Interpolate AABB for each animation, then merge (enlarge) the interpolated AABBs of the animations running concurrently.
That doesn't produce valid AABB's [when blending animations].
What I suggested is precompute the interpolated AABB of Animation A and, separately, of Animation B at several keyframes.
When animation A and B are both active at the same time, extend them.
I still don't follow.
If neither A nor B alone require the AABB to be extended, but blending A+B moves the character's fist 30cm outside the front of the AABB, how does your system know to extend the AABB to compensate?
But you're blending A + B. I'm talking about blending A + A' (A' is at a different time frame).
In the case you're specifying, there will be a third sample added specifically for the AABB between A and A' to deal with the increased depth.
For blending A + B, extending is the best/safest solution.
How do you extend the AABB? The increased depth is not present in A/A'/B/B'. The increased depth only appears after you blend A + B together.
It is possible for A + B to have bounds that have no relation whatsoever to the bounds of A and B individually. Look at the example again, or Johnny's example.
