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

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  * julia --- continuously varying Julia set.
   3  */
   4 #if 0
   5 static const char sccsid[] = "@(#)julia.c       4.03 97/04/10 xlockmore";
   6 #endif
   7
   8 /* Copyright (c) 1995 Sean McCullough <bankshot@mailhost.nmt.edu>.
   9  *
  10  * Permission to use, copy, modify, and distribute this software and its
  11  * documentation for any purpose and without fee is hereby granted,
  12  * provided that the above copyright notice appear in all copies and that
  13  * both that copyright notice and this permission notice appear in
  14  * supporting documentation.
  15  *
  16  * This file is provided AS IS with no warranties of any kind.  The author
  17  * shall have no liability with respect to the infringement of copyrights,
  18  * trade secrets or any patents by this file or any part thereof.  In no
  19  * event will the author be liable for any lost revenue or profits or
  20  * other special, indirect and consequential damages.
  21  *
  22  * Revision History:
  23  * 10-Jun-06: j.grahl@ucl.ac.uk: tweaked functions for parameter of Julia set
  24  * 28-May-97: jwz@jwz.org: added interactive frobbing with the mouse.
  25  * 10-May-97: jwz@jwz.org: turned into a standalone program.
  26  * 02-Dec-95: snagged boilerplate from hop.c
  27  *           used ifs {w0 = sqrt(x-c), w1 = -sqrt(x-c)} with random iteration
  28  *           to plot the julia set, and sinusoidially varied parameter for set
  29  *           and plotted parameter with a circle.
  30  */
  31
  32 /*-
  33  * One thing to note is that batchcount is the *depth* of the search tree,
  34  * so the number of points computed is 2^batchcount - 1.  I use 8 or 9
  35  * on a dx266 and it looks okay.  The sinusoidal variation of the parameter
  36  * might not be as interesting as it could, but it still gives an idea of
  37  * the effect of the parameter.
  38  */
  39
  40 #ifdef STANDALONE
  41 # define DEFAULTS       "*count:                  1000   \n" \
  42                                         "*cycles:                 20     \n" \
  43                                         "*delay:                  10000  \n" \
  44                                         "*ncolors:                200    \n" \
  45                                         "*fpsSolid:               true   \n" \
  46                                         "*ignoreRotation: True   \n" \
  47
  48 # define UNIFORM_COLORS
  49 # define release_julia 0
  50 # define reshape_julia 0
  51 # include "xlockmore.h"                         /* in xscreensaver distribution */
  52 #else  /* !STANDALONE */
  53 # include "xlock.h"                                     /* in xlockmore distribution */
  54 #endif /* !STANDALONE */
  55
  56
  57 #define DEF_MOUSE "False"
  58
  59 ENTRYPOINT ModeSpecOpt julia_opts = { 0, };
  60
  61
  62 #define numpoints ((0x2<<jp->depth)-1)
  63
  64 typedef struct {
  65         int         centerx;
  66         int         centery;    /* center of the screen */
  67         double      cr;
  68         double      ci;         /* julia params */
  69         int         depth;
  70         int         inc;
  71         int         circsize;
  72         int         erase;
  73         int         pix;
  74         long        itree;
  75         int         buffer;
  76         int         nbuffers;
  77         int         redrawing, redrawpos;
  78         Pixmap      pixmap;
  79 #ifndef HAVE_JWXYZ
  80         Cursor      cursor;
  81 #endif
  82         GC          stippledGC;
  83         XPoint    **pointBuffer;        /* pointer for XDrawPoints */
  84     Bool        button_down_p;
  85     int         mouse_x, mouse_y;
  86
  87 } juliastruct;
  88
  89 static juliastruct *julias = NULL;
  90
  91 /* How many segments to draw per cycle when redrawing */
  92 #define REDRAWSTEP 3
  93
  94 static void
  95 apply(juliastruct * jp, register double xr, register double xi, int d)
  96 {
  97         double      theta, r;
  98
  99         jp->pointBuffer[jp->buffer][jp->itree].x =
 100                 (int) (0.5 * xr * jp->centerx + jp->centerx);
 101         jp->pointBuffer[jp->buffer][jp->itree].y =
 102                 (int) (0.5 * xi * jp->centery + jp->centery);
 103         jp->itree++;
 104
 105         if (d > 0) {
 106                 xi -= jp->ci;
