This is more of a geometry question than a physics one, but it relates to my attempts to make breakable objects, as described in this thread: http://www.box2d.org/forum/viewtopic.php?f=3&t=1401&st=0&sk=t&sd=a
Maybe someone knows about this kind of thing, and can help.
Cue poorly-hand-drawn and photographed image... It was easier for me than drawing it on the computer, and hopefully gets the point across:
Shape A is a convex shape with an arbitrary number of edges/verts (but, if it helps, I can make it a low maximum number, like 8). Shape B may or may not be concave. Depending on which makes the maths easiest, I can define either shape as just their outside points (clockwise or anti-clockwise), or as a "triangle soup" that makes up the object.
What I want to work out, is that when A intersects B, to get some kind of workable description of C (either as the outside edge points, or as a "triangle soup"), which is the shape that's left from subtracting A from B. How might I go about doing something like that? Scissoring something to a rectangle is relatively straightforward, but I don't know how to go about doing something like this.