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

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  * braid --- draws random color-cyling rotating braids around a circle.
   3  */
   4 #if !defined( lint ) && !defined( SABER )
   5 static const char sccsid[] = "@(#)braid.c       4.00 97/01/01 xlockmore";
   6 #endif
   7
   8 /*
   9  * Copyright (c) 1995 by John Neil.
  10  *
  11  * Permission to use, copy, modify, and distribute this software and its
  12  * documentation for any purpose and without fee is hereby granted,
  13  * provided that the above copyright notice appear in all copies and that
  14  * both that copyright notice and this permission notice appear in
  15  * supporting documentation.
  16  *
  17  * This file is provided AS IS with no warranties of any kind.  The author
  18  * shall have no liability with respect to the infringement of copyrights,
  19  * trade secrets or any patents by this file or any part thereof.  In no
  20  * event will the author be liable for any lost revenue or profits or
  21  * other special, indirect and consequential damages.
  22  *
  23  * Revision History:
  24  * 10-May-97: jwz@jwz.org: turned into a standalone program.
  25  * 01-Sep-95: color knotted components differently, J. Neil.
  26  * 29-Aug-95: Written.  John Neil <neil@math.idbsu.edu>
  27  */
  28
  29 #ifdef STANDALONE
  30 # define PROGCLASS                                      "Braid"
  31 # define HACK_INIT                                      init_braid
  32 # define HACK_DRAW                                      draw_braid
  33 # define braid_opts                                     xlockmore_opts
  34 # define DEFAULTS       "*count:                15    \n"                       \
  35                                         "*size:            -7     \n"                   \
  36                                         "*cycles:               100   \n"                       \
  37                                         "*delay:                1000  \n"                       \
  38                                         "*ncolors:              64    \n"
  39 # define UNIFORM_COLORS
  40 # include "xlockmore.h"                         /* from the xscreensaver distribution */
  41 # include "erase.h"
  42 #else  /* !STANDALONE */
  43 # include "xlock.h"                                     /* from the xlockmore distribution */
  44 #endif /* !STANDALONE */
  45
  46 ModeSpecOpt braid_opts = {
  47   0, NULL, 0, NULL, NULL };
  48
  49
  50 #if defined( COLORROUND ) && defined( COLORCOMP )
  51 #undef COLORROUND
  52 #undef COLORCOMP
  53 #endif
  54
  55 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  56 #if 0
  57 /* to color in a circular pattern use COLORROUND */
  58 #define COLORROUND
  59 #else
  60 /* to color by component use COLORCOMP */
  61 #define COLORCOMP
  62 #endif
  63 #endif
  64
  65 #define MAXLENGTH  50           /* the maximum length of a braid word */
  66 #define MINLENGTH  8            /* the minimum length of a braid word */
  67 #define MAXSTRANDS  15          /* the maximum number of strands in the braid */
  68 #define MINSTRANDS  3           /* the minimum number of strands in the braid */
  69 #define SPINRATE  12.0          /* the rate at which the colors spin */
  70
  71 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  72 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  73
  74 typedef struct {
  75         int         braidword[MAXLENGTH];
  76         int         components[MAXSTRANDS];
  77         int         startcomp[MAXLENGTH][MAXSTRANDS];
  78         int         nstrands;
  79         int         braidlength;
  80         float       startcolor;
  81         int         center_x;
  82         int         center_y;
  83         float       min_radius;
  84         float       max_radius;
  85         float       top, bottom, left, right;
  86         int         age;
  87     int         color_direction;
  88 } braidtype;
  89
  90 static braidtype *braids = NULL;
  91
  92 static int
  93 applyword(braidtype * braid, int string, int position)
  94 {
  95         int         i, c;
  96
  97         c = string;
  98         for (i = position; i < braid->braidlength; i++) {
  99                 if (c == ABS(braid->braidword[i]))
 100                         c--;
 101                 else if (c == ABS(braid->braidword[i]) - 1)
 102                         c++;
 103         }
 104         for (i = 0; i < position; i++) {
 105                 if (c == ABS(braid->braidword[i]))
 106                         c--;
 107                 else if (c == ABS(braid->braidword[i]) - 1)
 108                         c++;
 109         }
 110         return c;
 111 }
 112
 113 #if 0
 114 static int
 115 applywordto(braidtype * braid, int string, int position)
 116 {
 117         int         i, c;
 118
 119         c = string;
 120         for (i = 0; i < position; i++) {
 121                 if (c == ABS(braid->braidword[i])) {
 122                         c--;
 123                 } else if (c == ABS(braid->braidword[i]) - 1) {
 124                         c++;
 125                 }
 126         }
 127         return c;
