Implementing OpenVR Interfaces

Table of Contents

• Versions
• State
• Implementation placement

This file describes some basic rules for implementing OpenVR interfaces inside st/openvr.

Versions

The "root" versions are always the latest versions in the OpenVR headers we target, and all older interfaces are implemented on top of these root versions, or are implemented on top of other older versions.

Old versions should be stored in the interfaces/old/ directory, and should be a single header file describing implementing the old version on top of the root version. Most interfaces are very similar between versions, so most functions can be implemented using the Forward_ macros available in the openvr_forward_macros.h header.

State

All state should live in objects owned by the latest implemented version of the IVRClientCore interface. No state should live in any other interfaces, as we may have multiple interface versions active at the same time and they should cleanly work together.

Implementation placement

Logic more than a line or two of code, or which interacts with state directly should be kept in abstracted objects such as xrt::state_trackers::openvr::Compositor. However, this is not a hard and fast rule, and some smaller code may make sense to keep within the interfaces. If any functions need to start having their own local helper functions, or starts growing past "converting data to an internal format, calling one function and converting back to what OpenVR expects", that's a strong hint to move it to the abstractions.