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_JWXYZ /* 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 if (state->xgwa.width < 100 || state->xgwa.height < 100) /* tiny window */
301 if (state->max_radius > 5)
302 state->max_radius = 5;
305 state->random_sizes_p = get_boolean_resource (dpy, "random", "Random");
307 /* If the initial window size is too small to hold all these balls,
308 make fewer of them...
311 float r = (state->random_sizes_p
312 ? state->max_radius * 0.7
313 : state->max_radius);
314 float ball_area = M_PI * r * r;
315 float balls_area = state->count * ball_area;
316 float window_area = state->xgwa.width * state->xgwa.height;
317 window_area *= 0.75; /* don't pack it completely full */
318 if (balls_area > window_area)
319 state->count = window_area / ball_area;
322 state->accx = get_float_resource (dpy, "wind", "Wind");
323 if (state->accx < -1.0 || state->accx > 1.0) state->accx = 0;
325 state->accy = get_float_resource (dpy, "gravity", "Gravity");
326 if (state->accy < -1.0 || state->accy > 1.0) state->accy = 0.01;
328 state->e = get_float_resource (dpy, "elasticity", "Elacitcity");
329 if (state->e < 0.2 || state->e > 1.0) state->e = 0.97;
331 state->tc = get_float_resource (dpy, "timeScale", "TimeScale");
332 if (state->tc <= 0 || state->tc > 10) state->tc = 1.0;
334 state->shake_p = get_boolean_resource (dpy, "shake", "Shake");
335 state->shake_threshold = get_float_resource (dpy, "shakeThreshold",
337 state->time_tick = 999999;
339 # ifdef HAVE_MOBILE /* Always obey real-world gravity */
340 state->shake_p = False;
344 state->fps_p = get_boolean_resource (dpy, "doFPS", "DoFPS");
348 char *fontname = get_string_resource (dpy, "fpsFont", "Font");
349 if (!fontname) fontname = "-*-courier-bold-r-normal-*-180-*";
350 font = XLoadQueryFont (dpy, fontname);
351 if (!font) font = XLoadQueryFont (dpy, "fixed");
353 gcv.font = font->fid;
354 gcv.foreground = get_pixel_resource(state->dpy, state->xgwa.colormap,
355 "textColor", "Foreground");
356 state->font_gc = XCreateGC(dpy, state->b,
357 GCFont|GCForeground|GCBackground, &gcv);
358 state->font_height = font->ascent + font->descent;
359 state->font_baseline = font->descent;
362 state->m = (float *) malloc (sizeof (*state->m) * (state->count + 1));
363 state->r = (float *) malloc (sizeof (*state->r) * (state->count + 1));
364 state->vx = (float *) malloc (sizeof (*state->vx) * (state->count + 1));
365 state->vy = (float *) malloc (sizeof (*state->vy) * (state->count + 1));
366 state->px = (float *) malloc (sizeof (*state->px) * (state->count + 1));
367 state->py = (float *) malloc (sizeof (*state->py) * (state->count + 1));
368 state->opx = (float *) malloc (sizeof (*state->opx) * (state->count + 1));
369 state->opy = (float *) malloc (sizeof (*state->opy) * (state->count + 1));
371 for (i=1; i<=state->count; i++)
373 state->px[i] = frand(extx) + state->xmin;
374 state->py[i] = frand(exty) + state->ymin;
375 state->vx[i] = frand(0.2) - 0.1;
376 state->vy[i] = frand(0.2) - 0.1;
378 state->r[i] = (state->random_sizes_p
379 ? ((0.2 + frand(0.8)) * state->max_radius)
380 : state->max_radius);
381 /*state->r[i] = pow(frand(1.0), state->sizegamma) * state->max_radius;*/
383 /* state->m[i] = pow(state->r[i],2) * M_PI; */
384 state->m[i] = pow(state->r[i],3) * M_PI * 1.3333;
387 memcpy (state->opx, state->px, sizeof (*state->opx) * (state->count + 1));
388 memcpy (state->opy, state->py, sizeof (*state->opx) * (state->count + 1));
394 /* Messes with gravity: permute "down" to be in a random direction.
