Add intersects_ray() method to OpenXRCompositionLayer

[dsnopek]

This is a follow-up to PR #89880

As discussed on this comment, since these composition layers are most likely going to be used for UI, developers will want to cast a ray and get the collision point. And given that two of the layer types (cylinder and equirect) are curved and all can be rotated and moved around, developers aren't going to want to independently figure out the math for that. :-)

So, this PR adds OpenXRCompositionLayer::intersects_ray() which returns UV coordinates where the ray intersects.

The main thing I'm unsure about is that its returns Vector2(-1.0, -1.0) in the case that there is no collision. An alternative would be to change the return type to Variant so we can return Vector2 when there is an intersection and null when there isn't, but that would make it impossible to use proper type hints. I'm not sure which alternative is better, but I have a slight preference for the former, so that's the one I went with.

Here is a test project (doesn't include the 'godot_openxr_vendors' plugin - you'll need to download that yourself):

openxr_composition_layer_test.zip

[BastiaanOlij]

Looks good, just need to make sure it works in global space.

Also needs a simple demo/test project. Just a simple XR sample that has all 3 composition layers, with a bit of code that uses the UV here to send mouse events/touch events to the viewport so we can verify the obtained UVs are correct.

Coincidentally, I just did that on stream yesterday and remembering the v needed to be 1.0 - v, which may apply here.

[dsnopek]

Looks good, just need to make sure it works in global space.

Since both XRController3D and XRCompositionLayer need to be children of XROrigin3D, I was doing this in XROrigin3D-space. But I think you're right that doing it all in global space would be better.

I'll update the PR and share my demo project soon!

[dsnopek]

@BastiaanOlij Thanks for the review!

I've made the requested changes and added a demo project to the PR description above.

[BastiaanOlij]

Since both XRController3D and XRCompositionLayer need to be children of XROrigin3D, I was doing this in XROrigin3D-space. But I think you're right that doing it all in global space would be better.

That would probably be true 99% of the time, but just wait for the one person who puts a screen on a moving platform... :)

[BastiaanOlij]

LGTM with all the changes :)

[akien-mga]

Thanks!