The Varjo XR-4 brings its own controllers, but Varjo disabled their support when third-party tracking drivers such as LPVR-CAD and LPVR-DUO are in use. While this will likely be fixed in a future version of Varjo BseBase, customers upgrading from the XR-3 might have workflows that already incorporate the Vive Controllers or other SteamVR controllers. These will continue to work with the SteamVR edition of the XR-4 but what about other versions of the headset?
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With the hardware in place, you need to have installed the LPVR driver for the hand controllers, and there is one additional configuration that you may have to make before being able to use the controllers. This will require editing the SteamVR configuration steamvr.vrsettings. It is usually stored in C:\Program Files (x86)\Steam\config\steamvr.vrsettings for SteamVR installed via Steam or in the config subfolder of your standalone SteamVR installation. In this file, look around for the "steamvr" object and add the "activateMultipleDrivers": true setting to it. If the setting already exists, make sure it is set to true. The relevant part of the file will end up looking something like this:
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There are lots of icons: one for the XR-4, two greyed out Varjo controllers, two LPVR icons and an icon for the Vive controller. On the SteamVR side everything works at this point. You can then follow our usual documentation to continue finish your setup.