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 !defined( lint ) && !defined( SABER )
   8 static const char sccsid[] = "@(#)braid.c       5.00 2000/11/01 xlockmore";
   9
  10 #endif
  11
  12 /*-
  13  * Copyright (c) 1995 by John Neil.
  14  *
  15  * Permission to use, copy, modify, and distribute this software and its
  16  * documentation for any purpose and without fee is hereby granted,
  17  * provided that the above copyright notice appear in all copies and that
  18  * both that copyright notice and this permission notice appear in
  19  * supporting documentation.
  20  *
  21  * This file is provided AS IS with no warranties of any kind.  The author
  22  * shall have no liability with respect to the infringement of copyrights,
  23  * trade secrets or any patents by this file or any part thereof.  In no
  24  * event will the author be liable for any lost revenue or profits or
  25  * other special, indirect and consequential damages.
  26  *
  27  * Revision History:
  28  * 01-Nov-2000: Allocation checks
  29  * 10-May-1997: Jamie Zawinski <jwz@jwz.org> compatible with xscreensaver
  30  * 01-Sep-1995: color knotted components differently, J. Neil.
  31  * 29-Aug-1995: Written.  John Neil <neil@math.idbsu.edu>
  32  */
  33
  34 #ifdef STANDALONE
  35 #define MODE_braid
  36 #define PROGCLASS "Braid"
  37 #define HACK_INIT init_braid
  38 #define HACK_DRAW draw_braid
  39 #define braid_opts xlockmore_opts
  40 #define DEFAULTS "*delay: 1000 \n" \
  41  "*count: 15 \n" \
  42  "*cycles: 100 \n" \
  43  "*size: -7 \n" \
  44  "*ncolors: 64 \n"
  45 #define UNIFORM_COLORS
  46 #include "xlockmore.h"
  47 #include "erase.h"
  48 #else /* STANDALONE */
  49 #include "xlock.h"
  50
  51 #endif /* STANDALONE */
  52
  53 #ifdef MODE_braid
  54
  55 ModeSpecOpt braid_opts =
  56 {0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
  57
  58 #ifdef USE_MODULES
  59 ModStruct   braid_description =
  60 {"braid", "init_braid", "draw_braid", "release_braid",
  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 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         MI_CLEARWINDOW(mi);
 188
 189         min_length = (braid->center_x > braid->center_y) ?
 190                 braid->center_y : braid->center_x;
 191         braid->min_radius = min_length * 0.30;
 192         braid->max_radius = min_length * 0.90;
 193
 194         if (MI_COUNT(mi) < MINSTRANDS)
 195                 braid->nstrands = MINSTRANDS;
 196         else
 197                 braid->nstrands = INTRAND(MINSTRANDS,
 198                                        MAX(MIN(MIN(MAXSTRANDS, MI_COUNT(mi)),
 199                                                (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
 200         braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
 201
 202         for (i = 0; i < braid->braidlength; i++) {
 203                 braid->braidword[i] =
 204                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 205                 if (i > 0)
 206                         while (braid->braidword[i] == -braid->braidword[i - 1])
 207                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 208         }
 209
 210         while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
 211                 braid->braidword[braid->braidlength - 1] =
 212                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 213
 214         do {
 215                 (void) memset((char *) used, 0, sizeof (used));
 216                 count = 0;
 217                 for (i = 0; i < braid->braidlength; i++)
 218                         used[ABS(braid->braidword[i])]++;
 219                 for (i = 0; i < braid->nstrands; i++)
 220                         count += (used[i] > 0) ? 1 : 0;
 221                 if (count < braid->nstrands - 1) {
 222                         braid->braidword[braid->braidlength] =
 223                                 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 224                         while (braid->braidword[braid->braidlength] ==
 225                                -braid->braidword[braid->braidlength - 1] &&
 226                                braid->braidword[0] == -braid->braidword[braid->braidlength])
 227                                 braid->braidword[braid->braidlength] =
 228                                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 229                         braid->braidlength++;
 230                 }
 231         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 232
 233         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 234                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 235         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 236            JoinRound); */
 237
 238         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 239         c = 1;
 240         comp = 0;
 241         braid->components[0] = 1;
 242         do {
 243                 i = comp;
 244                 do {
 245                         i = applyword(braid, i, 0);
 246                         braid->components[i] = braid->components[comp];
 247                 } while (i != comp);
 248                 count = 0;
 249                 for (i = 0; i < braid->nstrands; i++)
 250                         if (braid->components[i] == 0)
 251                                 count++;
 252                 if (count > 0) {
 253                         for (comp = 0; braid->components[comp] != 0; comp++);
 254                         braid->components[comp] = ++c;
