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 # include "xlockmore.h"                         /* in xscreensaver distribution */
  50 #else  /* !STANDALONE */
  51 # include "xlock.h"                                     /* in xlockmore distribution */
  52 #endif /* !STANDALONE */
  53
  54
  55 #define DEF_MOUSE "False"
  56
  57 ENTRYPOINT ModeSpecOpt julia_opts = { 0, };
  58
  59
  60 #define numpoints ((0x2<<jp->depth)-1)
  61
  62 typedef struct {
  63         int         centerx;
  64         int         centery;    /* center of the screen */
  65         double      cr;
  66         double      ci;         /* julia params */
  67         int         depth;
  68         int         inc;
  69         int         circsize;
  70         int         erase;
  71         int         pix;
  72         long        itree;
  73         int         buffer;
  74         int         nbuffers;
  75         int         redrawing, redrawpos;
  76         Pixmap      pixmap;
  77 #ifndef HAVE_COCOA
  78         Cursor      cursor;
  79 #endif
  80         GC          stippledGC;
  81         XPoint    **pointBuffer;        /* pointer for XDrawPoints */
  82     Bool        button_down_p;
  83     int         mouse_x, mouse_y;
  84
  85 } juliastruct;
  86
  87 static juliastruct *julias = NULL;
  88
  89 /* How many segments to draw per cycle when redrawing */
  90 #define REDRAWSTEP 3
  91
  92 static void
  93 apply(juliastruct * jp, register double xr, register double xi, int d)
  94 {
  95         double      theta, r;
  96
  97         jp->pointBuffer[jp->buffer][jp->itree].x =
  98                 (int) (0.5 * xr * jp->centerx + jp->centerx);
  99         jp->pointBuffer[jp->buffer][jp->itree].y =
 100                 (int) (0.5 * xi * jp->centery + jp->centery);
 101         jp->itree++;
 102
 103         if (d > 0) {
 104                 xi -= jp->ci;
 105                 xr -= jp->cr;
 106
 107 /* Avoid atan2: DOMAIN error message */
 108                 if (xi == 0.0 && xr == 0.0)
 109                         theta = 0.0;
 110                 else
 111                         theta = atan2(xi, xr) / 2.0;
 112
 113                 /*r = pow(xi * xi + xr * xr, 0.25); */
 114                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 115
 116                 xr = r * cos(theta);
 117                 xi = r * sin(theta);
 118
 119                 d--;
 120                 apply(jp, xr, xi, d);
 121                 apply(jp, -xr, -xi, d);
 122         }
 123 }
 124
 125 static void
 126 incr(ModeInfo * mi, juliastruct * jp)
 127 {
 128         if (jp->button_down_p)
 129           {
 130                 jp->cr = ((double) (jp->mouse_x + 2 - jp->centerx)) * 2 / jp->centerx;
 131                 jp->ci = ((double) (jp->mouse_y + 2 - jp->centery)) * 2 / jp->centery;
 132           }
 133         else
 134           {
 135 #if 0
 136                 jp->cr = 1.5 * (sin(M_PI * (jp->inc / 300.0)) *
 137                                                 sin(jp->inc * M_PI / 200.0));
 138                 jp->ci = 1.5 * (cos(M_PI * (jp->inc / 300.0)) *
 139                                                 cos(jp->inc * M_PI / 200.0));
 140
 141                 jp->cr += 0.5 * cos(M_PI * jp->inc / 400.0);
 142                 jp->ci += 0.5 * sin(M_PI * jp->inc / 400.0);
 143 #else
 144         jp->cr = 1.5 * (sin(M_PI * (jp->inc / 290.0)) *
 145                         sin(jp->inc * M_PI / 210.0));
 146         jp->ci = 1.5 * (cos(M_PI * (jp->inc / 310.0)) *
 147                         cos(jp->inc * M_PI / 190.0));
 148
 149         jp->cr += 0.5 * cos(M_PI * jp->inc / 395.0);
 150         jp->ci += 0.5 * sin(M_PI * jp->inc / 410.0);
 151 #endif
 152           }
 153 }
 154
 155 ENTRYPOINT void
 156 init_julia(ModeInfo * mi)
 157 {
 158         Display    *display = MI_DISPLAY(mi);
 159         Window      window = MI_WINDOW(mi);
 160         juliastruct *jp;
 161         XGCValues   gcv;
 162         int         i;
