public bool DoIntersect(LineSegment lineSegment1, LineSegment lineSegment2)
{
// Find the four orientations needed for general and special cases
int o1 = DetermineOrientation(lineSegment1.EndPoint1, lineSegment1.EndPoint2, lineSegment2.EndPoint1);
int o2 = DetermineOrientation(lineSegment1.EndPoint1, lineSegment1.EndPoint2, lineSegment2.EndPoint2);
int o3 = DetermineOrientation(lineSegment2.EndPoint1, lineSegment2.EndPoint2, lineSegment1.EndPoint1);
int o4 = DetermineOrientation(lineSegment2.EndPoint1, lineSegment2.EndPoint2, lineSegment1.EndPoint2);
// General case
if (o1 != o2 && o3 != o4)
return true;
// Special Cases
// p1, q1 and p2 are colinear and p2 lies on segment p1q1
if (o1 == 0 && IsOnSegment(lineSegment1.EndPoint1, lineSegment2.EndPoint1, lineSegment1.EndPoint2)) return true;
// p1, q1 and p2 are colinear and q2 lies on segment p1q1
if (o2 == 0 && IsOnSegment(lineSegment1.EndPoint1, lineSegment2.EndPoint2, lineSegment1.EndPoint2)) return true;
// p2, q2 and p1 are colinear and p1 lies on segment p2q2
if (o3 == 0 && IsOnSegment(lineSegment2.EndPoint1, lineSegment1.EndPoint1, lineSegment2.EndPoint2)) return true;
// p2, q2 and q1 are colinear and q1 lies on segment p2q2
if (o4 == 0 && IsOnSegment(lineSegment2.EndPoint1, lineSegment1.EndPoint2, lineSegment2.EndPoint2)) return true;
return false; // Doesn't fall in any of the above cases
}
private IEnumerable<Intersection> CheckIntersectionsAndAddToQueue(LineSegment lineSegment)
{
var intersections = new List<Intersection>();
if (_lineSegmentsQueue.Count > 0)
{
var firstLineSegment = _lineSegmentsQueue.Peek();
if (firstLineSegment.RightMostX < lineSegment.LeftMostX)
{
_lineSegmentsQueue.Dequeue();
}
foreach (var segment in _lineSegmentsQueue)
{
if (_intersectionChecker.DoIntersect(segment, lineSegment))
{
intersections.Add(new Intersection(segment, lineSegment));
}
}
_lineSegmentsQueue.Enqueue(lineSegment);
}
else
{
_lineSegmentsQueue.Enqueue(lineSegment);
}
return intersections;
}
public Intersection(LineSegment lineSegment1, LineSegment lineSegment2)
{
LineSegment1 = lineSegment1;
LineSegment2 = lineSegment2;
}