 128 }
 129 #endif
 130
 131 static int
 132 applywordbackto(braidtype * braid, int string, int position)
 133 {
 134         int         i, c;
 135
 136         c = string;
 137         for (i = position - 1; i >= 0; 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
 147 void
 148 init_braid(ModeInfo * mi)
 149 {
 150         Display    *display = MI_DISPLAY(mi);
 151         braidtype  *braid;
 152         int         used[MAXSTRANDS];
 153         int         i, count, comp, c;
 154         float       min_length;
 155
 156         if (braids == NULL) {
 157                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 158                                                 sizeof (braidtype))) == NULL)
 159                         return;
 160         }
 161         braid = &braids[MI_SCREEN(mi)];
 162
 163         braid->center_x = MI_WIN_WIDTH(mi) / 2;
 164         braid->center_y = MI_WIN_HEIGHT(mi) / 2;
 165         braid->age = 0;
 166
 167         /* jwz: go in the other direction sometimes. */
 168         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 169         XClearWindow(display, MI_WINDOW(mi));
 170
 171         min_length = (braid->center_x > braid->center_y) ?
 172                 braid->center_y : braid->center_x;
 173         braid->min_radius = min_length * 0.30;
 174         braid->max_radius = min_length * 0.90;
 175
 176         if (MI_BATCHCOUNT(mi) < MINSTRANDS)
 177                 braid->nstrands = MINSTRANDS;
 178         else
 179                 braid->nstrands = INTRAND(MINSTRANDS,
 180                                   MAX(MIN(MIN(MAXSTRANDS, MI_BATCHCOUNT(mi)),
 181                                           (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
 182         braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
 183
 184         for (i = 0; i < braid->braidlength; i++) {
 185                 braid->braidword[i] =
 186                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 187                 if (i > 0)
 188                         while (braid->braidword[i] == -braid->braidword[i - 1])
 189                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 190         }
 191
 192         while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
 193                 braid->braidword[braid->braidlength - 1] =
 194                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 195
 196         do {
 197                 (void) memset((char *) used, 0, sizeof (used));
 198                 count = 0;
 199                 for (i = 0; i < braid->braidlength; i++)
 200                         used[ABS(braid->braidword[i])]++;
 201                 for (i = 0; i < braid->nstrands; i++)
 202                         count += (used[i] > 0) ? 1 : 0;
 203                 if (count < braid->nstrands - 1) {
 204                         braid->braidword[braid->braidlength] =
 205                                 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 206                         while (braid->braidword[braid->braidlength] ==
 207                                -braid->braidword[braid->braidlength - 1] &&
 208                                braid->braidword[0] == -braid->braidword[braid->braidlength])
 209                                 braid->braidword[braid->braidlength] =
 210                                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 211                         braid->braidlength++;
 212                 }
 213         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 214
 215         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 216                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 217         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 218            JoinRound); */
 219
 220         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 221         c = 1;
 222         comp = 0;
 223         braid->components[0] = 1;
 224         do {
 225                 i = comp;
 226                 do {
 227                         i = applyword(braid, i, 0);
 228                         braid->components[i] = braid->components[comp];
 229                 } while (i != comp);
 230                 count = 0;
 231                 for (i = 0; i < braid->nstrands; i++)
 232                         if (braid->components[i] == 0)
 233                                 count++;
 234                 if (count > 0) {
 235                         for (comp = 0; braid->components[comp] != 0; comp++);
 236                         braid->components[comp] = ++c;
 237                 }
 238         } while (count > 0);
 239
 240         {
 241           int line_width = MI_SIZE(mi);
 242           if (line_width == 0)
 243                 line_width = -8;
 244           if (line_width < 0)
 245                 line_width = NRAND(-line_width)+1;
 246           if (line_width == 1)
 247                 line_width = 0;
 248           XSetLineAttributes(MI_DISPLAY(mi), MI_GC(mi), line_width,
 249                                                  LineSolid,
 250                                                  (line_width <= 3 ? CapButt : CapRound),
