Far Cry 4 missing high quality AA because of DX11?

[NTMBK]

Console versions of Far Cry 4 use an interesting anti aliasing method called HRAA, but this is missing entirely on the PC version. Digital Foundry has an interesting theory:

We usually see the PC version automatically trump the consoles when it comes to image quality via the ability to choose whatever resolution and anti-aliasing solution best suit your hardware and performance expectations, but in this case things aren't quite so straightforward. MSAA (in 2x, 4x, and 8x variants) and SMAA are provided in Far Cry 4, while owners of Nvidia cards also get the addition of TXAA. Out of all these solutions SMAA provides the best overall coverage while using little in the way of GPU resources: images appear clean and pretty artefact-free, although there is a visible amount of blur across the scenery that doesn't occur on consoles. It's clear that the HRAA used on the PS4 and Xbox One is a better overall solution to tackling jaggies while preserving texture detail, so its absence on PC is a missed opportunity. Based on the public information released to date by Ubisoft, it's probably the case that HRAA requires extremely low-level access to the GPU - DirectX 11 alone probably isn't up to the task.

http://www.eurogamer.net/articles/digitalfoundry-2014-far-cry-4-face-off

Of course this is an Ubisoft PC port, so... Still. Something to look forward to when we get DirectX 12.

 

[ShintaiDK]

http://www.nvidia.com/object/feature_hraa.html

 

[Gloomy]

http://www.nvidia.com/object/feature_hraa.html

Wrong HRAA.

 

[NTMBK]

http://www.nvidia.com/object/feature_hraa.html

Different HRAA.

 

[ShintaiDK]

Nomatter if DX is capable of it or not. AMD and nVidia still need to deliver drivers and cards that can do it.

CSAA for example was removed from Maxwell. While MFAA was added. Completely unrelated to DX11.

A bad PC port is a bad PC port. Not that the game runs any better on consoles.

 

[Pottuvoi]

It's pretty much impossible to have HRAA on PC with decent performance before drivers allow access to interpolators within pixel shader. (Allowing fast GBAA)
http://youtu.be/Bmy3Tt3Ottc?t=43m42s
Really doubt of this happening before DX12, perhaps even then.

HRAA also seems to use varied sample pattern to get filipquad and other tricks.
Anyway HRAA paper is very nice and worth the read, certainly shows how low access to HW can be worth more than just getting some pixels to screen faster.
http://michaldrobot.com/2014/08/13/hraa-siggraph-2014-slides-available/

http://www.nvidia.com/object/feature_hraa.html

Funnily Quicunx is somewhat similar to HRAAs flipquad in term of sharing samples with multiple pixels. (and so are AMD tent filters, Nvidia DSR smoothing factor and reconstruction filter of TXAA.)
It was on right path to get good quality AA, although at the time boxfilter was the right way to go as games were usually played in low resolution.
Now with 1440p and 4k displays the spatial resolution on monitors is high enough to allow small amount of sharpness to be sacrificed for an image stability.