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sbdykes
Up and Coming
October 28, 2017

1.19.0 SDK Octilinear extension

Documentation for the 1.19.0 SDK indicates that there is a new Octilinear rendering extension available, which "implements NVIDIA's Lens Matched Shading".  However, there are no details as to what exactly enabling this extension does.  Lens matched shading requires support/implementation in the game engine renderer/shaders, it's not something that you can just "automagically" support.  I'm presuming this does something to the effect of changing how the Oculus SDK is determining eye render target dimensions or the like (implied by the actual extension enum "ovrExtension_TextureLayout_Octilinear")...?

    2 replies

    sbdykesAuthor
    Up and Coming
    October 31, 2017
    Thanks for the reply.  Perhaps it's a mix-up of terminology; lens-matched shading (at least as described in NVIDIA presentations) requires special handling of w/depth values (LMS space versus linear space, etc.) in shaders, so given that we simply pass off rendered eye views to the Oculus runtime, I don't see how it could be handled solely on the Oculus runtime side unless it was doing something simple like performing some driver shenanigans to just discard pixels in the outer regions (and even then, how would it know *which* render targets it should be doing that to?).

    Don't get me wrong, I love free features!  I'd just as soon not have to do anything.  Anyhow, I'll keep an eye out for more info.  Thanks!
    Devlin1991
    Up and Coming
    November 27, 2017
    Is this enabled via driver level changes? Is it using the texture IDs from the Oculus swapchain functions as the triggers? I seen no performance change when enabling this extension but I suspect that's because our engine renders to our own FBO then blits the result to the Oculus supplied texture IDs. Could you provide a more verbose usage guide of this feature for those of us not using Unity or Unreal?
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