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@netscape.com: 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                                         "*eraseSpeed:   400 \n"                         \
  40                                         "*eraseMode:    -1 \n"
  41 # define UNIFORM_COLORS
  42 # include "xlockmore.h"                         /* from the xscreensaver distribution */
  43 # include "erase.h"
  44 #else  /* !STANDALONE */
  45 # include "xlock.h"                                     /* from the xlockmore distribution */
  46 #endif /* !STANDALONE */
  47
  48 ModeSpecOpt braid_opts = {
  49   0, NULL, 0, NULL, NULL };
  50
  51
  52 #if defined( COLORROUND ) && defined( COLORCOMP )
  53 #undef COLORROUND
  54 #undef COLORCOMP
  55 #endif
  56
  57 #if !defined( COLORROUND ) && !defined( COLORCOMP )
  58 #if 0
  59 /* to color in a circular pattern use COLORROUND */
  60 #define COLORROUND
  61 #else
  62 /* to color by component use COLORCOMP */
  63 #define COLORCOMP
  64 #endif
  65 #endif
  66
  67 #define MAXLENGTH  50           /* the maximum length of a braid word */
  68 #define MINLENGTH  8            /* the minimum length of a braid word */
  69 #define MAXSTRANDS  15          /* the maximum number of strands in the braid */
  70 #define MINSTRANDS  3           /* the minimum number of strands in the braid */
  71 #define SPINRATE  12.0          /* the rate at which the colors spin */
  72
  73 #define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
  74 #define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
  75
  76 typedef struct {
  77         int         braidword[MAXLENGTH];
  78         int         components[MAXSTRANDS];
  79         int         startcomp[MAXLENGTH][MAXSTRANDS];
  80         int         nstrands;
  81         int         braidlength;
  82         float       startcolor;
  83         int         center_x;
  84         int         center_y;
  85         float       min_radius;
  86         float       max_radius;
  87         float       top, bottom, left, right;
  88         int         age;
  89     int         color_direction;
  90 } braidtype;
  91
  92 static braidtype *braids = NULL;
  93
  94 static int
  95 applyword(braidtype * braid, int string, int position)
  96 {
  97         int         i, c;
  98
  99         c = string;
 100         for (i = position; i < braid->braidlength; i++) {
 101                 if (c == ABS(braid->braidword[i]))
 102                         c--;
 103                 else if (c == ABS(braid->braidword[i]) - 1)
 104                         c++;
 105         }
 106         for (i = 0; i < position; i++) {
 107                 if (c == ABS(braid->braidword[i]))
 108                         c--;
 109                 else if (c == ABS(braid->braidword[i]) - 1)
 110                         c++;
 111         }
 112         return c;
 113 }
 114
 115 #if 0
 116 static int
 117 applywordto(braidtype * braid, int string, int position)
 118 {
 119         int         i, c;
 120
 121         c = string;
 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         }
 129         return c;
 130 }
 131 #endif
 132
 133 static int
 134 applywordbackto(braidtype * braid, int string, int position)
 135 {
 136         int         i, c;
 137
 138         c = string;
 139         for (i = position - 1; i >= 0; 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
 149 void
 150 init_braid(ModeInfo * mi)
 151 {
 152         Display    *display = MI_DISPLAY(mi);
 153         braidtype  *braid;
 154         int         used[MAXSTRANDS];
 155         int         i, count, comp, c;
 156         float       min_length;
 157
 158         if (braids == NULL) {
 159                 if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
 160                                                 sizeof (braidtype))) == NULL)
 161                         return;
 162         }
 163         braid = &braids[MI_SCREEN(mi)];
 164
 165         braid->center_x = MI_WIN_WIDTH(mi) / 2;
 166         braid->center_y = MI_WIN_HEIGHT(mi) / 2;
 167         braid->age = 0;
 168
 169         /* jwz: go in the other direction sometimes. */
 170         braid->color_direction = ((LRAND() & 1) ? 1 : -1);
 171         XClearWindow(display, MI_WINDOW(mi));
 172
 173         min_length = (braid->center_x > braid->center_y) ?
