Would downsampling work for the Rift?

[sth]

I'm thinking that downscaling would have to be performed by the application rather than being forced via the GPU's control panel, as the scene needs to be rendered above the Rift's native resolution to prevent a loss of quality from warp compensation anyway. Since any application has to support the Rift natively (for which the resolution is known), I doubt that you would actually be able to select a different resolution anyway - only the type and amount of AA you want to apply.

Yes, that will be the proper way to do Rift support in games. But for any additional supersampling beyond what's needed to compensate for the warp losses, driver-based SSAA might be a bit faster than just further increasing the render buffer size.

On the other hand: Dynamically adjusting the buffer size could be a way to keep a steady framerate while offering the highest possible quality (= using a large render buffer for massive downsampling when there's enough power and dynamically reducing the render buffer size when the framerate drops). That wouldn't be possible with just driver-based SSAA.

I wonder how big the pixel magnification factor will be in the center of the shader (for determining the virtual resolution to compensate for the quality loss).

[PasticheDonkey]

yeah there's been variable resolution rendering in starbreezes' riddick escape from butcher bay and wipeout HD. it works nicely cos the fast movement that causes frame rate problems should look blurry anyway.

i consider the doom implementation of warping an ad hoc solution. the renderer should actually be rendering the required angles from the beginning in any new game build to support the rift.

[MSat]

Yes, that will be the proper way to do Rift support in games. But for any additional supersampling beyond what's needed to compensate for the warp losses, driver-based SSAA might be a bit faster than just further increasing the render buffer size.

On the other hand: Dynamically adjusting the buffer size could be a way to keep a steady framerate while offering the highest possible quality (= using a large render buffer for massive downsampling when there's enough power and dynamically reducing the render buffer size when the framerate drops). That wouldn't be possible with just driver-based SSAA.

I wonder how big the pixel magnification factor will be in the center of the shader (for determining the virtual resolution to compensate for the quality loss).

I didn't mean that a game should only render at the resolution needed to prevent detail loss due to warping, but rather that setting a virtual resolution in the GPU's driver utility might be a bad idea (the game would then have to render at an ever higher resolution than the virtual setting), or simply not even be possible. As I said, the type and amount of AA would probably have to be handled by the application. I am in no way arguing against the use of AA though

[sth]

I didn't mean that a game should only render at the resolution needed to prevent detail loss due to warping, but rather that setting a virtual resolution in the GPU's driver utility might be a bad idea (the game would then have to render at an ever higher resolution than the virtual setting), or simply not even be possible. As I said, the type and amount of AA would probably have to be handled by the application. I am in no way arguing against the use of AA though

No problem, I didn't understand it as arguing against AA.
I just think that right now, using driver-side SSAA for anything beyond detail compensation might offer a performance benefit over pure application-side downsampling.

But I agree that doing everything application-side is the better way to go overall – it's hardware independent, offers more flexibility and doesn't burden the user with dealing with driver settings.

[Pyry]

i consider the doom implementation of warping an ad hoc solution. the renderer should actually be rendering the required angles from the beginning in any new game build to support the rift.

Unfortunately, this is not really possible, because the Rift's distortion will turn lines into curves, and all graphics hardware is built around efficiently rasterizing (straight edged) triangles and quads. While you could try to approximate the distortion in the geometry by warping vertices around in a vertex program, the problem is that you'll create view-dependent cracks and gaps in your geometry. Rendering at a higher resolution and then doing a per-pixel warp is more expensive, but it avoids horrible artifacts, and is probably the best that can be done on current hardware.

[PasticheDonkey]

think of it more as varying FoV rendering over the image towards the edges.

[sth]

I don't think this is possible with any current graphics API.
I'd like to be proven wrong, though.

[PasticheDonkey]

well yeah they are designed around the normal use case. for now.

[Ryuuken24]

Hell, yeah! Downsampling works but, I've only tried 1080p, at 1600p it doesn't work. It's so strange, the games look better, it's a 20% increase in image quality, it's very noticeable. Someone should make a how to for other people, this is something they should try out. Cheers!