Exporting FBX Animation

[JH12]

I am having difficulties exporting FBX animations for use in a particular piece of software (Zapworks Studio for AR), in Houdini 19.  
Don't concern yourself too much about Zapworks, but my problem seems to align with the fact that all the FBX animations I export from Houdini are static if I open them in Windows 3D model viewer.  Unlike if I were to export a similar FBX animation using say Blender, which all works fine.  
At this stage I am just testing with super simple translate/rotation/scale on basic polygonal geo and using the FBX Output Rop / FBX Export.
Is there something I am missing here?  
I heard that Houdini exports FBX a bit differently, using point caches.  Perhaps this is something to do with it, but is there a way around this? 



 

[ryew]

I can't speak of Windows 3D Model Viewer's capabilities, but FBX Exports have been available for quite some time from Houdini, so I'd suggest checking your FBX exports are working fine in another package - Blender or Maya for example - to ensure they work there to narrow down whether the problem is the exports or the Windows viewer

[JH12]

I think it is more to do with how Houdini exports FBX animation, notice Sketchfab cannot read them either https://help.sketchfab.com/hc/en-us/articles/208259013-Houdini

[ryew]

So a known issue then; seems like you might need to go the longer route of piping your Houdini exports through one of the other packages that does work as a bridge then, assuming Blender and/or Maya exports of the same would play nice.

[Alain2131]

Hi, it sounds like you're animating the meshes with a transform node and trying to export this to FBX ?
That will result in a point cache. Maya will understand that (don't know about Blender, but I would think that it would work). But for other applications (especially game engines), point caches are not supported.
For maximum compatibility, bones should be used.

Here's three ways to animate something.
Point Cache, "Geo Anim" (where the actual transform of the object is animated), and Bone Anim.

Anytime you animate something from within a Geo node, it is a point cache. That green clock next to a node generally means Point Cache when exported (unless special care is applied !)

Once you have something animated in this fashion, depending on the case it can go from slightly complicated to a very big pain to convert it to bones.
Rigid bodies can be converted to bones (if packed. Unpacked can be harder), soft bodies without changing topologies can use Dem Bones Skinning Converter, and if you have changing topology, then I have some bad news for you..

Geo Anim is probably what you expected. If you animate a mesh in Maya, 3DS Max (and I'd imagine Blender as well), this is equivalent.

Bone Anim is what you want. Thankfully, KineFX came in and made life much easier. We can animate bones in SOPs !
Getting to know how to work with it is a necessary step (I'm very much a beginner with it).

(This is very probably not an ideal setup for KineFX, as I said I'm not used to it. Note that there are two bones, because with a single one, Maya was converting it to a group, and not understanding the skin.)

The FBX exports for the point_cache and the bone_anim are in their geo node, and for geo_anim, look into the OUT context.

Here's a scene with the three above examples (in Non Commercial - I tested on my work PC, and duplicated the setup on my home PC. You can do the same, back to Indie or whatever license that can export FBX).
fbx_anim_export_examples.hipnc

I hope I answered your question somewhere in there !

Edited November 7, 2021 by Alain2131

[JH12]

On 07/11/2021 at 4:53 PM, Alain2131 said:

I hope I answered your question somewhere in there !

This has clarified a lot for me, thank you so much for the detailed reply, greatly appreciated!