/* -*- Mode: C; tab-width: 4 -*- */
/* grav --- planets spinning around a pulsar */
#if 0
static const char sccsid[] = "@(#)grav.c 5.00 2000/11/01 xlockmore";
#endif
/*-
* Copyright (c) 1993 by Greg Boewring <gb@pobox.com>
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appear in all copies and that
* both that copyright notice and this permission notice appear in
* supporting documentation.
*
* This file is provided AS IS with no warranties of any kind. The author
* shall have no liability with respect to the infringement of copyrights,
* trade secrets or any patents by this file or any part thereof. In no
* event will the author be liable for any lost revenue or profits or
* other special, indirect and consequential damages.
*
* Revision History:
* 01-Nov-2000: Allocation checks
* 10-May-1997: Compatible with xscreensaver
* 11-Jul-1994: color version
* 06-Oct-1993: Written by Greg Bowering <gb@pobox.com>
*/
#ifdef STANDALONE
#define MODE_grav
#define DEFAULTS "*delay: 10000 \n" \
"*count: 12 \n" \
"*ncolors: 64 \n" \
"*fpsSolid: true \n" \
"*ignoreRotation: True \n" \
"*lowrez: True \n" \
#define BRIGHT_COLORS
# define release_grav 0
# define grav_handle_event 0
# include "xlockmore.h" /* in xscreensaver distribution */
#else /* STANDALONE */
# include "xlock.h" /* in xlockmore distribution */
#endif /* STANDALONE */
#ifdef MODE_grav
#define DEF_DECAY "True" /* Damping for decaying orbits */
#define DEF_TRAIL "True" /* For trails (works good in mono only) */
static Bool decay;
static Bool trail;
static XrmOptionDescRec opts[] =
{
{"-decay", ".grav.decay", XrmoptionNoArg, "on"},
{"+decay", ".grav.decay", XrmoptionNoArg, "off"},
{"-trail", ".grav.trail", XrmoptionNoArg, "on"},
{"+trail", ".grav.trail", XrmoptionNoArg, "off"}
};
static argtype vars[] =
{
{&decay, "decay", "Decay", DEF_DECAY, t_Bool},
{&trail, "trail", "Trail", DEF_TRAIL, t_Bool}
};
static OptionStruct desc[] =
{
{"-/+decay", "turn on/off decaying orbits"},
{"-/+trail", "turn on/off trail dots"}
};
ENTRYPOINT ModeSpecOpt grav_opts =
{sizeof opts / sizeof opts[0], opts, sizeof vars / sizeof vars[0], vars, desc};
#ifdef USE_MODULES
ModStruct grav_description =
{"grav", "init_grav", "draw_grav", (char *) NULL,
"refresh_grav", "init_grav", "free_grav", &grav_opts,
10000, -12, 1, 1, 64, 1.0, "",
"Shows orbiting planets", 0, NULL};
#endif
#define GRAV -0.02 /* Gravitational constant */
#define DIST 16.0
#define COLLIDE 0.0001
#define ALMOST 15.99
#define HALF 0.5
/* #define INTRINSIC_RADIUS 200.0 */
#define INTRINSIC_RADIUS ((float) (gp->height/5))
#define STARRADIUS (unsigned int)(gp->height/(2*DIST))
#define AVG_RADIUS (INTRINSIC_RADIUS/DIST)
#define RADIUS (unsigned int)(INTRINSIC_RADIUS/(POS(Z)+DIST))
#define XR HALF*ALMOST
#define YR HALF*ALMOST
