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);
// 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();
if (!NodingValidatorDisabled)
{
var nv = new EdgeNodingValidator(edgeList.Edges);
nv.checkValid();
}
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();
var polyBuilder = new PolygonBuilder(geomFact);
polyBuilder.Add(graph);
resultPolyList = polyBuilder.Polygons;
var lineBuilder = new LineBuilder(this, geomFact, ptLocator);
resultLineList = lineBuilder.Build(opCode);
var pointBuilder = new PointBuilder(this, geomFact, ptLocator);
resultPointList = pointBuilder.Build(opCode);
// gather the results from all calculations into a single Geometry for the result set
resultGeom = ComputeGeometry(resultPointList, resultLineList, resultPolyList);
}
