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  * 28-May-97: jwz@jwz.org: added interactive frobbing with the mouse.
  24  * 10-May-97: jwz@jwz.org: turned into a standalone program.
  25  * 02-Dec-95: snagged boilerplate from hop.c
  26  *           used ifs {w0 = sqrt(x-c), w1 = -sqrt(x-c)} with random iteration
  27  *           to plot the julia set, and sinusoidially varied parameter for set
  28  *           and plotted parameter with a circle.
  29  */
  30
  31 /*-
  32  * One thing to note is that batchcount is the *depth* of the search tree,
  33  * so the number of points computed is 2^batchcount - 1.  I use 8 or 9
  34  * on a dx266 and it looks okay.  The sinusoidal variation of the parameter
  35  * might not be as interesting as it could, but it still gives an idea of
  36  * the effect of the parameter.
  37  */
  38
  39 #ifdef STANDALONE
  40 # define PROGCLASS                                      "Julia"
  41 # define HACK_INIT                                      init_julia
  42 # define HACK_DRAW                                      draw_julia
  43 # define julia_opts                                     xlockmore_opts
  44 # define DEFAULTS       "*count:                1000  \n"                       \
  45                                         "*cycles:               20    \n"                       \
  46                                         "*delay:                10000 \n"                       \
  47                                         "*ncolors:              200   \n"
  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 static Bool track_p;
  56
  57 #define DEF_MOUSE "False"
  58
  59 static XrmOptionDescRec opts[] =
  60 {
  61         {"-mouse", ".julia.mouse", XrmoptionNoArg, "on"},
  62         {"+mouse", ".julia.mouse", XrmoptionNoArg, "off"},
  63 };
  64 static argtype vars[] =
  65 {
  66         {&track_p, "mouse", "Mouse", DEF_MOUSE, t_Bool},
  67 };
  68 static OptionStruct desc[] =
  69 {
  70         {"-/+mouse", "turn on/off mouse tracking"},
  71 };
  72
  73 ModeSpecOpt julia_opts = { 2, opts, 1, vars, desc };
  74
  75
  76 #define numpoints ((0x2<<jp->depth)-1)
  77
  78 typedef struct {
  79         int         centerx;
  80         int         centery;    /* center of the screen */
  81         double      cr;
  82         double      ci;         /* julia params */
  83         int         depth;
  84         int         inc;
  85         int         circsize;
  86         int         erase;
  87         int         pix;
  88         long        itree;
  89         int         buffer;
  90         int         nbuffers;
  91         int         redrawing, redrawpos;
  92         Pixmap      pixmap;
  93         Cursor      cursor;
  94         GC          stippledGC;
  95         XPoint    **pointBuffer;        /* pointer for XDrawPoints */
  96
  97 } juliastruct;
  98
  99 static juliastruct *julias = NULL;
 100
 101 /* How many segments to draw per cycle when redrawing */
 102 #define REDRAWSTEP 3
 103
 104 static void
 105 apply(juliastruct * jp, register double xr, register double xi, int d)
 106 {
 107         double      theta, r;
 108
 109         jp->pointBuffer[jp->buffer][jp->itree].x =
 110                 (int) (0.5 * xr * jp->centerx + jp->centerx);
 111         jp->pointBuffer[jp->buffer][jp->itree].y =
 112                 (int) (0.5 * xi * jp->centery + jp->centery);
 113         jp->itree++;
 114
 115         if (d > 0) {
 116                 xi -= jp->ci;
 117                 xr -= jp->cr;
 118
 119 /* Avoid atan2: DOMAIN error message */
 120                 if (xi == 0.0 && xr == 0.0)
 121                         theta = 0.0;
 122                 else
 123                         theta = atan2(xi, xr) / 2.0;
 124
 125                 /*r = pow(xi * xi + xr * xr, 0.25); */
 126                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 127
 128                 xr = r * cos(theta);
 129                 xi = r * sin(theta);
 130
 131                 d--;
 132                 apply(jp, xr, xi, d);
