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 # define braid_handle_event 0
  45 # include "xlockmore.h"
  46 # include "erase.h"
  47 #else /* STANDALONE */
  48 # include "xlock.h"
  49 # define ENTRYPOINT /**/
  50 #endif /* STANDALONE */
  51
  52 #ifdef MODE_braid
  53
  54 ENTRYPOINT ModeSpecOpt braid_opts = {0, NULL, 0, NULL, NULL};
  55
  56 #ifdef USE_MODULES
  57 ModStruct   braid_description =
  58 {"braid", "init_braid", "draw_braid", "release_braid",
  59  "refresh_braid", "init_braid", (char *) NULL, &braid_opts,
  60  1000, 15, 100, 1, 64, 1.0, "",
  61  "Shows random braids and knots", 0, NULL};
  62
  63 #endif
  64
  65 #if defined( COLORROUND ) && defined( COLORCOMP )
  66 #undef COLORROUND
  67 #undef COLORCOMP
  68 #endif
  69
  70 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  71 #if 0
  72 /* to color in a circular pattern use COLORROUND */
  73 #define COLORROUND
  74 #else
  75 /* to color by component use COLORCOMP */
  76 #define COLORCOMP
  77 #endif
  78 #endif
  79
  80 #define MAXLENGTH  50           /* the maximum length of a braid word */
  81 #define MINLENGTH  8            /* the minimum length of a braid word */
  82 #define MAXSTRANDS  15          /* the maximum number of strands in the braid */
  83 #define MINSTRANDS  3           /* the minimum number of strands in the braid */
  84 #define SPINRATE  12.0          /* the rate at which the colors spin */
  85
  86 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  87 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  88
  89 typedef struct {
  90         int         linewidth;
  91         int         braidword[MAXLENGTH];
  92         int         components[MAXSTRANDS];
  93         int         startcomp[MAXLENGTH][MAXSTRANDS];
  94         int         nstrands;
  95         int         braidlength;
  96         float       startcolor;
  97         int         center_x;
  98         int         center_y;
  99         float       min_radius;
 100         float       max_radius;
 101         float       top, bottom, left, right;
 102         int         age;
 103         int         color_direction;
 104 #ifdef STANDALONE
 105   eraser_state *eraser;
 106 #endif
 107 } braidtype;
 108
 109 static braidtype *braids = (braidtype *) NULL;
 110
 111 static int
 112 applyword(braidtype * braid, int string, int position)
 113 {
 114         int         i, c;
 115
 116         c = string;
 117         for (i = position; i < braid->braidlength; i++) {
 118                 if (c == ABS(braid->braidword[i]))
 119                         c--;
 120                 else if (c == ABS(braid->braidword[i]) - 1)
 121                         c++;
 122         }
 123         for (i = 0; i < position; i++) {
 124                 if (c == ABS(braid->braidword[i]))
 125                         c--;
 126                 else if (c == ABS(braid->braidword[i]) - 1)
 127                         c++;
 128         }
 129         return c;
 130 }
 131
 132 #if 0
 133 static int
 134 applywordto(braidtype * braid, int string, int position)
 135 {
 136         int         i, c;
 137
 138         c = string;
 139         for (i = 0; i < position; i++) {
 140                 if (c == ABS(braid->braidword[i])) {
 141                         c--;
 142                 } else if (c == ABS(braid->braidword[i]) - 1) {
 143                         c++;
 144                 }
 145         }
 146         return c;
 147 }
 148 #endif
 149
 150 static int
 151 applywordbackto(braidtype * braid, int string, int position)
 152 {
 153         int         i, c;
 154
 155         c = string;
 156         for (i = position - 1; i >= 0; i--) {
 157                 if (c == ABS(braid->braidword[i])) {
 158                         c--;
 159                 } else if (c == ABS(braid->braidword[i]) - 1) {
 160                         c++;
 161                 }
 162         }
 163         return c;
 164 }
 165
 166 ENTRYPOINT void
 167 init_braid(ModeInfo * mi)
 168 {
 169         braidtype  *braid;
 170         int         used[MAXSTRANDS];
 171         int         i, count, comp, c;
 172         float       min_length;
 173
 174         if (braids == NULL) {
 175                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 176                                                 sizeof (braidtype))) == NULL)
 177                         return;
 178         }
 179         braid = &braids[MI_SCREEN(mi)];
 180
 181         braid->center_x = MI_WIDTH(mi) / 2;
 182         braid->center_y = MI_HEIGHT(mi) / 2;
 183         braid->age = 0;
 184
 185         /* jwz: go in the other direction sometimes. */
 186         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 187
 188 #ifndef STANDALONE
 189         MI_CLEARWINDOW(mi);
 190 #endif
 191
 192         min_length = (braid->center_x > braid->center_y) ?
