ST_Force3D.java

/**
 * H2GIS is a library that brings spatial support to the H2 Database Engine
 * <http://www.h2database.com>. H2GIS is developed by CNRS
 * <http://www.cnrs.fr/>.
 *
 * This code is part of the H2GIS project. H2GIS 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;
 * version 3.0 of the License.
 *
 * H2GIS 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 <http://www.gnu.org/licenses/>.
 *
 *
 * For more information, please consult: <http://www.h2gis.org/>
 * or contact directly: info_at_h2gis.org
 */

package org.h2gis.functions.spatial.convert;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.CoordinateSequence;
import com.vividsolutions.jts.geom.CoordinateSequenceFilter;
import com.vividsolutions.jts.geom.Geometry;
import org.h2gis.api.DeterministicScalarFunction;

/**
 * Forces a Geometry into 3D mode by returning a copy with 
 * {@link Double.NaN} z-coordinates set to 0 (other z-coordinates are left untouched).
 *
 * @author Erwan Bocher
 */
public class ST_Force3D extends DeterministicScalarFunction {

    public ST_Force3D() {
        addProperty(PROP_REMARKS, "Forces the geometries into XYZ mode. This is an alias for ST_Force_3DZ.\n "
                + "If a geometry has no Z component, then a 0 Z coordinate is tacked on.");
    }

    @Override
    public String getJavaStaticMethod() {
        return "force3D";
    }

    /**
     * Converts a XY geometry to XYZ. If a geometry has no Z component, then a 0
     * Z coordinate is tacked on.
     *
     * @param geom
     * @return
     */
    public static Geometry force3D(Geometry geom) {
        if (geom == null) {
            return null;
        }
        Geometry outPut = (Geometry) geom.clone();
        outPut.apply(new CoordinateSequenceFilter() {
            private boolean done = false;

            @Override
            public boolean isGeometryChanged() {
                return true;
            }

            @Override
            public boolean isDone() {
                return done;
            }

            @Override
            public void filter(CoordinateSequence seq, int i) {
                Coordinate coord = seq.getCoordinate(i);
                double z = coord.z;
                if (Double.isNaN(z)) {
                    seq.setOrdinate(i, 2, 0);
                }
                if (i == seq.size()) {
                    done = true;
                }
            }
        });
        return outPut;
    }
}