/* gcc -o psycho psycho.c -I/usr/X11R6/include -L/usr/X11R6/lib -lX11 -lXext -lXxf86vm -lm
*/
#include <X11/Xlib.h>
#include <X11/extensions/Xext.h>
#include <X11/extensions/xf86vmode.h>
#include <signal.h>
#include <math.h>

#define GAMMA_COMPONENTS 3
#define GAMMA_RESOLUTION 256

/*
 * Ben Winslow <rain bluecherry.net> - 9/28/2001
 *
 * Modified Fri Sep 28 20:16:59 CDT 2001 by Zinx Verituse - Psychadelic color cycling :P
 */

Display *dpy;
unsigned short ramp_in[GAMMA_COMPONENTS][GAMMA_RESOLUTION];

void sighand(int sig) {
	XF86VidModeSetGammaRamp(dpy, DefaultScreen(dpy), GAMMA_RESOLUTION, ramp_in[0], ramp_in[1], ramp_in[2]);
	exit(sig);
}

int main(int argc, char *argv[])
{
	unsigned short ramp_out[GAMMA_COMPONENTS][GAMMA_RESOLUTION];
	int x, y;
	int n[GAMMA_COMPONENTS], nd[GAMMA_COMPONENTS], nt[GAMMA_COMPONENTS];

	dpy = XOpenDisplay(NULL);
	if (XF86VidModeGetGammaRamp(dpy, DefaultScreen(dpy), GAMMA_RESOLUTION, ramp_in[0], ramp_in[1], ramp_in[2]) == False)
		return 1;

	signal(SIGSEGV, sighand);
	signal(SIGTERM, sighand);
	signal(SIGINT, sighand);
	signal(SIGHUP, sighand);
	signal(SIGALRM, sighand);

	srand(time(NULL)+getpid());

	for (x = 0; x < GAMMA_COMPONENTS; x++) {
		n[x] = rand()%360;
		nd[x] = (rand()&1)?-1:1;
		nt[x] = rand()%720 + 100;
	}
	
	for (;;) {
		for (x = 0; x < GAMMA_COMPONENTS; x++) {
			for (y = 0; y < GAMMA_RESOLUTION; y++) {
				double t = (double)(y-GAMMA_RESOLUTION/2) / (double)(GAMMA_RESOLUTION/2);

//				t = cos((t*M_PI) + ((n[x]*M_PI)/180.0));
//				t = cos((t*(M_PI+M_PI_2)) + ((n[x]*M_PI)/180.0));
				t = cos((t*M_PI*0.8) + ((n[x]*M_PI)/180.0));
				ramp_out[x][y] = (t * 32767) + 32767;
			}

			if (--nt[x] < 0) {
				nd[x] = -nd[x];
				nt[x] = rand()%720 + 100;
			}

			n[x] += nd[x];

			if (n[x] < 0) n[x] += 360;
			else if (n[x] >= 360) n[x] -= 360;
		}

		if (XF86VidModeSetGammaRamp(dpy, DefaultScreen(dpy), GAMMA_RESOLUTION, ramp_out[0], ramp_out[1], ramp_out[2]) == False)
			return 1;
			
		usleep(10000);
	}

	/* Not reached */
}