397 shake (b_state *state)
399 float a = state->accx;
400 float b = state->accy;
401 int i = random() % 4;
426 state->time_since_shake = 0;
431 /* Look at the current time, and update state->time_since_shake.
432 Draw the FPS display if desired.
435 check_wall_clock (b_state *state, float max_d)
437 state->frame_count++;
439 if (state->time_tick++ > 20) /* don't call gettimeofday() too often -- it's slow. */
442 # ifdef GETTIMEOFDAY_TWO_ARGS
444 gettimeofday(&now, &tzp);
449 if (state->last_time.tv_sec == 0)
450 state->last_time = now;
452 state->time_tick = 0;
453 if (now.tv_sec == state->last_time.tv_sec)
456 state->time_since_shake += (now.tv_sec - state->last_time.tv_sec);
458 # ifdef HAVE_MOBILE /* Always obey real-world gravity */
460 float a = fabs (fabs(state->accx) > fabs(state->accy)
461 ? state->accx : state->accy);
462 int rot = current_device_rotation();
464 case 0: case 360: state->accx = 0; state->accy = a; break;
465 case -90: state->accx = -a; state->accy = 0; break;
466 case 90: state->accx = a; state->accy = 0; break;
467 case 180: case -180: state->accx = 0; state->accy = -a; break;
471 # endif /* HAVE_MOBILE */
475 float elapsed = ((now.tv_sec + (now.tv_usec / 1000000.0)) -
476 (state->last_time.tv_sec + (state->last_time.tv_usec / 1000000.0)));
477 float fps = state->frame_count / elapsed;
478 float cps = state->collision_count / elapsed;
480 sprintf (state->fps_str, "Collisions: %.3f/frame Max motion: %.3f",
483 draw_fps_string(state);
486 state->frame_count = 0;
487 state->collision_count = 0;
488 state->last_time = now;
492 /* Erases the balls at their previous positions, and draws the new ones.
495 repaint_balls (b_state *state)
499 int x1a, x2a, y1a, y2a;
501 int x1b, x2b, y1b, y2b;
504 #ifdef HAVE_JWXYZ /* Don't second-guess Quartz's double-buffering */
505 XClearWindow (state->dpy, state->b);
508 for (a=1; a <= state->count; a++)
512 x1a = (state->opx[a] - state->r[a] - state->xmin);
513 y1a = (state->opy[a] - state->r[a] - state->ymin);
514 x2a = (state->opx[a] + state->r[a] - state->xmin);
515 y2a = (state->opy[a] + state->r[a] - state->ymin);
518 x1b = (state->px[a] - state->r[a] - state->xmin);
519 y1b = (state->py[a] - state->r[a] - state->ymin);
520 x2b = (state->px[a] + state->r[a] - state->xmin);
521 y2b = (state->py[a] + state->r[a] - state->ymin);
523 #ifndef HAVE_JWXYZ /* Don't second-guess Quartz's double-buffering */
524 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
525 if (!state->dbeclear_p || !state->backb)
526 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
528 /* if (x1a != x1b || y1a != y1b) -- leaves turds if we optimize this */
530 gc = state->erase_gc;
531 XFillArc (state->dpy, state->b, gc,
532 x1a, y1a, x2a-x1a, y2a-y1a,
536 #endif /* !HAVE_JWXYZ */
538 if (state->mouse_ball == a)
539 gc = state->draw_gc2;
543 XFillArc (state->dpy, state->b, gc,
544 x1b, y1b, x2b-x1b, y2b-y1b,
549 /* distance this ball moved this frame */
550 float d = ((state->px[a] - state->opx[a]) *
551 (state->px[a] - state->opx[a]) +
552 (state->py[a] - state->opy[a]) *
553 (state->py[a] - state->opy[a]));
554 if (d > max_d) max_d = d;
557 state->opx[a] = state->px[a];
558 state->opy[a] = state->py[a];
562 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
563 && (state->backb ? state->dbeclear_p : 1)
564 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
566 draw_fps_string(state);
568 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
571 XdbeSwapInfo info[1];
572 info[0].swap_window = state->window;
573 info[0].swap_action = (state->dbeclear_p ? XdbeBackground : XdbeUndefined);
574 XdbeSwapBuffers (state->dpy, info, 1);
577 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
580 XCopyArea (state->dpy, state->b, state->window, state->erase_gc,
581 0, 0, state->xgwa.width, state->xgwa.height, 0, 0);
584 if (state->shake_p && state->time_since_shake > 5)
586 max_d /= state->max_radius;
587 if (max_d < state->shake_threshold || /* when its stable */
588 state->time_since_shake > 30) /* or when 30 secs has passed */
594 check_wall_clock (state, max_d);
598 /* Implements the laws of physics: move balls to their new positions.
