private static void ReversePolyPtLinks(OutPt pp)
{
if (pp == null)
return;
var pp1 = pp;
do
{
var pp2 = pp1.Next;
pp1.Next = pp1.Prev;
pp1.Prev = pp2;
pp1 = pp2;
} while (pp1 != pp);
}
private void AddOutPt(TEdge e, IntPoint pt)
{
Contract.Requires(e != null);
Contract.Requires(e.OutIdx < 0 || e.OutIdx < _polyOuts.Count);
var toFront = e.Side == EdgeSide.Left;
if (e.OutIdx < 0)
{
var outRec = CreateOutRec();
e.OutIdx = outRec.Idx;
var op = new OutPt();
outRec.Pts = op;
op.Pt = pt;
op.Next = op;
op.Prev = op;
SetHoleState(e, outRec);
}
else
{
var outRec = _polyOuts[e.OutIdx];
var op = outRec.Pts;
if (toFront && pt.Equals(op.Pt) ||
(!toFront && pt.Equals(op.Prev.Pt)))
return;
var op2 = new OutPt {
Pt = pt,
Next = op,
Prev = op.Prev
};
op2.Prev.Next = op2;
op.Prev = op2;
if (toFront)
outRec.Pts = op2;
}
}
private static int PointCount(OutPt pts)
{
if (pts == null)
return 0;
var result = 0;
var p = pts;
do
{
result++;
p = p.Next;
} while (p != pts);
return result;
}
private static bool Poly2ContainsPoly1(OutPt outPt1, OutPt outPt2)
{
Contract.Requires(outPt1 != null);
Contract.Requires(outPt2 != null);
var pt = outPt1;
//Because the polygons may be touching, we need to find a vertex that
//isn't touching the other polygon ...
if (InternalHelpers.PointOnPolygon(pt.Pt, outPt2))
{
pt = pt.Next;
while (pt != outPt1 && InternalHelpers.PointOnPolygon(pt.Pt, outPt2))
pt = pt.Next;
if (pt == outPt1)
return true;
}
return InternalHelpers.PointInPolygon(pt.Pt, outPt2);
}
private static OutPt InsertPolyPtBetween(OutPt p1, OutPt p2, IntPoint pt)
{
Contract.Requires(p1 != null);
Contract.Requires(p2 != null);
Contract.Ensures(Contract.Result<OutPt>() != null);
var result = new OutPt {Pt = pt};
if (p2 == p1.Next)
{
p1.Next = result;
p2.Prev = result;
result.Next = p2;
result.Prev = p1;
}
else
{
p2.Next = result;
p1.Prev = result;
result.Next = p1;
result.Prev = p2;
}
return result;
}
private static bool FindSegment(ref OutPt pp, ref IntPoint pt1, ref IntPoint pt2)
{
if (pp == null)
return false;
var pp2 = pp;
var pt1A = pt1;
var pt2A = pt2;
do
{
if (InternalHelpers.SlopesEqual(pt1A, pt2A, pp.Pt, pp.Prev.Pt) &&
InternalHelpers.SlopesEqual(pt1A, pt2A, pp.Pt) &&
GetOverlapSegment(pt1A, pt2A, pp.Pt, pp.Prev.Pt, out pt1, out pt2))
return true;
pp = pp.Next;
} while (pp != pp2);
return false;
}
private static void DisposeOutPts(OutPt pp)
{
Contract.Requires(pp == null || pp.Prev != null);
if (pp == null)
return;
pp.Prev.Next = null;
while (pp != null)
{
pp = pp.Next;
}
}
private bool JoinPoints(JoinRec j, out OutPt p1, out OutPt p2)
{
Contract.Requires(j != null);
Contract.Requires(j.Poly1Idx >= 0 && j.Poly1Idx < _polyOuts.Count);
Contract.Requires(j.Poly2Idx >= 0 && j.Poly2Idx < _polyOuts.Count);
p1 = null;
p2 = null;
var outRec1 = _polyOuts[j.Poly1Idx];
var outRec2 = _polyOuts[j.Poly2Idx];
if (outRec1 == null || outRec2 == null)
return false;
var pp1A = outRec1.Pts;
var pp2A = outRec2.Pts;
IntPoint pt1 = j.Pt2A, pt2 = j.Pt2B;
IntPoint pt3 = j.Pt1A, pt4 = j.Pt1B;
if (!FindSegment(ref pp1A, ref pt1, ref pt2))
return false;
if (outRec1 == outRec2)
{
//we're searching the same polygon for overlapping segments so
//segment 2 mustn't be the same as segment 1 ...
