THE BOOST.POLYGON LIBRARY

In the code snippet above the hypothetical polygon type CPolygon has been mapped to the library polygon concept and is used with library APIs to clip polygon list b against the bounding box of polygon list a and apply the disjoint-union of that with polygon list a deflated by some integer amount.  The end result is accumulated into a list of polygons with a union operation.  It is considerably more typing to describe this usage of the API than to code it, and the description is not much clearer than the code itself.  A picture is worth a thousand words.

In Boost.Polygon operations such as those shown above are free functions named for what they do, or are overloads of C++ operators that make it easy to infer from reading the code what to expect.  Operators are contained in the namespace boost::polygon::operators so that they can be used outside the boost::polygon namespace without bringing in the entire boost::polygon namespace.  Following the principle of least astonishment, the inferred behavior should generally match the actual behavior.  Conventions such as argument ordering (output arguments come first) and consistently applying the same semantics across different functions (accumulate) reduces the learning curve for new users while reducing the need to memorize semantics and argument ordering of many different functions for advanced users.

While the internal library code that implements this API is usually complex and cryptic due to heavy use of template meta-programming, the application of the library API in user code is usually simple and clear because it is free of any extraneous syntax.  The one exception to this is the mapping of user types to library concepts, which necessitates that the user perform some simple template programming and understand some of the internals of how the library concept type system works.  The examples below should aid the user in performing these programming tasks.

• Example files:
  • point_usage.cpp Using the library provided point data type and functions
  • custom_point.cpp Mapping a user defined point class to the library point_concept
  • polygon_usage.cpp Using the library provided polygon data types and functions
  • custom_polygon.cpp Mapping a user defined polygon class to the library polygon_concept
  • polygon_set_usage.cpp Using the library provided polygon set data types and functions
  • custom_polygon_set.cpp Mapping a user defined class to the library polygon_set_concept
  • connectivity_extraction_usage.cpp Using the connectivity extraction algorithm to build a connectivity graph on polygons
  • property_merge_usage.cpp Using the n-layer map-overlay algorithm on polygon data
• Tutorials:
  • Layout Versus Schematic Learn how to apply Boost.Polygon capabilities to implement a simplified circuit extraction application
  • Minkowski Sum Learn how to apply Boost.Polygon capabilities to implement Minkowski sum of polygon sets

We would like to thank: Thomas Klimpel, Frank Mori Hess, Barend Gehrels, Andreas Fabri, Jeffrey Hellrung, Tim Keitt, Markus Werle, Paul A. Bristow, Robert Stewart, Mathias Gaunard, Michael Fawcett, Steven Watanabe, Joachim Faulhaber, John Bytheway, Sebastian Redl, Mika Heiskanen, John Phillips, Kai Benndorf, Hartmut Kaiser, Arash Partow, Maurizio Vitale, Brandon Kohn, David Abrahams, Gordon Woodhull, Daniel James, John Maddock, Tom Brinkman, Bo Persson, Mateusz Loskot, Christian Henning, Jean-Sebastien Stoezel, for providing feedback and or formal review of the library as part of the boost submission process and Fernando Cacciola for graciously serving as review manager.