[OSM-dev] Advice sought on polygon-with-hole drawing

[Robert (Jamie) Munro]

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Frederik Ramm wrote:
| Hi,
|
|    I'm currently working on a Perl re-implementation of Osmarender. It
| is already almost feature complete; I've made an early announcement on
| the tiles at home list:
|
|
http://lists.openstreetmap.org/pipermail/tilesathome/2008-March/001903.html
|
| While the program generally aims to be 100% compatible to the XSLT
| implementation (using identical rule files), one thing I want to
| change is the way polygons with holes are drawn. I want to switch from
| the default evenodd rule (that relies on the directions of ways) to
| the nonzero rule, and use it like so (pseudo code, omitting all the
| filtering and layering stuff):

I think we should stick with the evenodd rule. It is not that difficult
for users when editing - colour on the right, it is neccesary for
coastlines, and there is nothing to gain by making it unneccesary. If
some renderers don't need the rule, it's going to be much harder to tell
people they are wrong when the draw things the wrong way round.

Robert (Jamie) Munro
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