 251                                                  JoinMiter);
 252         }
 253
 254
 255         for (i = 0; i < braid->nstrands; i++)
 256                 if (!(braid->components[i] & 1))
 257                         braid->components[i] *= -1;
 258 }
 259
 260 void
 261 draw_braid(ModeInfo * mi)
 262 {
 263         Display    *display = MI_DISPLAY(mi);
 264         Window      window = MI_WINDOW(mi);
 265         braidtype  *braid = &braids[MI_SCREEN(mi)];
 266         float       num_points, t_inc;
 267         float       theta, psi;
 268         float       t, r_diff;
 269         int         i, s;
 270         float       x_1, y_1, x_2, y_2, r1, r2;
 271         float       color, color_use = 0.0, color_inc;
 272
 273         num_points = 500.0;
 274         theta = (2.0 * M_PI) / (float) (braid->braidlength);
 275         t_inc = (2.0 * M_PI) / num_points;
 276         color_inc = (float) MI_NPIXELS(mi) / num_points;
 277         color_inc *= braid->color_direction;
 278
 279         braid->startcolor += SPINRATE * color_inc;
 280         if (braid->startcolor >= MI_NPIXELS(mi))
 281                 braid->startcolor = 0.0;
 282
 283         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 284
 285         color = braid->startcolor;
 286         psi = 0.0;
 287         for (i = 0; i < braid->braidlength; i++) {
 288                 psi += theta;
 289                 for (t = 0.0; t < theta; t += t_inc) {
 290 #ifdef COLORROUND
 291                         color += color_inc;
 292                         if (color >= (float) (MI_NPIXELS(mi)))
 293                                 color = 0.0;
 294                         color_use = color;
 295 #endif
 296                         for (s = 0; s < braid->nstrands; s++) {
 297                                 if (ABS(braid->braidword[i]) == s)
 298                                         continue;
 299                                 if (ABS(braid->braidword[i]) - 1 == s) {
 300                                         /* crosSINFg */
 301 #ifdef COLORCOMP
 302                                         if (MI_NPIXELS(mi) > 2) {
 303                                                 color_use = color + SPINRATE *
 304                                                         braid->components[applywordbackto(braid, s, i)] +
 305                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 306                                                 while (color_use >= (float) MI_NPIXELS(mi))
 307                                                         color_use -= (float) MI_NPIXELS(mi);
 308                                                 while (color_use < 0.0)
 309                                                         color_use += (float) MI_NPIXELS(mi);
 310                                         }
 311 #endif
 312 #ifdef COLORROUND
 313                                         if (MI_NPIXELS(mi) > 2) {
 314                                                 color_use += SPINRATE * color_inc;
 315                                                 while (color_use >= (float) (MI_NPIXELS(mi)))
 316                                                         color_use -= (float) MI_NPIXELS(mi);
 317                                         }
 318 #endif
 319                                         r1 = braid->min_radius + r_diff * (float) (s);
 320                                         r2 = braid->min_radius + r_diff * (float) (s + 1);
 321                                         if (braid->braidword[i] > 0 ||
 322                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 323                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 324                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 325                                                         COSF(t + psi) + braid->center_x;
 326                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 327                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 328                                                         SINF(t + psi) + braid->center_y;
 329                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 330                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 331                                                         COSF(t + t_inc + psi) + braid->center_x;
 332                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 333                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 334                                                         SINF(t + t_inc + psi) + braid->center_y;
 335                                                 if (MI_NPIXELS(mi) > 2)
 336                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 337                                                 else
 338                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 339
 340                                                 XDrawLine(display, window, MI_GC(mi),
 341                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 342                                         }
 343 #ifdef COLORCOMP
 344                                         if (MI_NPIXELS(mi) > 2) {
 345                                                 color_use = color + SPINRATE *
