//------------------------------------------------------------------------------
private PolyPt FixupOutPolygon(PolyPt p, bool stripPointyEdgesOnly = false)
{
//FixupOutPolygon() - removes duplicate points and simplifies consecutive
//parallel edges by removing the middle vertex.
if (p == null) return null;
PolyPt pp = p, result = p, lastOK = null;
for (; ; )
{
if (pp.prev == pp || pp.prev == pp.next)
{
DisposePolyPts(pp);
return null;
}
//test for duplicate points and for same slope (cross-product) ...
if (PointsEqual(pp.pt, pp.next.pt) ||
SlopesEqual(pp.prev.pt, pp.pt, pp.next.pt))
{
lastOK = null;
pp.prev.next = pp.next;
pp.next.prev = pp.prev;
PolyPt tmp = pp;
if (pp == result) result = pp.prev;
pp = pp.prev;
tmp = null;
}
else if (pp == lastOK) break;
else
{
if (lastOK == null) lastOK = pp;
pp = pp.next;
}
}
return result;
}
//------------------------------------------------------------------------------
private void DisposePolyPts(PolyPt pp)
{
if (pp == null) return;
PolyPt tmpPp = null;
pp.prev.next = null;
while (pp != null)
{
tmpPp = pp;
pp = pp.next;
tmpPp = null;
}
}
//------------------------------------------------------------------------------
private bool FindSegment(ref PolyPt pp, IntPoint pt1, IntPoint pt2)
{
if (pp == null) return false;
PolyPt pp2 = pp;
do
{
if (PointsEqual(pp.pt, pt1) &&
(PointsEqual(pp.next.pt, pt2) || PointsEqual(pp.prev.pt, pt2)))
return true;
pp = pp.next;
}
while (pp != pp2);
return false;
}
//------------------------------------------------------------------------------
private PolyPt AddPolyPt(TEdge4 e, IntPoint pt)
{
bool ToFront = (e.side == EdgeSide.esLeft);
if( e.outIdx < 0 )
{
PolyPt newPolyPt = new PolyPt();
newPolyPt.pt = pt;
newPolyPt.isHole = IsHole(e);
m_PolyPts.Add(newPolyPt);
newPolyPt.next = newPolyPt;
newPolyPt.prev = newPolyPt;
e.outIdx = m_PolyPts.Count-1;
return newPolyPt;
} else
{
PolyPt pp = m_PolyPts[e.outIdx];
if (ToFront && PointsEqual(pt, pp.pt)) return pp;
if (!ToFront && PointsEqual(pt, pp.prev.pt)) return pp.prev;
PolyPt newPolyPt = new PolyPt();
newPolyPt.pt = pt;
newPolyPt.isHole = pp.isHole;
newPolyPt.next = pp;
newPolyPt.prev = pp.prev;
newPolyPt.prev.next = newPolyPt;
pp.prev = newPolyPt;
if (ToFront) m_PolyPts[e.outIdx] = newPolyPt;
return newPolyPt;
}
}
//------------------------------------------------------------------------------
private void ReversePolyPtLinks(PolyPt pp)
{
PolyPt pp1;
PolyPt pp2;
pp1 = pp;
do
{
pp2 = pp1.next;
pp1.next = pp1.prev;
pp1.prev = pp2;
pp1 = pp2;
} while (pp1 != pp);
}
//------------------------------------------------------------------------------
private PolyPt PolygonBottom(PolyPt pp)
{
PolyPt p = pp.next;
PolyPt result = pp;
while (p != pp)
{
if (p.pt.Y > result.pt.Y) result = p;
else if (p.pt.Y == result.pt.Y && p.pt.X < result.pt.X) result = p;
p = p.next;
}
return result;
}
//------------------------------------------------------------------------------
private bool IsClockwise(PolyPt pt)
{
Int64 area = 0;
PolyPt startPt = pt;
do
{
area += (Int64)pt.pt.X * pt.next.pt.Y - (Int64)pt.next.pt.X * pt.pt.Y;
pt = pt.next;
}
while (pt != startPt);
//area = area /2;
return area > 0; //reverse of normal formula because assuming Y axis inverted
}
//------------------------------------------------------------------------------
private PolyPt InsertPolyPtBetween(PolyPt p1, PolyPt p2, IntPoint pt)
{
PolyPt result = new PolyPt();
result.pt = pt;
result.isHole = p1.isHole;
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;
}