Hi
Let me say this first: I am not really good at 3d graphics - I am the poor coder that has to do that stuff in our project, but I suck at the terminology.
> Do you want bone or object based animation?
Can you explain to me the difference? I can imagine what you mean by "object based" animation, what is "bone" based animation?
.3ds files do it like this: a matrix (actually different values - but you end up in a matrix) is stored for every mesh for every frame.
In every frame you take the mesh-matrix into account (i.e. multiply the current matrix by it) and render the mesh as usual (which means, to the end user, that it appears at a different position with different rotation and different scaling).
On the topic of uses:
Well, I use ac3d primarily for our game project, so my intention should be pretty clear
Anyway I think the most generic way is usually the "best" way.
The above way has the advantage that you can animate _any_ mesh in any way you want. The animations from a mesh apply to their child-meshes as well, which allows you to add some "dummy" meshes (that don't contain any vertices) so you can have the animation applied to the entire model using a single matrix only.
I have to admit I cannot really imagine any use that can not be done using this, but this may be due to the fact that I've never really been interested in 3d graphics a lot :-)
> Output to a video file?
This is, in my opinion, definitely mandatory. But also very easy: render each frame to a pixmap, then use mencoder to create the video. Only a small amount of code. We do it pretty similar in our project.
> Output to a renderer?
I have to admit that I'd like to know what you mean by that?
CU
Andi