 255                 }
 256         } while (count > 0);
 257
 258         braid->linewidth = MI_SIZE(mi);
 259
 260         if (braid->linewidth < 0)
 261                 braid->linewidth = NRAND(-braid->linewidth) + 1;
 262         if (braid->linewidth * braid->linewidth * 8 > MIN(MI_WIDTH(mi), MI_HEIGHT(mi)))
 263        braid->linewidth = MIN(1, (int) sqrt((double) MIN(MI_WIDTH(mi), MI_HEIGHT(mi)) / 8));
 264         for (i = 0; i < braid->nstrands; i++)
 265                 if (!(braid->components[i] & 1))
 266                         braid->components[i] *= -1;
 267 }
 268
 269 void
 270 draw_braid(ModeInfo * mi)
 271 {
 272         Display    *display = MI_DISPLAY(mi);
 273         Window      window = MI_WINDOW(mi);
 274         int         num_points = 500;
 275         float       t_inc;
 276         float       theta, psi;
 277         float       t, r_diff;
 278         int         i, s;
 279         float       x_1, y_1, x_2, y_2, r1, r2;
 280         float       color, color_use = 0.0, color_inc;
 281         braidtype  *braid;
 282
 283         if (braids == NULL)
 284                 return;
 285         braid = &braids[MI_SCREEN(mi)];
 286
 287         MI_IS_DRAWN(mi) = True;
 288         XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
 289                            LineSolid,
 290                            (braid->linewidth <= 3 ? CapButt : CapRound),
 291                            JoinMiter);
 292
 293         theta = (2.0 * M_PI) / (float) (braid->braidlength);
 294         t_inc = (2.0 * M_PI) / (float) num_points;
 295         color_inc = (float) MI_NPIXELS(mi) * braid->color_direction /
 296                 (float) num_points;
 297         braid->startcolor += SPINRATE * color_inc;
 298         if (((int) braid->startcolor) >= MI_NPIXELS(mi))
 299                 braid->startcolor = 0.0;
 300
 301         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 302
 303         color = braid->startcolor;
 304         psi = 0.0;
 305         for (i = 0; i < braid->braidlength; i++) {
 306                 psi += theta;
 307                 for (t = 0.0; t < theta; t += t_inc) {
 308 #ifdef COLORROUND
 309                         color += color_inc;
 310                         if (((int) color) >= MI_NPIXELS(mi))
 311                                 color = 0.0;
 312                         color_use = color;
 313 #endif
 314                         for (s = 0; s < braid->nstrands; s++) {
 315                                 if (ABS(braid->braidword[i]) == s)
 316                                         continue;
 317                                 if (ABS(braid->braidword[i]) - 1 == s) {
 318                                         /* crosSINFg */
 319 #ifdef COLORCOMP
 320                                         if (MI_NPIXELS(mi) > 2) {
 321                                                 color_use = color + SPINRATE *
 322                                                         braid->components[applywordbackto(braid, s, i)] +
 323                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 324                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 325                                                         color_use -= (float) MI_NPIXELS(mi);
 326                                                 while (((int) color_use) < 0)
 327                                                         color_use += (float) MI_NPIXELS(mi);
 328                                         }
 329 #endif
 330 #ifdef COLORROUND
 331                                         if (MI_NPIXELS(mi) > 2) {
 332                                                 color_use += SPINRATE * color_inc;
 333                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 334                                                         color_use -= (float) MI_NPIXELS(mi);
 335                                         }
 336 #endif
 337                                         r1 = braid->min_radius + r_diff * (float) (s);
 338                                         r2 = braid->min_radius + r_diff * (float) (s + 1);
 339                                         if (braid->braidword[i] > 0 ||
 340                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 341                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 342                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 343                                                         COSF(t + psi) + braid->center_x;
 344                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 345                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 346                                                         SINF(t + psi) + braid->center_y;
 347                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 348                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 349                                                         COSF(t + t_inc + psi) + braid->center_x;
 350                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 351                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 352                                                         SINF(t + t_inc + psi) + braid->center_y;
 353                                                 if (MI_NPIXELS(mi) > 2)
 354                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 355                                                 else
 356                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 357
 358                                                 XDrawLine(display, window, MI_GC(mi),
