Expose oculus-hand profile by adding assets

[felixtrz]

Add assets for the oculus-hand profile to enable CDN distribution and developer usage.

The oculus-hand profile has existed in the registry (packages/registry/profiles/oculus/oculus-hand.json) but was never exposed through the assets package. Without corresponding assets, the profile cannot be built into the distribution and remains unavailable on the CDN, making it effectively unusable by developers (it is not available from https://cdn.jsdelivr.net/npm/@webxr-input-profiles/assets@1.0.20/dist/profiles/profilesList.json).

Changes

• Added packages/assets/profiles/oculus-hand/profile.json configuration
• Added left.glb and right.glb hand models (reused from generic-hand)
• The profile will now be included in the built profilesList.json and distributed via CDN

Why reuse generic-hand models?

The oculus-hand profile is designed for hand tracking (not physical controllers), and the existing generic-hand models provide appropriate visual representation. The profile defines hand gesture inputs including:

• Pinch select (xr-standard-trigger)
• Swipe gestures (left, right, forward, backward)
• Tap-thumb gesture
• Menu button (left hand only)

Impact

Developers working with Oculus/Meta hand tracking can now load and visualize the oculus-hand profile through the standard WebXR input profiles library and CDN.

[cabanier]

I believe we skipped this profile for a reason. The oculus-hand profile is identical to generic-hand which is the fallback profile.
It's unfortunate that we added this profile because it doesn't add any new information.

[felixtrz]

@cabanier I see, this may be the case when we added this profile, but now it does add new information - it has the gestures in the gamepad buttons array which the generic-hand doesn't have; so by skipping this, developers will never have access to the gesture button mapping.

[cabanier]

Can you make it so that you grab the profiles from generic-hand?
That way you are pointing to the same assets and you won't have to add new glb's

[simonedevit]

Interested in this topic as I submitted a similar PR #278 two months ago.

There are two practical considerations that make it difficult to reuse generic-hand/left.glb and generic-hand/right.glb directly for the oculus-hand profile:

1. Cross-folder asset references are not allowed by the schema

Anything like:

{
    "profileId" : "oculus-hand",
    "overrides" : {
        "left": {
            "assetPath": "profiles/generic-hand/left.glb"
        }
    }
}

is invalid because it violates the filename constraint ^[a-z0-9]+(-[a-z0-9]+)*\.glb$ defined in the layout schema.

assetPath must be a plain filename, without directories or relative paths. This prevents any direct reuse of assets across folders.

2. Even if the schema restriction were bypassed, generic-hand lacks the required components

Even assuming we introduce workarounds such as modifying the validator, manually rewriting the assetPath at runtime, or injecting a fallback before creating the MotionController (all of which I would consider bad practices), the generic-hand models still do not define the components needed for oculus-hand, such as menu_pressed_min, swipe_left_pressed_min, swipe_right_pressed_min, and others.

This results in errors like the following:

Given these constraints, it might be worth considering a straightforward duplication of the `generic-hand` meshes within the `oculus-hand` folder, along with the additional component nodes required by this profile. This is the approach I followed in my earlier PR, and it avoids schema issues, removes the need for workarounds, and keeps the profile self-contained, though of course there may be alternative solutions the maintainers prefer.

[cabanier]

@felixtrz what do you think of the comments of @simonedevit? Could you apply these to your PR?