for (int i = 0, pointIndex = 0; i < positions.length; i += 9) {
triangle.set(0, positions[i], positions[i + 1], positions[i + 2]);
triangle.set(1, positions[i + 3], positions[i + 4], positions[i + 5]);
triangle.set(2, positions[i + 6], positions[i + 7], positions[i + 8]);
Vector3f n = triangle.getNormal();
float dotNX = Math.abs(n.dot(x));
float dorNY = Math.abs(n.dot(y));
float dotNZ = Math.abs(n.dot(z));
if (dotNX > borderAngle) {
if (dotNZ < borderAngle) {// discard X-coordinate
uvCoordinates[pointIndex++] = (triangle.get1().y - min.y) / ext[1];