private static void FindNewEvent(Segment s1, Segment s2, EventPoint eventPoint, RBTreeMap <EventPoint, LinkedList <Segment> > eventQueue)
{
//If two segments intersect below the sweep line, or on it and
//to the right of the current event point, and the intersection
//is not yet present as an event in Q:
//then insert a new event point in Q for this intersection
VecRat2 pointIntersection = new VecRat2();
SegRat2 segmentIntersection = new SegRat2();
//bool intersectionExists = Segment.ComputeIntersection(s1, s2, out pointIntersection);
//if (intersectionExists)
SegmentIntersectionType result = GeomAid.SegmentIntersection(s1.ToSegRat2(), s2.ToSegRat2(), ref pointIntersection, ref segmentIntersection);
if (result == SegmentIntersectionType.Point)
{
EventPoint newEventPoint = new EventPoint(null);
newEventPoint.Position = pointIntersection;
if (eventPoint.CompareTo(newEventPoint) < 0 && !eventQueue.ContainsKey(newEventPoint))
{
LinkedList <Segment> upperList = new LinkedList <Segment>();
eventQueue.Add(new RBTreeMapNode <EventPoint, LinkedList <Segment> >(newEventPoint, upperList));
}
}
else if (result == SegmentIntersectionType.Segment)
{
throw new NotImplementedException("Didn't think this would ever happen?!");
}
}
public LineProjectionTransform(SegRat2 s)
{
this.anchor = s.A;
this.dir = s.AB();
this.dot_anchor = dir * anchor;
this.inv_dir_len_sq = 1 / dir.LengthSquared();
}
public static SegmentIntersectionType ColinearSegmentIntersection(SegRat2 s, SegRat2 t, ref VecRat2 pointIntersection, ref SegRat2 segmentIntersection)
{
//This check is important for handling degenerate cases like s = [(x,y), (x,y)).
if (s.IsEmpty() || t.IsEmpty())
{
return(SegmentIntersectionType.None);
}
//This check is important because the LineProjectionTransform can only be formed with a non-point segment.
if (s.IsPoint())
{
if (ColinearPointInSegment(s.A, t))
{
pointIntersection = s.A;
return(SegmentIntersectionType.Point);
}
else
{
return(SegmentIntersectionType.None);
}
}
LineProjectionTransform transform = new LineProjectionTransform(s);
SegRat1 proj_s = transform.Project(s);
SegRat1 proj_t = transform.Project(t);
Rational proj_pointIntersection = new Rational();
SegRat1 proj_segmentIntersection = new SegRat1();
SegmentIntersectionType result = SegmentIntersection(
proj_s, proj_t, ref proj_pointIntersection, ref proj_segmentIntersection);
if (result == SegmentIntersectionType.Point)
{
pointIntersection = transform.Unproject(proj_pointIntersection);
}
else if (result == SegmentIntersectionType.Segment)
{
segmentIntersection = transform.Unproject(proj_segmentIntersection);
}
return(result);
}
private void FindNewEventPoint(OA_Segment segment1, OA_Segment segment2, OA_EventPoint eventPoint)
{
VecRat2 pointIntersection = new VecRat2();
SegRat2 segmentIntersection = new SegRat2();
SegmentIntersectionType result = GeomAid.SegmentIntersection(segment1.ToSegRat2(), segment2.ToSegRat2(), ref pointIntersection, ref segmentIntersection);
if (result == SegmentIntersectionType.Point)
{
OA_EventPoint newEventPoint = new OA_EventPoint(pointIntersection);
if (eventPoint.CompareTo(newEventPoint) < 0)
{
//Add the new event point if it isn't already in the event queue
eventQueue.Add(new RBTreeSetNode <OA_EventPoint>(newEventPoint));
}
}
else if (result == SegmentIntersectionType.Segment)
{
throw new NotImplementedException("Didn't think this would ever happen?!");
}
}
public static bool PointInSegment(VecRat2 p, SegRat2 s)
{
return(TurnTest(s, p) == 0 && ColinearPointInSegment(p, s));
}
public static bool ColinearPointInSegment(VecRat2 p, SegRat2 s)
{
LineProjectionTransform transform = new LineProjectionTransform(s);
return(PointInSegment(transform.Project(p), transform.Project(s)));
}
public static int TurnTest(SegRat2 s, VecRat2 p)
{
return(TurnTest(s.A, s.B, p));
}
//If the two segments are disjoint, then None is returned.
//Else, if the two segments are colinear, then either Segment is returned.
//Else, if the two segments are not colinear, Point is returned.
public static SegmentIntersectionType SegmentIntersection(SegRat2 s, SegRat2 t, ref VecRat2 pointIntersection, ref SegRat2 segmentIntersection)
{
//This check is important for handling degenerate cases like s = [(x,y), (x,y)).
if (s.IsEmpty() || t.IsEmpty())
{
return(SegmentIntersectionType.None);
}
//This check is important because the LineProjectionTransform can only be formed with a non-point segment.
if (s.IsPoint())
{
if (PointInSegment(s.A, t))
{
segmentIntersection = s;
return(SegmentIntersectionType.Segment);
}
else
{
return(SegmentIntersectionType.None);
}
}
int turn_s_ta = TurnTest(s, t.A);
int turn_s_tb = TurnTest(s, t.B);
if (turn_s_ta == 0 && turn_s_tb == 0)
{
return(ColinearSegmentIntersection(s, t, ref pointIntersection, ref segmentIntersection));
}
if (s.AClosed)
{
if (t.AClosed && s.A == t.A)
{
pointIntersection = s.A;
return(SegmentIntersectionType.Point);
}
else if (t.BClosed && s.B == t.B)
{
pointIntersection = s.B;
return(SegmentIntersectionType.Point);
}
}
if (s.BClosed)
{
if (t.AClosed && s.B == t.A)
{
pointIntersection = s.B;
return(SegmentIntersectionType.Point);
}
else if (t.BClosed && s.B == t.B)
{
pointIntersection = s.B;
return(SegmentIntersectionType.Point);
}
}
int turn_t_sa = TurnTest(t, s.A);
int turn_t_sb = TurnTest(t, s.B);
int val_s = turn_s_ta * turn_s_tb;
int val_t = turn_t_sa * turn_t_sb;
if (val_s < 0 && val_t < 0)
{
pointIntersection = LineIntersection(s, t);
return(SegmentIntersectionType.Point);
}
else
{
return(SegmentIntersectionType.None);
}
}
/// <summary>
/// Assumes the two lines u1-v1 and u2-v2 are not parallel.
/// </summary>
public static VecRat2 LineIntersection(SegRat2 s1, SegRat2 s2)
{
return(LineIntersection(s1.A, s1.B, s2.A, s2.B));
}
public SegRat1 Project(SegRat2 s)
{
return(new SegRat1(Project(s.A), Project(s.B), s.AClosed, s.BClosed));
}