mapnik-changes.md

Mapnik working copy of clipper.

Why this fork?

• We want to adapt Mapnik geometries to clipper algorithms in a zero-copy way.
• This fork reworks the clipper c++ code to be able to pass in specialized data structures
• This fork also provides a shell script to rename clipper X and Y variables lowercase so they can be the same as Mapnik
• Once we forked we found it useful to make a few other modifications like:
• Using stable_sort to ensure test results are stable across Linux and OS X: mapnik/node-mapnik#442 (comment)
• To avoid abort on uncatchable/invalid exception: https://github.com/mapnik/clipper/commit/7c73dedbed7abcbc3aa0acc3bfbd7a62ff75e5ec

Currently developing and using the r493-mapnik branch in:

• https://github.com/mapbox/mapnik-vector-tile
• https://github.com/mapnik/node-mapnik

Details:

• We are using r493 rather than r494 due this this bug introduced in r494: mapbox/mapnik-vector-tile#115
• We have not tested with any commit greater than r494 (http://sourceforge.net/p/polyclipping/code/HEAD/tree/)
• See our changes: https://github.com/mapnik/clipper/compare/r493...r493-mapnik