They should be able to map mesh shaders to PS5. Every major API has mesh shaders, GNM is the odd person out in this scenario
Current Generation Games Analysis Technical Discussion [2023] [XBSX|S, PS5, PC]
- Thread starter BRiT
- Start date
- Status
So that should mean that if the game (Alan Wake 2) doesn't work on RDNA1 GPUs then the PS5 has RDNA2 primitive shaders (and not RDNA1 primitive shaders lacking the per-primitive output attributes which seems to be the only difference). We'll know more when the game effectively lands. If it's running on 5700s with RDNA1 primitive shaders and how the game performs on PS5 vs XSX. I mean if they had a branch working on RDNA1 primitive shaders why would they not use it with RDNA1 GPUs?
By the way this blog is very interesting and confirms us that mesh shader is only an API on RDNA GPU (and so on Xbox Series), not a hardware. There is only primitive shaders hardware on RDNA GPUs with the RDNA2 version adding the per-primitive output attributes.
PS5 is a console. You can do whatever you want on console hardware knowing that the custom path would still hit an extremely large base of users.
They can certainly make AW2 work on PS5 without mesh shaders. They can do a combination of primitive with compute shaders etc.
I wouldn’t 1:1 with what’s on PC.
Yes. Mesh shaders map onto NGG hardware for AMD based cards. But NGG is likely being updated with each generation of RDNA family.
According to the dev they had an old buggy branch without mesh shaders (with vertex shaders) they dropped during development. All launch versions are using mesh shaders. From his/her deleted tweet. So again if they had a RDNA1 version working perfectly well on PS5 (which it does as they have being showing the PS5 version months ago) why wouldn't they use it on PC version?
Primitive shaders are not exposed in dx12 which the Game uses and I do Not even know If they are really exposed in RDNA1 on PC.According to the dev they had an old buggy branch without mesh shaders (with vertex shaders) they dropped during development. All launch versions are using mesh shaders. From his/her deleted tweet. So again if they had a RDNA1 version working perfectly well on PS5 (which it does as they have being showing the PS5 version months ago) why wouldn't they use it on PC version?
Why would the hardware be exposed on an API? Developers don't need to know how the API is implemented.
Well what if developers need either more performance/functionality to properly ship their games ? Exposing a closer abstraction whether it'd be primitive or mesh shaders is valuable in that case in comparison to the older geometry pipeline ...
Primitive Shader functionality needs to be accessible to the developer. It isn't through DX12U, which the game uses. To go around this limitation, the driver would need to give access through some kind of API. This would allow the Primitive Shader workloads to run on the hardware's NGG hardware.
AMD cancelled implicit Primitive Shader support back in 2018, which I think would have allowed the driver to decide when to turn VS stuff or GS stuff or whatever stuff into Primitive Shader to (potentially) get a speed-up. AMD announced they would release an explicit Primitive Shader API for Vega in the future. I don't think this ever happened.
I don't know what the status of PS support on the 5700 series is. According to "Timur's blog" (the Valve Linux driver dude) NGG doesn't work on the better selling Navi 14 (RX 5500) anyway.
Alan Wake 2 only supports DX12U cards. Additionally supporting a tiny collection of very niche, aged RDNA1 cards (the 5700/XT) through a custom path that still lacks other DX12U features wouldn't seem to be a good use of resources IMO.
@Lurkmass, do you know if Primitive Shader support is available for the RX 5700 on Windows?
Primitive shaders are actually used by the driver to compile vertex, tessellation, and geometry shaders on RDNA1 which is the extent of its support ...
But why would you do that? I think what devs like about playstation is the APIs target exactly what the hardware does. If a driver can take a mesh shader and convert it into primitive shaders which map to the hardware, then there's no reason to expose anything more than primitive shaders directly. Sony isn't building cross-vendor cross-generation APIs.
What do you mean by "exposed"? Technically doesn't the DX12 API expose the underlying hardware tech from both manufacturers? While they are not the same exact tech and maybe there is some walkarounds that the driver or developers must contend with when it comes to the AMD's solution, nevertheless both next gen geometry solutions are driving mesh shading on their respective GPUs.
Sony doesn't really need to expose mesh shaders. Primitive shaders are simply the "more explicit" option on AMD HW compared to mesh shaders ...
Seems Khronos then Microsoft announced support following the Siggraph presentation. https://blog.siggraph.org/2021/04/mesh-shaders-release-the-intrinsic-power-of-a-gpu.html/
Last edited:
I think I see the problem here.
When we are discussing DX12 Mesh Shaders - we are discussing Mesh Shader and Amplification Shader (or Task Shader for Nvidia).
Primitive Shaders align 1:1 with Mesh Shaders - but the question is whether PS5 supports Amplification Shaders to support 'Mesh Shaders' standard wholly.
The reason I bring this up, is because primitive shaders have been around since Vega, but the support for 'DX12U Mesh Shader' only begins at RDNA 2, if RDNA 1 was able to support Amplification shaders, it too would be able to support 'Mesh Shaders' in this sense.