 107                 xr -= jp->cr;
 108
 109 /* Avoid atan2: DOMAIN error message */
 110                 if (xi == 0.0 && xr == 0.0)
 111                         theta = 0.0;
 112                 else
 113                         theta = atan2(xi, xr) / 2.0;
 114
 115                 /*r = pow(xi * xi + xr * xr, 0.25); */
 116                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 117
 118                 xr = r * cos(theta);
 119                 xi = r * sin(theta);
 120
 121                 d--;
 122                 apply(jp, xr, xi, d);
 123                 apply(jp, -xr, -xi, d);
 124         }
 125 }
 126
 127 static void
 128 incr(ModeInfo * mi, juliastruct * jp)
 129 {
 130         if (jp->button_down_p)
 131           {
 132                 jp->cr = ((double) (jp->mouse_x + 2 - jp->centerx)) * 2 / jp->centerx;
 133                 jp->ci = ((double) (jp->mouse_y + 2 - jp->centery)) * 2 / jp->centery;
 134           }
 135         else
 136           {
 137 #if 0
 138                 jp->cr = 1.5 * (sin(M_PI * (jp->inc / 300.0)) *
 139                                                 sin(jp->inc * M_PI / 200.0));
 140                 jp->ci = 1.5 * (cos(M_PI * (jp->inc / 300.0)) *
 141                                                 cos(jp->inc * M_PI / 200.0));
 142
 143                 jp->cr += 0.5 * cos(M_PI * jp->inc / 400.0);
 144                 jp->ci += 0.5 * sin(M_PI * jp->inc / 400.0);
 145 #else
 146         jp->cr = 1.5 * (sin(M_PI * (jp->inc / 290.0)) *
 147                         sin(jp->inc * M_PI / 210.0));
 148         jp->ci = 1.5 * (cos(M_PI * (jp->inc / 310.0)) *
 149                         cos(jp->inc * M_PI / 190.0));
 150
 151         jp->cr += 0.5 * cos(M_PI * jp->inc / 395.0);
 152         jp->ci += 0.5 * sin(M_PI * jp->inc / 410.0);
 153 #endif
 154           }
 155 }
 156
 157 ENTRYPOINT void
 158 init_julia(ModeInfo * mi)
 159 {
 160         Display    *display = MI_DISPLAY(mi);
 161         Window      window = MI_WINDOW(mi);
 162         juliastruct *jp;
 163         XGCValues   gcv;
 164         int         i;
 165
 166         MI_INIT (mi, julias);
 167         jp = &julias[MI_SCREEN(mi)];
 168
 169         jp->centerx = MI_WIN_WIDTH(mi) / 2;
 170         jp->centery = MI_WIN_HEIGHT(mi) / 2;
 171
 172         jp->depth = MI_BATCHCOUNT(mi);
 173         if (jp->depth > 10)
 174                 jp->depth = 10;
 175
 176
 177 #ifndef HAVE_JWXYZ
 178         if (jp->button_down_p && !jp->cursor && !jp->cursor)
 179           {
 180                 Pixmap bit;
 181                 XColor black;
 182                 black.red = black.green = black.blue = 0;
 183                 black.flags = DoRed|DoGreen|DoBlue;
 184                 bit = XCreatePixmapFromBitmapData (display, window, "\000", 1, 1,
 185                                                                                    MI_WIN_BLACK_PIXEL(mi),
 186                                                                                    MI_WIN_BLACK_PIXEL(mi), 1);
 187                 jp->cursor = XCreatePixmapCursor (display, bit, bit, &black, &black,
 188                                                                                   0, 0);
 189                 XFreePixmap (display, bit);
 190           }
 191 #endif /* HAVE_JWXYZ */
 192
 193         if (jp->pixmap != None &&
 194             jp->circsize != (MIN(jp->centerx, jp->centery) / 60) * 2 + 1) {
 195                 XFreePixmap(display, jp->pixmap);
 196                 jp->pixmap = None;
 197         }
 198         if (jp->pixmap == None) {
 199                 GC          fg_gc = None, bg_gc = None;
 200
 201                 jp->circsize = MAX(8, (MIN(jp->centerx, jp->centery) / 96) * 2 + 1);
 202                 jp->pixmap = XCreatePixmap(display, window, jp->circsize, jp->circsize, 1);
 203                 gcv.foreground = 1;
 204                 fg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 205                 gcv.foreground = 0;
 206                 bg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 207                 XFillRectangle(display, jp->pixmap, bg_gc,
 208                                0, 0, jp->circsize, jp->circsize);
 209                 if (jp->circsize < 2)
 210                         XDrawPoint(display, jp->pixmap, fg_gc, 0, 0);
 211                 else
 212                         XFillArc(display, jp->pixmap, fg_gc,