 174                 braid->center_y : braid->center_x;
 175         braid->min_radius = min_length * 0.30;
 176         braid->max_radius = min_length * 0.90;
 177
 178         if (MI_BATCHCOUNT(mi) < MINSTRANDS)
 179                 braid->nstrands = MINSTRANDS;
 180         else
 181                 braid->nstrands = INTRAND(MINSTRANDS,
 182                                   MAX(MIN(MIN(MAXSTRANDS, MI_BATCHCOUNT(mi)),
 183                                           (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
 184         braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
 185
 186         for (i = 0; i < braid->braidlength; i++) {
 187                 braid->braidword[i] =
 188                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 189                 if (i > 0)
 190                         while (braid->braidword[i] == -braid->braidword[i - 1])
 191                                 braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 192         }
 193
 194         while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
 195                 braid->braidword[braid->braidlength - 1] =
 196                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 197
 198         do {
 199                 (void) memset((char *) used, 0, sizeof (used));
 200                 count = 0;
 201                 for (i = 0; i < braid->braidlength; i++)
 202                         used[ABS(braid->braidword[i])]++;
 203                 for (i = 0; i < braid->nstrands; i++)
 204                         count += (used[i] > 0) ? 1 : 0;
 205                 if (count < braid->nstrands - 1) {
 206                         braid->braidword[braid->braidlength] =
 207                                 INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 208                         while (braid->braidword[braid->braidlength] ==
 209                                -braid->braidword[braid->braidlength - 1] &&
 210                                braid->braidword[0] == -braid->braidword[braid->braidlength])
 211                                 braid->braidword[braid->braidlength] =
 212                                         INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
 213                         braid->braidlength++;
 214                 }
 215         } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
 216
 217         braid->startcolor = (MI_NPIXELS(mi) > 2) ?
 218                 (float) NRAND(MI_NPIXELS(mi)) : 0.0;
 219         /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
 220            JoinRound); */
 221
 222         (void) memset((char *) braid->components, 0, sizeof (braid->components));
 223         c = 1;
 224         comp = 0;
 225         braid->components[0] = 1;
 226         do {
 227                 i = comp;
 228                 do {
 229                         i = applyword(braid, i, 0);
 230                         braid->components[i] = braid->components[comp];
 231                 } while (i != comp);
 232                 count = 0;
 233                 for (i = 0; i < braid->nstrands; i++)
 234                         if (braid->components[i] == 0)
 235                                 count++;
 236                 if (count > 0) {
 237                         for (comp = 0; braid->components[comp] != 0; comp++);
 238                         braid->components[comp] = ++c;
 239                 }
 240         } while (count > 0);
 241
 242         {
 243           int line_width = MI_SIZE(mi);
 244           if (line_width == 0)
 245                 line_width = -8;
 246           if (line_width < 0)
 247                 line_width = NRAND(-line_width)+1;
 248           if (line_width == 1)
 249                 line_width = 0;
 250           XSetLineAttributes(MI_DISPLAY(mi), MI_GC(mi), line_width,
 251                                                  LineSolid,
 252                                                  (line_width <= 3 ? CapButt : CapRound),
 253                                                  JoinMiter);
 254         }
 255
 256
 257         for (i = 0; i < braid->nstrands; i++)
 258                 if (!(braid->components[i] & 1))
 259                         braid->components[i] *= -1;
 260 }
 261
 262 void
 263 draw_braid(ModeInfo * mi)
 264 {
 265         Display    *display = MI_DISPLAY(mi);
 266         Window      window = MI_WINDOW(mi);
 267         braidtype  *braid = &braids[MI_SCREEN(mi)];
 268         float       num_points, t_inc;
 269         float       theta, psi;
 270         float       t, r_diff;
 271         int         i, s;
 272         float       x_1, y_1, x_2, y_2, r1, r2;
 273         float       color, color_use = 0.0, color_inc;
 274
 275         num_points = 500.0;
 276         theta = (2.0 * M_PI) / (float) (braid->braidlength);
 277         t_inc = (2.0 * M_PI) / num_points;
 278         color_inc = (float) MI_NPIXELS(mi) / num_points;
 279         color_inc *= braid->color_direction;
 280
 281         braid->startcolor += SPINRATE * color_inc;
 282         if (braid->startcolor >= MI_NPIXELS(mi))
 283                 braid->startcolor = 0.0;
 284
 285         r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
 286
 287         color = braid->startcolor;
 288         psi = 0.0;
 289         for (i = 0; i < braid->braidlength; i++) {
 290                 psi += theta;
 291                 for (t = 0.0; t < theta; t += t_inc) {
 292 #ifdef COLORROUND
 293                         color += color_inc;
 294                         if (color >= (float) (MI_NPIXELS(mi)))
 295                                 color = 0.0;
 296                         color_use = color;
 297 #endif
 298                         for (s = 0; s < braid->nstrands; s++) {
 299                                 if (ABS(braid->braidword[i]) == s)
 300                                         continue;
 301                                 if (ABS(braid->braidword[i]) - 1 == s) {
 302                                         /* crosSINFg */
 303 #ifdef COLORCOMP
 304                                         if (MI_NPIXELS(mi) > 2) {
 305                                                 color_use = color + SPINRATE *
 306                                                         braid->components[applywordbackto(braid, s, i)] +
 307                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 308                                                 while (color_use >= (float) MI_NPIXELS(mi))
 309                                                         color_use -= (float) MI_NPIXELS(mi);
 310                                                 while (color_use < 0.0)
 311                                                         color_use += (float) MI_NPIXELS(mi);
 312                                         }
 313 #endif
 314 #ifdef COLORROUND
 315                                         if (MI_NPIXELS(mi) > 2) {
 316                                                 color_use += SPINRATE * color_inc;
 317                                                 while (color_use >= (float) (MI_NPIXELS(mi)))
 318                                                         color_use -= (float) MI_NPIXELS(mi);
 319                                         }
 320 #endif
 321                                         r1 = braid->min_radius + r_diff * (float) (s);
 322                                         r2 = braid->min_radius + r_diff * (float) (s + 1);