#define ZR HALF*ALMOST
#define VR 0.04
#define DIMENSIONS 3
#define X 0
#define Y 1
#define Z 2
#define DAMP 0.999999
#define MaxA 0.1 /* Maximum acceleration (w/ damping) */
#define POS(c) planet->P[c]
#define VEL(c) planet->V[c]
#define ACC(c) planet->A[c]
#define Planet(x,y)\
if ((x) >= 0 && (y) >= 0 && (x) <= gp->width && (y) <= gp->height) {\
if (planet->ri < 2)\
XDrawPoint(display, window, gc, (x), (y));\
else\
XFillArc(display, window, gc,\
(x) - planet->ri / 2, (y) - planet->ri / 2, planet->ri, planet->ri,\
0, 23040);\
}
#define FLOATRAND(min,max) ((min)+(LRAND()/MAXRAND)*((max)-(min)))
typedef struct {
double P[DIMENSIONS], V[DIMENSIONS], A[DIMENSIONS];
int xi, yi, ri;
unsigned long colors;
} planetstruct;
typedef struct {
int width, height;
int x, y, sr, nplanets;
unsigned long starcolor;
planetstruct *planets;
} gravstruct;
static gravstruct *gravs = (gravstruct *) NULL;
static void
init_planet(ModeInfo * mi, planetstruct * planet)
{
gravstruct *gp = &gravs[MI_SCREEN(mi)];
# ifdef HAVE_JWXYZ
jwxyz_XSetAntiAliasing (MI_DISPLAY(mi), MI_GC(mi), False);
# endif
if (MI_NPIXELS(mi) > 2)
planet->colors = MI_PIXEL(mi, NRAND(MI_NPIXELS(mi)));
else
planet->colors = MI_WHITE_PIXEL(mi);
/* Initialize positions */
POS(X) = FLOATRAND(-XR, XR);
POS(Y) = FLOATRAND(-YR, YR);
POS(Z) = FLOATRAND(-ZR, ZR);
if (POS(Z) > -ALMOST) {
planet->xi = (int)
((double) gp->width * (HALF + POS(X) / (POS(Z) + DIST)));
planet->yi = (int)
((double) gp->height * (HALF + POS(Y) / (POS(Z) + DIST)));
} else
planet->xi = planet->yi = -1;
planet->ri = RADIUS;
/* Initialize velocities */
VEL(X) = FLOATRAND(-VR, VR);
VEL(Y) = FLOATRAND(-VR, VR);
VEL(Z) = FLOATRAND(-VR, VR);
}
static void
draw_planet(ModeInfo * mi, planetstruct * planet)
{
Display *display = MI_DISPLAY(mi);
Window window = MI_WINDOW(mi);
GC gc = MI_GC(mi);
gravstruct *gp = &gravs[MI_SCREEN(mi)];
double D; /* A distance variable to work with */
register unsigned char cmpt;
D = POS(X) * POS(X) + POS(Y) * POS(Y) + POS(Z) * POS(Z);
if (D < COLLIDE)
D = COLLIDE;
D = sqrt(D);
D = D * D * D;
for (cmpt = X; cmpt < DIMENSIONS; cmpt++) {
ACC(cmpt) = POS(cmpt) * GRAV / D;
if (decay) {
if (ACC(cmpt) > MaxA)
ACC(cmpt) = MaxA;
else if (ACC(cmpt) < -MaxA)
ACC(cmpt) = -MaxA;
VEL(cmpt) = VEL(cmpt) + ACC(cmpt);
VEL(cmpt) *= DAMP;
} else {
/* update velocity */
VEL(cmpt) = VEL(cmpt) + ACC(cmpt);
}
/* update position */
POS(cmpt) = POS(cmpt) + VEL(cmpt);
}
gp->x = planet->xi;
gp->y = planet->yi;
if (POS(Z) > -ALMOST) {
planet->xi = (int)
((double) gp->width * (HALF + POS(X) / (POS(Z) + DIST)));
planet->yi = (int)
((double) gp->height * (HALF + POS(Y) / (POS(Z) + DIST)));
} else
planet->xi = planet->yi = -1;
/* Mask */
XSetForeground(display, gc, MI_BLACK_PIXEL(mi));
Planet(gp->x, gp->y);
