Add OpenXR Movement Demos

[BastiaanOlij]

This PR introduces two demo projects to show the two room scale movement options presented in the help pages found here:
https://docs.godotengine.org/en/stable/tutorials/xr/xr_room_scale.html

These demos have a few small improvements that should be applied to the help pages, and the help pages should reference these demos so people can try out the logic.

I plan to do a 3rd demo showing seated play but will submit that as a separate PR

[DigitalN8m4r3]

had time to test both,
no issues so far and i like the blackout fade that u have added (should be standard! in the xr tools)

thanks for the hardwork there, lookin forward to the third one

[goatchurchprime]

There are two projects with almost the same code. If the docs say that the Character body centric solution is inferior, maybe it shouldn't be included as it adds confusion. (I spent some time comparing between them to find out what was different between the two projects.)

Also, can the project name avoid having spaces? The Android exporter doesn't like it (for the package name), and it's just one more thing in the long list of (unavoidable) steps that stops the demo working on the Quest2 out of the box.

[DigitalN8m4r3]

There are two projects with almost the same code. If the docs say that the Character body centric solution is inferior, maybe it shouldn't be included as it adds confusion. (I spent some time comparing between them to find out what was different between the two projects.)

Also, can the project name avoid having spaces? The Android exporter doesn't like it (for the package name), and it's just one more thing in the long list of (unavoidable) steps that stops the demo working on the Quest2 out of the box.

going forward to keep backcompatibility it might be good to have both, after all not evry app/game needs a characterbody solution

[BastiaanOlij]

There are two projects with almost the same code. If the docs say that the Character body centric solution is inferior, maybe it shouldn't be included as it adds confusion. (I spent some time comparing between them to find out what was different between the two projects.)

The Character Body one is actually the preferred approach.

The origin centric version is an older approach still used by XR Tools.

Both are however valid approaches, having demos to show both options so people can see how they work and decide for themselves which is the better approach for them I think is a valid thing to have.

[Malcolmnixon]

Both work very nicely.

[Calinou]

Tested locally in Godot 4.1.3 on Linux, both demos can start, but they exit after the warning dialog about not having an HMD connected displays. I don't have a VR HMD to test them in real world conditions.

Log:

ERROR: Condition "!texture_allocs_cache.has(p_id)" is true.
   at: texture_free_data (drivers/gles3/storage/utilities.h:111)
ERROR: Cubemap Arrays are not supported in the GL Compatibility backend.
   at: texture_2d_layered_initialize (drivers/gles3/storage/texture_storage.cpp:763)
ERROR: Attempting to use an uninitialized RID
   at: get_or_null (./core/templates/rid_owner.h:199)
ERROR: Condition "!t" is true.
   at: texture_free (drivers/gles3/storage/texture_storage.cpp:705)
Godot Engine v4.1.3.stable.official.f06b6836a - https://godotengine.org
Error [GENERAL |  | OpenXR-Loader] : RuntimeManifestFile::FindManifestFiles - failed to determine active runtime file path for this environment
Error [GENERAL | xrEnumerateInstanceExtensionProperties | OpenXR-Loader] : RuntimeInterface::LoadRuntimes - unknown error
Error [GENERAL | xrEnumerateInstanceExtensionProperties | OpenXR-Loader] : RuntimeInterface::LoadRuntimes - failed to load a runtime
Error [GENERAL | xrEnumerateInstanceExtensionProperties | OpenXR-Loader] : Failed to find default runtime with RuntimeInterface::LoadRuntime()
Error [GENERAL | xrEnumerateInstanceExtensionProperties | OpenXR-Loader] : Failed querying extension properties
ERROR: OpenXR: Failed to enumerate number of extension properties
   at: load_supported_extensions (modules/openxr/openxr_api.cpp:175)
WARNING: OpenXR was requested but failed to start.
Please check if your HMD is connected.
When using Windows MR please note that WMR only has DirectX support, make sure SteamVR is your default OpenXR runtime.
Godot will start in normal mode.

     at: initialize_openxr_module (modules/openxr/register_types.cpp:125)

For consistency with other demos, demo folder names should be renamed to snake_case, e.g. openxr_character_centric_movement and openxr_origin_centric_movement.

[BastiaanOlij]

I wonder what the cubemap error is about, seems like an internal issue.

The demo will indeed not work if you don't have an HMD, that kind of comes with the territory with a VR demo :) We really need to get you one.

[Calinou]

Thanks!