bundles/addons/org.eclipse.apogy.addons.vehicle/src/org/eclipse/apogy/addons/vehicle/ClosestNeighbourIteratorProvider.java

/*******************************************************************************
 * Copyright (c) 2018 Agence spatiale canadienne / Canadian Space Agency
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Pierre Allard, 
 *     Regent L'Archeveque - initial API and implementation
 *     
 * SPDX-License-Identifier: EPL-1.0
 *     
 *******************************************************************************/
package org.eclipse.apogy.addons.vehicle;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import org.eclipse.apogy.common.geometry.data3d.CartesianTriangle;
import org.eclipse.apogy.common.geometry.data3d.CartesianTriangularMesh;
import org.jgrapht.DirectedGraph;
import org.jgrapht.alg.ConnectivityInspector;
import org.jgrapht.graph.DefaultDirectedGraph;
import org.jgrapht.graph.DefaultEdge;
import org.jgrapht.traverse.BreadthFirstIterator;

public class ClosestNeighbourIteratorProvider {
	private CartesianTriangularMesh mesh = null;
	private DirectedGraph<CartesianTriangle, DefaultEdge> graph = null;

	public ClosestNeighbourIteratorProvider(CartesianTriangularMesh mesh) {
		this.mesh = mesh;
	}

	public BreadthFirstIterator<CartesianTriangle, DefaultEdge> createBreadthFirstIterator(
			CartesianTriangle startTriangle) {
		if (startTriangle != null) {
			return new BreadthFirstIterator<CartesianTriangle, DefaultEdge>(getGraph(), startTriangle);
		} else {
			return new BreadthFirstIterator<CartesianTriangle, DefaultEdge>(getGraph());
		}
	}

	private DirectedGraph<CartesianTriangle, DefaultEdge> getGraph() {
		if (this.graph == null) {
			this.graph = new DefaultDirectedGraph<CartesianTriangle, DefaultEdge>(DefaultEdge.class);

			// Adds all triangles to the graph
			for (CartesianTriangle triangle : this.mesh.getPolygons()) {
				this.graph.addVertex(triangle);

			}

			// Adds edges between triangles representing neighbours relationships.
			for (CartesianTriangle triangle : this.mesh.getPolygons()) {
				List<CartesianTriangle> neighbours = this.mesh.getPolygonNeighbours(triangle);
				for (CartesianTriangle neighbour : neighbours) {
					if (!this.graph.containsEdge(triangle, neighbour)) {
						this.graph.addEdge(triangle, neighbour);
					}

					if (!this.graph.containsEdge(neighbour, triangle)) {
						this.graph.addEdge(neighbour, triangle);
					}
				}
			}

			// TODO Connects isolated group of triangle in a better way !
			ConnectivityInspector<CartesianTriangle, DefaultEdge> ci = new ConnectivityInspector<CartesianTriangle, DefaultEdge>(
					this.graph);
			List<Set<CartesianTriangle>> connectedSets = ci.connectedSets();
			for (Set<CartesianTriangle> set : connectedSets) {
				if (set.size() > 0) {
					// Creates a connection between this sets and the others.
					List<CartesianTriangle> setTriangles = new ArrayList<CartesianTriangle>(set);
					CartesianTriangle sourceTriangle = setTriangles.get(0);

					for (Set<CartesianTriangle> otherSet : connectedSets) {
						if (otherSet != set && otherSet.size() > 0) {
							List<CartesianTriangle> othersetTriangles = new ArrayList<CartesianTriangle>(otherSet);
							CartesianTriangle destinationTriangle = othersetTriangles.get(0);

							if (!this.graph.containsEdge(sourceTriangle, destinationTriangle)) {
								this.graph.addEdge(sourceTriangle, destinationTriangle);
							}

							if (!this.graph.containsEdge(destinationTriangle, sourceTriangle)) {
								this.graph.addEdge(destinationTriangle, sourceTriangle);
							}
						}
					}
				}
			}
		}
		return this.graph;
	}
}