gets first collision between line segment and square

line_square_collision.c

inline int line_square_collision(float ex, float ey, float sqx, float sqy, float sqhlen, float *ox, float *oy)
{
	if (!ox) {float x; ox = &x;}
	if (!oy) {float y; oy = &y;}
	int cx = (fabsf(sqx) <= sqhlen);
	int cy = (fabsf(sqy) <= sqhlen);
	if (cx && cy) {
		if (fabsf(ex - sqx) <= sqhlen && fabsf(ey - sqy) <= sqhlen) {
			*ox = ex; *oy = ey;
			return 1;
		}
		sqhlen *= -1;
	}
	*ox = (ex >= 0) ? sqx - sqhlen : sqx + sqhlen;
	*oy = (ey >= 0) ? sqy - sqhlen : sqy + sqhlen;
	if ((ex != 0) && ((!(cx ^ cy) && ((fabsf(ey * *ox) >= fabsf(ex * *oy)) ^ (sqhlen < 0))) || (cy && !cx)))
		goto collision;
	if (ey == 0) goto no_collision;
	float temp = ex; ex = ey, ey = temp;
	temp = sqx; sqx = sqy; sqy = temp;
	float *tptr; tptr = ox; ox = oy; oy = tptr;
	collision:
	if ((*ox * ex >= 0) && (fabsf(*ox) <= fabsf(ex))) {
		*oy = (*ox) * ey / ex;
		if (fabsf(*oy - sqy) <= fabsf(sqhlen))
			return 1;
	}
	no_collision:
	return (*ox = *oy = 0);
}