### Contents

- Boost.Polygon Main Page
- Design Overview
- Isotropy
- Coordinate Concept
- Interval Concept
- Point Concept
- Rectangle Concept
- Polygon 90 Concept
- Polygon 90 With Holes Concept
- Polygon 45 Concept
- Polygon 45 With Holes Concept
- Polygon Concept
- Polygon With Holes Concept
- Polygon 90 Set Concept
- Polygon 45 Set Concept
- Polygon Set Concept
- Connectivity Extraction 90
- Connectivity Extraction 45
- Connectivity Extraction
- Property Merge 90
- Property Merge 45
- Property Merge

### Other Resources

- GTL Boostcon 2009 Paper
- GTL Boostcon 2009 Presentation
- Performance Analysis
- Layout Versus Schematic Tutorial
- Minkowski Sum Tutorial

### Polygon Sponsor

# Connectivity Extraction 45

The connectivity extraction algorithm constructs the connectivity graph where input polygon sets are modeled as graph nodes and assigned node ids and overlap/touching between input polygon sets is modeled as graph edges. One supported graph formats is std::vector<std::set<int> > where node ids index into the vector and the sets of integers at each index are the ids of nodes for which an edge exists in the graph. It is required that such vector pre-allocate sufficient elements to store the graph generated by the algorithm, because only the operator[] is used internally to access the graph The other supported graph format is std::map<int, std::set<int> > which is slightly easier to work with, but potentially more expensive. Improving the interface to support more generic graph concepts is deferred to future work.

The following is the declaration of the connectivity extraction algorithm.

template <typename coordinate_type>
class connectivity_extraction_45;

Example code connectivity_extraction_usage.cpp demonstrates using the connectivity extraction algorithm to build a connectivity graph on geometry.

## Member Functions

connectivity_extraction_45() | Default constructor.
connectivity_extraction_45( const connectivity_extraction_45& that) | Copy construct.
unsigned int insert(const polygon_45_set_data<coordinate_type>& ps) | Insert a polygon set graph node, the value returned is the id of the graph node.
template <class GeoObjT> unsigned int insert(const GeoObjT& geoObj) | Insert a geometry object that is a refinement of polygon 45 set as a graph node, the return value is the id of the graph node.
template <class GraphT> void extract(GraphT& graph) | Accepts a graph object that conforms to the expectations defined above. Performs connectivity extraction and populates the graph object.

Copyright: | Copyright © Intel Corporation 2008-2010.
License: | Distributed under the Boost Software License, Version 1.0. (See accompanying file `LICENSE_1_0.txt` or copy at http://www.boost.org/LICENSE_1_0.txt)