README

Robust and tested library for boolean operations on polygons (union, intersection, difference, xor) in PHP.

Some improvements over other libraries: This one is tested (see end-to-end directory) and optimized to use polygons with large amount of vertex (ie, binary search when doing intersections between segments).

This library can use arrays with polygons, geojson strings or geojson files directly.

Resources

• To understand the algorithm, you can go here
• Based somewhat on the F. Martinez (2008) algorithm:
  • Website
  • A new algorithm for computing Boolean operations on polygons 2009 Research GateScience Direct
  • A simple algorithm for Boolean operations on polygons 2013

Examples

Some tests and demo implementation inside tests.php, extended coverage with PHPUnit:

• php tests.php
• ./vendor/bin/phpunit tests/
• ./vendor/phpstan/phpstan/phpstan --error-format=raw

For profiling:

• check that xdebug module is available and loaded: php -m | grep xdebug
• launch php with xdebug enabled: php
  -dxdebug.mode=profile
  -dxdebug.start_with_request=yes
  -dxdebug.output_dir=xdebug-profiler/
  tests.php

Tutorials and notes

• Interactive tutorial Polygon Clipping (Part 1)
• Interactive tutorial Polygon Clipping (Part 2)
• Notes on the Martinez-Rueda Polygon Clipping algorithm
• Let's build! Boolean operations of polygonsPart 1 - IntroductionPart 2 - Intersections

Improvements

• Speed improvement with inserts by bisection Pull

History

• This library is a port for PHP of pypolybool
• Previoulsy, was a port for JS of polybooljs
• Help from a .NET port