+++ /dev/null
-/* xscreensaver, Copyright (c) 1992, 1995, 1996, 1997, 1998
- * Jamie Zawinski <jwz@jwz.org>
- *
- * Permission to use, copy, modify, distribute, and sell this software and its
- * documentation for any purpose is hereby granted without fee, provided that
- * the above copyright notice appear in all copies and that both that
- * copyright notice and this permission notice appear in supporting
- * documentation. No representations are made about the suitability of this
- * software for any purpose. It is provided "as is" without express or
- * implied warranty.
- */
-
-/* Simulation of a pair of quasi-gravitational fields, maybe sorta kinda
- a little like the strong and weak electromagnetic forces. Derived from
- a Lispm screensaver by John Pezaris <pz@mit.edu>. Mouse control and
- viscosity added by "Philip Edward Cutone, III" <pc2d+@andrew.cmu.edu>.
-
- John sez:
-
- The simulation started out as a purely accurate gravitational simulation,
- but, with constant simulation step size, I quickly realized the field being
- simulated while grossly gravitational was, in fact, non-conservative. It
- also had the rather annoying behavior of dealing very badly with colliding
- orbs. Therefore, I implemented a negative-gravity region (with two
- thresholds; as I read your code, you only implemented one) to prevent orbs
- from every coming too close together, and added a viscosity factor if the
- speed of any orb got too fast. This provides a nice stable system with
- interesting behavior.
-
- I had experimented with a number of fields including the van der Waals
- force (very interesting orbiting behavior) and 1/r^3 gravity (not as
- interesting as 1/r^2). An even normal viscosity (rather than the
- thresholded version to bleed excess energy) is also not interesting.
- The 1/r^2, -1/r^2, -10/r^2 thresholds proved not only robust but also
- interesting -- the orbs never collided and the threshold viscosity fixed
- the non-conservational problem.
-
- Philip sez:
- > An even normal viscosity (rather than the thresholded version to
- > bleed excess energy) is also not interesting.
-
- unless you make about 200 points.... set the viscosity to about .8
- and drag the mouse through it. it makes a nice wave which travels
- through the field.
-
- And (always the troublemaker) Joe Keane <jgk@jgk.org> sez:
-
- Despite what John sez, the field being simulated is always conservative.
- The real problem is that it uses a simple hack, computing acceleration
- *based only on the starting position*, instead of a real differential
- equation solver. Thus you'll always have energy coming out of nowhere,
- although it's most blatant when balls get close together. If it were
- done right, you wouldn't need viscosity or artificial limits on how
- close the balls can get.
- */
-
-#include <stdio.h>
-#include <math.h>
-#include "screenhack.h"
-#include "spline.h"
-
-struct ball {
- double x, y;
- double vx, vy;
- double dx, dy;
- double mass;
- int size;
- int pixel_index;
- int hue;
-};
-
-static struct ball *balls;
-static int npoints;