 163
 164         if (julias == NULL) {
 165                 if ((julias = (juliastruct *) calloc(MI_NUM_SCREENS(mi),
 166                                               sizeof (juliastruct))) == NULL)
 167                         return;
 168         }
 169         jp = &julias[MI_SCREEN(mi)];
 170
 171         jp->centerx = MI_WIN_WIDTH(mi) / 2;
 172         jp->centery = MI_WIN_HEIGHT(mi) / 2;
 173
 174         jp->depth = MI_BATCHCOUNT(mi);
 175         if (jp->depth > 10)
 176                 jp->depth = 10;
 177
 178
 179 #ifndef HAVE_COCOA
 180         if (jp->button_down_p && !jp->cursor && !jp->cursor)
 181           {
 182                 Pixmap bit;
 183                 XColor black;
 184                 black.red = black.green = black.blue = 0;
 185                 black.flags = DoRed|DoGreen|DoBlue;
 186                 bit = XCreatePixmapFromBitmapData (display, window, "\000", 1, 1,
 187                                                                                    MI_WIN_BLACK_PIXEL(mi),
 188                                                                                    MI_WIN_BLACK_PIXEL(mi), 1);
 189                 jp->cursor = XCreatePixmapCursor (display, bit, bit, &black, &black,
 190                                                                                   0, 0);
 191                 XFreePixmap (display, bit);
 192           }
 193 #endif /* HAVE_COCOA */
 194
 195         if (jp->pixmap != None &&
 196             jp->circsize != (MIN(jp->centerx, jp->centery) / 60) * 2 + 1) {
 197                 XFreePixmap(display, jp->pixmap);
 198                 jp->pixmap = None;
 199         }
 200         if (jp->pixmap == None) {
 201                 GC          fg_gc = None, bg_gc = None;
 202
 203                 jp->circsize = MAX(8, (MIN(jp->centerx, jp->centery) / 96) * 2 + 1);
 204                 jp->pixmap = XCreatePixmap(display, window, jp->circsize, jp->circsize, 1);
 205                 gcv.foreground = 1;
 206                 fg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 207                 gcv.foreground = 0;
 208                 bg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 209                 XFillRectangle(display, jp->pixmap, bg_gc,
 210                                0, 0, jp->circsize, jp->circsize);
 211                 if (jp->circsize < 2)
 212                         XDrawPoint(display, jp->pixmap, fg_gc, 0, 0);
 213                 else
 214                         XFillArc(display, jp->pixmap, fg_gc,
 215                                  0, 0, jp->circsize, jp->circsize, 0, 23040);
 216                 if (fg_gc != None)
 217                         XFreeGC(display, fg_gc);
 218                 if (bg_gc != None)
 219                         XFreeGC(display, bg_gc);
 220         }
 221
 222 #ifndef HAVE_COCOA
 223         if (MI_WIN_IS_INROOT(mi))
 224           ;
 225         else if (jp->circsize > 0)
 226           XDefineCursor (display, window, jp->cursor);
 227         else
 228           XUndefineCursor (display, window);
 229 #endif /* HAVE_COCOA */
 230
 231         if (!jp->stippledGC) {
 232                 gcv.foreground = MI_WIN_BLACK_PIXEL(mi);
 233                 gcv.background = MI_WIN_BLACK_PIXEL(mi);
 234                 if ((jp->stippledGC = XCreateGC(display, window,
 235                                  GCForeground | GCBackground, &gcv)) == None)
 236                         return;
 237         }
 238         if (MI_NPIXELS(mi) > 2)
 239                 jp->pix = NRAND(MI_NPIXELS(mi));
 240         jp->inc = ((LRAND() & 1) * 2 - 1) * NRAND(200);
 241         jp->nbuffers = (MI_CYCLES(mi) + 1);
 242         if (!jp->pointBuffer)
 243                 jp->pointBuffer = (XPoint **) calloc(jp->nbuffers, sizeof (XPoint *));
 244         for (i = 0; i < jp->nbuffers; ++i)
 245                 if (jp->pointBuffer[i])
 246                         (void) memset((char *) jp->pointBuffer[i], 0,
