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Question Ray Tracing is in all next gen consoles

Muhammed

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Jul 8, 2009
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PS5 is now confirmed to have hardware RT, meaning Ray Tracing will now the next standard in making games. RTX will spread into even more games. I am interested to know what those who thought RT will never be mainstream now think?



The straw man in your question is trolling.

AT Moderator ElFenix
 
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zlatan

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Nah... The PS5 has a very different RT solution compared to what is implemented in DXR. Even the Xbox has an upgraded pipeline. So, hibrid RT will be the way to go in the future, but the current hardwares will be paperweights with the new consoles. They don't support the new pipeline, because the hardware designed aroud a fixed function unit, and it's need to be redesigned, to support the changes.

I think we need to wait two more generations to get a clean pipeline, and that might allow good upgradeability. Until then every new DXR version will require new hardwares.

There are three problems with the actual implementation.
- It's not support the 32-bit snorm format, because the fixed function hardware is not designed around it. This is a huge limitation, and it can sacrifice the performance and the memory too much, and the supported 32-bit float format don't gives you really better results.
- The used acceleration structures are not public, so it could result extremely wild performance variations depending on the scenes. This needs to be solved.
- The ray traversal stage is extremely limited. It should be programable.

There are other smaller problems, so I think the consoles will give some good basics, but on the PC, these can't be fixed without hardware changes.

I personally thinks that hibrid RT will be mainstream about 5-6 years from now. But not sooner.
 
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SPBHM

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there will be Navi with hardware RT in the not so distant future, that's probably the kind of implementation the consoles will be using?!

I do think that this is the wrong moment to invest heavily into any GPU if you are thinking longevity,
 

BFG10K

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PS5 is now confirmed to have hardware RT, meaning Ray Tracing will now the next standard in making games.
Sure, sure, just like 4K native games @ 4xMSAA are standard practice on today's consoles. Oh wait...

I am interested to know what those who thought RT will never be mainstream now think?
RTX on Turing is still an overpriced slideshow. Your post doesn't change that.
 
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jpiniero

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Oct 1, 2010
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RTX on Turing is still an overpriced slideshow. Your post doesn't change that.
The thing is, it's going to be much much worse on non-HW RT GPUs. And devs aren't going to take into account that a game might only be playable on Full Turing (and Navi 20), since the consoles are the main focus.
 

soresu

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PS5 is now confirmed to have hardware RT, meaning Ray Tracing will now the next standard in making games.
Standard is a fairly nebulous thing in a world where one of the highest performing games on the market is predicated on stylised NPR graphics.
 

Thala

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Nov 12, 2014
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Also:

The used acceleration structures are not public, so it could result extremely wild performance variations depending on the scenes. This needs to be solved.
They are not supposed to be public. Only interfaces are public as this allows HW manufactures to define the internal structures matching capabilties of the HW. Defining interfaces and leaving internals opaque is the only way of defining a HW independent API!
Besides, why should the programmer even care about how the acceleration structures are layed out? Its only the hardware implementation ever touching the internal acceleration structures.
Besides why is this supposed to be a problem, which needs to be solved? If the structures were public, then we would have a very serious problem...

The ray traversal stage is extremely limited. It should be programable.
Ray generation is totally programmable and ray hit and miss functionality is totally programmable. What part of ray traversal should be programmable? I mean it is a ray for all intents and purposes, which is supposed to travel in a straight line through the scene - nothing programmable needed here.
 
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zlatan

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Eh? I thought DXR was more or less implementation agnostic?
No. You can emulate the stages, but the fixed function hardware is designed to do one thing, and if it's change, for example to support more formats, than you need new hardwares, because the old ones won't support the new formats. But the emulation is always an option, even if the performance won't be great. So the older hardwares can emulate the stage with shaders to support the newer formats, but they can't support it with the originally designed fixed function hardware.
 

zlatan

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They are not supposed to be public.
On the consoles, it will be public. It is a must to get this work, because if we don't know the limits of the acceleration structures, than we don't able to calculate with the performance variations.

Ray generation is totally programmable and ray hit and miss functionality is totally programmable. What part of ray traversal should be programmable? I mean it is a ray for all intents and purposes, which is supposed to travel in a straight line through the scene - nothing programmable needed here.
I can't say too much about this, but the next step will be the custom BVHs.
 

Mopetar

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Jan 31, 2011
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PS5 is now confirmed to have hardware RT, meaning Ray Tracing will now the next standard in making games. RTX will spread into even more games. I am interested to know what those who thought RT will never be mainstream now think?
Just like all games now have VR options because the console manufacturers were pushing that last go around!

Oh wait, that didn't happen. The consoles will not be powerful enough to do ray tracing outside of a few limited situations. Even with dedicated hardware it will see limited use at most. A few first party titles might push it, but this isn't going to be the mainstream explosion of ray tracing that you imagine it to be.
 
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Thala

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No. You can emulate the stages, but the fixed function hardware is designed to do one thing, ..
There is nothing in DXR which requires fixed function hardware...this is actually the point of Soresu. You really mixing things up here...

And what actually _IS_ implemented in HW (say Turing) does not require new "formats" ever as it is described in DXR as a fixed functionality - namely that ray intersecting geometry is is found and for each intersecting triangle the barycentric uv-coordinates of the intersection point are calculated.
But the definition of which rays to shoot and what happen when a triangle is hit is totally SW defined via shaders.
 