 323                                         if (braid->braidword[i] > 0 ||
 324                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 325                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 326                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 327                                                         COSF(t + psi) + braid->center_x;
 328                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
 329                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
 330                                                         SINF(t + psi) + braid->center_y;
 331                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 332                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 333                                                         COSF(t + t_inc + psi) + braid->center_x;
 334                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
 335                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
 336                                                         SINF(t + t_inc + psi) + braid->center_y;
 337                                                 if (MI_NPIXELS(mi) > 2)
 338                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 339                                                 else
 340                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 341
 342                                                 XDrawLine(display, window, MI_GC(mi),
 343                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 344                                         }
 345 #ifdef COLORCOMP
 346                                         if (MI_NPIXELS(mi) > 2) {
 347                                                 color_use = color + SPINRATE *
 348                                                         braid->components[applywordbackto(braid, s + 1, i)] +
 349                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 350                                                 while (color_use >= (float) MI_NPIXELS(mi))
 351                                                         color_use -= (float) MI_NPIXELS(mi);
 352                                                 while (color_use < 0.0)
 353                                                         color_use += (float) MI_NPIXELS(mi);
 354                                         }
 355 #endif
 356                                         if (braid->braidword[i] < 0 ||
 357                                             (FABSF(t - theta / 2.0) > theta / 7.0)) {
 358                                                 x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 359                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 360                                                         COSF(t + psi) + braid->center_x;
 361                                                 y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
 362                                                         0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
 363                                                         SINF(t + psi) + braid->center_y;
 364                                                 x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 365                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 366                                                         COSF(t + t_inc + psi) + braid->center_x;
 367                                                 y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
 368                                                         0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
 369                                                         SINF(t + t_inc + psi) + braid->center_y;
 370                                                 if (MI_NPIXELS(mi) > 2)
 371                                                         XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 372                                                 else
 373                                                         XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 374
 375                                                 XDrawLine(display, window, MI_GC(mi),
 376                                                           (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 377                                         }
 378                                 } else {
 379                                         /* no crosSINFg */
 380 #ifdef COLORCOMP
 381                                         if (MI_NPIXELS(mi) > 2) {
 382                                                 color_use = color + SPINRATE *
 383                                                         braid->components[applywordbackto(braid, s, i)] +
 384                                                         (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
 385                                                 while (color_use >= (float) MI_NPIXELS(mi))
 386                                                         color_use -= (float) MI_NPIXELS(mi);
 387                                                 while (color_use < 0.0)
 388                                                         color_use += (float) MI_NPIXELS(mi);
 389                                         }
 390 #endif
 391 #ifdef COLORROUND
 392                                         if (MI_NPIXELS(mi) > 2) {
 393                                                 color_use += SPINRATE * color_inc;
 394                                                 while (color_use >= (float) MI_NPIXELS(mi))
 395                                                         color_use -= (float) MI_NPIXELS(mi);
 396                                         }
 397 #endif
 398                                         r1 = braid->min_radius + r_diff * (float) (s);
 399                                         x_1 = r1 * COSF(t + psi) + braid->center_x;
 400                                         y_1 = r1 * SINF(t + psi) + braid->center_y;
 401                                         x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
 402                                         y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
 403                                         if (MI_NPIXELS(mi) > 2)
 404                                                 XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
 405                                         else
 406                                                 XSetForeground(display, MI_GC(mi), MI_WIN_WHITE_PIXEL(mi));
 407
 408                                         XDrawLine(display, window, MI_GC(mi),
 409                                                   (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
 410                                 }
 411                         }
 412                 }
 413         }
 414
 415         if (++braid->age > MI_CYCLES(mi)) {
 416 #ifdef STANDALONE
 417           erase_full_window(MI_DISPLAY(mi), MI_WINDOW(mi));
 418 #endif
 419           init_braid(mi);
 420         }
 421 }
 422
 423 void
 424 release_braid(ModeInfo * mi)
 425 {
 426         if (braids != NULL) {
 427                 (void) free((void *) braids);
 428                 braids = NULL;
 429         }
 430 }
 431
 432 void
 433 refresh_braid(ModeInfo * mi)
 434 {
 435         /* Do nothing, it will refresh by itself */
 436 }