Add hit test support

[Rufus31415]

https://immersive-web.github.io/hit-test/

[gisornator]

Hey! I was testing Hit Test on iOS with great success but it seems to not work properly on Android. Any idea?

EDIT: Remote debugging gave me the following error

"PROD-BUILD.framework.js:92 Uncaught (in promise) DOMException: Failed to execute 'requestHitTestSource' on 'XRSession': Hit test feature is not supported by the session. at someurl-PROD-BUILD.framework.js:92:53710"

[Rufus31415]

Hi! This means your browser doesn't support hit test. But I should test that XRSession contains requestHitTestSource to warn if this feature is not supported

[gisornator]

Technically, the browser should support it. I tested it with Chrome 96.0.4664.92 (Android).

E.g. testing it through this works fine in the same browser: https://chromestatus.com/feature/4755348300759040

[gisornator]

One thing I found:

According to several resources, it seems that it is required to ask for hit-testing when starting the AR Session: https://developer.mozilla.org/en-US/docs/Web/API/XRSession/requestHitTestSource

So maybe (that's just a guess because I can try it earliest in the evening) that line 575 (SimpleWebXR.jslib) needs to be changed to require the hit-test module:

navigator.xr.requestSession(_isArSupported ? 'immersive-ar' : 'immersive-vr', { requiredFeatures: ["local", "hit-test"], optionalFeatures: ['local-floor', 'hand-tracking'] }).then(function (session)

[gisornator]

Okay, I was able to test it in the meantime and the solution from above worked now! I have a different issue now in regards of Unity's Input.Touch system. I'm not getting any errors in the console but I think this is related to the full screen.

[Rufus31415]

You are right, from now on, the hit-test feature shoul be declared, I'll add that here : https://github.com/Rufus31415/Simple-WebXR-Unity/blob/a9060413037d6b5dd985abba29ed17fcd51ff79d/com.rufus31415.simplewebxr/Runtime/Plugins/WebGL/SimpleWebXR.jslib#L575 Thanks

On Android, I know that for safety, in full screen mode, a new context is created and I'm not sure if Input.Touch which reacts on javascript events on the

still works. The only way to access the touch during a session is through the WebXR API with events InputSourceSelect, InputSourceSelectStart, ...

[gisornator]

Thanks for the quick response! Yea, I will try that later tonight :) do you have something in the examples on how to interact with UI elements and InputSourceSelect, etc?

[Rufus31415]

If you use it with MRTK, WebXR events are propagated to MRTK core. So you just have nothing special to do except choosing your input source in MRTK settings

[DeveloperARKids]

I cant touch my ui button and 3d collider when in AR mode fullscreen, so i cant have any interaction after AR start. any example to fix this?