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);
}
public static bool ColinearPointInSegment(VecRat2 p, SegRat2 s)
{
LineProjectionTransform transform = new LineProjectionTransform(s);
return(PointInSegment(transform.Project(p), transform.Project(s)));
}