-static int threshold;
-static int delay;
-static int global_size;
-static int segments;
-static Bool glow_p;
-static Bool orbit_p;
-static XPoint *point_stack;
-static int point_stack_size, point_stack_fp;
-static XColor *colors;
-static int ncolors;
-static int fg_index;
-static int color_shift;
-
-/*flip mods for mouse interaction*/
-static Bool mouse_p;
-int mouse_x, mouse_y, mouse_mass, root_x, root_y;
-static double viscosity;
-
-static enum object_mode {
- ball_mode, line_mode, polygon_mode, spline_mode, spline_filled_mode,
- tail_mode
-} mode;
-
-static GC draw_gc, erase_gc;
-
-#define MAX_SIZE 16
-
-#define min(a,b) ((a)<(b)?(a):(b))
-#define max(a,b) ((a)>(b)?(a):(b))
-
-static void
-init_balls (Display *dpy, Window window)
-{
- int i;
- XWindowAttributes xgwa;
- XGCValues gcv;
- int xlim, ylim, midx, midy, r, vx, vy;
- double th;
- Colormap cmap;
- char *mode_str;
- XGetWindowAttributes (dpy, window, &xgwa);
- xlim = xgwa.width;
- ylim = xgwa.height;
- cmap = xgwa.colormap;
- midx = xlim/2;
- midy = ylim/2;
- r = get_integer_resource ("radius", "Integer");
- if (r <= 0 || r > min (xlim/2, ylim/2))
- r = min (xlim/2, ylim/2) - 50;
- vx = get_integer_resource ("vx", "Integer");
- vy = get_integer_resource ("vy", "Integer");
- npoints = get_integer_resource ("points", "Integer");
- if (npoints < 1)
- npoints = 3 + (random () % 5);
- balls = (struct ball *) malloc (npoints * sizeof (struct ball));
- segments = get_integer_resource ("segments", "Integer");
- if (segments < 0) segments = 1;
- threshold = get_integer_resource ("threshold", "Integer");
- if (threshold < 0) threshold = 0;
- delay = get_integer_resource ("delay", "Integer");
- if (delay < 0) delay = 0;
- global_size = get_integer_resource ("size", "Integer");
- if (global_size < 0) global_size = 0;
- glow_p = get_boolean_resource ("glow", "Boolean");
- orbit_p = get_boolean_resource ("orbit", "Boolean");
- color_shift = get_integer_resource ("colorShift", "Integer");
- if (color_shift <= 0) color_shift = 5;
-
- /*flip mods for mouse interaction*/
- mouse_p = get_boolean_resource ("mouse", "Boolean");
- mouse_mass = get_integer_resource ("mouseSize", "Integer");
- mouse_mass = mouse_mass * mouse_mass *10;
-
- viscosity = get_float_resource ("viscosity", "Float");
-
- mode_str = get_string_resource ("mode", "Mode");
- if (! mode_str) mode = ball_mode;
- else if (!strcmp (mode_str, "balls")) mode = ball_mode;
- else if (!strcmp (mode_str, "lines")) mode = line_mode;
- else if (!strcmp (mode_str, "polygons")) mode = polygon_mode;
- else if (!strcmp (mode_str, "tails")) mode = tail_mode;
- else if (!strcmp (mode_str, "splines")) mode = spline_mode;
- else if (!strcmp (mode_str, "filled-splines")) mode = spline_filled_mode;
- else {
- fprintf (stderr,
- "%s: mode must be balls, lines, tails, polygons, splines, or\n\
- filled-splines, not \"%s\"\n",
- progname, mode_str);
- exit (1);
- }
-
- if (mode != ball_mode && mode != tail_mode) glow_p = False;
-
- if (mode == polygon_mode && npoints < 3)
- mode = line_mode;
-
- ncolors = get_integer_resource ("colors", "Colors");