 346                                                         braid->components[applywordbackto(braid, s + 1, i)] +
 347                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 348                                                 while (color_use >= (float) MI_NPIXELS(mi))
 349                                                         color_use -= (float) MI_NPIXELS(mi);
 350                                                 while (color_use < 0.0)
 351                                                         color_use += (float) MI_NPIXELS(mi);
 352                                         }
 353 #endif
 354                                         if (braid->braidword[i] < 0 ||
 355                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 356                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 357                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 358                                                         COSF(t + psi) + braid->center_x;
 359                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 360                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 361                                                         SINF(t + psi) + braid->center_y;
 362                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 363                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 364                                                         COSF(t + t_inc + psi) + braid->center_x;
 365                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 366                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 367                                                         SINF(t + t_inc + psi) + braid->center_y;
 368                                                 if (MI_NPIXELS(mi) > 2)
 369                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 370                                                 else
 371                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 372
 373                                                 XDrawLine(display, window, MI_GC(mi),
 374                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 375                                         }
 376                                 } else {
 377                                         /* no crosSINFg */
 378 #ifdef COLORCOMP
 379                                         if (MI_NPIXELS(mi) > 2) {
 380                                                 color_use = color + SPINRATE *
 381                                                         braid->components[applywordbackto(braid, s, i)] +
 382                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 383                                                 while (color_use >= (float) MI_NPIXELS(mi))
 384                                                         color_use -= (float) MI_NPIXELS(mi);
 385                                                 while (color_use < 0.0)
 386                                                         color_use += (float) MI_NPIXELS(mi);
 387                                         }
 388 #endif
 389 #ifdef COLORROUND
 390                                         if (MI_NPIXELS(mi) > 2) {
 391                                                 color_use += SPINRATE * color_inc;
 392                                                 while (color_use >= (float) MI_NPIXELS(mi))
 393                                                         color_use -= (float) MI_NPIXELS(mi);
 394                                         }
 395 #endif
 396                                         r1 = braid->min_radius + r_diff * (float) (s);
 397                                         x_1 = r1 * COSF(t + psi) + braid->center_x;
 398                                         y_1 = r1 * SINF(t + psi) + braid->center_y;
 399                                         x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
 400                                         y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
 401                                         if (MI_NPIXELS(mi) > 2)
 402                                                 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 403                                         else
 404                                                 XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 405
 406                                         XDrawLine(display, window, MI_GC(mi),
 407                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 408                                 }
 409                         }
 410                 }
 411         }
 412
 413         if (++braid->age > MI_CYCLES(mi)) {
 414 #ifdef STANDALONE
 415           erase_full_window(MI_DISPLAY(mi), MI_WINDOW(mi));
 416 #endif
 417           init_braid(mi);
 418         }
 419 }
 420
 421 void
 422 release_braid(ModeInfo * mi)
 423 {
 424         if (braids != NULL) {
 425                 (void) free((void *) braids);
 426                 braids = NULL;
 427         }
 428 }
 429
 430 void
 431 refresh_braid(ModeInfo * mi)
 432 {
 433         /* Do nothing, it will refresh by itself */
 434 }