lineLineMinimumPoints method

List<Vector3> lineLineMinimumPoints(dynamic line1, dynamic line2)

Implementation

List<Vector3> lineLineMinimumPoints(line1, line2) {
  Vector3 r = _v1.copy(line1.end).sub(line1.start);
  Vector3 s = _v2.copy(line2.end).sub(line2.start);
  Vector3 w = _v3.copy(line2.start).sub(line1.start);

  num a = r.dot(s), b = r.dot(r), c = s.dot(s), d = s.dot(w), e = r.dot(w);

  double t1;
  double t2;
  num divisor = b * c - a * a;

  if (Math.abs(divisor) < eps) {
    double d1 = -d / c;
    double d2 = (a - d) / c;

    if (Math.abs(d1 - 0.5) < Math.abs(d2 - 0.5)) {
      t1 = 0;
      t2 = d1;
    } else {
      t1 = 1;
      t2 = d2;
    }
  } else {
    t1 = (d * a + e * c) / divisor;
    t2 = (t1 * a - d) / c;
  }

  t2 = Math.max(0, Math.min(1, t2));
  t1 = Math.max(0, Math.min(1, t1));

  Vector3 point1 = r.multiplyScalar(t1).add(line1.start);
  Vector3 point2 = s.multiplyScalar(t2).add(line2.start);

  return [point1, point2];
}