Since the capsules are mathematically defined by a length and a radius there are no surfaces so I suggest using standard collision detection instead. There are standard intersection tests that return a collision normal along with a intersection distance. I'm guessing you can find it in most open source physics libraries or just google it.
If you need increased performance you can always attempt to use proxy objects or perhaps switch primitive from capsule to something easier.
Hope that helps, Pontus
Date: Wed, 3 Feb 2010 11:54:45 +0100 From: email@example.com To: firstname.lastname@example.org Subject: [Algorithms] Algorithm to return point to surface of concave volume
I have a point inside a concave volume, does anyone know of an algorithm to find the shortest vector from the point to the surface of the volume? The volume in this case is defined as the union of a number of overlapping capsules (lines with radius).