com.vividsolutions.jts.triangulate.NonEncroachingSplitPointFinder Maven / Gradle / Ivy

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/*
 * The JTS Topology Suite is a collection of Java classes that
 * implement the fundamental operations required to validate a given
 * geo-spatial data set to a known topological specification.
 *
 * Copyright (C) 2001 Vivid Solutions
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * For more information, contact:
 *
 *     Vivid Solutions
 *     Suite #1A
 *     2328 Government Street
 *     Victoria BC  V8T 5G5
 *     Canada
 *
 *     (250)385-6040
 *     www.vividsolutions.com
 */

package com.vividsolutions.jts.triangulate;


import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.LineSegment;

/**
 * A strategy for finding constraint split points which attempts to maximise the length of the split
 * segments while preventing further encroachment. (This is not always possible for narrow angles).
 * 
 * @author Martin Davis
 */
public class NonEncroachingSplitPointFinder implements ConstraintSplitPointFinder {

    public NonEncroachingSplitPointFinder() {}

    /**
     * A basic strategy for finding split points when nothing extra is known about the geometry of
     * the situation.
     * 
     * @param seg the encroached segment
     * @param encroachPt the encroaching point
     * @return the point at which to split the encroached segment
     */
    public Coordinate findSplitPoint(Segment seg, Coordinate encroachPt) {
        LineSegment lineSeg = seg.getLineSegment();
        double segLen = lineSeg.getLength();
        double midPtLen = segLen / 2;
        SplitSegment splitSeg = new SplitSegment(lineSeg);

        Coordinate projPt = projectedSplitPoint(seg, encroachPt);
        /**
         * Compute the largest diameter (length) that will produce a split segment which is not
         * still encroached upon by the encroaching point (The length is reduced slightly by a
         * safety factor)
         */
        double nonEncroachDiam = projPt.distance(encroachPt) * 2 * 0.8; // .99;
        double maxSplitLen = nonEncroachDiam;
        if (maxSplitLen > midPtLen) {
            maxSplitLen = midPtLen;
        }
        splitSeg.setMinimumLength(maxSplitLen);

        splitSeg.splitAt(projPt);

        return splitSeg.getSplitPoint();
    }

    /**
     * Computes a split point which is the projection of the encroaching point on the segment
     * 
     * @param seg
     * @param encroachPt
     * @return a split point on the segment
     */
    public static Coordinate projectedSplitPoint(Segment seg, Coordinate encroachPt) {
        LineSegment lineSeg = seg.getLineSegment();
        Coordinate projPt = lineSeg.project(encroachPt);
        return projPt;
    }
}