 133                 apply(jp, -xr, -xi, d);
 134         }
 135 }
 136
 137 static void
 138 incr(ModeInfo * mi, juliastruct * jp)
 139 {
 140         int cx, cy;
 141
 142         if (track_p)
 143           {
 144                 Window r, c;
 145                 int rx, ry;
 146                 unsigned int m;
 147                 XQueryPointer(MI_DISPLAY(mi), MI_WINDOW(mi),
 148                                           &r, &c, &rx, &ry, &cx, &cy, &m);
 149                 if (cx <= 0 || cy <= 0 ||
 150                         cx >= MI_WIN_WIDTH(mi) || cy >= MI_WIN_HEIGHT(mi))
 151                   goto NOTRACK;
 152           }
 153
 154         if (track_p)
 155           {
 156                 jp->cr = ((double) (cx + 2 - jp->centerx)) * 2 / jp->centerx;
 157                 jp->ci = ((double) (cy + 2 - jp->centery)) * 2 / jp->centery;
 158           }
 159         else
 160           {
 161           NOTRACK:
 162                 jp->cr = 1.5 * (sin(M_PI * (jp->inc / 300.0)) *
 163                                                 sin(jp->inc * M_PI / 200.0));
 164                 jp->ci = 1.5 * (cos(M_PI * (jp->inc / 300.0)) *
 165                                                 cos(jp->inc * M_PI / 200.0));
 166
 167                 jp->cr += 0.5 * cos(M_PI * jp->inc / 400.0);
 168                 jp->ci += 0.5 * sin(M_PI * jp->inc / 400.0);
 169           }
 170 }
 171
 172 void
 173 init_julia(ModeInfo * mi)
 174 {
 175         Display    *display = MI_DISPLAY(mi);
 176         Window      window = MI_WINDOW(mi);
 177         juliastruct *jp;
 178         XGCValues   gcv;
 179         int         i;
 180
 181         if (julias == NULL) {
 182                 if ((julias = (juliastruct *) calloc(MI_NUM_SCREENS(mi),
 183                                               sizeof (juliastruct))) == NULL)
 184                         return;
 185         }
 186         jp = &julias[MI_SCREEN(mi)];
 187
 188         jp->centerx = MI_WIN_WIDTH(mi) / 2;
 189         jp->centery = MI_WIN_HEIGHT(mi) / 2;
 190
 191         jp->depth = MI_BATCHCOUNT(mi);
 192         if (jp->depth > 10)
 193                 jp->depth = 10;
 194
 195
 196         if (track_p && !jp->cursor)
 197           {
 198                 Pixmap bit;
 199                 XColor black;
 200                 black.red = black.green = black.blue = 0;
 201                 black.flags = DoRed|DoGreen|DoBlue;
 202                 bit = XCreatePixmapFromBitmapData (display, window, "\000", 1, 1,
 203                                                                                    MI_WIN_BLACK_PIXEL(mi),
 204                                                                                    MI_WIN_BLACK_PIXEL(mi), 1);
 205                 jp->cursor = XCreatePixmapCursor (display, bit, bit, &black, &black,
 206                                                                                   0, 0);
 207                 XFreePixmap (display, bit);
 208           }
 209
 210         if (jp->pixmap != None &&
 211             jp->circsize != (MIN(jp->centerx, jp->centery) / 60) * 2 + 1) {
 212                 XFreePixmap(display, jp->pixmap);
 213                 jp->pixmap = None;
 214         }
 215         if (jp->pixmap == None) {
 216                 GC          fg_gc = None, bg_gc = None;
 217
 218                 jp->circsize = (MIN(jp->centerx, jp->centery) / 96) * 2 + 1;
 219                 jp->pixmap = XCreatePixmap(display, window, jp->circsize, jp->circsize, 1);
 220                 gcv.foreground = 1;
 221                 fg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 222                 gcv.foreground = 0;
 223                 bg_gc = XCreateGC(display, jp->pixmap, GCForeground, &gcv);
 224                 XFillRectangle(display, jp->pixmap, bg_gc,
 225                                0, 0, jp->circsize, jp->circsize);
 226                 if (jp->circsize < 2)
 227                         XDrawPoint(display, jp->pixmap, fg_gc, 0, 0);
 228                 else
 229                         XFillArc(display, jp->pixmap, fg_gc,
