[Bf-animsys] Import of Joints (issues with leaf bones)

[Joshua Leung]

Hi,

Unless I'm missing something, why don't we just skip all animation on
child-less joints?

Some special subcases of this would be:
1) If a joint has no parent and no child, then it becomes a free-standing
bone of length 1 (default orientation?). Any transforms on that joint are
just mapped to that bone. (While bones of length 1 are probably too long,
users can easily adjust these post import. Otherwise, we could just set a
custom bone shape on such bones by default to hide the fact that they are
long buggers)
2) For a joint at the end of a chain, we could probably assume that any
positional information it stores is already attended to via the bone that
is formed between it and its parent


Regards,
Joshua



On Wed, Nov 27, 2013 at 2:38 AM, Gaia <gaia.clary at machinimatrix.org> wrote:

> Hi;
>
> When i try to import a rig (skeleton) from Maya (using collada)
> then i get into troublebecause Maya supports Joints and
> parent-child associations between joints.
>
> It is straight forward and easy to translate a parent-child
> association between 2 joints into one corresponding Blender
> Bone with head and tail. In this casethe parent-joint defines
> the bone-head, and the child-joint defines the bone-tail.
>
> That does no longer work nicely when a joint has no more child
> associations.In that case i can not find a straightforward
> transformation to a Blender bone.
>
> While the imported Joint still can define the bone-head, i
> have to guess the bone-tail. Actually this is exactly what is
> done right now when importing a skeletonfrom Collada. But
> this approach never creates satisfying results.
>
> So far i found 3 possible ways to get this fixed somehow:
>
> - One straight forward solution would be to allow zero length
>    bones (head==tail)in blender. But i guess this will result in
>    very ugly issues. So i believe this solution has to be skipped
>    right away.
>
> - One other solution could be to introduce "Joints" as bones with
>    head but no tail.Joints would need to contain a transformation
>    matrix in that case. Actually this iscurrently my favorite
>    solution.
>
> - And the most ugly solution would be to create "Mini Bones"
>    for leaf joints, that is: The bone tail is placed a tiny bit
>    away from the bone head (0.001 Blender units for exmaple)
> But then these bones would become very small and maybe you won't
>    find them in the display. so this is also not a good solution :(
>
> So what would make sense to you from the viewpoint of an animator ?
> What would be a good working solution for this ?
>
> And from a coder's point of view: What would be the best way to
> solve thisissue ?
>
> thanks,
> Gaia
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