1 /* fluidballs, Copyright (c) 2000 by Peter Birtles <peter@bqdesign.com.au>
3 * Permission to use, copy, modify, distribute, and sell this software and its
4 * documentation for any purpose is hereby granted without fee, provided that
5 * the above copyright notice appear in all copies and that both that
6 * copyright notice and this permission notice appear in supporting
7 * documentation. No representations are made about the suitability of this
8 * software for any purpose. It is provided "as is" without express or
11 * Ported to X11 and xscreensaver by jwz, 27-Feb-2002.
13 * http://astronomy.swin.edu.au/~pbourke/modelling/fluid/
15 * Some physics improvements by Steven Barker <steve@blckknght.org>
19 * Specifying a distribution in the ball sizes (with a gamma curve, possibly).
20 * Brownian motion, for that extra touch of realism.
22 * It would be nice to detect when there are more balls than fit in
23 * the window, and scale the number of balls back. Useful for the
24 * xscreensaver-demo preview, which is often too tight by default.
28 #include "screenhack.h"
31 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
33 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
38 XWindowAttributes xgwa;
41 Pixmap b, ba; /* double-buffer to reduce flicker */
42 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
45 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
47 GC draw_gc; /* most of the balls */
48 GC draw_gc2; /* the ball being dragged with the mouse */
53 int count; /* number of balls */
54 float xmin, ymin; /* rectangle of window, relative to root */
57 int mouse_ball; /* index of ball being dragged, or 0 if none. */
59 float tc; /* time constant (time-warp multiplier) */
60 float accx; /* horizontal acceleration (wind) */
61 float accy; /* vertical acceleration (gravity) */
63 float *vx, *vy; /* current ball velocities */
64 float *px, *py; /* current ball positions */
65 float *opx, *opy; /* previous ball positions */
66 float *r; /* ball radiuses */
68 float *m; /* ball mass, precalculated */
69 float e; /* coeficient of elasticity */
70 float max_radius; /* largest radius of any ball */
72 Bool random_sizes_p; /* Whether balls should be various sizes up to max. */
73 Bool shake_p; /* Whether to mess with gravity when things settle. */
74 Bool dbuf; /* Whether we're using double buffering. */
75 float shake_threshold;
78 Bool fps_p; /* Whether to draw some text at the bottom. */
87 struct timeval last_time;
92 /* Draws the frames per second string */
94 draw_fps_string (b_state *state)
96 XFillRectangle (state->dpy, state->b, state->erase_gc,
97 0, state->xgwa.height - state->font_height*3 - 20,
98 state->xgwa.width, state->font_height*3 + 20);
99 XDrawImageString (state->dpy, state->b, state->font_gc,
100 10, state->xgwa.height - state->font_height*2 -
101 state->font_baseline - 10,
102 state->fps_str, strlen(state->fps_str));
105 /* Finds the origin of the window relative to the root window, by
106 walking up the window tree until it reaches the top.
109 window_origin (Display *dpy, Window window, int *x, int *y)
111 XTranslateCoordinates (dpy, window, RootWindow (dpy, DefaultScreen (dpy)),
112 0, 0, x, y, &window);
116 /* Queries the window position to see if the window has moved or resized.
117 We poll this instead of waiting for ConfigureNotify events, because
118 when the window manager moves the window, only one ConfigureNotify
119 comes in: at the end of the motion. If we poll, we can react to the
120 new position while the window is still being moved. (Assuming the WM
121 does OpaqueMove, of course.)