 193                 braid->center_y : braid->center_x;
 194         braid->min_radius = min_length * 0.30;
 195         braid->max_radius = min_length * 0.90;
 196
 197         if (MI_COUNT(mi) < MINSTRANDS)
 198                 braid->nstrands = MINSTRANDS;
 199         else
 200                 braid->nstrands = INTRAND(MINSTRANDS,
 201                                        MAX(MIN(MIN(MAXSTRANDS, MI_COUNT(mi)),
 202                                                (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
 203         braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
 204
 205         for (i = 0; i < braid->braidlength; i++) {
 206                 braid->braidword[i] =
 207                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 208                 if (i > 0)
 209                         while (braid->braidword[i] == -braid->braidword[i - 1])
 210                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 211         }
 212
 213         while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
 214                 braid->braidword[braid->braidlength - 1] =
 215                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 216
 217         do {
 218                 (void) memset((char *) used, 0, sizeof (used));
 219                 count = 0;
 220                 for (i = 0; i < braid->braidlength; i++)
 221                         used[ABS(braid->braidword[i])]++;
 222                 for (i = 0; i < braid->nstrands; i++)
 223                         count += (used[i] > 0) ? 1 : 0;
 224                 if (count < braid->nstrands - 1) {
 225                         braid->braidword[braid->braidlength] =
 226                                 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 227                         while (braid->braidword[braid->braidlength] ==
 228                                -braid->braidword[braid->braidlength - 1] &&
 229                                braid->braidword[0] == -braid->braidword[braid->braidlength])
 230                                 braid->braidword[braid->braidlength] =
 231                                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 232                         braid->braidlength++;
 233                 }
 234         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 235
 236         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 237                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 238         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 239            JoinRound); */
 240
 241         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 242         c = 1;
 243         comp = 0;
 244         braid->components[0] = 1;
 245         do {
 246                 i = comp;
 247                 do {
 248                         i = applyword(braid, i, 0);
 249                         braid->components[i] = braid->components[comp];
 250                 } while (i != comp);
 251                 count = 0;
 252                 for (i = 0; i < braid->nstrands; i++)
 253                         if (braid->components[i] == 0)
 254                                 count++;
 255                 if (count > 0) {
 256                         for (comp = 0; braid->components[comp] != 0; comp++);
 257                         braid->components[comp] = ++c;
 258                 }
 259         } while (count > 0);
 260
 261         braid->linewidth = MI_SIZE(mi);
 262
 263         if (braid->linewidth < 0)
 264                 braid->linewidth = NRAND(-braid->linewidth) + 1;
 265         if (braid->linewidth * braid->linewidth * 8 > MIN(MI_WIDTH(mi), MI_HEIGHT(mi)))
 266        braid->linewidth = MIN(1, (int) sqrt((double) MIN(MI_WIDTH(mi), MI_HEIGHT(mi)) / 8));
 267         for (i = 0; i < braid->nstrands; i++)
 268                 if (!(braid->components[i] & 1))
 269                         braid->components[i] *= -1;
 270 }
 271
 272 ENTRYPOINT void
 273 draw_braid(ModeInfo * mi)
 274 {
 275         Display    *display = MI_DISPLAY(mi);
 276         Window      window = MI_WINDOW(mi);
 277         int         num_points = 500;
 278         float       t_inc;
 279         float       theta, psi;
 280         float       t, r_diff;
 281         int         i, s;
 282         float       x_1, y_1, x_2, y_2, r1, r2;
 283         float       color, color_use = 0.0, color_inc;
 284         braidtype  *braid;
 285
 286         if (braids == NULL)
 287                 return;
 288         braid = &braids[MI_SCREEN(mi)];
 289
 290 #ifdef STANDALONE
 291     if (braid->eraser) {
 292       braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
 293       return;
 294     }
 295 #endif
 296
 297         MI_IS_DRAWN(mi) = True;
 298         XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
 299                            LineSolid,
 300                            (braid->linewidth <= 3 ? CapButt : CapRound),
 301                            JoinMiter);
 302
 303         theta = (2.0 * M_PI) / (float) (braid->braidlength);
 304         t_inc = (2.0 * M_PI) / (float) num_points;
 305         color_inc = (float) MI_NPIXELS(mi) * braid->color_direction /
 306                 (float) num_points;
 307         braid->startcolor += SPINRATE * color_inc;
 308         if (((int) braid->startcolor) >= MI_NPIXELS(mi))
 309                 braid->startcolor = 0.0;
 310
 311         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 312
 313         color = braid->startcolor;
 314         psi = 0.0;
 315         for (i = 0; i < braid->braidlength; i++) {
 316                 psi += theta;
 317                 for (t = 0.0; t < theta; t += t_inc) {
 318 #ifdef COLORROUND
 319                         color += color_inc;
 320                         if (((int) color) >= MI_NPIXELS(mi))
 321                                 color = 0.0;
 322                         color_use = color;
 323 #endif
 324                         for (s = 0; s < braid->nstrands; s++) {
 325                                 if (ABS(braid->braidword[i]) == s)
 326                                         continue;
 327                                 if (ABS(braid->braidword[i]) - 1 == s) {
 328                                         /* crosSINFg */
 329 #ifdef COLORCOMP
 330                                         if (MI_NPIXELS(mi) > 2) {
 331                                                 color_use = color + SPINRATE *
 332                                                         braid->components[applywordbackto(braid, s, i)] +
 333                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 334                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 335                                                         color_use -= (float) MI_NPIXELS(mi);
 336                                                 while (((int) color_use) < 0)
 337                                                         color_use += (float) MI_NPIXELS(mi);
 338                                         }
 339 #endif
 340 #ifdef COLORROUND
 341                                         if (MI_NPIXELS(mi) > 2) {
 342                                                 color_use += SPINRATE * color_inc;
 343                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 344                                                         color_use -= (float) MI_NPIXELS(mi);
 345                                         }
 346 #endif
