public static TriangleIntersection2d CalcTriangleIntersection2d(xy a1, xy b1, xy c1, xy a2, xy b2, xy c2)
{
#if PP_DEBUG
Console.Out.WriteLine("tri 1: a={0} b={1} c={2}", a1, b1, c1);
Console.Out.WriteLine("tri 2: a={0} b={1} c={2}", a2, b2, c2);
#endif
TriangleIntersection2d pts = new TriangleIntersection2d();
List <seg2d> segs = new List <seg2d>();
CalcSegmentTriangleIntersection2d(pts, segs, a1, b1, a2, b2, c2);
CalcSegmentTriangleIntersection2d(pts, segs, b1, c1, a2, b2, c2);
CalcSegmentTriangleIntersection2d(pts, segs, c1, a1, a2, b2, c2);
CalcSegmentTriangleIntersection2d(pts, segs, a2, b2, a1, b1, c1);
CalcSegmentTriangleIntersection2d(pts, segs, b2, c2, a1, b1, c1);
CalcSegmentTriangleIntersection2d(pts, segs, c2, a2, a1, b1, c1);
TriangleIntersection2d ti = new TriangleIntersection2d();
Debug.Assert(
(segs.Count >= 0) &&
(segs.Count <= 6)
);
switch (segs.Count)
{
case 0:
{
Debug.Assert(
(pts.Count == 0) ||
(pts.Count == 1)
);
if (pts.Count == 0)
{
return(ti);
}
else // if (pts.Count == 1)
{
ti.Add(pts[0]);
return(ti);
}
}
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
{
int i = 0;
seg2d cur = segs[i];
ti.Add(cur.a);
ti.Add(cur.b);
segs.Remove(cur);
xy lastpt = cur.b;
while (segs.Count > 0)
{
xy nextpt;
find_seg(segs, lastpt, out nextpt, out cur);
ti.Add(nextpt);
segs.Remove(cur);
lastpt = nextpt;
}
break;
}
}
return(ti);
}
public static void CalcSegmentTriangleIntersection2d(TriangleIntersection2d pts, List <seg2d> segs, xy a, xy b, xy ta, xy tb, xy tc)
{
TriangleIntersection2d ti2 = new TriangleIntersection2d();
SegIntersection si;
xy q1;
xy q2;
if (ut.PointInsideTriangle(a, ta, tb, tc))
{
ti2.Add(a);
}
si = ut.GetSegIntersection(a, b, ta, tb, out q1, out q2);
if (si == SegIntersection.Point)
{
ti2.Add(q1);
}
else if (si == SegIntersection.Overlap)
{
ti2.Add(q1);
ti2.Add(q2);
}
si = ut.GetSegIntersection(a, b, tb, tc, out q1, out q2);
if (si == SegIntersection.Point)
{
ti2.Add(q1);
}
else if (si == SegIntersection.Overlap)
{
ti2.Add(q1);
ti2.Add(q2);
}
si = ut.GetSegIntersection(a, b, tc, ta, out q1, out q2);
if (si == SegIntersection.Point)
{
ti2.Add(q1);
}
else if (si == SegIntersection.Overlap)
{
ti2.Add(q1);
ti2.Add(q2);
}
if (ut.PointInsideTriangle(b, ta, tb, tc))
{
ti2.Add(b);
}
Debug.Assert(
(ti2.Count == 0) ||
(ti2.Count == 1) ||
(ti2.Count == 2)
);
if (ti2.Count == 0)
{
return;
}
else if (ti2.Count == 1)
{
pts.Add(ti2[0]);
}
else // if (ti2.Count == 2)
{
add_seg(segs, ti2[0], ti2[1]);
}
}