Direct3D feature levels discussion

Trim the variable name to something like VPAndRTArrayIndexToRasterizerWithoutGSEmulation and strip ending Supported from the all other capability bits as well...
 
Now, a table has surfaced that shows a list of current AMD, NVIDIA and Intel GPUs, detailing their support of different DirectX 12 functions. If the table is to be believed, ll three expansion stages of the GCN architecture are indeed fully compatible with DX12.

dx12-amd-nvidia-table-rs.png


The following graphics cards would thus be compatible with all previously released DirectX 12 features:

  • AMD Radeon R9 Series Graphics
  • AMD Radeon R7 Series Graphics
  • AMD Radeon R5 240 graphics
  • AMD Radeon HD 8000 Series Graphics for OEM system (HD 8570 and up)
  • AMD Radeon HD 8000M Series Graphics for Notebooks
  • AMD Radeon HD 7000 Series graphics (HD 7730 and up)
  • AMD Radeon HD 7000M Series Graphics for Notebooks (HD 7730M and up)
  • AMD A4 / A6 / A8 / A10-7000 Series APUs (codenamed "Kaveri")
  • AMD A6 / A8 / A10 PRO-7000 Series APUs (codenamed "Kaveri")
  • AMD E1 / A4 / A10 Micro-6000 Series APUs (codenamed "Mullins")
  • AMD E1 / E2 / A4 / A6 / A8-6000 Series APUs (codenamed "Beema")
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http://www.hardwareluxx.com/index.p...ture-to-offer-full-level-directx-support.html
 
This picture originates from a Brazilian forum and copies a table posted on a Hungarian forum with no attributed source of information (could as well be this thread on Anandtech forum).

It's wrong on several important counts, for example: none of GCN chips support rasterizer ordered views, conservative rasterization, or tiled resources tier 3 (ie. "volume tiled resources" with Texture3D support), as shown by the D3D12 feature checking tool. GCN 1.1/1.2 cards support tiled resourced tier 2 (with Texture2D support) and feature level 12_0, GCN 1.0 "only" supports tiled resources tier 1 and feature level 11_1. Double precision floats are supported across the entire GCN range.

Kepler and Maxwell-1 do support resource binding tier 2, and do not support typed UAV load for additional texture formats - this leaves them at feature level 11_0. Maxwell-2 is currently the only card which supports feature level 12_1.

Conservative depth, SAD4 or dedicated atomic counter are not part of the latest SDK, neither is "emulated" tier 3 for tiled resources, whatever that means.


As for the complete list of Direct3D 12 compatible GPUs and APUs, AMD revealed it on their blog nearly a month ago.
 
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But is that extension usable? The performance on previous drivers made it impractical even for simple cases (if I remember Andrew correctly). I mean my cpu can support feature level 12_1 too, but that's not really saying much. :p
 
willardjuice said:
But is that extension usable? The performance on previous drivers made it impractical even for simple cases (if I remember Andrew correctly). I mean my cpu can support feature level 12_1 too, but that's not really saying much. :p
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Yeah it was ridiculously bad when I briefly tested it... like turn it on even with a trivial pixel shader and no actual synchronization going on and your frame takes 300ms+. Hopefully that was just a bug or some sort of test implementation, but suffice it to say I'll believe they can support it efficiently when I see it :) Hopefully Fiji supports it natively in any case; the sooner ROV support is ubiquitous the sooner games can start relying on OIT and similar things that you can do with it without having to have engine fallbacks.

And yeah, that table is utterly wrong on almost every count. You could probably invert all the values and it would be just as close to correct. Some of the things don't even really make sense as to what they are noting from an API point of view.
 
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At this point, not everything can be divulged but NVIDIA wanted to be sure we understood that there were two very different aspects of the DX12 story: better CPU utilizing and efficiency along with new features that require new hardware.

In terms of new features, there are currently two different feature levels: Feature Level 12.0 and Feature Level 12.1. Feature level 12.0 supports new rendering technologies like tiled resources, bindless textures and typed UAV access. 12.1 is more advanced and includes the 12.0 features but adds conservative raster and raster ordered views.

NVIDIA says that GM200 supports another feature as well: volume tiled resources. This additional feature brings support for 3D textures to be used in the tiled resource capability, utilizing less memory by only storing the specific tiles of textures required for rendering at that time. The tiled resources feature listed as a requirement for Feature Level 12.0 only needs to support 2D textures. With a 3D texture though a developer has the ability to store an additional dimension of data; NVIDIA gave an example of smoke where the third dimension of texture might indicate the pressure of the fluid, changing the color and response of the physics based on that 3rd dimension of data.

980ti-10.jpg


There is a still lot yet to be shown or discussed about DX12 but we can confirm now that Maxwell will support DirectX 12 Feature Level 12.1 as well as the volume tiled resources capability.
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http://www.pcper.com/reviews/Graphi...view-Matching-TITAN-X-650/DX12-Support-GameWo
 
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Well, apparently, for what I see AMD does support ROV even if what you tested was very slow! And it was stated above GCN did not supported it!

But honestly... i would doubt AMD (or any other) would show support for something if performances were that bad... So unless someone tells me otherwise I would be tempted to believe what you tested was premature? Any more recent testing?

As for the atomic counter... Check this and this! Is it related?
 
Metal_Spirit said:
Well, apparently, for what I see AMD does support ROV even if what you tested was very slow! And it was stated above GCN did not supported it!

But honestly... i would doubt AMD (or any other) would show support for something if performances were that bad... So unless someone tells me otherwise I would be tempted to believe what you tested was premature? Any more recent testing?
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It's not that he tested and it was slow. AMD Direct3D 12 driver at the moment does not report support for ROV. This means you can't use it period. This has nothing to do with OpenGL.

Metal_Spirit said:
As for the atomic counter... Check this and this! Is it related?
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Again this is OpenGL extension. Most of operations mentioned in this extension is already included in D3D 11. What that "dedicated atomic counter" is supposed to be we can't tell because it's not in D3D 12 specs.
 
Locuza said:
Which seems very unlikely and it's very unfortunate that AMD isn't contributing to an modern Feature-Level.
Nvidia does since November 2014 and Intel at least supports ROVs.
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Level 12_0 mostly leverages on GCN features. Nvidia cards before Maxwell 2 will emulate some features in software.

12.1 was created for Maxwell 2. Of course AMD is behind on those.
 
Ethatron said:
silent_guy used tripple negation (well, 2.5 really). Intentional? I don't think this isn't no DX9.3 situation. LOL
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"I think it doesn't matter a great deal. " better? ;)

Not that sebbi is wrong about it being very useful, but there's a difference between useful and necessary. I assume most games will do things the hard way...
 
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