public void Build(GeometryGraph geomGraph)
{
// compute nodes for intersections between previously noded edges
ComputeIntersectionNodes(geomGraph, 0);
// Copy the labelling for the nodes in the parent Geometry. These override
// any labels determined by intersections.
CopyNodesAndLabels(geomGraph, 0);
//Build EdgeEnds for all intersections.
EdgeEndBuilder eeBuilder = new EdgeEndBuilder();
ArrayList eeList = eeBuilder.ComputeEdgeEnds(geomGraph.EdgeIterator);
InsertEdgeEnds(eeList);
}
public IntersectionMatrix ComputeIM()
{
IntersectionMatrix im = new IntersectionMatrix();
// since Geometries are finite and embedded in a 2-D space, the EE element must always be 2
im.SetValue(LocationType.Exterior, LocationType.Exterior, 2);
// if the Geometries don't overlap there is nothing to do
if (!arg[0].Geometry.Bounds.Intersects(arg[1].Geometry.Bounds))
{
ComputeDisjointIM(im);
return(im);
}
arg[0].ComputeSelfNodes(li, false);
arg[1].ComputeSelfNodes(li, false);
// compute intersections between edges of the two input geometries
SegmentIntersector intersector = arg[0].ComputeEdgeIntersections(arg[1], li, false);
//System.out.println("computeIM: # segment intersection tests: " + intersector.numTests);
ComputeIntersectionNodes(0);
ComputeIntersectionNodes(1);
// Copy the labelling for the nodes in the parent Geometries. These override
// any labels determined by intersections between the geometries.
CopyNodesAndLabels(0);
CopyNodesAndLabels(1);
// complete the labelling for any nodes which only have a label for a single geometry
LabelIsolatedNodes();
// If a proper intersection was found, we can set a lower bound on the IM.
ComputeProperIntersectionIM(intersector, im);
// Now process improper intersections
// (eg where one or other of the geometries has a vertex at the intersection point)
// We need to compute the edge graph at all nodes to determine the IM.
// build EdgeEnds for all intersections
EdgeEndBuilder eeBuilder = new EdgeEndBuilder();
ArrayList ee0 = eeBuilder.ComputeEdgeEnds(arg[0].EdgeIterator);
InsertEdgeEnds(ee0);
ArrayList ee1 = eeBuilder.ComputeEdgeEnds(arg[1].EdgeIterator);
InsertEdgeEnds(ee1);
LabelNodeEdges();
// Compute the labeling for isolated components
// Isolated components are components that do not touch any
// other components in the graph.
// They can be identified by the fact that they will
// contain labels containing ONLY a single element, the one
// for their parent geometry.
// We only need to check components contained in the input graphs, since
// isolated components will not have been replaced by new components
// formed by intersections.
LabelIsolatedEdges(0, 1);
LabelIsolatedEdges(1, 0);
// update the IM from all components
UpdateIM(im);
return(im);
}
