JTS最近发布了1.11版本，新增了：
计算Delaunay三角网和Voronoi多边形：
[cc lang="java"]
import java.util.ArrayList;
import java.util.Collection;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryCollection;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.triangulate.DelaunayTriangulationBuilder;
import com.vividsolutions.jts.triangulate.VoronoiDiagramBuilder;
/**
*
* @author Sun Ning/SNDA
* @since 2010-3-3
*/
public class DelaunayAndVoronoiApp {
/**
* create some predefined sites
* @return
*/
public static Collection getPredefinedSites(){
double[][] coords = {{100,27},{28, 50},{29, 40},{32, 90}, {12, 26}};
ArrayList coordinates = new ArrayList(coords.length);
for(int i=0; i<coords.length; i++){
coordinates.add(new Coordinate(coords[i][0], coords[i][1]));
}
return coordinates;
}
/**
*
* @param coords
* @return a geometry collection of triangulations
*/
public static Geometry buildDelaunayTriangulation(Collection coords){
DelaunayTriangulationBuilder builder = new DelaunayTriangulationBuilder();
builder.setSites(coords);
return builder.getTriangles(new GeometryFactory());
}
/**
*
* @param coords
* @return a collection of polygons
*/
public static Geometry buildVoronoiDiagram(Collection coords){
VoronoiDiagramBuilder builder = new VoronoiDiagramBuilder();
builder.setSites(coords);
return builder.getDiagram(new GeometryFactory());
}
/**
*
* @param args
*/
public static void main(String[] args){
Collection coordinates = getPredefinedSites();
/**
* Delauny
*/
GeometryCollection triangulations
= (GeometryCollection)buildDelaunayTriangulation(coordinates);
int total = triangulations.getNumGeometries();
System.out.printf(“Total triangulations: %d\n”, total);
for(int i=0; i<total; i++){
Geometry g = triangulations.getGeometryN(i);
Coordinate[] coords = g.getCoordinates();
System.out.printf("Triangulation %d: ", i);
for(Coordinate c : coords){
System.out.printf("(%.3f, %.3f) ", c.x, c.y);
}
System.out.println();
}
/**
* Voronoi
*/
GeometryCollection diagram = (GeometryCollection)
buildVoronoiDiagram(coordinates);
int totalDia = diagram.getNumGeometries();
for(int i=0; i<totalDia; i++){
Geometry g = diagram.getGeometryN(i);
Coordinate[] coords = g.getCoordinates();
System.out.printf("Diagram %d: ", i);
for(Coordinate c : coords){
System.out.printf("(%.3f, %.3f) ", c.x, c.y);
}
System.out.println();
}
}
}
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输出：
[cc lang="text"]
Total triangulations: 5
Triangulation 0: (32.000, 90.000) (12.000, 26.000) (28.000, 50.000) (32.000, 90.000)
Triangulation 1: (32.000, 90.000) (28.000, 50.000) (100.000, 27.000) (32.000, 90.000)
Triangulation 2: (100.000, 27.000) (28.000, 50.000) (29.000, 40.000) (100.000, 27.000)
Triangulation 3: (100.000, 27.000) (29.000, 40.000) (12.000, 26.000) (100.000, 27.000)
Triangulation 4: (12.000, 26.000) (29.000, 40.000) (28.000, 50.000) (12.000, 26.000)
Diagram 0: (-76.000, 88.625) (-76.000, 178.000) (176.713, 178.000) (72.699, 65.730) (-38.235, 76.824) (-76.000, 88.625)
Diagram 1: (-76.000, -62.000) (-76.000, 88.625) (-38.235, 76.824) (11.978, 43.348) (56.422, -10.619) (57.006, -62.000) (-76.000, -62.000)
Diagram 2: (11.978, 43.348) (-38.235, 76.824) (72.699, 65.730) (67.316, 48.882) (11.978, 43.348)
Diagram 3: (176.713, 178.000) (188.000, 178.000) (188.000, -62.000) (57.006, -62.000) (56.422, -10.619) (67.316, 48.882) (72.699, 65.730) (176.713, 178.000)
Diagram 4: (11.978, 43.348) (67.316, 48.882) (56.422, -10.619) (11.978, 43.348)
[/cc]
将Geometry对象转换成Shape对象，绘制在JPanel上：
[cc lang="java"]
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.util.Collection;
import javax.swing.JFrame;
import javax.swing.JPanel;
import com.vividsolutions.jts.awt.ShapeWriter;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import java.util.Random;
/**
*
* @author Sun Ning/SNDA
* @since 2010-3-3
*/
public class JTS2Awt {
public static void showUI(final Shape… shape){
JFrame jframe = new JFrame("JTS Geometry to AWT Shape");
JPanel jp = new JPanel(){
@Override
public void paint(Graphics g){
super.paint(g);
Graphics2D g2d = (Graphics2D)g;
if(shape != null){
for(Shape s: shape){
g2d.setColor(new Color(Color.HSBtoRGB(new Random().nextFloat(), 1f, 0.6f)));
g2d.draw(s);
}
}
}
};
jp.setPreferredSize(new Dimension(150, 150));
jframe.getContentPane().add(jp);
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.pack();
jframe.setVisible(true);
}
public static Shape toShape(Geometry geom){
ShapeWriter writer = new ShapeWriter();
return writer.toShape(geom);
}
public static void main(String[] args){
Collection coords = DelaunayAndVoronoiApp.getPredefinedSites();
Geometry geomT = DelaunayAndVoronoiApp.buildDelaunayTriangulation(coords);
Geometry geomD = DelaunayAndVoronoiApp.buildVoronoiDiagram(coords);
showUI(toShape(geomT), toShape(geomD));
}
}
[/cc]
