internal bool SegmentIntersection(xy p, xy q, out xy pt1, out xy pt2)
{
TriSegIntersect ti = new TriSegIntersect();
if (this.PointInside(p))
{
ti.Add(p);
}
if (this.PointInside(q))
{
ti.Add(q);
}
xy z1, z2;
SegIntersection si = ut.GetSegIntersection(a, b, p, q, out z1, out z2);
if (si == SegIntersection.Overlap)
{
pt1 = z1;
pt2 = z2;
return(true);
}
if (si == SegIntersection.Point)
{
ti.Add(z1);
}
si = ut.GetSegIntersection(b, c, p, q, out z1, out z2);
if (si == SegIntersection.Overlap)
{
pt1 = z1;
pt2 = z2;
return(true);
}
if (si == SegIntersection.Point)
{
ti.Add(z1);
}
si = ut.GetSegIntersection(c, a, p, q, out z1, out z2);
if (si == SegIntersection.Overlap)
{
pt1 = z1;
pt2 = z2;
return(true);
}
if (si == SegIntersection.Point)
{
ti.Add(z1);
}
if (ti.q1 == null)
{
pt1 = null;
pt2 = null;
return(false);
}
pt1 = ti.q1;
if (ti.q2 != null)
{
pt2 = ti.q2;
}
else
{
pt2 = null;
}
return(true);
}
public static void SplitSegment(List <seginfo2d> result, seg2d s1, Poly2dWithExtraStuff p2)
{
foreach (seg2d s2 in p2.segs)
{
if (fp.eq_inches(s1.a, s2.a) && fp.eq_inches(s1.b, s2.b))
{
// same segment.
result.Add(new seginfo2d(s1, SegmentInfo.Same));
// nothing else can happen. stop now.
return;
}
else if (fp.eq_inches(s1.a, s2.b) && fp.eq_inches(s1.b, s2.a))
{
// same segment, but reversed
result.Add(new seginfo2d(s1, SegmentInfo.Opposite));
// nothing else can happen. stop now.
return;
}
else
{
xy q1;
xy q2;
SegIntersection si = ut.GetSegIntersection(s1, s2, out q1, out q2);
if (si == SegIntersection.Point)
{
if (
fp.eq_inches(q1, s1.a) ||
fp.eq_inches(q1, s1.b)
)
{
// an endpoint. this doesn't count as a hit.
// ignore this
}
else
{
SplitSegment(result, new seg2d(s1.a, q1), p2);
SplitSegment(result, new seg2d(q1, s1.b), p2);
return;
}
}
else if (si == SegIntersection.Overlap)
{
SegmentInfo dir;
xy v1 = (s1.b - s1.a).normalize_in_place();
xy v2 = (s2.b - s2.a).normalize_in_place();
if (fp.eq_unitvec(v1, v2))
{
dir = SegmentInfo.Same;
}
else
{
dir = SegmentInfo.Opposite;
}
if (
fp.eq_inches(s1.a, q1) &&
fp.eq_inches(s1.b, q2)
)
{
result.Add(new seginfo2d(s1, dir));
}
else if (
fp.eq_inches(s1.a, q2) &&
fp.eq_inches(s1.b, q1)
)
{
result.Add(new seginfo2d(s1, dir));
}
else if (fp.eq_inches(s1.a, q1))
{
result.Add(new seginfo2d(new seg2d(s1.a, q2), dir));
SplitSegment(result, new seg2d(q2, s1.b), p2);
}
else if (fp.eq_inches(s1.a, q2))
{
result.Add(new seginfo2d(new seg2d(s1.a, q1), dir));
SplitSegment(result, new seg2d(q1, s1.b), p2);
}
else if (fp.eq_inches(s1.b, q1))
{
SplitSegment(result, new seg2d(s1.a, q2), p2);
result.Add(new seginfo2d(new seg2d(q2, s1.b), dir));
}
else if (fp.eq_inches(s1.b, q2))
{
SplitSegment(result, new seg2d(s1.a, q1), p2);
result.Add(new seginfo2d(new seg2d(q1, s1.b), dir));
}
else
{
// both q1 and q2 are somewhere inside s1
xy z1 = q1 - s1.a;
xy z2 = q2 - s1.a;
if (z1.magnitude_squared() < z2.magnitude_squared())
{
// q1 is closer
SplitSegment(result, new seg2d(s1.a, q1), p2);
result.Add(new seginfo2d(new seg2d(q1, q2), dir));
SplitSegment(result, new seg2d(q2, s1.b), p2);
}
else
{
// q2 is closer
SplitSegment(result, new seg2d(s1.a, q2), p2);
result.Add(new seginfo2d(new seg2d(q2, q1), dir));
SplitSegment(result, new seg2d(q1, s1.b), p2);
}
}
return;
}
}
}
result.Add(new seginfo2d(s1, p2));
}
