signalprocesser.voronoi.representation.triangulation.SharedEdgeRemoval Maven / Gradle / Ivy
/*
* "Concave" hulls by Glenn Hudson and Matt Duckham
*
* Source code downloaded from https://archive.md/l3Un5#selection-571.0-587.218 on 3rd November 2021.
*
* - This software is Copyright (C) 2008 Glenn Hudson released under Gnu Public License (GPL). Under
* GPL you are free to use, modify, and redistribute the software. Please acknowledge Glenn Hudson
* and Matt Duckham as the source of this software if you do use or adapt the code in further research
* or other work. For full details of GPL see http://www.gnu.org/licenses/gpl-3.0.txt.
* - This software comes with no warranty of any kind, expressed or implied.
*
* A paper with full details of the characteristic hulls algorithm is published in Pattern Recognition.
* Duckham, M., Kulik, L., Worboys, M.F., Galton, A. (2008) Efficient generation of simple polygons for
* characterizing the shape of a set of points in the plane. Pattern Recognition v41, 3224-3236
*
* The software was developed by Glenn Hudson while working with me as an RA. The characteristic shapes
* algorithm is collaborative work between Matt Duckham, Lars Kulik, Antony Galton, and Mike Worboys.
*
*/
package signalprocesser.voronoi.representation.triangulation;
import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeMap;
public class SharedEdgeRemoval {
/* ***************************************************** */
// Comparator for removeEdgesInOrderFromOuterBoundary() method
private static final Comparator EDGELENGTH_COMPARATOR = new Comparator() {
public int compare(VHalfEdge e1, VHalfEdge e2) {
if (e1.getLength() > e2.getLength()) return -1;
else if (e1.getLength() < e2.getLength()) return 1;
else {
// Note: duplicates are removed from the TreeMap that uses
// this comparator - so we really don't want to edges to
// be considered identical (not specified in java documentation)
if (e1.getY() < e2.getY()) return -1;
else if (e1.getY() > e2.getY()) return 1;
else if (e1.getX() < e2.getX()) return -1;
else if (e1.getX() > e2.getX()) return 1;
else return 0;
}
}
};
/* ***************************************************** */
// Reduce a system from it's outer boundary inward starting from
// it's longest length outer boundaries and moving inward
public static void removeEdgesInOrderFromOuterBoundary(VHalfEdge _outeredge, int length_cutoff) {
// Collect a list of outer edges
OrderedEdgeList outeredges = new OrderedEdgeList(_outeredge);
//System.out.println();
//System.out.println("************************************************");
//System.out.println("*** removeEdgesInOrderFromOuterBoundary()");
// Remove edges until we can't remove any more
boolean haschanged;
int edgesremoved = 0;
do {
haschanged = false;
Iterator iter = outeredges.values().iterator();
while ( iter.hasNext() ) {
VHalfEdge edge = iter.next();
//System.out.println("Considering removal of edge (" + edge.vertex.id + "," + edge.getConnectedVertex().id + ") - length=" + edge.getLength());
// Return if the length of the given edge is less than or equal to
// the minimum value allowed (i.e. the cut-off value)
if ( edge.getLength()<=length_cutoff ) {
return;
}
// Cannot remove if removal would leave only _one_ edge
// left coming from the given vertex.
if ( edge.vertex.getEdges().size()<=2 || edge.getConnectedVertex().getEdges().size()<=2 ) {
//System.out.println("Irregular");
continue;
}
// Cannot remove if removal would leave a _point_ where
// _two shapes_ are connected
VHalfEdge inneredge = edge.getConnectedVertex().getEdge(edge.vertex);
VVertex innertriangletopvertex = inneredge.next.getConnectedVertex();
if ( innertriangletopvertex.getEdge(TriangulationRepresentation.OUTER_VERTEXNUMBER)!=null ) {
//System.out.println("Irregular");
continue;
}
// Remove the edge if it's valid to do so
iter.remove();
edgesremoved++;
removeSingleOuterEdge( edge , outeredges );
haschanged = true;
break;
}
} while (( haschanged)
&&
( TriangulationRepresentation.MAX_EDGES_TO_REMOVE < 0
|| edgesremoved {
/* ************************************************* */
// Constructor
private OrderedEdgeList(VHalfEdge outeredge) {
super(EDGELENGTH_COMPARATOR);
addOuterEdges(outeredge);
}
public void addOuterEdges(VHalfEdge outeredge) {
// Check is not null and next is not null
if ( outeredge==null || outeredge.next==null ) {
return;
}
// Go round outside of shape
VHalfEdge curredge = outeredge;
do {
super.put(curredge, curredge);
} while ( (curredge=curredge.next).next!=null && curredge!=outeredge );
}
/* ************************************************* */
// Methods
public void addEdge(VHalfEdge edge) {
super.put(edge, edge);
}
/* ************************************************* */
}
/* ***************************************************** */
}