 247                                       numpoints * sizeof (XPoint));
 248                 else
 249                         jp->pointBuffer[i] = (XPoint *) calloc(numpoints, sizeof (XPoint));
 250         jp->buffer = 0;
 251         jp->redrawing = 0;
 252         jp->erase = 0;
 253         XClearWindow(display, window);
 254 }
 255
 256
 257 static void
 258 reshape_julia (ModeInfo *mi, int w, int h)
 259 {
 260   init_julia (mi);
 261 }
 262
 263
 264 ENTRYPOINT Bool
 265 julia_handle_event (ModeInfo *mi, XEvent *event)
 266 {
 267   juliastruct *jp = &julias[MI_SCREEN(mi)];
 268
 269   if (event->xany.type == ButtonPress &&
 270       event->xbutton.button == Button1)
 271     {
 272       jp->button_down_p = True;
 273       jp->mouse_x = event->xbutton.x;
 274       jp->mouse_y = event->xbutton.y;
 275       return True;
 276     }
 277   else if (event->xany.type == ButtonRelease &&
 278            event->xbutton.button == Button1)
 279     {
 280       jp->button_down_p = False;
 281       return True;
 282     }
 283   else if (event->xany.type == MotionNotify && jp->button_down_p)
 284     {
 285       jp->mouse_x = event->xmotion.x;
 286       jp->mouse_y = event->xmotion.y;
 287       return True;
 288     }
 289
 290   return False;
 291 }
 292
 293
 294
 295 /* hack: moved here by jwz. */
 296 #define ERASE_IMAGE(d,w,g,x,y,xl,yl,xs,ys) \
 297 if (yl<y) \
 298 (y<yl+ys)?XFillRectangle(d,w,g,xl,yl,xs,y-yl): \
 299 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 300 else if (yl>y) \
 301 (y>yl-ys)?XFillRectangle(d,w,g,xl,y+ys,xs,yl-y): \
 302 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 303 if (xl<x) \
 304 (x<xl+xs)?XFillRectangle(d,w,g,xl,yl,x-xl,ys): \
 305 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 306 else if (xl>x) \
 307 (x>xl-xs)?XFillRectangle(d,w,g,x+xs,yl,xl-x,ys): \
 308 XFillRectangle(d,w,g,xl,yl,xs,ys)
 309
 310
 311 ENTRYPOINT void
 312 draw_julia (ModeInfo * mi)
 313 {
 314         Display    *display = MI_DISPLAY(mi);
 315         Window      window = MI_WINDOW(mi);
 316         GC          gc = MI_GC(mi);
 317         juliastruct *jp = &julias[MI_SCREEN(mi)];
 318         double      r, theta;
 319         register double xr = 0.0, xi = 0.0;
 320         int         k = 64, rnd = 0, i, j;
 321         XPoint     *xp = jp->pointBuffer[jp->buffer], old_circle, new_circle;
 322
 323         old_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 324         old_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 325         incr(mi, jp);
 326         new_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 327         new_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 328         XSetForeground(display, gc, MI_WIN_BLACK_PIXEL(mi));
 329         XFillArc(display, window, gc,
 330              old_circle.x-jp->circsize/2-2,
 331              old_circle.y-jp->circsize/2-2,
 332              jp->circsize+4, jp->circsize+4,
 333              0, 360*64);
 334         /* draw a circle at the c-parameter so you can see it's effect on the
 335            structure of the julia set */
 336         XSetForeground(display, jp->stippledGC, MI_WIN_WHITE_PIXEL(mi));
 337 #ifndef HAVE_COCOA
 338         XSetTSOrigin(display, jp->stippledGC, new_circle.x, new_circle.y);
 339         XSetStipple(display, jp->stippledGC, jp->pixmap);
 340         XSetFillStyle(display, jp->stippledGC, FillOpaqueStippled);
 341 #endif /* HAVE_COCOA */
 342         XDrawArc(display, window, jp->stippledGC,
 343              new_circle.x-jp->circsize/2,
 344              new_circle.y-jp->circsize/2,
 345              jp->circsize, jp->circsize,
 346              0, 360*64);
 347
 348         if (jp->erase == 1) {
 349                 XDrawPoints(display, window, gc,
 350                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 351         }
 352         jp->inc++;
 353         if (MI_NPIXELS(mi) > 2) {
 354                 XSetForeground(display, gc, MI_PIXEL(mi, jp->pix));
 355                 if (++jp->pix >= MI_NPIXELS(mi))