 230                                  0, 0, jp->circsize, jp->circsize, 0, 23040);
 231                 if (fg_gc != None)
 232                         XFreeGC(display, fg_gc);
 233                 if (bg_gc != None)
 234                         XFreeGC(display, bg_gc);
 235         }
 236
 237         if (MI_WIN_IS_INROOT(mi))
 238           ;
 239         else if (jp->circsize > 0)
 240           XDefineCursor (display, window, jp->cursor);
 241         else
 242           XUndefineCursor (display, window);
 243
 244         if (!jp->stippledGC) {
 245                 gcv.foreground = MI_WIN_BLACK_PIXEL(mi);
 246                 gcv.background = MI_WIN_BLACK_PIXEL(mi);
 247                 if ((jp->stippledGC = XCreateGC(display, window,
 248                                  GCForeground | GCBackground, &gcv)) == None)
 249                         return;
 250         }
 251         if (MI_NPIXELS(mi) > 2)
 252                 jp->pix = NRAND(MI_NPIXELS(mi));
 253         jp->inc = ((LRAND() & 1) * 2 - 1) * NRAND(200);
 254         jp->nbuffers = (MI_CYCLES(mi) + 1);
 255         if (!jp->pointBuffer)
 256                 jp->pointBuffer = (XPoint **) calloc(jp->nbuffers, sizeof (XPoint *));
 257         for (i = 0; i < jp->nbuffers; ++i)
 258                 if (jp->pointBuffer[i])
 259                         (void) memset((char *) jp->pointBuffer[i], 0,
 260                                       numpoints * sizeof (XPoint));
 261                 else
 262                         jp->pointBuffer[i] = (XPoint *) calloc(numpoints, sizeof (XPoint));
 263         jp->buffer = 0;
 264         jp->redrawing = 0;
 265         jp->erase = 0;
 266         XClearWindow(display, window);
 267 }
 268
 269
 270 /* hack: moved here by jwz. */
 271 #define ERASE_IMAGE(d,w,g,x,y,xl,yl,xs,ys) \
 272 if (yl<y) \
 273 (y<yl+ys)?XFillRectangle(d,w,g,xl,yl,xs,y-yl): \
 274 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 275 else if (yl>y) \
 276 (y>yl-ys)?XFillRectangle(d,w,g,xl,y+ys,xs,yl-y): \
 277 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 278 if (xl<x) \
 279 (x<xl+xs)?XFillRectangle(d,w,g,xl,yl,x-xl,ys): \
 280 XFillRectangle(d,w,g,xl,yl,xs,ys); \
 281 else if (xl>x) \
 282 (x>xl-xs)?XFillRectangle(d,w,g,x+xs,yl,xl-x,ys): \
 283 XFillRectangle(d,w,g,xl,yl,xs,ys)
 284
 285
 286 void
 287 draw_julia(ModeInfo * mi)
 288 {
 289         Display    *display = MI_DISPLAY(mi);
 290         Window      window = MI_WINDOW(mi);
 291         GC          gc = MI_GC(mi);
 292         juliastruct *jp = &julias[MI_SCREEN(mi)];
 293         double      r, theta;
 294         register double xr = 0.0, xi = 0.0;
 295         int         k = 64, rnd = 0, i, j;
 296         XPoint     *xp = jp->pointBuffer[jp->buffer], old_circle, new_circle;
 297
 298         old_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 299         old_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 300         incr(mi, jp);
 301         new_circle.x = (int) (jp->centerx * jp->cr / 2) + jp->centerx - 2;
 302         new_circle.y = (int) (jp->centery * jp->ci / 2) + jp->centery - 2;
 303         XSetForeground(display, gc, MI_WIN_BLACK_PIXEL(mi));
 304         ERASE_IMAGE(display, window, gc, new_circle.x, new_circle.y,
 305                     old_circle.x, old_circle.y, jp->circsize, jp->circsize);
 306         /* draw a circle at the c-parameter so you can see it's effect on the
 307            structure of the julia set */
 308         XSetTSOrigin(display, jp->stippledGC, new_circle.x, new_circle.y);
 309         XSetForeground(display, jp->stippledGC, MI_WIN_WHITE_PIXEL(mi));
 310         XSetStipple(display, jp->stippledGC, jp->pixmap);
 311         XSetFillStyle(display, jp->stippledGC, FillOpaqueStippled);
 312         XFillRectangle(display, window, jp->stippledGC, new_circle.x, new_circle.y,
 313                        jp->circsize, jp->circsize);
 314         XFlush(display);
 315         if (jp->erase == 1) {
 316                 XDrawPoints(display, window, gc,
 317                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 318         }