 213                                  0, 0, jp->circsize, jp->circsize, 0, 23040);
 214                 if (fg_gc != None)
 215                         XFreeGC(display, fg_gc);
 216                 if (bg_gc != None)
 217                         XFreeGC(display, bg_gc);
 218         }
 219
 220 #ifndef HAVE_JWXYZ
 221         if (MI_WIN_IS_INROOT(mi))
 222           ;
 223         else if (jp->circsize > 0)
 224           XDefineCursor (display, window, jp->cursor);
 225         else
 226           XUndefineCursor (display, window);
 227 #endif /* HAVE_JWXYZ */
 228
 229         if (!jp->stippledGC) {
 230                 gcv.foreground = MI_WIN_BLACK_PIXEL(mi);
 231                 gcv.background = MI_WIN_BLACK_PIXEL(mi);
 232                 if ((jp->stippledGC = XCreateGC(display, window,
 233                                  GCForeground | GCBackground, &gcv)) == None)
 234                         return;
 235         }
 236         if (MI_NPIXELS(mi) > 2)
 237                 jp->pix = NRAND(MI_NPIXELS(mi));
 238         jp->inc = ((LRAND() & 1) * 2 - 1) * NRAND(200);
 239         jp->nbuffers = (MI_CYCLES(mi) + 1);
 240         if (!jp->pointBuffer)
 241                 jp->pointBuffer = (XPoint **) calloc(jp->nbuffers, sizeof (XPoint *));
 242         for (i = 0; i < jp->nbuffers; ++i)
 243                 if (jp->pointBuffer[i])
 244                         (void) memset((char *) jp->pointBuffer[i], 0,
 245                                       numpoints * sizeof (XPoint));
 246                 else
 247                         jp->pointBuffer[i] = (XPoint *) calloc(numpoints, sizeof (XPoint));
 248         jp->buffer = 0;
 249         jp->redrawing = 0;
 250         jp->erase = 0;
 251         XClearWindow(display, window);
 252 }
 253
 254
 255 ENTRYPOINT Bool
 256 julia_handle_event (ModeInfo *mi, XEvent *event)
 257 {
 258   juliastruct *jp = &julias[MI_SCREEN(mi)];
 259
 260   if (event->xany.type == ButtonPress &&
 261       event->xbutton.button == Button1)
 262     {
 263       jp->button_down_p = True;
 264       jp->mouse_x = event->xbutton.x;
 265       jp->mouse_y = event->xbutton.y;
 266       return True;
 267     }
 268   else if (event->xany.type == ButtonRelease &&
 269            event->xbutton.button == Button1)
 270     {
 271       jp->button_down_p = False;
 272       return True;
 273     }
 274   else if (event->xany.type == MotionNotify && jp->button_down_p)
 275     {
 276       jp->mouse_x = event->xmotion.x;
 277       jp->mouse_y = event->xmotion.y;
 278       return True;
 279     }
 280
 281   return False;
 282 }
 283
 284
 285
 286 /* hack: moved here by jwz. */
 287 #define ERASE_IMAGE(d,w,g,x,y,xl,yl,xs,ys) \
 288 if (yl<y) \
 289 (y<yl+ys)?XFillRectangle(d,w,g,xl,yl,xs,y-yl): \
 290 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 291 else if (yl>y) \
 292 (y>yl-ys)?XFillRectangle(d,w,g,xl,y+ys,xs,yl-y): \
 293 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 294 if (xl<x) \
 295 (x<xl+xs)?XFillRectangle(d,w,g,xl,yl,x-xl,ys): \
 296 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 297 else if (xl>x) \
 298 (x>xl-xs)?XFillRectangle(d,w,g,x+xs,yl,xl-x,ys): \
 299 XFillRectangle(d,w,g,xl,yl,xs,ys)
 300
 301
 302 ENTRYPOINT void
 303 draw_julia (ModeInfo * mi)
 304 {
 305         Display    *display = MI_DISPLAY(mi);
 306         Window      window = MI_WINDOW(mi);
 307         GC          gc = MI_GC(mi);
 308         juliastruct *jp = &julias[MI_SCREEN(mi)];
 309         double      r, theta;
 310         register double xr = 0.0, xi = 0.0;
 311         int         k = 64, rnd = 0, i, j;
 312         XPoint     *xp = jp->pointBuffer[jp->buffer], old_circle, new_circle;
 313
 314         old_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 315         old_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 316         incr(mi, jp);
 317         new_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 318         new_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 319         XSetForeground(display, gc, MI_WIN_BLACK_PIXEL(mi));
 320         XFillArc(display, window, gc,
 321              old_circle.x-jp->circsize/2-2,
 322              old_circle.y-jp->circsize/2-2,
 323              jp->circsize+4, jp->circsize+4,
 324              0, 360*64);
 325         /* draw a circle at the c-parameter so you can see it's effect on the
 326            structure of the julia set */
