package com.vividsolutions.jts.operation.overlay.snap;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.operation.overlay.OverlayOp;
import com.vividsolutions.jts.precision.CommonBitsRemover;
/**
* Performs an overlay operation using snapping and enhanced precision
* to improve the robustness of the result.
* This class <i>always</i> uses snapping.
* This is less performant than the standard JTS overlay code,
* and may even introduce errors which were not present in the original data.
* For this reason, this class should only be used
* if the standard overlay code fails to produce a correct result.
*
* @author Martin Davis
* @version 1.7
*/
public class SnapOverlayOp
{
public static Geometry overlayOp(Geometry g0, Geometry g1, int opCode)
{
SnapOverlayOp op = new SnapOverlayOp(g0, g1);
return op.getResultGeometry(opCode);
}
public static Geometry intersection(Geometry g0, Geometry g1)
{
return overlayOp(g0, g1, OverlayOp.INTERSECTION);
}
public static Geometry union(Geometry g0, Geometry g1)
{
return overlayOp(g0, g1, OverlayOp.UNION);
}
public static Geometry difference(Geometry g0, Geometry g1)
{
return overlayOp(g0, g1, OverlayOp.DIFFERENCE);
}
public static Geometry symDifference(Geometry g0, Geometry g1)
{
return overlayOp(g0, g1, OverlayOp.SYMDIFFERENCE);
}
private Geometry[] geom = new Geometry[2];
private double snapTolerance;
public SnapOverlayOp(Geometry g1, Geometry g2)
{
geom[0] = g1;
geom[1] = g2;
computeSnapTolerance();
}
private void computeSnapTolerance()
{
snapTolerance = GeometrySnapper.computeOverlaySnapTolerance(geom[0], geom[1]);
// System.out.println("Snap tol = " + snapTolerance);
}
public Geometry getResultGeometry(int opCode)
{
// Geometry[] selfSnapGeom = new Geometry[] { selfSnap(geom[0]), selfSnap(geom[1])};
Geometry[] prepGeom = snap(geom);
Geometry result = OverlayOp.overlayOp(prepGeom[0], prepGeom[1], opCode);
return prepareResult(result);
}
private Geometry selfSnap(Geometry geom)
{
GeometrySnapper snapper0 = new GeometrySnapper(geom);
Geometry snapGeom = snapper0.snapTo(geom, snapTolerance);
//System.out.println("Self-snapped: " + snapGeom);
//System.out.println();
return snapGeom;
}
private Geometry[] snap(Geometry[] geom)
{
Geometry[] remGeom = removeCommonBits(geom);
// MD - testing only
// Geometry[] remGeom = geom;
Geometry[] snapGeom = GeometrySnapper.snap(remGeom[0], remGeom[1], snapTolerance);
// MD - may want to do this at some point, but it adds cycles
// checkValid(snapGeom[0]);
// checkValid(snapGeom[1]);
/*
System.out.println("Snapped geoms: ");
System.out.println(snapGeom[0]);
System.out.println(snapGeom[1]);
*/
return snapGeom;
}
private Geometry prepareResult(Geometry geom)
{
cbr.addCommonBits(geom);
return geom;
}
private CommonBitsRemover cbr;
private Geometry[] removeCommonBits(Geometry[] geom)
{
cbr = new CommonBitsRemover();
cbr.add(geom[0]);
cbr.add(geom[1]);
Geometry remGeom[] = new Geometry[2];
remGeom[0] = cbr.removeCommonBits((Geometry) geom[0].clone());
remGeom[1] = cbr.removeCommonBits((Geometry) geom[1].clone());
return remGeom;
}
private void checkValid(Geometry g)
{
if (! g.isValid()) {
System.out.println("Snapped geometry is invalid");
}
}
}