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 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" \
  40  "*count: 15 \n" \
  41  "*cycles: 100 \n" \
  42  "*size: -7 \n" \
  43  "*ncolors: 64 \n"
  44 #define UNIFORM_COLORS
  45 #include "xlockmore.h"
  46 #include "erase.h"
  47 #else /* STANDALONE */
  48 #include "xlock.h"
  49
  50 #endif /* STANDALONE */
  51
  52 #ifdef MODE_braid
  53
  54 ModeSpecOpt braid_opts =
  55 {0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
  56
  57 #ifdef USE_MODULES
  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};
  63
  64 #endif
  65
  66 #if defined( COLORROUND ) && defined( COLORCOMP )
  67 #undef COLORROUND
  68 #undef COLORCOMP
  69 #endif
  70
  71 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  72 #if 0
  73 /* to color in a circular pattern use COLORROUND */
  74 #define COLORROUND
  75 #else
  76 /* to color by component use COLORCOMP */
  77 #define COLORCOMP
  78 #endif
  79 #endif
  80
  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 */
  86
  87 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  88 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  89
  90 typedef struct {
  91         int         linewidth;
  92         int         braidword[MAXLENGTH];
  93         int         components[MAXSTRANDS];
  94         int         startcomp[MAXLENGTH][MAXSTRANDS];
  95         int         nstrands;
  96         int         braidlength;
  97         float       startcolor;
  98         int         center_x;
  99         int         center_y;
 100         float       min_radius;
 101         float       max_radius;
 102         float       top, bottom, left, right;
 103         int         age;
 104         int         color_direction;
 105 } braidtype;
 106
 107 static braidtype *braids = (braidtype *) NULL;
 108
 109 static int
 110 applyword(braidtype * braid, int string, int position)
 111 {
 112         int         i, c;
 113
 114         c = string;
 115         for (i = position; i < braid->braidlength; i++) {
 116                 if (c == ABS(braid->braidword[i]))
 117                         c--;
 118                 else if (c == ABS(braid->braidword[i]) - 1)
 119                         c++;
 120         }
 121         for (i = 0; i < position; i++) {
 122                 if (c == ABS(braid->braidword[i]))
 123                         c--;
 124                 else if (c == ABS(braid->braidword[i]) - 1)
 125                         c++;
 126         }
 127         return c;
 128 }
 129
 130 #if 0
 131 static int
 132 applywordto(braidtype * braid, int string, int position)
 133 {
 134         int         i, c;
 135
 136         c = string;
 137         for (i = 0; i < position; i++) {
 138                 if (c == ABS(braid->braidword[i])) {
 139                         c--;
 140                 } else if (c == ABS(braid->braidword[i]) - 1) {
 141                         c++;
 142                 }
 143         }
 144         return c;
 145 }
 146 #endif
 147
 148 static int
 149 applywordbackto(braidtype * braid, int string, int position)
 150 {
 151         int         i, c;
 152
 153         c = string;
 154         for (i = position - 1; i >= 0; i--) {
 155                 if (c == ABS(braid->braidword[i])) {
 156                         c--;
 157                 } else if (c == ABS(braid->braidword[i]) - 1) {
 158                         c++;
 159                 }
 160         }
 161         return c;
 162 }
 163
 164 void
 165 init_braid(ModeInfo * mi)
 166 {
 167         braidtype  *braid;
 168         int         used[MAXSTRANDS];
 169         int         i, count, comp, c;
 170         float       min_length;
 171
 172         if (braids == NULL) {
 173                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 174                                                 sizeof (braidtype))) == NULL)
 175                         return;
 176         }
 177         braid = &braids[MI_SCREEN(mi)];
 178
 179         braid->center_x = MI_WIDTH(mi) / 2;
 180         braid->center_y = MI_HEIGHT(mi) / 2;
 181         braid->age = 0;
 182
 183         /* jwz: go in the other direction sometimes. */
 184         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 185
 186         MI_CLEARWINDOW(mi);
 187
 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;
 192
 193         if (MI_COUNT(mi) < MINSTRANDS)
 194                 braid->nstrands = MINSTRANDS;
 195         else
 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));
 200
 201         for (i = 0; i < braid->braidlength; i++) {
 202                 braid->braidword[i] =
 203                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 204                 if (i > 0)
 205                         while (braid->braidword[i] == -braid->braidword[i - 1])
 206                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 207         }
 208
 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);
 212
 213         do {
 214                 (void) memset((char *) used, 0, sizeof (used));
 215                 count = 0;
 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++;
 229                 }
 230         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 231
 232         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 233                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 234         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 235            JoinRound); */
