private static void FillRightConcaveEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
Fill(tcx, node.Next);
if (node.Next.Point != edge.P)
{
// Next above or below edge?
if (TriangulationUtil.Orient2d(edge.Q, node.Next.Point, edge.P) == Orientation.CCW)
{
// Below
if (TriangulationUtil.Orient2d(node.Point, node.Next.Point, node.Next.Next.Point) == Orientation.CCW)
{
// Next is concave
FillRightConcaveEdgeEvent(tcx, edge, node);
}
else
{
// Next is convex
}
}
}
}
/// <summary>
/// Creates a new front triangle and legalize it
/// </summary>
private static AdvancingFrontNode NewFrontTriangle(DTSweepContext tcx, TriangulationPoint point, AdvancingFrontNode node)
{
AdvancingFrontNode newNode;
DelaunayTriangle triangle;
triangle = new DelaunayTriangle(point, node.Point, node.Next.Point);
triangle.MarkNeighbor(node.Triangle);
tcx.Triangles.Add(triangle);
newNode = new AdvancingFrontNode(point);
newNode.Next = node.Next;
newNode.Prev = node;
node.Next.Prev = newNode;
node.Next = newNode;
tcx.AddNode(newNode); // XXX: BST
if (!Legalize(tcx, triangle))
{
tcx.MapTriangleToNodes(triangle);
}
return(newNode);
}
private static void FillEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
if (tcx.EdgeEvent.Right)
{
FillRightAboveEdgeEvent(tcx, edge, node);
}
else
{
FillLeftAboveEdgeEvent(tcx, edge, node);
}
}
/// <summary>
/// We will traverse the entire advancing front and fill it to form a convex hull.
/// </summary>
private static void TurnAdvancingFrontConvex(DTSweepContext tcx, AdvancingFrontNode b, AdvancingFrontNode c)
{
AdvancingFrontNode first = b;
while (c != tcx.Front.Tail)
{
if (TriangulationUtil.Orient2d(b.Point, c.Point, c.Next.Point) == Orientation.CCW)
{
// [b,c,d] Concave - fill around c
Fill(tcx, c);
c = c.Next;
}
else
{
// [b,c,d] Convex
if (b != first && TriangulationUtil.Orient2d(b.Prev.Point, b.Point, c.Point) == Orientation.CCW)
{
// [a,b,c] Concave - fill around b
Fill(tcx, b);
b = b.Prev;
}
else
{
// [a,b,c] Convex - nothing to fill
b = c;
c = c.Next;
}
}
}
}