124 check_window_moved (b_state *state)
126 float oxmin = state->xmin;
127 float oxmax = state->xmax;
128 float oymin = state->ymin;
129 float oymax = state->ymax;
131 XGetWindowAttributes (state->dpy, state->window, &state->xgwa);
132 window_origin (state->dpy, state->window, &wx, &wy);
135 state->xmax = state->xmin + state->xgwa.width;
136 state->ymax = state->ymin + state->xgwa.height - (state->font_height*3) -
137 (state->font_height ? 22 : 0);
139 if (state->dbuf && (state->ba))
141 if (oxmax != state->xmax || oymax != state->ymax)
143 XFreePixmap (state->dpy, state->ba);
144 state->ba = XCreatePixmap (state->dpy, state->window,
145 state->xgwa.width, state->xgwa.height,
147 XFillRectangle (state->dpy, state->ba, state->erase_gc, 0, 0,
148 state->xgwa.width, state->xgwa.height);
149 state->b = state->ba;
154 /* Only need to erase the window if the origin moved */
155 if (oxmin != state->xmin || oymin != state->ymin)
156 XClearWindow (state->dpy, state->window);
157 else if (state->fps_p && oymax != state->ymax)
158 XFillRectangle (state->dpy, state->b, state->erase_gc,
159 0, state->xgwa.height - state->font_height*3,
160 state->xgwa.width, state->font_height*3);
165 /* Returns the position of the mouse relative to the root window.
168 query_mouse (b_state *state, int *x, int *y)
170 Window root1, child1;
171 int mouse_x, mouse_y, root_x, root_y;
173 if (XQueryPointer (state->dpy, state->window, &root1, &child1,
174 &root_x, &root_y, &mouse_x, &mouse_y, &mask))
186 /* Re-pick the colors of the balls, and the mouse-ball.
189 recolor (b_state *state)
192 XFreeColors (state->dpy, state->xgwa.colormap, &state->fg.pixel, 1, 0);
193 if (state->fg2.flags)
194 XFreeColors (state->dpy, state->xgwa.colormap, &state->fg2.pixel, 1, 0);
196 state->fg.flags = DoRed|DoGreen|DoBlue;
197 state->fg.red = 0x8888 + (random() % 0x8888);
198 state->fg.green = 0x8888 + (random() % 0x8888);
199 state->fg.blue = 0x8888 + (random() % 0x8888);
201 state->fg2.flags = DoRed|DoGreen|DoBlue;
202 state->fg2.red = 0x8888 + (random() % 0x8888);
203 state->fg2.green = 0x8888 + (random() % 0x8888);
204 state->fg2.blue = 0x8888 + (random() % 0x8888);
206 if (XAllocColor (state->dpy, state->xgwa.colormap, &state->fg))
207 XSetForeground (state->dpy, state->draw_gc, state->fg.pixel);
209 if (XAllocColor (state->dpy, state->xgwa.colormap, &state->fg2))
210 XSetForeground (state->dpy, state->draw_gc2, state->fg2.pixel);
213 /* Initialize the state structure and various X data.
216 fluidballs_init (Display *dpy, Window window)
220 b_state *state = (b_state *) calloc (1, sizeof(*state));
224 state->window = window;
225 state->delay = get_integer_resource (dpy, "delay", "Integer");
227 check_window_moved (state);
229 state->dbuf = get_boolean_resource (dpy, "doubleBuffer", "Boolean");
231 # ifdef HAVE_COCOA /* Don't second-guess Quartz's double-buffering */
237 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
238 state->dbeclear_p = get_boolean_resource (dpy, "useDBEClear", "Boolean");
239 if (state->dbeclear_p)
240 state->b = xdbe_get_backbuffer (dpy, window, XdbeBackground);
242 state->b = xdbe_get_backbuffer (dpy, window, XdbeUndefined);
243 state->backb = state->b;
244 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
248 state->ba = XCreatePixmap (state->dpy, state->window,
249 state->xgwa.width, state->xgwa.height,
251 state->b = state->ba;