 319         jp->inc++;
 320         if (MI_NPIXELS(mi) > 2) {
 321                 XSetForeground(display, gc, MI_PIXEL(mi, jp->pix));
 322                 if (++jp->pix >= MI_NPIXELS(mi))
 323                         jp->pix = 0;
 324         } else
 325                 XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
 326         while (k--) {
 327
 328                 /* save calls to LRAND by using bit shifts over and over on the same
 329                    int for 32 iterations, then get a new random int */
 330                 if (!(k % 32))
 331                         rnd = LRAND();
 332
 333                 /* complex sqrt: x^0.5 = radius^0.5*(cos(theta/2) + i*sin(theta/2)) */
 334
 335                 xi -= jp->ci;
 336                 xr -= jp->cr;
 337
 338                 /* Avoid atan2: DOMAIN error message */
 339                 if (xi == 0.0 && xr == 0.0)
 340                         theta = 0.0;
 341                 else
 342                         theta = atan2(xi, xr) / 2.0;
 343
 344                 /*r = pow(xi * xi + xr * xr, 0.25); */
 345                 r = sqrt(sqrt(xi * xi + xr * xr));      /* 3 times faster */
 346
 347                 xr = r * cos(theta);
 348                 xi = r * sin(theta);
 349
 350                 if ((rnd >> (k % 32)) & 0x1) {
 351                         xi = -xi;
 352                         xr = -xr;
 353                 }
 354                 xp->x = jp->centerx + (int) ((jp->centerx >> 1) * xr);
 355                 xp->y = jp->centery + (int) ((jp->centery >> 1) * xi);
 356                 xp++;
 357         }
 358
 359         jp->itree = 0;
 360         apply(jp, xr, xi, jp->depth);
 361
 362         XDrawPoints(display, window, gc,
 363                     jp->pointBuffer[jp->buffer], numpoints, CoordModeOrigin);
 364
 365         jp->buffer++;
 366         if (jp->buffer > jp->nbuffers - 1) {
 367                 jp->buffer -= jp->nbuffers;
 368                 jp->erase = 1;
 369         }
 370         if (jp->redrawing) {
 371                 for (i = 0; i < REDRAWSTEP; i++) {
 372                         j = (jp->buffer - jp->redrawpos + jp->nbuffers) % jp->nbuffers;
 373                         XDrawPoints(display, window, gc,
 374                              jp->pointBuffer[j], numpoints, CoordModeOrigin);
 375
 376                         if (++(jp->redrawpos) >= jp->nbuffers) {
 377                                 jp->redrawing = 0;
 378                                 break;
 379                         }
 380                 }
 381         }
 382 }
 383
 384 void
 385 release_julia(ModeInfo * mi)
 386 {
 387         if (julias != NULL) {
 388                 int         screen;
 389
 390                 for (screen = 0; screen < MI_NUM_SCREENS(mi); screen++) {
 391                         Display    *display = MI_DISPLAY(mi);
 392                         juliastruct *jp = &julias[screen];
 393                         int         buffer;
 394
 395                         if (jp->pointBuffer) {
 396                                 for (buffer = 0; buffer < jp->nbuffers; buffer++)
 397                                         if (jp->pointBuffer[buffer])
 398                                                 (void) free((void *) jp->pointBuffer[buffer]);
 399                                 (void) free((void *) jp->pointBuffer);
 400                         }
 401                         if (jp->stippledGC != None)
 402                                 XFreeGC(display, jp->stippledGC);
 403                         if (jp->pixmap != None)
 404                                 XFreePixmap(display, jp->pixmap);
 405                         if (jp->cursor)
 406                           XFreeCursor (display, jp->cursor);
 407                 }
 408                 (void) free((void *) julias);
 409                 julias = NULL;
 410         }
 411 }
 412
 413 void
 414 refresh_julia(ModeInfo * mi)
 415 {
 416         juliastruct *jp = &julias[MI_SCREEN(mi)];
 417
 418         jp->redrawing = 1;
 419         jp->redrawpos = 0;
 420 }