Khronos documents the importance of Amplification/Task Shaders here as well as Mesh Shader best practices:
Task shaders call Mesh Shaders, and that is where the actual power lies in 'mesh shading'. Basically, you're sending a compute like kernel to invoke hundreds of mesh shaders at once. But it's a little more complex than that, but I suspect largely that is what they are doing on PS5. The beauty is that the firmware will do the work for you on DX12.
the thing is, for RDNA 1 this is going to be awkward without task shaders. While RDNA can leverage drivers to compile the existing front end into into primitive shaders for NGG, it has no way to divide and explicitly call the work like a task shader does, it requires explicit coding. You would need to have full control over the primitive shaders and the compute shader to call them in order for this to work - something the PS5 can do, but something PC cannot.
The reality is, I think without an amplification/task shader, it's a lot of work to write a compute shader based system to schedule the work for primitive shaders to work off. On DX12, the amplification shader handles all of this for you, the compute and graphics queues are working together. I don't think that PS5 can make the graphics and compute queues work together in tandem (compute queue waiting on the graphics queue to signal when to submit the next load), and if not, everyone needs to write their own highly specialized custom compute shaders that schedule workloads primitive shader processing. A bit like what Epic has done with Nanite for instance.
Last edited:
@iroboto I've never seen anything super compelling about PS5 being rdna1. Everything I've ever seen says it's a custom rdna2 gpu. I expect that if Alan Wake 2 runs fine with D3D12 on PC with an RDNA2 gpu that there's no reason to doubt PS5 can't do all of the same things without an explicit Mesh Shader API. Mesh Shaders are just an API. It's not the hardware. They need hardware features to implement the API, but it seems like RDNA2 does that fine with NGG (primitive shaders). On Series X the AMD driver is going to take the mesh shader and turn it into some primitive shader, compute shader that maps to the hardware. On PS5 they'll just write primitive shaders and compute shaders directly (I think). For all I know PS5 actually has some mesh shader API. I don't think GNM is actually public. From what I've heard they tend to keep the API closer to the hardware, so I suspect it doesn't. What I'm getting at is I doubt there's a hardware departure here between PS5 and Series X/S. It's just a different API. On PC RDNA1 and Pascal do not support mesh shaders so they'd have to use the old vertex pipeline.
Interview with David Wang (AMD). Might need to translate.
西川善司の3DGE：Primitive Shader対Mesh Shaderの真実。ジオメトリパイプライン戦争の内幕とAMDのゲーマー向けGPU戦略
去る2022年12月，AMDのRadeon GPU戦略を統括するDavid Wang氏とRick Bergman氏に，インタビューする機会を得た。本稿では，彼らに聞いた「Primitive Shader対Mesh Shader」のジオメトリパイプライン標準化争いの実情と，今後のゲーマー向けGPU戦略についてをレポートしたい。
www-4gamer-net.translate.goog
Last edited:
I think if Amplification shaders were available on PS5, Mesh Shaders would have been in full use much earlier. It's much faster. I think because PS5 doesn't have Amplification shaders, developers would have to write their own compute shaders in conjunction with the primitive shaders to get the same net effect that Amp+Mesh does on DX12. And most are probably not up to the task of doing that.
The firmware needs to support amplification shaders, the drivers make the call to the firmware, and the firmware calls the available instruction set.
On DirectX, Amplification shaders are executed on Async Compute queue where it simultaneously dispatches both a compute and graphics queue in parallel, and the compute and graphics queue wait off another.
That requires hardware for the queues to communicate to each other in this way. But as written above, if you are willing to do it, you can write your own compute shaders that can do this type of work.
As per RDNA - the compute units haven't changed much from RDNA 1 to 2, with the exception of RT and some faster matrices math for AI.
But the render backends are unchanged from RDNA 1, and Xbox Series all use RBEs from RDNA 2. Then there is also support for VRS and SFS.
These are all hardware features on the graphics pipeline (Mesh shaders included).
MS took significantly longer to get their devkits out to developers and cited that they needed to wait for these items to be done before they could start building.
Last edited:
Interview with David Wang (AMD). Might need to translate.
西川善司の3DGE：Primitive Shader対Mesh Shaderの真実。ジオメトリパイプライン戦争の内幕とAMDのゲーマー向けGPU戦略
去る2022年12月，AMDのRadeon GPU戦略を統括するDavid Wang氏とRick Bergman氏に，インタビューする機会を得た。本稿では，彼らに聞いた「Primitive Shader対Mesh Shader」のジオメトリパイプライン標準化争いの実情と，今後のゲーマー向けGPU戦略についてをレポートしたい。www-4gamer-net.translate.goog
I'm just skimming this but it looks like it's pretty much what I said. Direct3D mesh shaders are implemented with primitive shaders on AMD. PS5 SDK (API) uses primitive shaders explicitly. I don't see anything about differences in hardware capability, unless I'm missing it. If you can quote out something that explicitly says PS5 is RDNA1 or not, I'd be interested, but I'm not interested in reading all of that right now.
Mesh shaders are in use in UE5. Cross-gen games, and pc games that support RDNA1 and Pascal have no choice but to support the old vertex shader pipeline, and that's still a lot of consoles and gpus. Adoption was always going to be slow. People seem fairly upset that Alan Wake 2 may only support rdna2 and RTX 20x0 series and higher.
- Status
Similar threads
