@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Corner other = (Corner) obj;
		if (e1 == null) {
			if (other.e1 != null)
				return false;
		} else if (!e1.equals(other.e1))
			return false;
		if (e2 == null) {
			if (other.e2 != null)
				return false;
		} else if (!e2.equals(other.e2))
			return false;
		return true;
	}