256 state->b = state->window;
259 /* Select ButtonRelease events on the external window, if no other app has
260 already selected it (only one app can select it at a time: BadAccess. */
262 if (! (state->xgwa.all_event_masks & ButtonReleaseMask))
263 XSelectInput (state->dpy, state->window,
264 state->xgwa.your_event_mask | ButtonReleaseMask);
267 gcv.foreground = get_pixel_resource(state->dpy, state->xgwa.colormap,
268 "foreground", "Foreground");
269 gcv.background = get_pixel_resource(state->dpy, state->xgwa.colormap,
270 "background", "Background");
271 state->draw_gc = XCreateGC (state->dpy, state->b,
272 GCForeground|GCBackground, &gcv);
274 gcv.foreground = get_pixel_resource(state->dpy, state->xgwa.colormap,
275 "mouseForeground", "MouseForeground");
276 state->draw_gc2 = XCreateGC (state->dpy, state->b,
277 GCForeground|GCBackground, &gcv);
279 gcv.foreground = gcv.background;
280 state->erase_gc = XCreateGC (state->dpy, state->b,
281 GCForeground|GCBackground, &gcv);
285 XFillRectangle (state->dpy, state->ba, state->erase_gc, 0, 0,
286 state->xgwa.width, state->xgwa.height);
290 extx = state->xmax - state->xmin;
291 exty = state->ymax - state->ymin;
293 state->count = get_integer_resource (dpy, "count", "Count");
294 if (state->count < 1) state->count = 20;
296 state->max_radius = get_float_resource (dpy, "size", "Size") / 2;
297 if (state->max_radius < 1.0) state->max_radius = 1.0;
299 state->random_sizes_p = get_boolean_resource (dpy, "random", "Random");
301 /* If the initial window size is too small to hold all these balls,
302 make fewer of them...
305 float r = (state->random_sizes_p
306 ? state->max_radius * 0.7
307 : state->max_radius);
308 float ball_area = M_PI * r * r;
309 float balls_area = state->count * ball_area;
310 float window_area = state->xgwa.width * state->xgwa.height;
311 window_area *= 0.75; /* don't pack it completely full */
312 if (balls_area > window_area)
313 state->count = window_area / ball_area;
316 state->accx = get_float_resource (dpy, "wind", "Wind");
317 if (state->accx < -1.0 || state->accx > 1.0) state->accx = 0;
319 state->accy = get_float_resource (dpy, "gravity", "Gravity");
320 if (state->accy < -1.0 || state->accy > 1.0) state->accy = 0.01;
322 state->e = get_float_resource (dpy, "elasticity", "Elacitcity");
323 if (state->e < 0.2 || state->e > 1.0) state->e = 0.97;
325 state->tc = get_float_resource (dpy, "timeScale", "TimeScale");
326 if (state->tc <= 0 || state->tc > 10) state->tc = 1.0;
328 state->shake_p = get_boolean_resource (dpy, "shake", "Shake");
329 state->shake_threshold = get_float_resource (dpy, "shakeThreshold",
332 state->fps_p = get_boolean_resource (dpy, "doFPS", "DoFPS");
336 char *fontname = get_string_resource (dpy, "fpsFont", "Font");
337 if (!fontname) fontname = "-*-courier-bold-r-normal-*-180-*";
338 font = XLoadQueryFont (dpy, fontname);
339 if (!font) font = XLoadQueryFont (dpy, "fixed");
341 gcv.font = font->fid;
342 gcv.foreground = get_pixel_resource(state->dpy, state->xgwa.colormap,
343 "textColor", "Foreground");
344 state->font_gc = XCreateGC(dpy, state->b,
345 GCFont|GCForeground|GCBackground, &gcv);
346 state->font_height = font->ascent + font->descent;
347 state->font_baseline = font->descent;
350 state->m = (float *) malloc (sizeof (*state->m) * (state->count + 1));
351 state->r = (float *) malloc (sizeof (*state->r) * (state->count + 1));
