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