Documentation: Request for examples

[hybridherbst]

Are there examples for useful (or not) graphs to look at?

Things that come to mind:

• how to play an animation – I partially figured this one out
• how to swap a material
• how to make an object visible/invisible (I understand this might require an extension)
• how to activate a material variant
• how to switch to another scene from the glTF file
• how to build a LookAt of sorts (e.g. a quad always aligns to the camera)

[lexaknyazev]

how to swap a material

pointer/set + KHR_materials_variants (limitations apply, TBD).

how to make an object visible/invisible

pointer/set + KHR_node_visibility

how to switch to another scene from the glTF file

Good question, maybe the /scene property could be made mutable

how to build a LookAt of sorts (e.g. a quad always aligns to the camera)

Not possible at the moment as the user's viewpoint is not exposed

[hybridherbst]

Thanks!

pointer/set + KHR_materials_variants

Not sure I understand this, the variants extension contains data but no notion of an „active variant index“ to the best of my understanding.

LookAt…not possible at the moment

Understood. Seeing that there is lots of talk about behavior graphs somehow being „better“ and convertible from trigger/action lists, this is quite disappointing to me — even Apple’s QuickLook, which gives away zero data about the users viewpoint, has a LookAt behavior (and so does Adobe’s Aero if I’m not mistaken).

[lexaknyazev]

the variants extension contains data but no notion of an „active variant index“

Yes, it will be a virtual asset object model property.

[hybridherbst]

I started to port one of our Needle sample files to KHR_interactivity by hand, to get a feel for it. The original uses our NEEDLE_components extension in glTF, which are designed to be compatible with USDZ/QuickLook.

Original using NEEDLE_components: https://engine.needle.tools/samples-uploads/usdz-animator/

Using KHR_interactivity:
NeedleAnimatedCharacter.glb.zip

Thanks to #9, the glb can be loaded directly into the editor and starts being interactive.

Here's a video:

Screen.Recording.2024-08-27.at.00.42.17.mov