352 state->vx = (float *) malloc (sizeof (*state->vx) * (state->count + 1));
353 state->vy = (float *) malloc (sizeof (*state->vy) * (state->count + 1));
354 state->px = (float *) malloc (sizeof (*state->px) * (state->count + 1));
355 state->py = (float *) malloc (sizeof (*state->py) * (state->count + 1));
356 state->opx = (float *) malloc (sizeof (*state->opx) * (state->count + 1));
357 state->opy = (float *) malloc (sizeof (*state->opy) * (state->count + 1));
359 for (i=1; i<=state->count; i++)
361 state->px[i] = frand(extx) + state->xmin;
362 state->py[i] = frand(exty) + state->ymin;
363 state->vx[i] = frand(0.2) - 0.1;
364 state->vy[i] = frand(0.2) - 0.1;
366 state->r[i] = (state->random_sizes_p
367 ? ((0.2 + frand(0.8)) * state->max_radius)
368 : state->max_radius);
369 /*state->r[i] = pow(frand(1.0), state->sizegamma) * state->max_radius;*/
371 /* state->m[i] = pow(state->r[i],2) * M_PI; */
372 state->m[i] = pow(state->r[i],3) * M_PI * 1.3333;
375 memcpy (state->opx, state->px, sizeof (*state->opx) * (state->count + 1));
376 memcpy (state->opy, state->py, sizeof (*state->opx) * (state->count + 1));
382 /* Messes with gravity: permute "down" to be in a random direction.
385 shake (b_state *state)
387 float a = state->accx;
388 float b = state->accy;
389 int i = random() % 4;
414 state->time_since_shake = 0;
419 /* Look at the current time, and update state->time_since_shake.
420 Draw the FPS display if desired.
423 check_wall_clock (b_state *state, float max_d)
425 state->frame_count++;
427 if (state->time_tick++ > 20) /* don't call gettimeofday() too often -- it's slow. */
430 # ifdef GETTIMEOFDAY_TWO_ARGS
432 gettimeofday(&now, &tzp);
437 if (state->last_time.tv_sec == 0)
438 state->last_time = now;
440 state->time_tick = 0;
441 if (now.tv_sec == state->last_time.tv_sec)
444 state->time_since_shake += (now.tv_sec - state->last_time.tv_sec);
448 float elapsed = ((now.tv_sec + (now.tv_usec / 1000000.0)) -
449 (state->last_time.tv_sec + (state->last_time.tv_usec / 1000000.0)));
450 float fps = state->frame_count / elapsed;
451 float cps = state->collision_count / elapsed;
453 sprintf (state->fps_str, "Collisions: %.3f/frame Max motion: %.3f",
456 draw_fps_string(state);
459 state->frame_count = 0;
460 state->collision_count = 0;
461 state->last_time = now;
465 /* Erases the balls at their previous positions, and draws the new ones.
468 repaint_balls (b_state *state)
471 int x1a, x2a, y1a, y2a;
472 int x1b, x2b, y1b, y2b;
475 #ifdef HAVE_COCOA /* Don't second-guess Quartz's double-buffering */
476 XClearWindow (state->dpy, state->b);
479 for (a=1; a <= state->count; a++)
482 x1a = (state->opx[a] - state->r[a] - state->xmin);
483 y1a = (state->opy[a] - state->r[a] - state->ymin);
484 x2a = (state->opx[a] + state->r[a] - state->xmin);
485 y2a = (state->opy[a] + state->r[a] - state->ymin);
487 x1b = (state->px[a] - state->r[a] - state->xmin);
488 y1b = (state->py[a] - state->r[a] - state->ymin);
489 x2b = (state->px[a] + state->r[a] - state->xmin);
490 y2b = (state->py[a] + state->r[a] - state->ymin);
492 #ifndef HAVE_COCOA /* Don't second-guess Quartz's double-buffering */
493 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
494 if (!state->dbeclear_p || !state->backb)
495 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
497 /* if (x1a != x1b || y1a != y1b) -- leaves turds if we optimize this */
499 gc = state->erase_gc;
