public static bool PointInSegment(Rational p, SegRat1 s)
{
s.NormalizeOrientation();
return((s.AClosed && p == s.A) ||
(s.BClosed && p == s.B) ||
(s.A < p && p < s.B));
}
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 SegmentIntersectionType SegmentIntersection(SegRat1 s, SegRat1 t, ref Rational pointIntersection, ref SegRat1 segmentIntersection)
{
//This check is important for handling degenerate cases like s = [x, x).
if (s.IsEmpty() || t.IsEmpty())
{
return(SegmentIntersectionType.None);
}
s.NormalizeOrientation();
t.NormalizeOrientation();
if (s.A > t.A)
{
MathAid.Swap(ref s, ref t);
}
if (s.B < t.A)
{
return(SegmentIntersectionType.None);
}
if (s.B == t.A)
{
if (s.BClosed && t.AClosed)
{
pointIntersection = s.B;
return(SegmentIntersectionType.Point);
}
else
{
return(SegmentIntersectionType.None);
}
}
Rational b = Rational.Min(s.B, t.B);
segmentIntersection.A = t.A;
segmentIntersection.B = b;
segmentIntersection.AClosed = (t.AClosed && (s.A < t.A || (s.AClosed && s.A == t.A)));
segmentIntersection.BClosed = ((s.BClosed && t.BClosed) || (s.BClosed && b < t.B) || (t.BClosed && b < s.B));
return(SegmentIntersectionType.Segment);
}
public SegRat2 Unproject(SegRat1 dot_s)
{
return(new SegRat2(Unproject(dot_s.A), Unproject(dot_s.B), dot_s.AClosed, dot_s.BClosed));
}