Major performance regression in the SteamVR plugin (affects all released games)

Development Platform & Builds XR Development
1

I submitted this to answer hub, but thought many people might want to see it here:

The engine does a hard coded check on the CRC of the hidden area mesh returned from SteamVR, and if it doesn’t match the hardcoded value, it skips generating a visible area mesh (used for speeding up post processing).

At some point the SteamVR API has started returning hidden area mesh with a different CRC, and so the UE4 SteamVR plugin now just doesn’t generate a visible area mesh at all, resulting in much slower (~15%) post processing.

I don’t know when SteamVR started returning that different mesh, but as soon as it did, every released UE4 game was affected because of this hardcoded CRC value.

2

Upvoted on answerhub. I’d like to hope they fix it soon, but has a strong doubts :frowning:

3

There is a pull request with a fix now:

https://github.com/EpicGames/UnrealEngine/pull/3868