[x3d-public] Blender > Exporting rig transforms to HAnim?

[John Carlson]

I had a thought that this might be handled by NURBS?

John

On Tue, Jun 27, 2023 at 7:19 AM Michalis Kamburelis <
michalis.kambi at gmail.com> wrote:

> Indeed glTF has additional interpolation options, and I think it would
> make sense to add them to X3D.
>
> Looks like X3DOM and view3dscene/Castle Game Engine go in this
> direction already :)
>
> 1. X3DOM has SFString "interpolation" field, default "LINEAR", see
> https://doc.x3dom.org/author/Interpolation/X3DInterpolatorNode.html .
> Andreas above explained how it supports "CUBICSPLINE" option.
>
> 2. view3dscene / Castle Game Engine allow to use "STEP" interpolation
> explicitly.
>
>     For this, we add such field:
>
>     SFString [in,out]   interpolation  "LINEAR" # range: ["LINEAR"|"STEP"]
>
>     .. to all X3DInterpolatorNode descendants (so, all interpolator
> nodes). This seems exactly like X3DOM, we just added "STEP", where
> X3DOM added "CUBICSPLINE". In the end we should probably have all
> ["LINEAR"|"STEP"|"CUBICSPLINE"].
>
> 3. Note that even without this field, with default linear
> interpolation, it was possible to have effectively step interpolation,
> as Andreas mentions. You can just duplicate keys in the middle, like
>
>     key [0 0.33 0.33 0.66 0.66]
>     keyValue [10 10 20 20 30 30]
>     # interpolation "LINEAR"
>
>     This is valid with X3D ("""keys shall be monotonically
> non-decreasing""" according to spec).
>
>     It is equivalent to
>
>     key [0 0.33 0.66]
>     keyValue [10 20 30]
>     interpolation "STEP"
>
>     Using explicit "STEP" is slightly better, as you need 50% less
> memory to store it, less computation (no need to do lerp or detect
> this special case to optimize), and seems just simpler for authors --
> it specifies intention explicitly, which makes sense, also if one
> hopes a round-trip e.g. import to Blender and export to Blender.
>
>     Having such additional interpolation options seems common, glTF
> and Blender too have them (
>
> https://docs.blender.org/manual/en/latest/editors/graph_editor/fcurves/properties.html#editors-graph-fcurves-settings-interpolation
> ).
>
> 4. Note that view3dscene / Castle Game Engine do not support
> "CUBICSPLINE" interpolation yet, but we plan to.
>
>     For now we support curve interpolation by adding extra
> intermediate keys to the linear interpolation -- so, we have
> needlessly more keys / key values. But this is only a temporary
> solution, we want to support "CUBICSPLINE" properly, like X3DOM.
>
> Regards,
> Michalis
>
> niedz., 25 cze 2023 o 05:33 Andreas Plesch <andreasplesch at gmail.com>
> napisał(a):
> >
> > > Date: Sat, 24 Jun 2023 10:11:03 -0700
> > > From: Joseph D Williams <joedwil at earthlink.net>
> > > To: Michalis Kamburelis <michalis.kambi at gmail.com>
> > > Cc: GPU Group <gpugroup at gmail.com>,  X3D Graphics public mailing list
> > >         <x3d-public at web3d.org>
> > > Subject: Re: [x3d-public] Blender > Exporting rig transforms to HAnim?
> >
> > > Which shows that yes, you have a list of the key times that just have
> to be ascending. Default is  linear interpolation between keyvalues. Now
> new to me, I like the STEP option where value not interpolated but stays
> the same until next keyvalue change. For that effect, gltf makes it easier.
> I want that STEP option in x3d! And then there is also the cubic spline
> with specified tangents. Me want that one too.
> >
> > In order to support glTF x3dom added a CUBICSPLINE with tangents
> > option to interpolators, in the same form as glTF, eg. three values
> > (in tangent, value, out tangent) per key. Parallel to glTF x3dom
> > interpolators have a "interpolation" SFString field which can have
> > "LINEAR" and "CUBICSPLINE" values. I suspect due to glTF support other
> > viewers also already do something like that and could expose such a
> > mode to regular X3D.
> >
> > A STEP option is already elegantly solved by X3D with duplicate keys
> > with different values in series. That allows mixing step wise and
> > linear interpolation in one animation. x3dom just translates glTF STEP
> > to that format which is very straightforward. A dedicated STEP option
> > would be 50% more efficient in storage but I am not sure if this is
> > enough of a benefit to justify duplication of existing functionality.
> > It may not or it may as x3dom already does it internally for glTF. It
> > would be possible to add to x3d as well but perhaps not necessary.
> >
> > Andreas
> >
> > _______________________________________________
> > x3d-public mailing list
> > x3d-public at web3d.org
> > http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>
> _______________________________________________
> x3d-public mailing list
> x3d-public at web3d.org
> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://web3d.org/pipermail/x3d-public_web3d.org/attachments/20230627/ab42751c/attachment-0001.html>