/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jts.operation.buffer.validate;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.CoordinateFilter;
import org.locationtech.jts.geom.CoordinateSequence;
import org.locationtech.jts.geom.CoordinateSequenceFilter;
import org.locationtech.jts.geom.Geometry;
/**
* Finds the approximate maximum distance from a buffer curve to
* the originating geometry.
* This is similar to the Discrete Oriented Hausdorff distance
* from the buffer curve to the input.
* <p>
* The approximate maximum distance is determined by testing
* all vertices in the buffer curve, as well
* as midpoints of the curve segments.
* Due to the way buffer curves are constructed, this
* should be a very close approximation.
*
* @author mbdavis
*
*/
public class BufferCurveMaximumDistanceFinder
{
private Geometry inputGeom;
private PointPairDistance maxPtDist = new PointPairDistance();
public BufferCurveMaximumDistanceFinder(Geometry inputGeom)
{
this.inputGeom = inputGeom;
}
public double findDistance(Geometry bufferCurve)
{
computeMaxVertexDistance(bufferCurve);
computeMaxMidpointDistance(bufferCurve);
return maxPtDist.getDistance();
}
public PointPairDistance getDistancePoints()
{
return maxPtDist;
}
private void computeMaxVertexDistance(Geometry curve)
{
MaxPointDistanceFilter distFilter = new MaxPointDistanceFilter(inputGeom);
curve.apply(distFilter);
maxPtDist.setMaximum(distFilter.getMaxPointDistance());
}
private void computeMaxMidpointDistance(Geometry curve)
{
MaxMidpointDistanceFilter distFilter = new MaxMidpointDistanceFilter(inputGeom);
curve.apply(distFilter);
maxPtDist.setMaximum(distFilter.getMaxPointDistance());
}
public static class MaxPointDistanceFilter implements CoordinateFilter {
private PointPairDistance maxPtDist = new PointPairDistance();
private PointPairDistance minPtDist = new PointPairDistance();
private Geometry geom;
public MaxPointDistanceFilter(Geometry geom) {
this.geom = geom;
}
public void filter(Coordinate pt) {
minPtDist.initialize();
DistanceToPointFinder.computeDistance(geom, pt, minPtDist);
maxPtDist.setMaximum(minPtDist);
}
public PointPairDistance getMaxPointDistance() {
return maxPtDist;
}
}
public static class MaxMidpointDistanceFilter
implements CoordinateSequenceFilter
{
private PointPairDistance maxPtDist = new PointPairDistance();
private PointPairDistance minPtDist = new PointPairDistance();
private Geometry geom;
public MaxMidpointDistanceFilter(Geometry geom) {
this.geom = geom;
}
public void filter(CoordinateSequence seq, int index)
{
if (index == 0)
return;
Coordinate p0 = seq.getCoordinate(index - 1);
Coordinate p1 = seq.getCoordinate(index);
Coordinate midPt = new Coordinate(
(p0.x + p1.x)/2,
(p0.y + p1.y)/2);
minPtDist.initialize();
DistanceToPointFinder.computeDistance(geom, midPt, minPtDist);
maxPtDist.setMaximum(minPtDist);
}
public boolean isGeometryChanged() { return false; }
public boolean isDone() { return false; }
public PointPairDistance getMaxPointDistance() {
return maxPtDist;
}
}
}