 347                                         r1 = braid->min_radius + r_diff * (float) (s);
 348                                         r2 = braid->min_radius + r_diff * (float) (s + 1);
 349                                         if (braid->braidword[i] > 0 ||
 350                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 351                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 352                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 353                                                         COSF(t + psi) + braid->center_x;
 354                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 355                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 356                                                         SINF(t + psi) + braid->center_y;
 357                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 358                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 359                                                         COSF(t + t_inc + psi) + braid->center_x;
 360                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 361                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 362                                                         SINF(t + t_inc + psi) + braid->center_y;
 363                                                 if (MI_NPIXELS(mi) > 2)
 364                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 365                                                 else
 366                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 367
 368                                                 XDrawLine(display, window, MI_GC(mi),
 369                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 370                                         }
 371 #ifdef COLORCOMP
 372                                         if (MI_NPIXELS(mi) > 2) {
 373                                                 color_use = color + SPINRATE *
 374                                                         braid->components[applywordbackto(braid, s + 1, i)] +
 375                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 376                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 377                                                         color_use -= (float) MI_NPIXELS(mi);
 378                                                 while (((int) color_use) < 0)
 379                                                         color_use += (float) MI_NPIXELS(mi);
 380                                         }
 381 #endif
 382                                         if (braid->braidword[i] < 0 ||
 383                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 384                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 385                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 386                                                         COSF(t + psi) + braid->center_x;
 387                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 388                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 389                                                         SINF(t + psi) + braid->center_y;
 390                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 391                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 392                                                         COSF(t + t_inc + psi) + braid->center_x;
 393                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 394                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 395                                                         SINF(t + t_inc + psi) + braid->center_y;
 396                                                 if (MI_NPIXELS(mi) > 2)
 397                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 398                                                 else
 399                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 400
 401                                                 XDrawLine(display, window, MI_GC(mi),
 402                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 403                                         }
 404                                 } else {
 405                                         /* no crosSINFg */
 406 #ifdef COLORCOMP
 407                                         if (MI_NPIXELS(mi) > 2) {
 408                                                 color_use = color + SPINRATE *
 409                                                         braid->components[applywordbackto(braid, s, i)] +
 410                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 411                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 412                                                         color_use -= (float) MI_NPIXELS(mi);
 413                                                 while (((int) color_use) < 0)
 414                                                         color_use += (float) MI_NPIXELS(mi);
 415                                         }
 416 #endif
 417 #ifdef COLORROUND
 418                                         if (MI_NPIXELS(mi) > 2) {
 419                                                 color_use += SPINRATE * color_inc;
 420                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 421                                                         color_use -= (float) MI_NPIXELS(mi);
 422                                         }
 423 #endif
 424                                         r1 = braid->min_radius + r_diff * (float) (s);
 425                                         x_1 = r1 * COSF(t + psi) + braid->center_x;
 426                                         y_1 = r1 * SINF(t + psi) + braid->center_y;
 427                                         x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
 428                                         y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
 429                                         if (MI_NPIXELS(mi) > 2)
 430                                                 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 431                                         else
 432                                                 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 433
 434                                         XDrawLine(display, window, MI_GC(mi),
 435                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 436                                 }
 437                         }
 438                 }
 439         }
 440         XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
 441
 442         if (++braid->age > MI_CYCLES(mi)) {
 443 #ifdef STANDALONE
 444       braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
 445 #endif
 446                 init_braid(mi);
 447         }
 448 }
 449
 450 ENTRYPOINT void
 451 reshape_braid(ModeInfo * mi, int width, int height)
 452 {
 453   XClearWindow (MI_DISPLAY (mi), MI_WINDOW(mi));
 454   init_braid (mi);
 455 }
 456
 457 ENTRYPOINT void
 458 release_braid(ModeInfo * mi)
 459 {
 460         if (braids != NULL) {
 461                 (void) free((void *) braids);
 462                 braids = (braidtype *) NULL;
 463         }
 464 }
 465
 466 ENTRYPOINT void
 467 refresh_braid(ModeInfo * mi)
 468 {
 469         MI_CLEARWINDOW(mi);
 470 }
 471
 472 XSCREENSAVER_MODULE ("Braid", braid)
 473
 474 #endif /* MODE_braid */