function deltaRight(left, top) {

	let d = 0;

	// If there is an edge, and no crossing edges, continue.
	if(top[3] === 1 && left[1] !== 1 && left[3] !== 1) {

		d += 1;

	}

	/* If an edge was previously found, there is another edge and there are no
	crossing edges, continue. */
	if(d === 1 && top[2] === 1 && left[0] !== 1 && left[2] !== 1) {

		d += 1;

	}

	return d;

}