pp2A = pp1A.Next;
if (!FindSegment(ref pp2A, ref pt3, ref pt4) || (pp2A == pp1A))
return false;
}
else if (!FindSegment(ref pp2A, ref pt3, ref pt4))
return false;
if (!GetOverlapSegment(pt1, pt2, pt3, pt4, out pt1, out pt2))
return false;
OutPt p3, p4, prev = pp1A.Prev;
//get p1 & p2 polypts - the overlap start & endpoints on poly1
if (pp1A.Pt.Equals(pt1))
p1 = pp1A;
else if (prev.Pt.Equals(pt1))
p1 = prev;
else
p1 = InsertPolyPtBetween(pp1A, prev, pt1);
if (pp1A.Pt.Equals(pt2))
p2 = pp1A;
else if (prev.Pt.Equals(pt2))
p2 = prev;
else if ((p1 == pp1A) || (p1 == prev))
p2 = InsertPolyPtBetween(pp1A, prev, pt2);
else if (Pt3IsBetweenPt1AndPt2(pp1A.Pt, p1.Pt, pt2))
p2 = InsertPolyPtBetween(pp1A, p1, pt2);
else
p2 = InsertPolyPtBetween(p1, prev, pt2);
//get p3 & p4 polypts - the overlap start & endpoints on poly2
prev = pp2A.Prev;
if (pp2A.Pt.Equals(pt1))
p3 = pp2A;
else if (prev.Pt.Equals(pt1))
p3 = prev;
else
p3 = InsertPolyPtBetween(pp2A, prev, pt1);
if (pp2A.Pt.Equals(pt2))
p4 = pp2A;
else if (prev.Pt.Equals(pt2))
p4 = prev;
else if ((p3 == pp2A) || (p3 == prev))
p4 = InsertPolyPtBetween(pp2A, prev, pt2);
else if (Pt3IsBetweenPt1AndPt2(pp2A.Pt, p3.Pt, pt2))
p4 = InsertPolyPtBetween(pp2A, p3, pt2);
else
p4 = InsertPolyPtBetween(p3, prev, pt2);
//p1.pt == p3.pt and p2.pt == p4.pt so join p1 to p3 and p2 to p4 ...
if (p1.Next == p2 && p3.Prev == p4)
{
p1.Next = p3;
p3.Prev = p1;
p2.Prev = p4;
p4.Next = p2;
return true;
}
else if (p1.Prev == p2 && p3.Next == p4)
{
p1.Prev = p3;
p3.Next = p1;
p2.Next = p4;
p4.Prev = p2;
return true;
}
else
return false; //an orientation is probably wrong
}
private void FixupJoinRecs(JoinRec j, OutPt pt, int startIdx)
{
for (var k = startIdx; k < _joins.Count; k++)
{
var j2 = _joins[k];
if (j2.Poly1Idx == j.Poly1Idx && InternalHelpers.PointIsVertex(j2.Pt1A, pt))
j2.Poly1Idx = j.Poly2Idx;
if (j2.Poly2Idx == j.Poly1Idx && InternalHelpers.PointIsVertex(j2.Pt2A, pt))
j2.Poly2Idx = j.Poly2Idx;
}
}