[Bf-committers] blender2.5's new IK

[Benoit Bolsee]

On Mon, 31 Aug 2009 10:49:32 +0200 Brecht Van Lommel
<brecht at blender.org> wrote :
> 
> I don't think the cache is good default behavior for 
> animators. It may be for robotics but Blender is primarily an 
> application for animations, so in my opinion it should be 
> disabled by default. When you're posing a character on a 
> particular frame, you want to see how it looks immediately, 
> while you're grabbing the hand. Seeing it only when you 
> release, or even later in a playback, that would be a big 
> step back in my opinion.
> 

The new solver is stateful, which implies caching the pose for previous
frames if you want to be able to go back and forth in time in a reliable
way. Having a stateful solver has some definite advantages: speed and
consistency of the armature movements. The drawback is the cache issues
that we are discussing now.
Actually it is possible to disable caching (as it's done in the BGE). In
this case, the solver simply starts from the current pose position in
all cases. This has the advantage of being fast all the time but it
makes the animation unreliable: running the same animation twice might
give a different result since the start pose of the second run is the
end pose of the first run. I don't think this is a desirable effect but
it can be an option in the solver.

/benoit