- if (ncolors < 2) ncolors = 2;
- if (ncolors <= 2) mono_p = True;
- colors = 0;
-
- if (!mono_p)
- {
- fg_index = 0;
- switch (mode)
- {
- case ball_mode:
- if (glow_p)
- {
- int H = random() % 360;
- double S1 = 0.25;
- double S2 = 1.00;
- double V = frand(0.25) + 0.75;
- colors = (XColor *) malloc(sizeof(*colors) * (ncolors+1));
- make_color_ramp (dpy, cmap, H, S1, V, H, S2, V, colors, &ncolors,
- False, True, False);
- }
- else
- {
- ncolors = npoints;
- colors = (XColor *) malloc(sizeof(*colors) * (ncolors+1));
- make_random_colormap (dpy, xgwa.visual, cmap, colors, &ncolors,
- True, True, False, True);
- }
- break;
- case line_mode:
- case polygon_mode:
- case spline_mode:
- case spline_filled_mode:
- case tail_mode:
- colors = (XColor *) malloc(sizeof(*colors) * (ncolors+1));
- make_smooth_colormap (dpy, xgwa.visual, cmap, colors, &ncolors,
- True, False, True);
- break;
- default:
- abort ();
- }
- }
-
- if (!mono_p && ncolors <= 2)
- {
- if (colors) free (colors);
- colors = 0;
- mono_p = True;
- }
-
- if (mode != ball_mode)
- {
- int size = (segments ? segments : 1);
- point_stack_size = size * (npoints + 1);
- point_stack = (XPoint *) calloc (point_stack_size, sizeof (XPoint));
- point_stack_fp = 0;
- }
-
- gcv.line_width = (mode == tail_mode
- ? (global_size ? global_size : (MAX_SIZE * 2 / 3))
- : 1);
- gcv.cap_style = (mode == tail_mode ? CapRound : CapButt);
-
- if (mono_p)
- gcv.foreground = get_pixel_resource("foreground", "Foreground", dpy, cmap);
- else
- gcv.foreground = colors[fg_index].pixel;
- draw_gc = XCreateGC (dpy, window, GCForeground|GCLineWidth|GCCapStyle, &gcv);
-
- gcv.foreground = get_pixel_resource("background", "Background", dpy, cmap);
- erase_gc = XCreateGC (dpy, window, GCForeground|GCLineWidth|GCCapStyle,&gcv);
-
-
-#define rand_size() min (MAX_SIZE, 8 + (random () % (MAX_SIZE - 9)))
-
- if (orbit_p && !global_size)
- /* To orbit, all objects must be the same mass, or the math gets
- really hairy... */
- global_size = rand_size ();
-
- th = frand (M_PI+M_PI);
- for (i = 0; i < npoints; i++)
- {
- int new_size = (global_size ? global_size : rand_size ());
- balls [i].dx = 0;
- balls [i].dy = 0;
- balls [i].size = new_size;
- balls [i].mass = (new_size * new_size * 10);
- balls [i].x = midx + r * cos (i * ((M_PI+M_PI) / npoints) + th);
- balls [i].y = midy + r * sin (i * ((M_PI+M_PI) / npoints) + th);
- if (! orbit_p)
- {
- balls [i].vx = vx ? vx : ((6.0 - (random () % 11)) / 8.0);
- balls [i].vy = vy ? vy : ((6.0 - (random () % 11)) / 8.0);
- }
- if (mono_p || mode != ball_mode)
- balls [i].pixel_index = -1;
- else if (glow_p)
- balls [i].pixel_index = 0;
- else
- balls [i].pixel_index = random() % ncolors;
- }
-
- if (orbit_p)
- {
- double a = 0;
- double v;
- double v_mult = get_float_resource ("vMult", "Float");
- if (v_mult == 0.0) v_mult = 1.0;
-
- for (i = 1; i < npoints; i++)
- {
- double _2ipi_n = (2 * i * M_PI / npoints);
- double x = r * cos (_2ipi_n);
- double y = r * sin (_2ipi_n);
- double distx = r - x;
- double dist2 = (distx * distx) + (y * y);