500 XFillArc (state->dpy, state->b, gc,
501 x1a, y1a, x2a-x1a, y2a-y1a,
505 #endif /* !HAVE_COCOA */
507 if (state->mouse_ball == a)
508 gc = state->draw_gc2;
512 XFillArc (state->dpy, state->b, gc,
513 x1b, y1b, x2b-x1b, y2b-y1b,
518 /* distance this ball moved this frame */
519 float d = ((state->px[a] - state->opx[a]) *
520 (state->px[a] - state->opx[a]) +
521 (state->py[a] - state->opy[a]) *
522 (state->py[a] - state->opy[a]));
523 if (d > max_d) max_d = d;
526 state->opx[a] = state->px[a];
527 state->opy[a] = state->py[a];
531 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
532 && (state->backb ? state->dbeclear_p : 1)
533 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
535 draw_fps_string(state);
537 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
540 XdbeSwapInfo info[1];
541 info[0].swap_window = state->window;
542 info[0].swap_action = (state->dbeclear_p ? XdbeBackground : XdbeUndefined);
543 XdbeSwapBuffers (state->dpy, info, 1);
546 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
549 XCopyArea (state->dpy, state->b, state->window, state->erase_gc,
550 0, 0, state->xgwa.width, state->xgwa.height, 0, 0);
553 if (state->shake_p && state->time_since_shake > 5)
555 max_d /= state->max_radius;
556 if (max_d < state->shake_threshold || /* when its stable */
557 state->time_since_shake > 30) /* or when 30 secs has passed */
563 check_wall_clock (state, max_d);
567 /* Implements the laws of physics: move balls to their new positions.
570 update_balls (b_state *state)
573 float d, vxa, vya, vxb, vyb, dd, cdx, cdy;
574 float ma, mb, vca, vcb, dva, dvb;
577 check_window_moved (state);
579 /* If we're currently tracking the mouse, update that ball first.
581 if (state->mouse_ball != 0)
583 int mouse_x, mouse_y;
584 query_mouse (state, &mouse_x, &mouse_y);
585 state->px[state->mouse_ball] = mouse_x;
586 state->py[state->mouse_ball] = mouse_y;
587 state->vx[state->mouse_ball] =
589 (state->px[state->mouse_ball] - state->opx[state->mouse_ball]) *
591 state->vy[state->mouse_ball] =
593 (state->py[state->mouse_ball] - state->opy[state->mouse_ball]) *
597 /* For each ball, compute the influence of every other ball. */
598 for (a=1; a <= state->count - 1; a++)
599 for (b=a + 1; b <= state->count; b++)
601 d = ((state->px[a] - state->px[b]) *
602 (state->px[a] - state->px[b]) +
603 (state->py[a] - state->py[b]) *
604 (state->py[a] - state->py[b]));
605 dee2 = (state->r[a] + state->r[b]) *
606 (state->r[a] + state->r[b]);
609 state->collision_count++;
611 dd = state->r[a] + state->r[b] - d;
613 cdx = (state->px[b] - state->px[a]) / d;
614 cdy = (state->py[b] - state->py[a]) / d;
616 /* Move each ball apart from the other by half the
617 * 'collision' distance.
619 state->px[a] -= 0.5 * dd * cdx;
620 state->py[a] -= 0.5 * dd * cdy;
621 state->px[b] += 0.5 * dd * cdx;
622 state->py[b] += 0.5 * dd * cdy;
632 vca = vxa * cdx + vya * cdy; /* the component of each velocity */
633 vcb = vxb * cdx + vyb * cdy; /* along the axis of the collision */
635 /* elastic collison */
636 dva = (vca * (ma - mb) + vcb * 2 * mb) / (ma + mb) - vca;
637 dvb = (vcb * (mb - ma) + vca * 2 * ma) / (ma + mb) - vcb;
639 dva *= state->e; /* some energy lost to inelasticity */
643 dva += (frand (50) - 25) / ma; /* q: why are elves so chaotic? */
644 dvb += (frand (50) - 25) / mb; /* a: brownian motion. */
659 /* Force all balls to be on screen.
