void checkMinMax(Point3f pt, Point3f pointMin, Point3f pointMax) {
		float t = pt.x;
		if (t < pointMin.x)
			pointMin.x = t;
		else if (t > pointMax.x)
			pointMax.x = t;
		t = pt.y;
		if (t < pointMin.y)
			pointMin.y = t;
		else if (t > pointMax.y)
			pointMax.y = t;
		t = pt.z;
		if (t < pointMin.z)
			pointMin.z = t;
		else if (t > pointMax.z)
			pointMax.z = t;
	}