Muhammed

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Jul 8, 2009
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So, hibrid RT will be the way to go in the future
I am not debating that, It's always about hybrid RT, we are far away yet still to fully ray traced scenes.
Hybrid RT will gain faster adoption though.

because the hardware designed aroud a fixed function unit, and it's need to be redesigned, to support the changes.
It's not, it's an invisible layer underneath the API, even Pascal can repurpose it's ALUs to run DXR games without any fixed function RT hardware, it's that much transparent.
There are other smaller problems, so I think the consoles will give some good basics, but on the PC, these can't be fixed without hardware changes.
So you are saying that PS5 will have a better RT performance than an RTX 2080Ti?
 

soresu

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Dec 19, 2014
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You can emulate the stages
Ugh... I tire of seeing the word emulate everywhere it is not appropriate, even if MS are the ones doing it.

Raytracing has been done with standard GPGPU using CUDA and OpenCL for years now, and soon with Vulkan too (Otoy's Octane Render is switching to Vulkan Compute from CUDA/Optix).

It is not emulation - it is just not accelerated by fixed hardware - so basically a driver is running an actual GPGPU raytracing framework/kernel as a fallback, or specifically the traversal/intersection parts of a RT kernel addressed by said fixed hardware in the optimal system.

Emulation would imply a standard design it was emulating - so if DXR is supposed to be agnostic of hardware implementation it means the software fallback/polyfill cannot be emulation?
 
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soresu

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I mean it is a ray for all intents and purposes, which is supposed to travel in a straight line through the scene - nothing programmable needed here.
Not entirely sure that is accurate - given object refraction shaders, lens shaders, SSS shaders require a ray to pass through a medium, surely that constitutes traversal programmability?

Or are those events intersection?
 
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zlatan

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There is nothing in DXR which requires fixed function hardware...this is actually the point of Soresu. You really mixing things up here...
Never said it requires.

And what actually _IS_ implemented in HW (say Turing) does not require new "formats" ever as it is described in DXR as a fixed functionality - namely that ray intersecting geometry is is found and for each intersecting triangle the barycentric uv-coordinates of the intersection point are calculated.
But the definition of which rays to shoot and what happen when a triangle is hit is totally SW defined via shaders.
It can't support 32-bit snorm format. The hardware was not designed for this. So for this format, you need a new hardware. The 32-bit float format, which is supported by Turing is very inefficient. But DXR is in an early generation, so this is not a big problem, you can buy a new hardwave next year easily.
 

Thala

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Emulation would imply a standard design it was emulating - so if DXR is supposed to be agnostic of hardware implementation it means the software fallback/polyfill cannot be emulation?
Precisely, it is only described as interfaces and provided functionality...never in terms of design or implementation specification.

That having said, for DXR the specification looks like this on top level:

The programmer provides the geometry (which is converted into accelerated structures, which are private to the implementation), the shader which defines the rays to shoot (ake the raygen shader), the shaders to be run, when a polygon is hit (aka hit shaders), the shaders to be run when no polygon is hit (aka the miss shader) and the implementation provides that each hit shader is triggered when a polygon is hit and the miss shader is triggered when no polygon is hit.

On Turing the shaders using pretty much the same compute resources as are used for legacy rasterization - only the triggering of the shaders is different (see above) and the shaders have additional information available (e.g.the intersection point with the ray).

In some sense you could say, that DXR extension is the specification of an additional method of how shaders can be invoked based on ray intersection tests.
 

zlatan

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Mar 15, 2011
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I am not debating that, It's always about hybrid RT, we are far away yet still to fully ray traced scenes.
Yes we are probably 20 years away from that.

It's not, it's an invisible layer underneath the API, even Pascal can repurpose it's ALUs to run DXR games without any fixed function RT hardware, it's that much transparent.
And that's good. The actual hardwares can support the changes via shaders. But you need a hardware based solution to achive good performance, so there will be newer hardwares.

So you are saying that PS5 will have a better RT performance than an RTX 2080Ti?
I wouldn't compare these, because PS5 do this with a different graphics pipeline. If DXR would allow that pipeline, probably the PC hardwares can get the same speed. But todays hardwares are not enough, they are too limited. These are more like a test, nothing else.
 

zlatan

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Mar 15, 2011
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Ugh... I tire of seeing the word emulate everywhere it is not appropriate, even if MS are the ones doing it.

Raytracing has been done with standard GPGPU using CUDA and OpenCL for years now, and soon with Vulkan too (Otoy's Octane Render is switching to Vulkan Compute from CUDA/Optix).

It is not emulation - it is just not accelerated by fixed hardware - so basically a driver is running an actual GPGPU raytracing framework/kernel as a fallback, or specifically the traversal/intersection parts of a RT kernel addressed by said fixed hardware in the optimal system.

Emulation would imply a standard design it was emulating - so if DXR is supposed to be agnostic of hardware implementation it means the software fallback/polyfill cannot be emulation?
I can accept this, so when I said emulation, I think about a shader-based solution.

The actual hardwares won't support the new features on their fixed function hardwares. But they can support the changes via shaders.
 
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soresu

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But todays hardwares are not enough, they are too limited.
From what I have read on a handful of papers discussing acceleration structures and hardware arch's, the problem seems to lie in memory consumption more than the actual logic of it, almost every one of them discussed a specific method/technique to mitigate memory problems.
 

Thala

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From what I have read on a handful of papers discussing acceleration structures and hardware arch's, the problem seems to lie in memory consumption more than the actual logic of it, almost every one of them discussed a specific method/technique to mitigate memory problems.
Therefore the acceleration structs are *cough* private - allowing a very wide range of implementations...but the functionality is always the same and does not need *cough* "new features" as it provides precisely what is needed :)
That is unless you want to do something completely different than raytracing...
 
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