mbostock/d3 — pull request #821 by jasondavies (2012-09-24 09:31:54+00:00)
Title: Add projection.{line,polygon} support to d3.geo.path.

Something along these lines?

I'd be happy to develop this in d3-plugins first if you prefer, e.g. a wrapper to test the concept. I guess I could call it d3.geo.projection.clip, and it would return new GeoJSON feature instead of an SVG path.