/// <summary>
/// This implementation will use simple node traversal algorithm to find a point on the front
/// </summary>
public AdvancingFrontNode LocatePoint(TriangulationPoint point)
{
double px = point.X;
AdvancingFrontNode node = _search;
double nx = node.Point.X;
// ReSharper disable CompareOfFloatsByEqualityOperator
if (px == nx)
// ReSharper restore CompareOfFloatsByEqualityOperator
{
if (!point.Equals(node.Point))
{
// We might have two nodes with same x value for a short time
if (point.Equals(node.Prev.Point))
{
node = node.Prev;
}
else if (point.Equals(node.Next.Point))
{
node = node.Next;
}
else
{
throw new Exception("Failed to find Node for given afront point");
}
}
}
else if (px < nx)
{
while ((node = node.Prev) != null)
{
if (point.Equals(node.Point))
{
break;
}
}
}
else
{
while ((node = node.Next) != null)
{
if (point.Equals(node.Point))
{
break;
}
}
}
_search = node;
return(node);
}
private static void FlipEdgeEvent(DTSweepContext tcx, TriangulationPoint ep, TriangulationPoint eq, DelaunayTriangle t, TriangulationPoint p)
{
DelaunayTriangle ot = t.NeighborAcrossFrom(p);
TriangulationPoint op = ot.OppositePoint(t, p);
if (ot == null)
{
// If we want to integrate the fillEdgeEvent do it here
// With current implementation we should never get here
throw new InvalidOperationException("[BUG:FIXME] FLIP failed due to missing triangle");
}
if (tcx.IsDebugEnabled)
{
tcx.DebugContext.PrimaryTriangle = t;
tcx.DebugContext.SecondaryTriangle = ot;
} // TODO: remove
bool inScanArea = TriangulationUtil.InScanArea(p, t.PointCCWFrom(p), t.PointCWFrom(p), op);
if (inScanArea)
{
// Lets rotate shared edge one vertex CW
RotateTrianglePair(t, p, ot, op);
tcx.MapTriangleToNodes(t);
tcx.MapTriangleToNodes(ot);
if (p.Equals(eq) && op.Equals(ep))
{
if (eq.Equals(tcx.EdgeEvent.ConstrainedEdge.Q) && ep.Equals(tcx.EdgeEvent.ConstrainedEdge.P))
{
if (tcx.IsDebugEnabled)
{
Console.WriteLine("[FLIP] - constrained edge done"); // TODO: remove
}
t.MarkConstrainedEdge(ep, eq);
ot.MarkConstrainedEdge(ep, eq);
Legalize(tcx, t);
Legalize(tcx, ot);
}
else
{
if (tcx.IsDebugEnabled)
{
Console.WriteLine("[FLIP] - subedge done"); // TODO: remove
}
// XXX: I think one of the triangles should be legalized here?
}
}
else
{
if (tcx.IsDebugEnabled)
{
Console.WriteLine("[FLIP] - flipping and continuing with triangle still crossing edge"); // TODO: remove
}
Orientation o = TriangulationUtil.Orient2d(eq, op, ep);
t = NextFlipTriangle(tcx, o, t, ot, p, op);
FlipEdgeEvent(tcx, ep, eq, t, p);
}
}
else
{
TriangulationPoint newP;
if (NextFlipPoint(ep, eq, ot, op, out newP))
{
FlipScanEdgeEvent(tcx, ep, eq, t, ot, newP);
EdgeEvent(tcx, ep, eq, t, p);
}
}
}
/// <summary>
/// If this is a Delaunay Triangulation of a pointset we need to fill so the triangle mesh gets a ConvexHull
/// </summary>
private static void FinalizationConvexHull(DTSweepContext tcx)
{
DelaunayTriangle t1, t2;
AdvancingFrontNode n1 = tcx.Front.Head.Next;
AdvancingFrontNode n2 = n1.Next;
TurnAdvancingFrontConvex(tcx, n1, n2);
// Lets remove triangles connected to the two "algorithm" points
// XXX: When the first three nodes are points in a triangle we need to do a flip before
// removing triangles or we will lose a valid triangle.
// Same for last three nodes!
// !!! If I implement ConvexHull for lower right and left boundary this fix should not be
// needed and the removed triangles will be added again by default
n1 = tcx.Front.Tail.Prev;
if (n1.Triangle.Contains(n1.Next.Point) && n1.Triangle.Contains(n1.Prev.Point))
{
t1 = n1.Triangle.NeighborAcrossFrom(n1.Point);
RotateTrianglePair(n1.Triangle, n1.Point, t1, t1.OppositePoint(n1.Triangle, n1.Point));
tcx.MapTriangleToNodes(n1.Triangle);
tcx.MapTriangleToNodes(t1);
}
n1 = tcx.Front.Head.Next;
if (n1.Triangle.Contains(n1.Prev.Point) && n1.Triangle.Contains(n1.Next.Point))
{
t1 = n1.Triangle.NeighborAcrossFrom(n1.Point);
RotateTrianglePair(n1.Triangle, n1.Point, t1, t1.OppositePoint(n1.Triangle, n1.Point));
tcx.MapTriangleToNodes(n1.Triangle);
tcx.MapTriangleToNodes(t1);
}
// Lower right boundary
TriangulationPoint first = tcx.Front.Head.Point;
n2 = tcx.Front.Tail.Prev;
t1 = n2.Triangle;
TriangulationPoint p1 = n2.Point;
n2.Triangle = null;
do
{
tcx.RemoveFromList(t1);
p1 = t1.PointCCWFrom(p1);
if (p1.Equals(first))
{
break;
}
t2 = t1.NeighborCCWFrom(p1);
t1.Clear();
t1 = t2;
} while (true);
// Lower left boundary
first = tcx.Front.Head.Next.Point;
p1 = t1.PointCWFrom(tcx.Front.Head.Point);
t2 = t1.NeighborCWFrom(tcx.Front.Head.Point);
t1.Clear();
t1 = t2;
while (p1.Equals(first))
{
tcx.RemoveFromList(t1);
p1 = t1.PointCCWFrom(p1);
t2 = t1.NeighborCCWFrom(p1);
t1.Clear();
t1 = t2;
}
// Remove current head and tail node now that we have removed all triangles attached
// to them. Then set new head and tail node points
tcx.Front.Head = tcx.Front.Head.Next;
tcx.Front.Head.Prev = null;
tcx.Front.Tail = tcx.Front.Tail.Prev;
tcx.Front.Tail.Next = null;
}