- double dist = sqrt (dist2);
- double a1 = ((balls[i].mass / dist2) *
- ((dist < threshold) ? -1.0 : 1.0) *
- (distx / dist));
- a += a1;
- }
- if (a < 0.0)
- {
- fprintf (stderr, "%s: domain error: forces on balls too great\n",
- progname);
- exit (-1);
- }
- v = sqrt (a * r) * v_mult;
- for (i = 0; i < npoints; i++)
- {
- double k = ((2 * i * M_PI / npoints) + th);
- balls [i].vx = -v * sin (k);
- balls [i].vy = v * cos (k);
- }
- }
-
- if (mono_p) glow_p = False;
- XClearWindow (dpy, window);
-}
-
-static void
-compute_force (int i, double *dx_ret, double *dy_ret)
-{
- int j;
- double x_dist, y_dist, dist, dist2;
- *dx_ret = 0;
- *dy_ret = 0;
- for (j = 0; j < npoints; j++)
- {
- if (i == j) continue;
- x_dist = balls [j].x - balls [i].x;
- y_dist = balls [j].y - balls [i].y;
- dist2 = (x_dist * x_dist) + (y_dist * y_dist);
- dist = sqrt (dist2);
-
- if (dist > 0.1) /* the balls are not overlapping */
- {
- double new_acc = ((balls[j].mass / dist2) *
- ((dist < threshold) ? -1.0 : 1.0));
- double new_acc_dist = new_acc / dist;
- *dx_ret += new_acc_dist * x_dist;
- *dy_ret += new_acc_dist * y_dist;
- }
- else
- { /* the balls are overlapping; move randomly */
- *dx_ret += (frand (10.0) - 5.0);
- *dy_ret += (frand (10.0) - 5.0);
- }
- }
-
- if (mouse_p)
- {
- x_dist = mouse_x - balls [i].x;
- y_dist = mouse_y - balls [i].y;
- dist2 = (x_dist * x_dist) + (y_dist * y_dist);
- dist = sqrt (dist2);
-
- if (dist > 0.1) /* the balls are not overlapping */
- {
- double new_acc = ((mouse_mass / dist2) *
- ((dist < threshold) ? -1.0 : 1.0));
- double new_acc_dist = new_acc / dist;
- *dx_ret += new_acc_dist * x_dist;
- *dy_ret += new_acc_dist * y_dist;
- }
- else
- { /* the balls are overlapping; move randomly */
- *dx_ret += (frand (10.0) - 5.0);
- *dy_ret += (frand (10.0) - 5.0);
- }
- }
-}
-
-static void
-run_balls (Display *dpy, Window window)
-{
- int last_point_stack_fp = point_stack_fp;
- static int tick = 500, xlim, ylim;
- static Colormap cmap;
- int i;
-
- /*flip mods for mouse interaction*/
- Window root1, child1;
- unsigned int mask;
- if (mouse_p)
- {
- XQueryPointer(dpy, window, &root1, &child1,
- &root_x, &root_y, &mouse_x, &mouse_y, &mask);
- }
-
- if (tick++ == 500)
- {
- XWindowAttributes xgwa;
- XGetWindowAttributes (dpy, window, &xgwa);
- tick = 0;
- xlim = xgwa.width;
- ylim = xgwa.height;
- cmap = xgwa.colormap;
- }
-
- /* compute the force of attraction/repulsion among all balls */
- for (i = 0; i < npoints; i++)
- compute_force (i, &balls[i].dx, &balls[i].dy);
-
- /* move the balls according to the forces now in effect */
- for (i = 0; i < npoints; i++)
- {
- double old_x = balls[i].x;
- double old_y = balls[i].y;
- double new_x, new_y;
- int size = balls[i].size;
- balls[i].vx += balls[i].dx;
- balls[i].vy += balls[i].dy;
-
- /* don't let them get too fast: impose a terminal velocity
- (actually, make the medium have friction) */
- if (balls[i].vx > 10)
- {
- balls[i].vx *= 0.9;
- balls[i].dx = 0;
- }
- else if (viscosity != 1)
- {
- balls[i].vx *= viscosity;
- }
-
- if (balls[i].vy > 10)
- {
