Vive performance

[robert.blodgett]

Hi, i have noticed with our scenes that perform very well in non-VR mode are getting twice the draw calls, (of course you might think), when using the Vive.

 

However, with certain new techniques, one can avoid doubling the draw calls.  I'm wondering if Unigine is implementing these techniques?

 

This one discusses using instancing so you that you only do one set of draw calls for both eyes:

https://docs.google.com/presentation/d/19x9XDjUvkW_9gsfsMQzt3hZbRNziVsoCEHOn4AercAc/edit#slide=id.p

 

 

An alternative approach is to use the multi-GPU affinity feature in the LiquidVR api:

https://github.com/GPUOpen-LibrariesAndSDKs/LiquidVR/blob/master/doc/LiquidVR.pdf

 

or, for nvidia, the VR SLI feature or Single Stereo Pass mentioned here:

https://developer.nvidia.com/vrworks

 

thanks.

[silent]

Hi Robert,

 

These optimizations are indeed will give you more performance, but it will broke some internal engine ones.

 

We had no time yet to experiment with them, but the very first one (with draw calls reduction) will probably be the best choice and in addition cross-platform and cross-vendor friendly. The only disadvantage here - VRAM usage for G-Buffers will be doubled. VR SLI and LiquidVR are vendor-specific, hardware-limited and require a complex mechanism of memory synchronization between GPUs.

 

Thanks!

[robert.blodgett]

Fyi, SteamVR was updated on Nov 15 with a performance boosting feature called "asynchronous reprojection."  This seems to help quite a bit.  Works currently only for NVIDIA cards.  Of course we can hope for more optimizations on the Unigine side.

[demostenes]

Hi, i have noticed with our scenes that perform very well in non-VR mode are getting twice the draw calls, (of course you might think), when using the Vive.

 

 

 

Double draw calls will became not big issue when DX12/Vulcan is supported...