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