/*
 * meltdown -- mess up the screen
 */
/*
 * Copyright 1990 David Lemke and Network Computing Devices
 *
 * 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, and that the name of Network Computing Devices not be 
 * used in advertising or publicity pertaining to distribution of the 
 * software without specific, written prior permission.  Network Computing 
 * Devices makes no representations about the suitability of this software 
 * for any purpose.  It is provided "as is" without express or implied 
 * warranty.
 *
 * NETWORK COMPUTING DEVICES DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS 
 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
 * IN NO EVENT SHALL NETWORK COMPUTING DEVICES BE LIABLE FOR ANY SPECIAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE 
 * OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Author:  	
 *		Dave Lemke
 *		lemke@ncd.com
 *
 *		Network Computing Devices, Inc
 *		350 North Bernardo Ave
 *		Mountain View, CA 94043
 *
 *		@(#)meltdown.c	1.2	90/02/22
 *
 */

#include	<X11/Xlib.h>
#include	<stdio.h>

#define	MIN_SIZE	10
#define	MAX_SIZE	100

#define	MIN_DIST	10

#define	MIN_WIDTH	30
#define	WIDTH_ADD	20

#define	FINISHED	50

#define	rnd(x)	(random() % (x))

#define	min(a, b)	((a) < (b) ? (a) : (b))
#define	max(a, b)	((a) > (b) ? (a) : (b))

Display	*dpy;
Window	win;
GC	copygc, fillgc;
int	screen;
int	depth;

short	**heights;

usage()
{
	fprintf(stderr, "Usage:  meltdown [-planes] [-display <displayname>]\n");
	exit(1);
}

main(argc, argv)
int	argc;
char	**argv;
{
char	*display = NULL;
unsigned long	vmask;
XSetWindowAttributes	xswat;
XGCValues	gcvals;
Bool	use_planes = False;
int	i;

	srandom(getpid());

	for (i = 1; i < argc; i++)	{
		if (strncmp(argv[i], "-dis", 4) == 0)	{
			if (argv[i+1])
				display = argv[++i];
			else
				usage();
		} else if (strncmp(argv[i], "-p", 2) == 0)	{
			use_planes = 1;
		}	else
			usage();
	}

	if ((dpy = XOpenDisplay(display)) == NULL)	{
		fprintf(stderr, "can't open display\n");
		exit(0);
	}

	screen = DefaultScreen(dpy);

	xswat.override_redirect = True;
	xswat.do_not_propagate_mask = KeyPressMask | KeyReleaseMask |
		ButtonPressMask | ButtonReleaseMask;
	vmask = CWOverrideRedirect | CWDontPropagate;
	win = XCreateWindow(dpy, RootWindow(dpy, screen), 0, 0, 
		DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
		0, CopyFromParent, CopyFromParent, CopyFromParent, vmask,
		&xswat);
	XMapWindow(dpy, win);

	gcvals.graphics_exposures = False;
	/* copyplane gc wants to leave the data alone */
	gcvals.foreground = 1;
	gcvals.background = 0;
	copygc = XCreateGC(dpy, win, 
		GCForeground | GCBackground | GCGraphicsExposures, &gcvals);

	gcvals.foreground = BlackPixel(dpy, screen);
	fillgc = XCreateGC(dpy, win, GCForeground, &gcvals);


	XSync(dpy, 0);
	sleep(1);

	if (use_planes)	{
		do_planes();
	} else	{
		do_all();
	}

	/* NOTREACHED */
	exit(0);
}

do_planes()
{
int	finished = 0;
int	width, xloc, yloc, dist, size, i;
short	**heights;

	heights = (short **) malloc(DisplayPlanes(dpy, screen));
	for (i = 0; i < DisplayPlanes(dpy, screen); i++)
		heights[i] = (short *) calloc(sizeof(short),
			DisplayWidth(dpy, screen));
	while (1)	{
		depth = rnd(DisplayPlanes(dpy, screen));
		width = rnd(MIN_WIDTH) + WIDTH_ADD;

		xloc = calc_xloc(width);

		yloc = DisplayHeight(dpy, screen);
		for (i = xloc; i < (xloc + width); i++)	{
			yloc = min(yloc, heights[depth][i]);
		}
		if (yloc == DisplayHeight(dpy, screen))
			continue;

		dist = rnd(yloc/10 + MIN_DIST);
		size = rnd(max(yloc + MIN_SIZE, MAX_SIZE));

		XSetPlaneMask(dpy, copygc, 1 << depth);
		XSetPlaneMask(dpy, fillgc, 1 << depth);
		XCopyArea(dpy, win, win, copygc, 
			xloc, yloc, 
			width, size,
			xloc, yloc + dist);
		XFillRectangle(dpy, win, fillgc, 
			xloc, yloc, 
			width, dist);
		yloc += dist;
		for (i = xloc; i < (xloc + width); i++)	{
		    if ((heights[depth][i] < (DisplayHeight(dpy, screen) - MIN_SIZE))
		        && (yloc >= (DisplayHeight(dpy, screen) - MIN_SIZE)))
				finished++;

		    heights[depth][i] = max(heights[depth][i], yloc);
		}
		if (finished >= (DisplayWidth(dpy, screen) - FINISHED)) {
			XSync(dpy, 0);
			exit(0);
		}
	}
}

do_all()
{
int	finished = 0;
int	width, xloc, yloc, dist, size, i;
short	*heights;

	heights = (short *) calloc(sizeof(short), DisplayWidth(dpy, screen));

	while (1)	{
		depth = rnd(DisplayPlanes(dpy, screen));
		width = rnd(MIN_WIDTH) + WIDTH_ADD;

		xloc = calc_xloc(width);

		yloc = DisplayHeight(dpy, screen);
		for (i = xloc; i < (xloc + width); i++)	{
			yloc = min(yloc, heights[i]);
		}
		if (yloc == DisplayHeight(dpy, screen))
			continue;

		dist = rnd(yloc/10 + MIN_DIST);
		size = rnd(max(yloc + MIN_SIZE, MAX_SIZE));

		XCopyArea(dpy, win, win, copygc, 
			xloc, yloc, 
			width, size,
			xloc, yloc + dist);
		XFillRectangle(dpy, win, fillgc, 
			xloc, yloc, 
			width, dist);
		yloc += dist;
		for (i = xloc; i < (xloc + width); i++)	{
		    if ((heights[i] < (DisplayHeight(dpy, screen) - MIN_SIZE))
		        && (yloc >= (DisplayHeight(dpy, screen) - MIN_SIZE)))
				finished++;

		    heights[i] = max(heights[i], yloc);
		}
		if (finished >= (DisplayWidth(dpy, screen) - FINISHED))	{
			XSync(dpy, 0);
			exit(0);
		}
	}
}

int
calc_xloc(width)
int	width;
{
int	xloc;

	/* give values near edges a better chance */
	xloc = rnd(DisplayWidth(dpy, screen) + MIN_WIDTH) - MIN_WIDTH;

	if ((xloc + width) > DisplayWidth(dpy, screen))
		xloc = DisplayWidth(dpy, screen) - width;
	else if (xloc < 0)
		xloc = 0;

	return xloc;
}