orientationIndex method

int orientationIndex(LineSegment seg)

Determines the orientation of a LineSegment relative to this segment. The concept of orientation is specified as follows: Given two line segments A and L,

• A is to the left of a segment L if A lies wholly in the closed half-plane lying to the left of L
• A is to the right of a segment L if A lies wholly in the closed half-plane lying to the right of L
• otherwise, A has indeterminate orientation relative to L. This happens if A is collinear with L or if A crosses the line determined by L.

@param seg the LineSegment to compare

@return 1 if seg is to the left of this segment @return -1 if seg is to the right of this segment @return 0 if seg is collinear to or crosses this segment

Implementation

int orientationIndex(LineSegment seg) {
  int orient0 = Orientation.index(p0, p1, seg.p0);
  int orient1 = Orientation.index(p0, p1, seg.p1);
  // this handles the case where the points are L or collinear
  if (orient0 >= 0 && orient1 >= 0) return math.max(orient0, orient1);
  // this handles the case where the points are R or collinear
  if (orient0 <= 0 && orient1 <= 0) return math.max(orient0, orient1);
  // points lie on opposite sides ==> indeterminate orientation
  return 0;
}