public static void Add(List <seg2d> segs, seg2d s)
{
if (!Contains(segs, s))
{
segs.Add(s);
}
}
public static bool Contains(List <seg2d> segs, seg2d s)
{
foreach (seg2d seg in segs)
{
if (eq(seg, s))
{
return(true);
}
}
return(false);
}
public static void add_seg(List <seg2d> segs, xy a, xy b)
{
seg2d already = find_seg(segs, a, b);
if (already != null)
{
return;
}
segs.Add(new seg2d(a, b));
}
internal SegmentInfo GetInfo(seg2d s)
{
// since we have split every segment such that it
// intersects with none others, we can now simply test the midpoint
if (PointInside((s.a + s.b) / 2))
{
return(SegmentInfo.Inside);
}
else
{
return(SegmentInfo.Outside);
}
}
public static seg2d find_seg_a(List <seg2d> segs, xy p, out xy next)
{
next = null;
seg2d result = null;
foreach (seg2d s in segs)
{
if (fp.eq_inches(s.a, p))
{
next = s.b;
result = s;
break;
}
}
return(result);
}
public static bool eq(seg2d s1, seg2d s2)
{
if (
fp.eq_inches(s1.a, s2.a) &&
fp.eq_inches(s1.b, s2.b)
)
{
return(true);
}
if (
fp.eq_inches(s1.a, s2.b) &&
fp.eq_inches(s1.b, s2.a)
)
{
return(true);
}
return(false);
}
public static void find_seg(List <seg2d> segs, xy p, out xy nextpt, out seg2d seg)
{
seg = null;
nextpt = null;
foreach (seg2d s in segs)
{
if (fp.eq_inches(s.a, p))
{
seg = s;
nextpt = s.b;
break;
}
if (fp.eq_inches(s.b, p))
{
seg = s;
nextpt = s.a;
break;
}
}
Debug.Assert(seg != null);
}
public seginfo2d(seg2d s, Poly2dWithExtraStuff p)
{
seg = s;
info = p.GetInfo(s);
}
public seginfo2d(seg2d s, SegmentInfo si)
{
seg = s;
info = si;
}
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));
}
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);
}