- balls[i].vy *= 0.9;
- balls[i].dy = 0;
- }
- else if (viscosity != 1)
- {
- balls[i].vy *= viscosity;
- }
-
- balls[i].x += balls[i].vx;
- balls[i].y += balls[i].vy;
-
- /* bounce off the walls */
- if (balls[i].x >= (xlim - balls[i].size))
- {
- balls[i].x = (xlim - balls[i].size - 1);
- if (balls[i].vx > 0)
- balls[i].vx = -balls[i].vx;
- }
- if (balls[i].y >= (ylim - balls[i].size))
- {
- balls[i].y = (ylim - balls[i].size - 1);
- if (balls[i].vy > 0)
- balls[i].vy = -balls[i].vy;
- }
- if (balls[i].x <= 0)
- {
- balls[i].x = 0;
- if (balls[i].vx < 0)
- balls[i].vx = -balls[i].vx;
- }
- if (balls[i].y <= 0)
- {
- balls[i].y = 0;
- if (balls[i].vy < 0)
- balls[i].vy = -balls[i].vy;
- }
-
- new_x = balls[i].x;
- new_y = balls[i].y;
-
- if (!mono_p)
- {
- if (mode == ball_mode)
- {
- if (glow_p)
- {
- /* make color saturation be related to particle
- acceleration. */
- double limit = 0.5;
- double s, fraction;
- double vx = balls [i].dx;
- double vy = balls [i].dy;
- if (vx < 0) vx = -vx;
- if (vy < 0) vy = -vy;
- fraction = vx + vy;
- if (fraction > limit) fraction = limit;
-
- s = 1 - (fraction / limit);
- balls[i].pixel_index = (ncolors * s);
- }
- XSetForeground (dpy, draw_gc,
- colors[balls[i].pixel_index].pixel);
- }
- }
-
- if (mode == ball_mode)
- {
- XFillArc (dpy, window, erase_gc, (int) old_x, (int) old_y,
- size, size, 0, 360*64);
- XFillArc (dpy, window, draw_gc, (int) new_x, (int) new_y,
- size, size, 0, 360*64);
- }
- else
- {
- point_stack [point_stack_fp].x = new_x;
- point_stack [point_stack_fp].y = new_y;
- point_stack_fp++;
- }
- }
-
- /* draw the lines or polygons after computing all points */
- if (mode != ball_mode)
- {
- point_stack [point_stack_fp].x = balls [0].x; /* close the polygon */
- point_stack [point_stack_fp].y = balls [0].y;
- point_stack_fp++;
- if (point_stack_fp == point_stack_size)
- point_stack_fp = 0;
- else if (point_stack_fp > point_stack_size) /* better be aligned */
- abort ();
- if (!mono_p)
- {
- static int tick = 0;
- if (tick++ == color_shift)
- {
- tick = 0;
- fg_index = (fg_index + 1) % ncolors;
- XSetForeground (dpy, draw_gc, colors[fg_index].pixel);
- }
- }
- }
-
- switch (mode)
- {
- case ball_mode:
- break;
- case line_mode:
- if (segments > 0)
- XDrawLines (dpy, window, erase_gc, point_stack + point_stack_fp,
- npoints + 1, CoordModeOrigin);
- XDrawLines (dpy, window, draw_gc, point_stack + last_point_stack_fp,
- npoints + 1, CoordModeOrigin);
- break;
- case polygon_mode:
- if (segments > 0)
- XFillPolygon (dpy, window, erase_gc, point_stack + point_stack_fp,
- npoints + 1, (npoints == 3 ? Convex : Complex),
- CoordModeOrigin);
- XFillPolygon (dpy, window, draw_gc, point_stack + last_point_stack_fp,
- npoints + 1, (npoints == 3 ? Convex : Complex),
- CoordModeOrigin);
- break;
- case tail_mode:
- {
- for (i = 0; i < npoints; i++)
- {
- int index = point_stack_fp + i;
- int next_index = (index + (npoints + 1)) % point_stack_size;
- XDrawLine (dpy, window, erase_gc,
- point_stack [index].x,
- point_stack [index].y,
- point_stack [next_index].x,
- point_stack [next_index].y);
