[X3D-Ecosystem] Geometry nodes in Blender.

[John Carlson]

I’ve moved discussion here to include others:
https://projects.blender.org/extensions/io_scene_x3d/issues/64
<https://projects.blender.org/extensions/io_scene_x3d/issues/64#issuecomment-1374368>

On Sat, Dec 21, 2024 at 11:58 AM John Carlson <yottzumm at gmail.com> wrote:

> The trick on export is to traverse the non-bone joint+ hierarchy, and get
> the bone_parent to retrieve the bone head (joint center).  Then I look up
> the vertex groups from the bone name to get the weights and coordIndexes.
>
> Now the question is, do I put animations on bone joints or non-bone
> joints.  I think bone joints is best.  So when I traverse the non-bone
> hierarchy, I ignore empties that are joints, and do any animation on
> transforms or sites (which carry the mesh).  I am not aware that I can
> animate segments.  I still am not convinced that I’ll be able to
> distinguish Sites and Segments from Transforms on output.  I guess segments
> are direct children of joints.
>
> On Sat, Dec 21, 2024 at 9:26 AM John Carlson <yottzumm at gmail.com> wrote:
>
>> In summary, on Blender import, to enable x3d transform animation, I have
>> to create empty objects.   To enable skin weights, I need bones. That means
>> 2 hierarchies because armature has 2 hierarchies, one empties, etc, and one
>> bones.  We can’t multiply out the transform hierarchy and set matrix world
>> like we do in production because of transform animation.  I agree, it’s
>> super simple without animation.
>>
>> Some collada models expect the matrixes to be multiplied out on x3d
>> reimport and have hierarchical meshes. They don’t have animation.  Please
>> provide collada models with animation.  We might be able to fix x3d export
>> here if someone tells me how to handle hierarchical meshes.  In general,
>> all objects in blender have transforms, so this needs to be thought out.
>> Primarily, I think, each x3d object equivalent will have a transform and a
>> shape on export. I don’t know how I’m going to convert empties to sites and
>> segments except by name.  I think that’s implemented, I forget if I
>> disabled it or it’s not available on import.  This is one reason why the
>> exporter is in flux.  We probably can create an option on export.
>>
>> Some models have both skin and segments. We need segments to support
>> sites.
>>
>> Do we want animation import?  What I can probably do is detect animation
>> and  turn on hierarchical loading.
>>
>> At this point, OpenUSD looks super attractive if they opened up the .usda
>> grammar.  AFAIK, every prim has a matrix.
>>
>> If someone has a snapshot of an object attached to a parent bone in the
>> blender hierarchy, that would be super helpful.
>>
>> John
>>
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://web3d.org/pipermail/x3d-ecosystem_web3d.org/attachments/20241221/9cef3c55/attachment.html>