/* et_3.r - Luigi Morelli */

int	d;


main()

int	degree;
int	range;
int	gradi;

{
	while (1) {
		d = damage();
		degree = plot_course(rand(1000), rand(1000));
		gradi = degree;
		drive (degree, 50);
		while ((loc_x() >= 13) && (loc_x() <= 987) && (loc_y() >= 15) && (loc_y() <= 985)) {
			gradi += 11;
			while ((range = scan (gradi, 8)) > 0) {
				cannon (gradi, range);
				drive (gradi, 50);
			}
			if (d != damage())
				fuga();
		}
		drive (degree, 0);
	}
}


/* fuga function, permette il rientro qualora il danno */
/* diventi ingente */
fuga()
int	direz;

{
	direz = plot_course (512, 487);
	while ((loc_x() > 50) && (loc_y() > 50) && (loc_y() < 950) && (loc_x() < 950))
		drive (direz, 100);
	drive (direz, 20);
	d = damage();
}


/* plot course function, return degree heading to */
/* reach destination x, y; uses atan() trig function */
plot_course(xx, yy)
int	xx, yy;

{
	int	dd;
	int	x, y;
	int	scale;
	int	curx, cury;

	scale = 100000;  /* scale for trig functions */
	curx = loc_x();  /* get current location */
	cury = loc_y();
	x = curx - xx;
	y = cury - yy;

	/* atan only returns -90 to +90, so figure out how to use */
	/* the atan() value */

	if (x == 0) {      /* x is zero, we either move due north or south */
		if (yy > cury)
			dd = 90;        /* north */
		else
			dd = 270;       /* south */
	} else {
		if (yy < cury) {
			if (xx > curx)
				dd = 360 + atan((scale * y) / x);  /* south-east, quadrant 4 */
			else
				dd = 180 + atan((scale * y) / x);  /* south-west, quadrant 3 */
		} else {
			if (xx > curx)
				dd = atan((scale * y) / x);        /* north-east, quadrant 1 */
			else
				dd = 180 + atan((scale * y) / x);  /* north-west, quadrant 2 */
		}
	}
	return (dd);
}