[X3D-Ecosystem] Geometry nodes in Blender.

[John Carlson]

The hard case is the segment and site geometry in my mind.

John

On Fri, Dec 20, 2024 at 4:07 AM Michalis Kamburelis <
michalis.kambi at gmail.com> wrote:

> > I think what you're saying is break a bone into 2 pieces, one with head
> plus center (now tail) and one with center (now head) plus tail.   This
> seems like an excellent idea.  I'm going to think on it a bit.
> > My question is, what do I name the 2 pieces?  I'm guessing something
> that I can combine on export.
>
> Indeed.
>
> As for new bone names: "Leg1_center" (when you need to add new Blender
> bone when "Leg1" joint has non-zero center in X3D/H-Anim) would look
> reasonable for me (and code can figure out what happened and invert
> it, so you can have round-trip that later exports it back into one
> "Leg1" joint with non-zero center). But that's just a suggestion.
>
> > This sounds like Zeno's paradox where I'm just trying to put weights
> where they don't go.  The weights go on the joints.  We only have weights
> for joints on import. ((well, I don't know all of X3D).
>
> Weights describe how much each joint influences each vertex. This is
> equal in Blender, X3D/H-Anim, glTF.
>
> I'm not sure if what you're saying is equivalent, but if yes -> OK :)
>
> > Remember I'm doing this in python, not in the Blender GUI.
>
> Sure, but it should be similar. That is, Blender's Python API exposes
> a superset of things that you can do from GUI and it uses the same
> terminology, mostly. And you can observe in Blender's console what
> your interactive operation "means" in Python, it's a valid way to
> learn Blender's Python API.
>
> > It sounds like I should give up on ever trying to import site or segment
> geometry, and *try* to do Joints and skin.
>
> I'm not sure what do you mean here :)
>
> The H-Anim "skin" (one mesh, with joints and weights) should map to
> Blender, because it is exactly the same concept in Blender. (OK, not
> *exactly* the same, e.g. Blender, because of history, calls "bones"
> what X3D/H-Anim and glTF call "joints"; but it is close to equivalent,
> for 3D graphic artists these are the same things).
>
> You don't need to "give up" on anything, from what I can see. Just
> import/export X3D/H-Anim skin to Blender's skin (Armature). This is
> what 3D artists would expect.
>
> Other features (like attaching rigid objects to sites, without skin)
> are a separate thing. They can be imported/exported e.g. as bones'
> children. But these are separate things, I'd advise to focus on the
> hard case (skin) first :)
>
> Regards,
> Michalis
>
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