Can someone clarify this for me: (1) What is a keyframe system in a FPS? (2)(a)Am I right in assuming you need two separate frames in order to interpolate the intermediate frames between them? (2)(b) Does this mean you have to interpolate the values for every object and therefore every vertex in the world? (3) (a) How do you go about programming this? In particular, if you only need the keyframes applied to rotations (in order to smooth the animation) can you just use keyframes when you rotate or do you have to use them the whole time? (4) Do most FPS''s use keyframes, or do they make their games rotation smoother a different way (quaternions?) ? Paulcoz, again.

1) It means that an animation is represented as a list of rotations that occur to a node of the skeleton over time. Each node will have it''s own list and the nodes should be hierarchical (rotations applied to a node will affect all of its children too). You don''t necessarily need one rotation for every frame though. It depends on how smooth that model needs to be and how much processing power you have available.

2)a) In general, yes. For cyclic animations, you will always be interpolating between two frames.

2)b) Well only the animated ones. You transform every node of the object, then transform the vertices based on the node transforms and their relative positions.

3) I think the easiest thing to do is to only store rotation keyframes for the nodes, since your skeleton probably won''t need to deform, and store one set of translation keyframes that are applied to the root node.

4) Don''t know how most FPS''s do it, but if they are smart they would use keyframes and store the rotations as quats to make interpolation easier.

Hi FalloutBoy,

I probably should have mentioned I am particularly interested in using keyframes, quats or some other method to smooth CAMERA ROTATIONS rather than animation / models etc..

Thanks,
Paulcoz.