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Retarget apex blendshapes from animated skeleton

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alexandrkchaika
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Hello everyone,

I'm looking for the best workflow to retarget blendshape animation from an original animated skeleton to the sliders on a new Apex rig.

My source skeleton has animated attributes that drive the blendshapes. My new Apex rig has corresponding blendshape sliders created by the auto-rig tool. I want to use the animation from the source skeleton to drive these sliders procedurally.

I've been exploring how to connect them, but I'm not sure of the standard approach. Is there a way to drive these abstract slider controls from skeleton attributes?

As an alternative, I was wondering if it's possible to procedurally generate or modify an Apex .clip file with this animation data. Could a script be used to write the skeleton's animation into a clip that I can then apply to the rig?

Any advice or examples on how to achieve this would be a great help.

Thanks in advance!
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edward
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Here's an example I had lying around for just the eyebrows. Basically, you just need to remap the animation values in to a detail attribute named "parms" that changes every frame. Then the APEX Add Animation SOP can create channel primitives inside your APEX scene using it.

Attachments:
blendshape_example.png (668.4 KB)

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luoqiulin
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https://vimeo.com/user3971456/videos [vimeo.com]
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coonerdltd
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I have problems with the python...Can you shear an example?
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edward
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Here's the code. But you need to make sure you customize this for your FBX file and rig so that the names match. Also, if you have too old a Houdini version, you might not even have the "fbx_custom_attributes" geometry attribute when you import.
node = hou.pwd()
geo = node.geometry()

old_attrib_name = "fbx_custom_attributes"
new_attrib_name = "parms"

old_attrib = geo.findPointAttrib("fbx_custom_attributes")
old_dict = geo.points()[0].attribValue(old_attrib)

new_attrib = geo.addAttrib(hou.attribType.Global, "parms", {})
geo.setGlobalAttribValue(new_attrib, old_dict)
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tamte
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in case your parms are on point 0 as suggested in the above code you can also use
Attribute Promote SOP
- Original Class: Point
- New Class: Detail
- Promotion Method: First Match
- Original Name: fbx_custom_attributes
- New Name: Parms

then you can append Attribute Adjust Dictionary and its Rename Keys multiparm to adjust your mapping, you can also use wildcards when renaming
e.g. (again using above example)
From: browDown*
to: CTRL_*_brow_down_start_x

etc...
Edited by tamte - Oct. 14, 2025 16:37:33
Tomas Slancik
CG Supervisor
Framestore, NY
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