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

[Andreas Plesch]

> 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