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

   1 /* -*- Mode: C; tab-width: 4 -*- */
   2 /*-
   3  * braid --- random braids around a circle and then changes the color in
   4  *           a rotational pattern
   5  */
   6
   7 #if 0
   8 static const char sccsid[] = "@(#)braid.c       5.00 2000/11/01 xlockmore";
   9 #endif
  10
  11 /*-
  12  * Copyright (c) 1995 by John Neil.
  13  *
  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.
  19  *
  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.
  25  *
  26  * Revision History:
  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>
  31  */
  32
  33 #ifdef STANDALONE
  34 # define MODE_braid
  35 # define DEFAULTS  "*delay: 1000 \n" \
  36                                    "*count: 15 \n" \
  37                                    "*cycles: 100 \n" \
  38                                    "*size: -7 \n" \
  39                                    "*ncolors: 64 \n" \
  40                                    "*fpsSolid: true \n" \
  41                                    "*ignoreRotation: True" \
  42
  43 # define UNIFORM_COLORS
  44 # include "xlockmore.h"
  45 # include "erase.h"
  46 #else /* STANDALONE */
  47 # include "xlock.h"
  48 # define ENTRYPOINT /**/
  49 #endif /* STANDALONE */
  50
  51 #ifdef MODE_braid
  52
  53 ENTRYPOINT ModeSpecOpt braid_opts = {0, NULL, 0, NULL, NULL};
  54
  55 #ifdef USE_MODULES
  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};
  61
  62 #endif
  63
  64 #if defined( COLORROUND ) && defined( COLORCOMP )
  65 #undef COLORROUND
  66 #undef COLORCOMP
  67 #endif
  68
  69 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  70 #if 0
  71 /* to color in a circular pattern use COLORROUND */
  72 #define COLORROUND
  73 #else
  74 /* to color by component use COLORCOMP */
  75 #define COLORCOMP
  76 #endif
  77 #endif
  78
  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 */
  84
  85 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  86 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  87
  88 typedef struct {
  89         int         linewidth;
  90         int         braidword[MAXLENGTH];
  91         int         components[MAXSTRANDS];
  92         int         startcomp[MAXLENGTH][MAXSTRANDS];
  93         int         nstrands;
  94         int         braidlength;
  95         float       startcolor;
  96         int         center_x;
  97         int         center_y;
  98         float       min_radius;
  99         float       max_radius;
 100         float       top, bottom, left, right;
 101         int         age;
 102         int         color_direction;
 103 #ifdef STANDALONE
 104   eraser_state *eraser;
 105 #endif
 106 } braidtype;
 107
 108 static braidtype *braids = (braidtype *) NULL;
 109
 110 static int
 111 applyword(braidtype * braid, int string, int position)
 112 {
 113         int         i, c;
 114
 115         c = string;
 116         for (i = position; i < braid->braidlength; i++) {
 117                 if (c == ABS(braid->braidword[i]))
 118                         c--;
 119                 else if (c == ABS(braid->braidword[i]) - 1)
 120                         c++;
 121         }
 122         for (i = 0; i < position; i++) {
 123                 if (c == ABS(braid->braidword[i]))
 124                         c--;
 125                 else if (c == ABS(braid->braidword[i]) - 1)
 126                         c++;
 127         }
 128         return c;
 129 }
 130
 131 #if 0
 132 static int
 133 applywordto(braidtype * braid, int string, int position)
 134 {
 135         int         i, c;
 136
 137         c = string;
 138         for (i = 0; i < position; i++) {
 139                 if (c == ABS(braid->braidword[i])) {
 140                         c--;
 141                 } else if (c == ABS(braid->braidword[i]) - 1) {
 142                         c++;
 143                 }
 144         }
 145         return c;
 146 }
 147 #endif
 148
 149 static int
 150 applywordbackto(braidtype * braid, int string, int position)
 151 {
 152         int         i, c;
 153
 154         c = string;
 155         for (i = position - 1; i >= 0; i--) {
 156                 if (c == ABS(braid->braidword[i])) {
 157                         c--;
 158                 } else if (c == ABS(braid->braidword[i]) - 1) {
 159                         c++;
 160                 }
 161         }
 162         return c;
 163 }
 164
 165 ENTRYPOINT void
 166 init_braid(ModeInfo * mi)
 167 {
 168         braidtype  *braid;
 169         int         used[MAXSTRANDS];
 170         int         i, count, comp, c;
 171         float       min_length;
 172
 173         if (braids == NULL) {
 174                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 175                                                 sizeof (braidtype))) == NULL)
 176                         return;
 177         }
 178         braid = &braids[MI_SCREEN(mi)];
 179
 180         braid->center_x = MI_WIDTH(mi) / 2;
 181         braid->center_y = MI_HEIGHT(mi) / 2;
 182         braid->age = 0;
 183
 184         /* jwz: go in the other direction sometimes. */
 185         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 186
 187 #ifndef STANDALONE
 188         MI_CLEARWINDOW(mi);
 189 #endif
 190
 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;
 195
 196         if (MI_COUNT(mi) < MINSTRANDS)
 197                 braid->nstrands = MINSTRANDS;
 198         else
 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 -1, braid->nstrands * 6));
 203
 204         for (i = 0; i < braid->braidlength; i++) {
 205                 braid->braidword[i] =
 206                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 207                 if (i > 0)
 208                         while (braid->braidword[i] == -braid->braidword[i - 1])
 209                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 210         }
 211
 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);
 215
 216         do {
 217                 (void) memset((char *) used, 0, sizeof (used));
 218                 count = 0;
 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++;
 232                 }
 233         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 234
 235         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 236                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 237         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 238            JoinRound); */
