private static void FillLeftAboveEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
while (node.Prev.Point.X > edge.P.X)
{
// Check if next node is below the edge
Orientation o1 = TriangulationUtil.Orient2D(edge.Q, node.Prev.Point, edge.P);
if (o1 == Orientation.CW)
{
FillLeftBelowEdgeEvent(tcx, edge, node);
}
else
{
node = node.Prev;
}
}
}
private static void FillLeftBelowEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
if (node.Point.X > edge.P.X)
{
if (TriangulationUtil.Orient2D(node.Point, node.Prev.Point, node.Prev.Prev.Point) == Orientation.CW)
{
// Concave
FillLeftConcaveEdgeEvent(tcx, edge, node);
}
else
{
// Convex
FillLeftConvexEdgeEvent(tcx, edge, node);
// Retry this one
FillLeftBelowEdgeEvent(tcx, edge, node);
}
}
}
private static void FillRightConvexEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
// Next concave or convex?
if (TriangulationUtil.Orient2D(node.Next.Point, node.Next.Next.Point, node.Next.Next.Next.Point) ==
Orientation.CCW)
{
// Concave
FillRightConcaveEdgeEvent(tcx, edge, node.Next);
}
else
{
// Convex
// Next above or below edge?
if (TriangulationUtil.Orient2D(edge.Q, node.Next.Next.Point, edge.P) == Orientation.CCW)
{
// Below
FillRightConvexEdgeEvent(tcx, edge, node.Next);
}
else
{
// Above
}
}
}
private static void FillLeftConcaveEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
Fill(tcx, node.Prev);
if (node.Prev.Point != edge.P)
{
// Next above or below edge?
if (TriangulationUtil.Orient2D(edge.Q, node.Prev.Point, edge.P) == Orientation.CW)
{
// Below
if (TriangulationUtil.Orient2D(node.Point, node.Prev.Point, node.Prev.Prev.Point) == Orientation.CW)
{
// Next is concave
FillLeftConcaveEdgeEvent(tcx, edge, node);
}
else
{
// Next is convex
}
}
}
}
private static void FillEdgeEvent(DTSweepContext tcx, DTSweepConstraint edge, AdvancingFrontNode node)
{
if (tcx.EdgeEvent.Right)
{
FillRightAboveEdgeEvent(tcx, edge, node);
}
else
{
FillLeftAboveEdgeEvent(tcx, edge, node);
}
}