Class EdgeConnectedTriangleTraversal

1	/*
2	* Copyright (c) 2016 Vivid Solutions.
3	*
4	* All rights reserved. This program and the accompanying materials
5	* are made available under the terms of the Eclipse Public License 2.0
6	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
7	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
8	* and the Eclipse Distribution License is available at
9	*
10	* http://www.eclipse.org/org/documents/edl-v10.php.
11	*/
12
13	package org.locationtech.jts.triangulate.quadedge;
14
15	import java.util.Collection;
16	import java.util.LinkedList;
17
18	/**
19	* A framework to visit sets of edge-connected {@link QuadEdgeTriangle}s in breadth-first order
20	*
21	* @author Martin Davis
22	* @version 1.0
23	*/
24	public class EdgeConnectedTriangleTraversal {
25	private LinkedList triQueue = new LinkedList();
26
27	public EdgeConnectedTriangleTraversal() {}
28
29	public void init(QuadEdgeTriangle tri) {
30	triQueue.addLast(tri);
31	}
32
33	/**
34	* Called to initialize the traversal queue with a given set of {@link QuadEdgeTriangle}s
35	*
36	* @param tris a collection of QuadEdgeTriangle
37	*/
38	public void init(Collection tris) {
39	triQueue.addAll(tris);
40	}
41
42	/**
43	* Subclasses can call this method to add a triangle to the end of the queue. This is useful for
44	* initializing the queue to a chosen set of triangles.
45	*
46	* @param tri a triangle
47	*/
48	/*
49	* protected void addLast(QuadEdgeTriangle tri) { triQueue.addLast(tri); }
50	*/
51
52	/**
53	* Subclasses call this method to perform the visiting process.
54	*/
55	public void visitAll(TraversalVisitor visitor) {
56	while (!triQueue.isEmpty()) {
57	QuadEdgeTriangle tri = (QuadEdgeTriangle) triQueue.removeFirst();
58	process(tri, visitor);
59	}
60	}
61
62	private void process(QuadEdgeTriangle currTri, TraversalVisitor visitor) {
63	currTri.getNeighbours();
64	for (int i = 0; i < 3; i++) {
65	QuadEdgeTriangle neighTri = (QuadEdgeTriangle) currTri.getEdge(i).sym().getData();
66	if (neighTri == null)
67	continue;
68	if (visitor.visit(currTri, i, neighTri))
69	triQueue.addLast(neighTri);
70	}
71	}
72
73	}
74