I'm thinking weight paint but maybe I mean Dynamic Paint or even something else I'm unaware of. I have cell fractured a long thin cylinder which I am dropping onto a plane using Blender 2.71 Render (not BGE). It has been rotated a little so that its contact with the plane starts at the lowest shard and works its way to the top. Of course, the whole thing simply falls apart on first contact. So, I use rigid body constraints and this works fine keeping it together. What I want, however, is a progressive shatter as the cylinder shards come into contact. In other words, I want the shards which have not yet reached the plane to stay intact. Keyframing this one shard at a time is tedious, prone to error, and all but impossible when there are hundreds of shards.
Can I use weight paint or anything else to control the enable function (or any other property or function) associated with the constraints to switch from enabled to not enabled as a function of time (or frame number)(in other words, as a function of color)?