Xna ModelBones - How to move them away from eachother?

Hello I know th开发者_StackOverflow中文版at one can get absolute transforms of bones in a model.. But how to move them away (like inflating) ? I think to do so, I need to move them forward to their local positions but what I have is the absolute transfoms by

Model.CopyAbsoluteBoneTransformsTo(ModelAllTransforms);

How to proceed further ? I mean I can use

mesh.ParentBone.Transform = Matrix.CreateTranslation(?) * ModelAllTransforms;

but what would be the ? sign ..

Thanks a lot! :)

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The direction you're looking for is basically the local bone's absolute transform minus the center, then normalized.

Something like this:

//"time" is your timing value, "speed" is some float value
Vector3 direction = bone.Translation - center;
direction.Normalize();
Vector3 translate = time * speed * direction;
bone.Translation += translate;