Box2D has always had a function called TestSegment for colliding segments with shapes, but it really needed conversion into proper raycasts. Check out a Demo.
gamedev
b2ConcaveArc
My first proper contribution to the wonderful Box2D engine, specifically the Flash port. I’ve added a third shape type to the engine, which dramatically increases the possible shapes you can describe. Hopefully my contribution will also show other people how to add shapes, and some of the deeper aspects of the engine.
It’s easier to describe than see, so try out a demo: Demo