Re: [Algorithms] HDR and MSAA

[Aras P. <ne...@gm...>]

> The half-life lost coast is said to work on all DX9 class hardware
> with MSAA. However the demo I've seen  HDRFormats and another that is
> said to work with RGBE formats doesn't seem to support any sort of
> antialiasing .Obviously you can't expect the expontential E to scale
> well since its expotential not linear, but in any of the cases I'd
> expect to see some sort of smoothing, but it still appears jagged.

There was a presentation on Valve's HDR somewhere. Basically it looks
like they are not using RGBE; they are using plain RGBA, with tone
mapping performed at the end of any shader. So they do not output HDR
colors anywhere. The reason they can do this is that all their shaders
seem to be single-pass (i.e. lighting is not accumulated in multiple
passes anywhere).

> The odd thing is the RT's (render targets) for
> RGBE in the demo is using a 6x antialiasing (with a StretchRect over
> to the back buffer) yet I don't see any antialiasing effect.

I tried this a couple of years ago, and while it worked on NVIDIA
hardware, it did not work on ATI hardware (at least then). In a sense
that color channels were multisampled, but alpha channel was not. I
think someone said to me that ATI hardware does not resolve alpha
channel when doing MSAA'd render target to non-AA surface blit, or it
does not multisample alpha channels at all.

-- 
Aras Pranckevicius
work: www.unity3d.com
home: nesnausk.org/nearaz