 239
 240         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 241         c = 1;
 242         comp = 0;
 243         braid->components[0] = 1;
 244         do {
 245                 i = comp;
 246                 do {
 247                         i = applyword(braid, i, 0);
 248                         braid->components[i] = braid->components[comp];
 249                 } while (i != comp);
 250                 count = 0;
 251                 for (i = 0; i < braid->nstrands; i++)
 252                         if (braid->components[i] == 0)
 253                                 count++;
 254                 if (count > 0) {
 255                         for (comp = 0; braid->components[comp] != 0; comp++);
 256                         braid->components[comp] = ++c;
 257                 }
 258         } while (count > 0);
 259
 260         braid->linewidth = MI_SIZE(mi);
 261
 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;
 269 }
 270
 271 ENTRYPOINT void
 272 draw_braid(ModeInfo * mi)
 273 {
 274         Display    *display = MI_DISPLAY(mi);
 275         Window      window = MI_WINDOW(mi);
 276         int         num_points = 500;
 277         float       t_inc;
 278         float       theta, psi;
 279         float       t, r_diff;
 280         int         i, s;
 281         float       x_1, y_1, x_2, y_2, r1, r2;
 282         float       color, color_use = 0.0, color_inc;
 283         braidtype  *braid;
 284
 285         if (braids == NULL)
 286                 return;
 287         braid = &braids[MI_SCREEN(mi)];
 288
 289 #ifdef STANDALONE
 290     if (braid->eraser) {
 291       braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
 292       return;
 293     }
 294 #endif
 295
 296         MI_IS_DRAWN(mi) = True;
 297         XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
 298                            LineSolid,
 299                            (braid->linewidth <= 3 ? CapButt : CapRound),
 300                            JoinMiter);
 301
 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 /
 305                 (float) num_points;
 306         braid->startcolor += SPINRATE * color_inc;
 307         if (((int) braid->startcolor) >= MI_NPIXELS(mi))
 308                 braid->startcolor = 0.0;
 309
 310         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 311
 312         color = braid->startcolor;
 313         psi = 0.0;
 314         for (i = 0; i < braid->braidlength; i++) {
 315                 psi += theta;
 316                 for (t = 0.0; t < theta; t += t_inc) {
 317 #ifdef COLORROUND
 318                         color += color_inc;
 319                         if (((int) color) >= MI_NPIXELS(mi))
 320                                 color = 0.0;
 321                         color_use = color;
 322 #endif
 323                         for (s = 0; s < braid->nstrands; s++) {
 324                                 if (ABS(braid->braidword[i]) == s)
 325                                         continue;
 326                                 if (ABS(braid->braidword[i]) - 1 == s) {
 327                                         /* crosSINFg */
 328 #ifdef COLORCOMP
 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);
 337                                         }
 338 #endif
 339 #ifdef COLORROUND
 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);
 344                                         }
 345 #endif
 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));
 364                                                 else
 365                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 366
 367                                                 XDrawLine(display, window, MI_GC(mi),
 368                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 369                                         }
 370 #ifdef COLORCOMP
 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);
 379                                         }
 380 #endif
 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));
 397                                                 else
 398                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 399
 400                                                 XDrawLine(display, window, MI_GC(mi),
 401                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 402                                         }
 403                                 } else {
 404                                         /* no crosSINFg */
 405 #ifdef COLORCOMP
 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);
 414                                         }
 415 #endif
 416 #ifdef COLORROUND
 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);
 421                                         }
 422 #endif
 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));
 430                                         else
 431                                                 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 432
 433                                         XDrawLine(display, window, MI_GC(mi),
 434                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 435                                 }
 436                         }
 437                 }
 438         }
 439         XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
 440
 441         if (++braid->age > MI_CYCLES(mi)) {
 442 #ifdef STANDALONE
 443       braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
 444 #endif
 445                 init_braid(mi);
 446         }
 447 }
 448
 449 ENTRYPOINT void
 450 reshape_braid(ModeInfo * mi, int width, int height)
 451 {
 452   XClearWindow (MI_DISPLAY (mi), MI_WINDOW(mi));
 453   init_braid (mi);
 454 }
 455
 456 ENTRYPOINT Bool
 457 braid_handle_event (ModeInfo *mi, XEvent *event)
 458 {
 459   if (screenhack_event_helper (MI_DISPLAY(mi), MI_WINDOW(mi), event))
 460     {
 461       reshape_braid (mi, MI_WIDTH(mi), MI_HEIGHT(mi));
 462       return True;
 463     }
 464
 465   return False;
 466 }
 467
 468 ENTRYPOINT void
 469 release_braid(ModeInfo * mi)
 470 {
 471         if (braids != NULL) {
 472                 (void) free((void *) braids);
 473                 braids = (braidtype *) NULL;
 474         }
 475 }
 476
 477 ENTRYPOINT void
 478 refresh_braid(ModeInfo * mi)
 479 {
 480         MI_CLEARWINDOW(mi);
 481 }
 482
 483 XSCREENSAVER_MODULE ("Braid", braid)
 484
 485 #endif /* MODE_braid */