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))); }