601 update_balls (b_state *state)
604 float d, vxa, vya, vxb, vyb, dd, cdx, cdy;
605 float ma, mb, vca, vcb, dva, dvb;
608 check_window_moved (state);
610 /* If we're currently tracking the mouse, update that ball first.
612 if (state->mouse_ball != 0)
614 int mouse_x, mouse_y;
615 query_mouse (state, &mouse_x, &mouse_y);
616 state->px[state->mouse_ball] = mouse_x;
617 state->py[state->mouse_ball] = mouse_y;
618 state->vx[state->mouse_ball] =
620 (state->px[state->mouse_ball] - state->opx[state->mouse_ball]) *
622 state->vy[state->mouse_ball] =
624 (state->py[state->mouse_ball] - state->opy[state->mouse_ball]) *
628 /* For each ball, compute the influence of every other ball. */
629 for (a=1; a <= state->count - 1; a++)
630 for (b=a + 1; b <= state->count; b++)
632 d = ((state->px[a] - state->px[b]) *
633 (state->px[a] - state->px[b]) +
634 (state->py[a] - state->py[b]) *
635 (state->py[a] - state->py[b]));
636 dee2 = (state->r[a] + state->r[b]) *
637 (state->r[a] + state->r[b]);
640 state->collision_count++;
642 dd = state->r[a] + state->r[b] - d;
644 cdx = (state->px[b] - state->px[a]) / d;
645 cdy = (state->py[b] - state->py[a]) / d;
647 /* Move each ball apart from the other by half the
648 * 'collision' distance.
650 state->px[a] -= 0.5 * dd * cdx;
651 state->py[a] -= 0.5 * dd * cdy;
652 state->px[b] += 0.5 * dd * cdx;
653 state->py[b] += 0.5 * dd * cdy;
663 vca = vxa * cdx + vya * cdy; /* the component of each velocity */
664 vcb = vxb * cdx + vyb * cdy; /* along the axis of the collision */
666 /* elastic collison */
667 dva = (vca * (ma - mb) + vcb * 2 * mb) / (ma + mb) - vca;
668 dvb = (vcb * (mb - ma) + vca * 2 * ma) / (ma + mb) - vcb;
670 dva *= state->e; /* some energy lost to inelasticity */
674 dva += (frand (50) - 25) / ma; /* q: why are elves so chaotic? */
675 dvb += (frand (50) - 25) / mb; /* a: brownian motion. */
690 /* Force all balls to be on screen.