 327         XSetForeground(display, jp->stippledGC, MI_WIN_WHITE_PIXEL(mi));
 328 #ifndef HAVE_JWXYZ
 329         XSetTSOrigin(display, jp->stippledGC, new_circle.x, new_circle.y);
 330         XSetStipple(display, jp->stippledGC, jp->pixmap);
 331         XSetFillStyle(display, jp->stippledGC, FillOpaqueStippled);
 332 #endif /* HAVE_JWXYZ */
 333         XDrawArc(display, window, jp->stippledGC,
 334              new_circle.x-jp->circsize/2,
 335              new_circle.y-jp->circsize/2,
 336              jp->circsize, jp->circsize,
 337              0, 360*64);
 338
 339         if (jp->erase == 1) {
 340                 XDrawPoints(display, window, gc,
 341                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 342         }
 343         jp->inc++;
 344         if (MI_NPIXELS(mi) > 2) {
 345                 XSetForeground(display, gc, MI_PIXEL(mi, jp->pix));
 346                 if (++jp->pix >= MI_NPIXELS(mi))
 347                         jp->pix = 0;
 348         } else
 349                 XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
 350         while (k--) {
 351
 352                 /* save calls to LRAND by using bit shifts over and over on the same
 353                    int for 32 iterations, then get a new random int */
 354                 if (!(k % 32))
 355                         rnd = LRAND();
 356
 357                 /* complex sqrt: x^0.5 = radius^0.5*(cos(theta/2) + i*sin(theta/2)) */
 358
 359                 xi -= jp->ci;
 360                 xr -= jp->cr;
 361
 362                 /* Avoid atan2: DOMAIN error message */
 363                 if (xi == 0.0 && xr == 0.0)
 364                         theta = 0.0;
 365                 else
 366                         theta = atan2(xi, xr) / 2.0;
 367
 368                 /*r = pow(xi * xi + xr * xr, 0.25); */
 369                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 370
 371                 xr = r * cos(theta);
 372                 xi = r * sin(theta);
 373
 374                 if ((rnd >> (k % 32)) & 0x1) {
 375                         xi = -xi;
 376                         xr = -xr;
 377                 }
 378                 xp->x = jp->centerx + (int) ((jp->centerx >> 1) * xr);
 379                 xp->y = jp->centery + (int) ((jp->centery >> 1) * xi);
 380                 xp++;
 381         }
 382
 383         jp->itree = 0;
 384         apply(jp, xr, xi, jp->depth);
 385
 386         XDrawPoints(display, window, gc,
 387                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 388
 389         jp->buffer++;
 390         if (jp->buffer > jp->nbuffers - 1) {
 391                 jp->buffer -= jp->nbuffers;
 392                 jp->erase = 1;
 393         }
 394         if (jp->redrawing) {
 395                 for (i = 0; i < REDRAWSTEP; i++) {
 396                         j = (jp->buffer - jp->redrawpos + jp->nbuffers) % jp->nbuffers;
 397                         XDrawPoints(display, window, gc,
 398                              jp->pointBuffer[j], numpoints, CoordModeOrigin);
 399
 400                         if (++(jp->redrawpos) >= jp->nbuffers) {
 401                                 jp->redrawing = 0;
 402                                 break;
 403                         }
 404                 }
 405         }
 406 }
 407
 408 ENTRYPOINT void
 409 free_julia (ModeInfo * mi)
 410 {
 411         Display    *display = MI_DISPLAY(mi);
 412         juliastruct *jp = &julias[MI_SCREEN(mi)];
 413         int         buffer;
 414
 415         if (jp->pointBuffer) {
 416                 for (buffer = 0; buffer < jp->nbuffers; buffer++)
 417                         if (jp->pointBuffer[buffer])
 418                                 (void) free((void *) jp->pointBuffer[buffer]);
 419                 (void) free((void *) jp->pointBuffer);
 420         }
 421         if (jp->stippledGC != None)
 422                 XFreeGC(display, jp->stippledGC);
 423         if (jp->pixmap != None)
 424                 XFreePixmap(display, jp->pixmap);
 425 #ifndef HAVE_JWXYZ
 426         if (jp->cursor)
 427           XFreeCursor (display, jp->cursor);
 428 #endif
 429 }
 430
 431 #ifndef STANDALONE
 432 ENTRYPOINT void
 433 refresh_julia (ModeInfo * mi)
 434 {
 435         juliastruct *jp = &julias[MI_SCREEN(mi)];
 436
 437         jp->redrawing = 1;
 438         jp->redrawpos = 0;
 439 }
 440 #endif
 441
 442 XSCREENSAVER_MODULE ("Julia", julia)