-
- index = last_point_stack_fp + i;
- next_index = (index - (npoints + 1)) % point_stack_size;
- if (next_index < 0) next_index += point_stack_size;
- if (point_stack [next_index].x == 0 &&
- point_stack [next_index].y == 0)
- continue;
- XDrawLine (dpy, window, draw_gc,
- point_stack [index].x,
- point_stack [index].y,
- point_stack [next_index].x,
- point_stack [next_index].y);
- }
- }
- break;
- case spline_mode:
- case spline_filled_mode:
- {
- static spline *s = 0;
- if (! s) s = make_spline (npoints);
- if (segments > 0)
- {
- for (i = 0; i < npoints; i++)
- {
- s->control_x [i] = point_stack [point_stack_fp + i].x;
- s->control_y [i] = point_stack [point_stack_fp + i].y;
- }
- compute_closed_spline (s);
- if (mode == spline_filled_mode)
- XFillPolygon (dpy, window, erase_gc, s->points, s->n_points,
- (s->n_points == 3 ? Convex : Complex),
- CoordModeOrigin);
- else
- XDrawLines (dpy, window, erase_gc, s->points, s->n_points,
- CoordModeOrigin);
- }
- for (i = 0; i < npoints; i++)
- {
- s->control_x [i] = point_stack [last_point_stack_fp + i].x;
- s->control_y [i] = point_stack [last_point_stack_fp + i].y;
- }
- compute_closed_spline (s);
- if (mode == spline_filled_mode)
- XFillPolygon (dpy, window, draw_gc, s->points, s->n_points,
- (s->n_points == 3 ? Convex : Complex),
- CoordModeOrigin);
- else
- XDrawLines (dpy, window, draw_gc, s->points, s->n_points,
- CoordModeOrigin);
- }
- break;
- default:
- abort ();
- }
-
- XSync (dpy, False);
-}
-
-\f
-char *progclass = "Attraction";
-
-char *defaults [] = {
- ".background: black",
- ".foreground: white",
- "*mode: balls",
- "*points: 0",
- "*size: 0",
- "*colors: 200",
- "*threshold: 100",
- "*delay: 10000",
- "*glow: false",
- "*mouseSize: 10",
- "*mouse: false",
- "*viscosity: 1",
- "*orbit: false",
- "*colorShift: 3",
- "*segments: 500",
- "*vMult: 0.9",
- 0
-};
-
-XrmOptionDescRec options [] = {
- { "-mode", ".mode", XrmoptionSepArg, 0 },
- { "-colors", ".colors", XrmoptionSepArg, 0 },
- { "-points", ".points", XrmoptionSepArg, 0 },
- { "-color-shift", ".colorShift", XrmoptionSepArg, 0 },
- { "-threshold", ".threshold", XrmoptionSepArg, 0 },
- { "-segments", ".segments", XrmoptionSepArg, 0 },
- { "-delay", ".delay", XrmoptionSepArg, 0 },
- { "-size", ".size", XrmoptionSepArg, 0 },
- { "-radius", ".radius", XrmoptionSepArg, 0 },
- { "-vx", ".vx", XrmoptionSepArg, 0 },
- { "-vy", ".vy", XrmoptionSepArg, 0 },
- { "-vmult", ".vMult", XrmoptionSepArg, 0 },
- { "-mouse-size", ".mouseSize", XrmoptionSepArg, 0 },
- { "-mouse", ".mouse", XrmoptionNoArg, "true" },
- { "-nomouse", ".mouse", XrmoptionNoArg, "false" },
- { "-viscosity", ".viscosity", XrmoptionSepArg, 0 },
- { "-glow", ".glow", XrmoptionNoArg, "true" },
- { "-noglow", ".glow", XrmoptionNoArg, "false" },
- { "-orbit", ".orbit", XrmoptionNoArg, "true" },
- { 0, 0, 0, 0 }
-};
-
-void
-screenhack (Display *dpy, Window window)
-{
- init_balls (dpy, window);
- while (1)
- {
- run_balls (dpy, window);
- screenhack_handle_events (dpy);
- if (delay) usleep (delay);
- }
-}
projects / xscreensaver / blobdiff