 356                         jp->pix = 0;
 357         } else
 358                 XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
 359         while (k--) {
 360
 361                 /* save calls to LRAND by using bit shifts over and over on the same
 362                    int for 32 iterations, then get a new random int */
 363                 if (!(k % 32))
 364                         rnd = LRAND();
 365
 366                 /* complex sqrt: x^0.5 = radius^0.5*(cos(theta/2) + i*sin(theta/2)) */
 367
 368                 xi -= jp->ci;
 369                 xr -= jp->cr;
 370
 371                 /* Avoid atan2: DOMAIN error message */
 372                 if (xi == 0.0 && xr == 0.0)
 373                         theta = 0.0;
 374                 else
 375                         theta = atan2(xi, xr) / 2.0;
 376
 377                 /*r = pow(xi * xi + xr * xr, 0.25); */
 378                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 379
 380                 xr = r * cos(theta);
 381                 xi = r * sin(theta);
 382
 383                 if ((rnd >> (k % 32)) & 0x1) {
 384                         xi = -xi;
 385                         xr = -xr;
 386                 }
 387                 xp->x = jp->centerx + (int) ((jp->centerx >> 1) * xr);
 388                 xp->y = jp->centery + (int) ((jp->centery >> 1) * xi);
 389                 xp++;
 390         }
 391
 392         jp->itree = 0;
 393         apply(jp, xr, xi, jp->depth);
 394
 395         XDrawPoints(display, window, gc,
 396                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 397
 398         jp->buffer++;
 399         if (jp->buffer > jp->nbuffers - 1) {
 400                 jp->buffer -= jp->nbuffers;
 401                 jp->erase = 1;
 402         }
 403         if (jp->redrawing) {
 404                 for (i = 0; i < REDRAWSTEP; i++) {
 405                         j = (jp->buffer - jp->redrawpos + jp->nbuffers) % jp->nbuffers;
 406                         XDrawPoints(display, window, gc,
 407                              jp->pointBuffer[j], numpoints, CoordModeOrigin);
 408
 409                         if (++(jp->redrawpos) >= jp->nbuffers) {
 410                                 jp->redrawing = 0;
 411                                 break;
 412                         }
 413                 }
 414         }
 415 }
 416
 417 ENTRYPOINT void
 418 release_julia (ModeInfo * mi)
 419 {
 420         if (julias != NULL) {
 421                 int         screen;
 422
 423                 for (screen = 0; screen < MI_NUM_SCREENS(mi); screen++) {
 424                         Display    *display = MI_DISPLAY(mi);
 425                         juliastruct *jp = &julias[screen];
 426                         int         buffer;
 427
 428                         if (jp->pointBuffer) {
 429                                 for (buffer = 0; buffer < jp->nbuffers; buffer++)
 430                                         if (jp->pointBuffer[buffer])
 431                                                 (void) free((void *) jp->pointBuffer[buffer]);
 432                                 (void) free((void *) jp->pointBuffer);
 433                         }
 434                         if (jp->stippledGC != None)
 435                                 XFreeGC(display, jp->stippledGC);
 436                         if (jp->pixmap != None)
 437                                 XFreePixmap(display, jp->pixmap);
 438 #ifndef HAVE_COCOA
 439                         if (jp->cursor)
 440                           XFreeCursor (display, jp->cursor);
 441 #endif
 442                 }
 443                 (void) free((void *) julias);
 444                 julias = NULL;
 445         }
 446 }
 447
 448 ENTRYPOINT void
 449 refresh_julia (ModeInfo * mi)
 450 {
 451         juliastruct *jp = &julias[MI_SCREEN(mi)];
 452
 453         jp->redrawing = 1;
 454         jp->redrawpos = 0;
 455 }
 456
 457 XSCREENSAVER_MODULE ("Julia", julia)