661 for (a=1; a <= state->count; a++)
663 if (state->px[a] <= (state->xmin + state->r[a]))
665 state->px[a] = state->xmin + state->r[a];
666 state->vx[a] = -state->vx[a] * state->e;
668 if (state->px[a] >= (state->xmax - state->r[a]))
670 state->px[a] = state->xmax - state->r[a];
671 state->vx[a] = -state->vx[a] * state->e;
673 if (state->py[a] <= (state->ymin + state->r[a]))
675 state->py[a] = state->ymin + state->r[a];
676 state->vy[a] = -state->vy[a] * state->e;
678 if (state->py[a] >= (state->ymax - state->r[a]))
680 state->py[a] = state->ymax - state->r[a];
681 state->vy[a] = -state->vy[a] * state->e;
685 /* Apply gravity to all balls.
687 for (a=1; a <= state->count; a++)
688 if (a != state->mouse_ball)
690 state->vx[a] += state->accx * state->tc;
691 state->vy[a] += state->accy * state->tc;
692 state->px[a] += state->vx[a] * state->tc;
693 state->py[a] += state->vy[a] * state->tc;
698 /* Handle X events, specifically, allow a ball to be picked up with the mouse.
701 fluidballs_event (Display *dpy, Window window, void *closure, XEvent *event)
703 b_state *state = (b_state *) closure;
705 if (event->xany.type == ButtonPress)
708 XTranslateCoordinates (dpy, window, RootWindow (dpy, DefaultScreen(dpy)),
709 event->xbutton.x, event->xbutton.y, &rx, &ry,
712 if (state->mouse_ball != 0) /* second down-click? drop the ball. */
714 state->mouse_ball = 0;
718 for (i=1; i <= state->count; i++)
720 float d = ((state->px[i] - rx) * (state->px[i] - rx) +
721 (state->py[i] - ry) * (state->py[i] - ry));
722 float r = state->r[i];
725 state->mouse_ball = i;
731 else if (event->xany.type == ButtonRelease) /* drop the ball */
733 state->mouse_ball = 0;
741 fluidballs_draw (Display *dpy, Window window, void *closure)
743 b_state *state = (b_state *) closure;
744 repaint_balls(state);
750 fluidballs_reshape (Display *dpy, Window window, void *closure,
751 unsigned int w, unsigned int h)
756 fluidballs_free (Display *dpy, Window window, void *closure)
758 b_state *state = (b_state *) closure;
763 static const char *fluidballs_defaults [] = {
764 ".background: black",
765 ".foreground: yellow",
767 "*mouseForeground: white",
777 "*shakeThreshold: 0.015",
778 "*doubleBuffer: True",
779 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
781 "*useDBEClear: True",
782 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
786 static XrmOptionDescRec fluidballs_options [] = {
787 { "-delay", ".delay", XrmoptionSepArg, 0 },
788 { "-count", ".count", XrmoptionSepArg, 0 },
789 { "-size", ".size", XrmoptionSepArg, 0 },
790 { "-count", ".count", XrmoptionSepArg, 0 },
791 { "-gravity", ".gravity", XrmoptionSepArg, 0 },
792 { "-wind", ".wind", XrmoptionSepArg, 0 },
793 { "-elasticity", ".elasticity", XrmoptionSepArg, 0 },
794 { "-shake", ".shake", XrmoptionNoArg, "True" },
795 { "-no-shake", ".shake", XrmoptionNoArg, "False" },
796 { "-random", ".random", XrmoptionNoArg, "True" },
797 { "-no-random", ".random", XrmoptionNoArg, "False" },
798 { "-nonrandom", ".random", XrmoptionNoArg, "False" },
799 { "-db", ".doubleBuffer", XrmoptionNoArg, "True" },
800 { "-no-db", ".doubleBuffer", XrmoptionNoArg, "False" },
805 XSCREENSAVER_MODULE ("FluidBalls", fluidballs)