Hi all,
I am interested in creating an openxr layer to implement FoV tangent so that I can present my square ratioed BigScreenBeyond (2560x2560 per eye) as having a widescreen ratio (2560x1440) and just blank out the region outside of that. The goal being to reduce the computational overhead involved with rendering unnecessary detail for simracing (where even in real world racing, these areas are not visible because of the helmet being worm by the driver)
OpenXR-Toolkit (which has been closed down) has a feature that sounds, at first glance, suspiciously like this. But it’s not. It just masks the upper and lower regions and doesn’t provide a performance boost. I asked the author of OXR-TK and he suggested forking his repository which I have done here
and then modifying it like this
Doing FOV Tangent from there is pretty simple if you only target OpenXR runtimes that have
fovMutable(see OpenXR spec for a description of what that means, and I believe SteamVR does support that, you can use OpenXR Explorer to inspect this capability). To do the FOV Tangent, all you need to do is hookxrEnumerateViewConfigurationViews()and compute the reduced resolution corresponding to the modified FOV. The rest of the fov_modifier code above should remain the same.
However, I’m stuck at the first hurdle. Even though I’ve been able to build his repo on my dev machine, and install it implicitly on my gaming machine (in the registry). However, it isn’t showing up in the layers tab in SteamVR (am I expecting too much there?) and when I try to start my VR game (iRacing) the VR headset won’t start up. If I disable the plugin, the VR game works again so clearly something is not working in the layer code.
I have no idea how to debug this, I don’t know where the logs go. Where is the first place for me to look?
I’ve tried running the version of the code directly as forked from the OXR-TK author, but also with some modifications. It has exactly the same impact. I would note that although I know a bunch of other programming languages, I don’t know C++ or the OpenXR API so in this instance I cheated and used chatgpt to help me with the modifications he suggested. It looks very much like what he suggested, and it compiles, but I can’t be sure it is doing exactly what is needed… but that shouldn’t really matter at this stage because I can’t even get his code to work as-is.
Reading the code, the logs should be showing up in
std::string logFile = (std::filesystem::path(getenv("LOCALAPPDATA")) / std::filesystem::path(LayerName + ".log")).string();
logStream.open(logFile, std::ios_base::ate);
but I can’t see anything.
