/// <summary>
/// Rotates a triangle pair one vertex CW
/// n2 n2
/// P +-----+ P +-----+
/// | t /| |\ t |
/// | / | | \ |
/// n1| / |n3 n1| \ |n3
/// | / | after CW | \ |
/// |/ oT | | oT \|
/// +-----+ oP +-----+
/// n4 n4
/// </summary>
private static void RotateTrianglePair(DelaunayTriangle t, TriangulationPoint p, DelaunayTriangle ot, TriangulationPoint op)
{
DelaunayTriangle n1 = t.NeighborCCW(p);
DelaunayTriangle n2 = t.NeighborCW(p);
DelaunayTriangle n3 = ot.NeighborCCW(op);
DelaunayTriangle n4 = ot.NeighborCW(op);
bool ce1 = t.GetConstrainedEdgeCCW(p);
bool ce2 = t.GetConstrainedEdgeCW(p);
bool ce3 = ot.GetConstrainedEdgeCCW(op);
bool ce4 = ot.GetConstrainedEdgeCW(op);
bool de1 = t.GetDelaunayEdgeCCW(p);
bool de2 = t.GetDelaunayEdgeCW(p);
bool de3 = ot.GetDelaunayEdgeCCW(op);
bool de4 = ot.GetDelaunayEdgeCW(op);
t.Legalize(p, op);
ot.Legalize(op, p);
// Remap dEdge
ot.SetDelaunayEdgeCCW(p, de1);
t.SetDelaunayEdgeCW(p, de2);
t.SetDelaunayEdgeCCW(op, de3);
ot.SetDelaunayEdgeCW(op, de4);
// Remap cEdge
ot.SetConstrainedEdgeCCW(p, ce1);
t.SetConstrainedEdgeCW(p, ce2);
t.SetConstrainedEdgeCCW(op, ce3);
ot.SetConstrainedEdgeCW(op, ce4);
// Remap neighbors
// XXX: might optimize the markNeighbor by keeping track of
// what side should be assigned to what neighbor after the
// rotation. Now mark neighbor does lots of testing to find
// the right side.
t.Neighbors.Clear();
ot.Neighbors.Clear();
if (n1 != null)
{
ot.MarkNeighbor(n1);
}
if (n2 != null)
{
t.MarkNeighbor(n2);
}
if (n3 != null)
{
t.MarkNeighbor(n3);
}
if (n4 != null)
{
ot.MarkNeighbor(n4);
}
t.MarkNeighbor(ot);
}
private static void EdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle triangle, TriangulationPoint point)
{
if (IsEdgeSideOfTriangle(triangle, ep, eq))
{
return;
}
TriangulationPoint p1 = triangle.PointCCW(point);
Orientation o1 = TriangulationUtil.Orient2d(eq, p1, ep);
if (o1 == Orientation.Collinear)
{
if (triangle.Contains(eq, p1))
{
triangle.MarkConstrainedEdge(eq, p1);
// We are modifying the constraint maybe it would be better to
// not change the given constraint and just keep a variable for the new constraint
tcx.EdgeEvent.ConstrainedEdge.Q = p1;
triangle = triangle.NeighborAcross(point);
EdgeEvent(tcx, ep, p1, triangle, p1);
}
else
{
throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet");
}
if (tcx.IsDebugEnabled)
{
Debug.WriteLine("EdgeEvent - Point on constrained edge");
}
return;
}
TriangulationPoint p2 = triangle.PointCW(point);
Orientation o2 = TriangulationUtil.Orient2d(eq, p2, ep);
if (o2 == Orientation.Collinear)
{
if (triangle.Contains(eq, p2))
{
triangle.MarkConstrainedEdge(eq, p2);
// We are modifying the constraint maybe it would be better to
// not change the given constraint and just keep a variable for the new constraint
tcx.EdgeEvent.ConstrainedEdge.Q = p2;
triangle = triangle.NeighborAcross(point);
EdgeEvent(tcx, ep, p2, triangle, p2);
}
else
{
throw new PointOnEdgeException("EdgeEvent - Point on constrained edge not supported yet");
}
if (tcx.IsDebugEnabled)
{
Debug.WriteLine("EdgeEvent - Point on constrained edge");
}
return;
}
if (o1 == o2)
{
// Need to decide if we are rotating CW or CCW to get to a triangle
// that will cross edge
if (o1 == Orientation.CW)
{
triangle = triangle.NeighborCCW(point);
}
else
{
triangle = triangle.NeighborCW(point);
}
EdgeEvent(tcx, ep, eq, triangle, point);
}
else
{
// This triangle crosses constraint so lets flippin start!
FlipEdgeEvent(tcx, ep, eq, triangle, point);
}
}