 359                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 360                                         }
 361 #ifdef COLORCOMP
 362                                         if (MI_NPIXELS(mi) > 2) {
 363                                                 color_use = color + SPINRATE *
 364                                                         braid->components[applywordbackto(braid, s + 1, i)] +
 365                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 366                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 367                                                         color_use -= (float) MI_NPIXELS(mi);
 368                                                 while (((int) color_use) < 0)
 369                                                         color_use += (float) MI_NPIXELS(mi);
 370                                         }
 371 #endif
 372                                         if (braid->braidword[i] < 0 ||
 373                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 374                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 375                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 376                                                         COSF(t + psi) + braid->center_x;
 377                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 378                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 379                                                         SINF(t + psi) + braid->center_y;
 380                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 381                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 382                                                         COSF(t + t_inc + psi) + braid->center_x;
 383                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 384                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 385                                                         SINF(t + t_inc + psi) + braid->center_y;
 386                                                 if (MI_NPIXELS(mi) > 2)
 387                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 388                                                 else
 389                                                         XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 390
 391                                                 XDrawLine(display, window, MI_GC(mi),
 392                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 393                                         }
 394                                 } else {
 395                                         /* no crosSINFg */
 396 #ifdef COLORCOMP
 397                                         if (MI_NPIXELS(mi) > 2) {
 398                                                 color_use = color + SPINRATE *
 399                                                         braid->components[applywordbackto(braid, s, i)] +
 400                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 401                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 402                                                         color_use -= (float) MI_NPIXELS(mi);
 403                                                 while (((int) color_use) < 0)
 404                                                         color_use += (float) MI_NPIXELS(mi);
 405                                         }
 406 #endif
 407 #ifdef COLORROUND
 408                                         if (MI_NPIXELS(mi) > 2) {
 409                                                 color_use += SPINRATE * color_inc;
 410                                                 while (((int) color_use) >= MI_NPIXELS(mi))
 411                                                         color_use -= (float) MI_NPIXELS(mi);
 412                                         }
 413 #endif
 414                                         r1 = braid->min_radius + r_diff * (float) (s);
 415                                         x_1 = r1 * COSF(t + psi) + braid->center_x;
 416                                         y_1 = r1 * SINF(t + psi) + braid->center_y;
 417                                         x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
 418                                         y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
 419                                         if (MI_NPIXELS(mi) > 2)
 420                                                 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 421                                         else
 422                                                 XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
 423
 424                                         XDrawLine(display, window, MI_GC(mi),
 425                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 426                                 }
 427                         }
 428                 }
 429         }
 430         XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
 431
 432         if (++braid->age > MI_CYCLES(mi)) {
 433 #ifdef STANDALONE
 434           erase_full_window(MI_DISPLAY(mi), MI_WINDOW(mi));
 435 #endif
 436                 init_braid(mi);
 437         }
 438 }
 439
 440 void
 441 release_braid(ModeInfo * mi)
 442 {
 443         if (braids != NULL) {
 444                 (void) free((void *) braids);
 445                 braids = (braidtype *) NULL;
 446         }
 447 }
 448
 449 void
 450 refresh_braid(ModeInfo * mi)
 451 {
 452         MI_CLEARWINDOW(mi);
 453 }
 454
 455 #endif /* MODE_braid */