692 for (a=1; a <= state->count; a++)
694 if (state->px[a] <= (state->xmin + state->r[a]))
696 state->px[a] = state->xmin + state->r[a];
697 state->vx[a] = -state->vx[a] * state->e;
699 if (state->px[a] >= (state->xmax - state->r[a]))
701 state->px[a] = state->xmax - state->r[a];
702 state->vx[a] = -state->vx[a] * state->e;
704 if (state->py[a] <= (state->ymin + state->r[a]))
706 state->py[a] = state->ymin + state->r[a];
707 state->vy[a] = -state->vy[a] * state->e;
709 if (state->py[a] >= (state->ymax - state->r[a]))
711 state->py[a] = state->ymax - state->r[a];
712 state->vy[a] = -state->vy[a] * state->e;
716 /* Apply gravity to all balls.
718 for (a=1; a <= state->count; a++)
719 if (a != state->mouse_ball)
721 state->vx[a] += state->accx * state->tc;
722 state->vy[a] += state->accy * state->tc;
723 state->px[a] += state->vx[a] * state->tc;
724 state->py[a] += state->vy[a] * state->tc;
729 /* Handle X events, specifically, allow a ball to be picked up with the mouse.
732 fluidballs_event (Display *dpy, Window window, void *closure, XEvent *event)
734 b_state *state = (b_state *) closure;
736 if (event->xany.type == ButtonPress)
739 XTranslateCoordinates (dpy, window, RootWindow (dpy, DefaultScreen(dpy)),
740 event->xbutton.x, event->xbutton.y, &rx, &ry,
743 if (state->mouse_ball != 0) /* second down-click? drop the ball. */
745 state->mouse_ball = 0;
750 /* When trying to pick up a ball, first look for a click directly
751 inside the ball; but if we don't find it, expand the radius
752 outward until we find something nearby.
754 float max = state->max_radius * 4;
755 float step = max / 10;
757 for (r2 = step; r2 < max; r2 += step) {
758 for (i = 1; i <= state->count; i++)
760 float d = ((state->px[i] - rx) * (state->px[i] - rx) +
761 (state->py[i] - ry) * (state->py[i] - ry));
762 float r = state->r[i];
766 state->mouse_ball = i;
774 else if (event->xany.type == ButtonRelease) /* drop the ball */
776 state->mouse_ball = 0;
784 fluidballs_draw (Display *dpy, Window window, void *closure)
786 b_state *state = (b_state *) closure;
787 repaint_balls(state);
793 fluidballs_reshape (Display *dpy, Window window, void *closure,
794 unsigned int w, unsigned int h)
799 fluidballs_free (Display *dpy, Window window, void *closure)
801 b_state *state = (b_state *) closure;
806 static const char *fluidballs_defaults [] = {
807 ".background: black",
808 ".foreground: yellow",
809 ".textColor: yellow",
810 "*mouseForeground: white",
820 "*shakeThreshold: 0.015",
821 "*doubleBuffer: True",
822 #ifdef HAVE_DOUBLE_BUFFER_EXTENSION
824 "*useDBEClear: True",
825 #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
827 "*ignoreRotation: True",
832 static XrmOptionDescRec fluidballs_options [] = {
833 { "-delay", ".delay", XrmoptionSepArg, 0 },
834 { "-count", ".count", XrmoptionSepArg, 0 },
835 { "-size", ".size", XrmoptionSepArg, 0 },
836 { "-count", ".count", XrmoptionSepArg, 0 },
837 { "-gravity", ".gravity", XrmoptionSepArg, 0 },
838 { "-wind", ".wind", XrmoptionSepArg, 0 },
839 { "-elasticity", ".elasticity", XrmoptionSepArg, 0 },
840 { "-shake", ".shake", XrmoptionNoArg, "True" },
841 { "-no-shake", ".shake", XrmoptionNoArg, "False" },
842 { "-random", ".random", XrmoptionNoArg, "True" },
843 { "-no-random", ".random", XrmoptionNoArg, "False" },
844 { "-nonrandom", ".random", XrmoptionNoArg, "False" },
845 { "-db", ".doubleBuffer", XrmoptionNoArg, "True" },
846 { "-no-db", ".doubleBuffer", XrmoptionNoArg, "False" },
851 XSCREENSAVER_MODULE ("FluidBalls", fluidballs)