axiosengine/axios/Common/Decomposition/CDT/Delaunay/Sweep/AdvancingFront.cs

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2012-03-19 23:57:59 +00:00
/* Poly2Tri
* Copyright (c) 2009-2010, Poly2Tri Contributors
* http://code.google.com/p/poly2tri/
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of Poly2Tri nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// Changes from the Java version
// Removed BST code, but not all artifacts of it
// Future possibilities
// Eliminate Add/RemoveNode ?
// Comments comments and more comments!
using System;
using System.Text;
namespace Poly2Tri.Triangulation.Delaunay.Sweep
{
/**
* @author Thomas Åhlen (thahlen@gmail.com)
*/
public class AdvancingFront
{
public AdvancingFrontNode Head;
protected AdvancingFrontNode Search;
public AdvancingFrontNode Tail;
public AdvancingFront(AdvancingFrontNode head, AdvancingFrontNode tail)
{
Head = head;
Tail = tail;
Search = head;
AddNode(head);
AddNode(tail);
}
public void AddNode(AdvancingFrontNode node)
{
//_searchTree.put(node.key, node);
}
public void RemoveNode(AdvancingFrontNode node)
{
//_searchTree.delete( node.key );
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
AdvancingFrontNode node = Head;
while (node != Tail)
{
sb.Append(node.Point.X).Append("->");
node = node.Next;
}
sb.Append(Tail.Point.X);
return sb.ToString();
}
/// <summary>
/// MM: This seems to be used by LocateNode to guess a position in the implicit linked list of AdvancingFrontNodes near x
/// Removed an overload that depended on this being exact
/// </summary>
private AdvancingFrontNode FindSearchNode(double x)
{
// TODO: implement BST index
return Search;
}
/// <summary>
/// We use a balancing tree to locate a node smaller or equal to given key value
/// </summary>
public AdvancingFrontNode LocateNode(TriangulationPoint point)
{
return LocateNode(point.X);
}
private AdvancingFrontNode LocateNode(double x)
{
AdvancingFrontNode node = FindSearchNode(x);
if (x < node.Value)
{
while ((node = node.Prev) != null)
if (x >= node.Value)
{
Search = node;
return node;
}
}
else
{
while ((node = node.Next) != null)
if (x < node.Value)
{
Search = node.Prev;
return node.Prev;
}
}
return null;
}
/// <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 = FindSearchNode(px);
double nx = node.Point.X;
if (px == nx)
{
if (point != node.Point)
{
// We might have two nodes with same x value for a short time
if (point == node.Prev.Point)
{
node = node.Prev;
}
else if (point == node.Next.Point)
{
node = node.Next;
}
else
{
throw new Exception("Failed to find Node for given afront point");
//node = null;
}
}
}
else if (px < nx)
{
while ((node = node.Prev) != null)
{
if (point == node.Point)
{
break;
}
}
}
else
{
while ((node = node.Next) != null)
{
if (point == node.Point)
{
break;
}
}
}
Search = node;
return node;
}
}
}