/// <summary> /// /// </summary> /// <param name="opCode"></param> private void ComputeOverlay(SpatialFunction opCode) { // copy points from input Geometries. // This ensures that any Point geometries // in the input are considered for inclusion in the result set CopyPoints(0); CopyPoints(1); // node the input Geometries Arg[0].ComputeSelfNodes(LineIntersector, false); Arg[1].ComputeSelfNodes(LineIntersector, false); // --- Needs to convert args to monotonic edges or something. // compute intersections between edges of the two input geometries Arg[0].ComputeEdgeIntersections(Arg[1], LineIntersector, true); IList baseSplitEdges = new ArrayList(); Arg[0].ComputeSplitEdges(baseSplitEdges); Arg[1].ComputeSplitEdges(baseSplitEdges); // add the noded edges to this result graph InsertUniqueEdges(baseSplitEdges); ComputeLabelsFromDepths(); ReplaceCollapsedEdges(); _graph.AddEdges(_edgeList.Edges); ComputeLabelling(); LabelIncompleteNodes(); /* * The ordering of building the result Geometries is important. * Areas must be built before lines, which must be built before points. * This is so that lines which are covered by areas are not included * explicitly, and similarly for points. */ FindResultAreaEdges(opCode); CancelDuplicateResultEdges(); PolygonBuilder polyBuilder = new PolygonBuilder(_geomFact); polyBuilder.Add(_graph); _resultPolyList = polyBuilder.Polygons; LineBuilder lineBuilder = new LineBuilder(this, _geomFact, _ptLocator); _resultLineList = lineBuilder.Build(opCode); PointBuilder pointBuilder = new PointBuilder(this, _geomFact); _resultPointList = pointBuilder.Build(opCode); // gather the results from all calculations into a single Geometry for the result set _resultGeom = ComputeGeometry(_resultPointList, _resultLineList, _resultPolyList); }