if (trail) {
XSetForeground(display, gc, planet->colors);
XDrawPoint(display, MI_WINDOW(mi), gc, gp->x, gp->y);
}
/* Move */
gp->x = planet->xi;
gp->y = planet->yi;
planet->ri = RADIUS;
/* Redraw */
XSetForeground(display, gc, planet->colors);
Planet(gp->x, gp->y);
}
ENTRYPOINT void
init_grav(ModeInfo * mi)
{
unsigned char ball;
gravstruct *gp;
MI_INIT (mi, gravs);
gp = &gravs[MI_SCREEN(mi)];
gp->width = MI_WIDTH(mi);
gp->height = MI_HEIGHT(mi);
gp->sr = STARRADIUS;
gp->nplanets = MI_COUNT(mi);
if (gp->nplanets < 0) {
if (gp->planets) {
(void) free((void *) gp->planets);
gp->planets = (planetstruct *) NULL;
}
gp->nplanets = NRAND(-gp->nplanets) + 1; /* Add 1 so its not too boring */
}
if (gp->planets == NULL) {
if ((gp->planets = (planetstruct *) calloc(gp->nplanets,
sizeof (planetstruct))) == NULL)
return;
}
MI_CLEARWINDOW(mi);
if (MI_NPIXELS(mi) > 2)
gp->starcolor = MI_PIXEL(mi, NRAND(MI_NPIXELS(mi)));
else
gp->starcolor = MI_WHITE_PIXEL(mi);
for (ball = 0; ball < (unsigned char) gp->nplanets; ball++)
init_planet(mi, &gp->planets[ball]);
}
ENTRYPOINT void
draw_grav(ModeInfo * mi)
{
Display *display = MI_DISPLAY(mi);
Window window = MI_WINDOW(mi);
GC gc = MI_GC(mi);
register unsigned char ball;
gravstruct *gp;
if (gravs == NULL)
return;
gp = &gravs[MI_SCREEN(mi)];
if (gp->planets == NULL)
return;
if (!MI_IS_DRAWN(mi)) {
for (ball = 0; ball < (unsigned char) gp->nplanets; ball++) {
planetstruct *planet = &gp->planets[ball];
/* Draw planets */
Planet(planet->xi, planet->yi);
}
/* Draw centrepoint */
XDrawArc(display, MI_WINDOW(mi), gc,
gp->width / 2 - gp->sr / 2, gp->height / 2 - gp->sr / 2, gp->sr, gp->sr,
0, 23040);
}
MI_IS_DRAWN(mi) = True;
/* Mask centrepoint */
XSetForeground(display, gc, MI_BLACK_PIXEL(mi));
XDrawArc(display, window, gc,
gp->width / 2 - gp->sr / 2, gp->height / 2 - gp->sr / 2, gp->sr, gp->sr,
0, 23040);
/* Resize centrepoint */
switch (NRAND(4)) {
case 0:
if (gp->sr < (int) STARRADIUS)
gp->sr++;
break;
case 1:
if (gp->sr > 2)
gp->sr--;
}
/* Draw centrepoint */
XSetForeground(display, gc, gp->starcolor);
XDrawArc(display, window, gc,
gp->width / 2 - gp->sr / 2, gp->height / 2 - gp->sr / 2, gp->sr, gp->sr,
0, 23040);
for (ball = 0; ball < (unsigned char) gp->nplanets; ball++)
draw_planet(mi, &gp->planets[ball]);
}
ENTRYPOINT void
reshape_grav(ModeInfo * mi, int width, int height)
{
gravstruct *gp = &gravs[MI_SCREEN(mi)];
gp->width = width;
gp->height = height;
XClearWindow (MI_DISPLAY (mi), MI_WINDOW(mi));
}
ENTRYPOINT void
free_grav(ModeInfo * mi)
{
gravstruct *gp = &gravs[MI_SCREEN(mi)];
if (gp->planets)
(void) free((void *) gp->planets);
}
#ifndef STANDALONE
ENTRYPOINT void
refresh_grav(ModeInfo * mi)
{
MI_CLEARWINDOW(mi);
}
#endif
XSCREENSAVER_MODULE ("Grav", grav)
#endif /* MODE_grav */