 236
 237         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 238         c = 1;
 239         comp = 0;
 240         braid->components[0] = 1;
 241         do {
 242                 i = comp;
 243                 do {
 244                         i = applyword(braid, i, 0);
 245                         braid->components[i] = braid->components[comp];
 246                 } while (i != comp);
 247                 count = 0;
 248                 for (i = 0; i < braid->nstrands; i++)
 249                         if (braid->components[i] == 0)
 250                                 count++;
 251                 if (count > 0) {
 252                         for (comp = 0; braid->components[comp] != 0; comp++);
 253                         braid->components[comp] = ++c;
 254                 }
 255         } while (count > 0);
 256
 257         braid->linewidth = MI_SIZE(mi);
 258
 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;
 266 }
 267
 268 void
 269 draw_braid(ModeInfo * mi)
 270 {
 271         Display    *display = MI_DISPLAY(mi);
 272         Window      window = MI_WINDOW(mi);
 273         int         num_points = 500;
 274         float       t_inc;
 275         float       theta, psi;
 276         float       t, r_diff;
 277         int         i, s;
 278         float       x_1, y_1, x_2, y_2, r1, r2;
 279         float       color, color_use = 0.0, color_inc;
 280         braidtype  *braid;
 281
 282         if (braids == NULL)
 283                 return;
 284         braid = &braids[MI_SCREEN(mi)];
 285
 286         MI_IS_DRAWN(mi) = True;
 287         XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
 288                            LineSolid,
 289                            (braid->linewidth <= 3 ? CapButt : CapRound),
 290                            JoinMiter);
 291
 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 /
 295                 (float) num_points;
 296         braid->startcolor += SPINRATE * color_inc;
 297         if (((int) braid->startcolor) >= MI_NPIXELS(mi))
 298                 braid->startcolor = 0.0;
 299
 300         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 301
 302         color = braid->startcolor;
 303         psi = 0.0;
 304         for (i = 0; i < braid->braidlength; i++) {
 305                 psi += theta;
 306                 for (t = 0.0; t < theta; t += t_inc) {
 307 #ifdef COLORROUND
 308                         color += color_inc;
 309                         if (((int) color) >= MI_NPIXELS(mi))
 310                                 color = 0.0;
 311                         color_use = color;
 312 #endif
 313                         for (s = 0; s < braid->nstrands; s++) {
 314                                 if (ABS(braid->braidword[i]) == s)
 315                                         continue;
 316                                 if (ABS(braid->braidword[i]) - 1 == s) {
 317                                         /* crosSINFg */
 318 #ifdef COLORCOMP
 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);
 327                                         }
 328 #endif
 329 #ifdef COLORROUND
 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);
 334                                         }
 335 #endif
 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));
 354                                                 else
 355                                                         XSetForeground(display, MI_GC(mi), MI_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 #ifdef COLORCOMP
 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);
 369                                         }
 370 #endif
 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));
 387                                                 else
 388                                                         XSetForeground(display, MI_GC(mi), MI_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                                 } else {
 394                                         /* no crosSINFg */
 395 #ifdef COLORCOMP
 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);
 404                                         }
 405 #endif
 406 #ifdef COLORROUND
 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);
 411                                         }
 412 #endif
 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));
 420                                         else
 421                                                 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 422
 423                                         XDrawLine(display, window, MI_GC(mi),
 424                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 425                                 }
 426                         }
 427                 }
 428         }
 429         XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
 430
 431         if (++braid->age > MI_CYCLES(mi)) {
 432 #ifdef STANDALONE
 433           erase_full_window(MI_DISPLAY(mi), MI_WINDOW(mi));
 434 #endif
 435                 init_braid(mi);
 436         }
 437 }
 438
 439 void
 440 release_braid(ModeInfo * mi)
 441 {
 442         if (braids != NULL) {
 443                 (void) free((void *) braids);
 444                 braids = (braidtype *) NULL;
 445         }
 446 }
 447
 448 void
 449 refresh_braid(ModeInfo * mi)
 450 {
 451         MI_CLEARWINDOW(mi);
 452 }
 453
 454 #endif /* MODE_braid */