components[comp] = ++c;
 236                 }
 237         } while (count > 0);
 238
 239         for (i = 0; i < braid->nstrands; i++)
 240                 if (!(braid->components[i] & 1))
 241                         braid->components[i] *= -1;
 242 }
 243
 244 void
 245 draw_braid(ModeInfo * mi)
 246 {
 247         Display    *display = MI_DISPLAY(mi);
 248         Window      window = MI_WINDOW(mi);
 249         braidtype  *braid = &braids[MI_SCREEN(mi)];
 250         float       num_points, t_inc;
 251         float       theta, psi;
 252         float       t, r_diff;
 253         int         i, s;
 254         float       x_1, y_1, x_2, y_2, r1, r2;
 255         float       color, color_use = 0.0, color_inc;
 256
 257         num_points = 500.0;
 258         theta = (2.0 * M_PI) / (float) (braid->braidlength);
 259         t_inc = (2.0 * M_PI) / num_points;
 260         color_inc = (float) MI_NPIXELS(mi) / num_points;
 261         color_inc *= braid->color_direction;
 262
 263         braid->startcolor += SPINRATE * color_inc;
 264         if (braid->startcolor >= MI_NPIXELS(mi))
 265                 braid->startcolor = 0.0;
 266
 267         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 268
 269         color = braid->startcolor;
 270         psi = 0.0;
 271         for (i = 0; i < braid->braidlength; i++) {
 272                 psi += theta;
 273                 for (t = 0.0; t < theta; t += t_inc) {
 274 #ifdef COLORROUND
 275                         color += color_inc;
 276                         if (color >= (float) (MI_NPIXELS(mi)))
 277                                 color = 0.0;
 278                         color_use = color;
 279 #endif
 280                         for (s = 0; s < braid->nstrands; s++) {
 281                                 if (ABS(braid->braidword[i]) == s)
 282                                         continue;
 283                                 if (ABS(braid->braidword[i]) - 1 == s) {
 284                                         /* crosSINFg */
 285 #ifdef COLORCOMP
 286                                         if (MI_NPIXELS(mi) > 2) {
 287                                                 color_use = color + SPINRATE *
 288                                                         braid->components[applywordbackto(braid, s, i)] +
 289                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 290                                                 while (color_use >= (float) MI_NPIXELS(mi))
 291                                                         color_use -= (float) MI_NPIXELS(mi);
 292                                                 while (color_use < 0.0)
 293                                                         color_use += (float) MI_NPIXELS(mi);
 294                                         }
 295 #endif
 296 #ifdef COLORROUND
 297                                         if (MI_NPIXELS(mi) > 2) {
 298                                                 color_use += SPINRATE * color_inc;
 299                                                 while (color_use >= (float) (MI_NPIXELS(mi)))
 300                                                         color_use -= (float) MI_NPIXELS(mi);
 301                                         }
 302 #endif
 303                                         r1 = braid->min_radius + r_diff * (float) (s);
 304                                         r2 = braid->min_radius + r_diff * (float) (s + 1);
 305                                         if (braid->braidword[i] > 0 ||
 306                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 307                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 308                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 309                                                         COSF(t + psi) + braid->center_x;
 310                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 311                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 312                                                         SINF(t + psi) + braid->center_y;
 313                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 314                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 315                                                         COSF(t + t_inc + psi) + braid->center_x;
 316                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 317                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 318                                                         SINF(t + t_inc + psi) + braid->center_y;
 319                                                 if (MI_NPIXELS(mi) > 2)
 320                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 321                                                 else
 322                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 323
 324                                                 XDrawLine(display, window, MI_GC(mi),
 325                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 326                                         }
 327 #ifdef COLORCOMP
 328                                         if (MI_NPIXELS(mi) > 2) {
 329                                                 color_use = color + SPINRATE *
 330                                                         braid->components[applywordbackto(braid, s + 1, i)] +
 331                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 332                                                 while (color_use >= (float) MI_NPIXELS(mi))
 333                                                         color_use -= (float) MI_NPIXELS(mi);
 334                                                 while (color_use < 0.0)
 335                                                         color_use += (float) MI_NPIXELS(mi);
 336                                         }
 337 #endif
 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)) * r1 +
 341                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 342                                                         COSF(t + psi) + braid->center_x;
 343                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 344                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 345                                                         SINF(t + psi) + braid->center_y;
 346                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 347                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 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)) * r1 +
 350                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 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));
 354                                                 else
 355                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 356
 357                                                 XDrawLine(display, window, MI_GC(mi),
 358                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 359                                         }
 360                                 } else {
 361                                         /* no crosSINFg */
 362 #ifdef COLORCOMP
 363                                         if (MI_NPIXELS(mi) > 2) {
 364                                                 color_use = color + SPINRATE *
 365                                                         braid->components[applywordbackto(braid, s, i)] +
 366                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 367                                                 while (color_use >= (float) MI_NPIXELS(mi))
 368                                                         color_use -= (float) MI_NPIXELS(mi);
 369                                                 while (color_use < 0.0)
 370                                                         color_use += (float) MI_NPIXELS(mi);
 371                                         }
 372 #endif
 373 #ifdef COLORROUND
 374                                         if (MI_NPIXELS(mi) > 2) {
 375                                                 color_use += SPINRATE * color_inc;
 376                                                 while (color_use >= (float) MI_NPIXELS(mi))
 377                                                         color_use -= (float) MI_NPIXELS(mi);
 378                                         }
 379 #endif
 380                                         r1 = braid->min_radius + r_diff * (float) (s);
 381                                         x_1 = r1 * COSF(t + psi) + braid->center_x;
 382                                         y_1 = r1 * SINF(t + psi) + braid->center_y;
 383                                         x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
 384                                         y_2 = r1 * 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));
 387                                         else
 388                                                 XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 389
 390                                         XDrawLine(display, window, MI_GC(mi),
 391                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 392                                 }
 393                         }
 394                 }
 395         }
 396
 397         if (++braid->age > MI_CYCLES(mi))
 398                 init_braid(mi);
 399 }
 400
 401 void
 402 release_braid(ModeInfo * mi)
 403 {
 404         if (braids != NULL) {
 405                 (void) free((void *) braids);
 406                 braids = NULL;
 407         }
 408 }
 409
 410 void
 411 refresh_braid(ModeInfo * mi)
 412 {
 413         /* Do nothing, it will refresh by itself */
 414 }