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News Rendering Engineer at EpicGames: DirectX RayTracing and Vulkan Optix holds everything back in PC land

M1chl

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Well, DXR (and very DXR-like Vulkan extension as well as Optix) is the only way to do hardware ray tracing on PC. It doesn’t mean that it’s good. It’s a big black box and developers can’t really do some of the things that low-level hardware access could allow.

I mean, are you familiar with late 90 PC? Where you don't have sounds or your game running in less colors and all that shit? On PC there is a fucking challenge to make piece of software works on literally millions of combination of HW. So yeah his bitching does not really mean much.
 

hyperbertha

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Panajev2001a

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He actually goes more in depth about the advantages of being able to have low level access to the RT HW and the BVH accelerator structure (in terms of fine grain updates and data streaming in and out) that DXR does not give devs. Why? BC issues across GPU’ vendors and generations of GPU’s from the same vendor too which console developers normally do not take for granted and thus are able to optimise more.

Then again with the HotChips presentation hearing from the Xbox engineers, again, that console environments allowing much more optimisation than an equivalently specced Windows desktop was yet another reminder of why having a universal abstracted interface leaves a lot of untapped potential (as if people did need such a reminder really, but maybe some do...).
 
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llien

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He actually goes more in depth about the advantages of being able to have low level access to the RT HW and the BVH accelerator structure (in terms of fine grain updates and data streaming in and out) that DXR does not give devs. Why? BC issues across GPU’ vendors and generations of GPU’s from the same vendor too which console developers normally do not take for granted and thus are able to optimise more.

Then again with the HotChips presentation hearing from the Xbox engineers, again, that console environments allowing much more optimisation than an equivalently specced Windows desktop was yet another reminder of why having a universal abstracted interface leaves a lot of untapped potential (as if people did need such a reminder really, but maybe some do...).
Let's extrapolate that to DirectX as a whole, shall we?
It holds back gaming, right?

There are APIs that suck and APIs that don't.

DXR is a half baked thought pushed out as API.
 
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acm2000

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RT has got to be the most Over rated and useless tech I have seen in some time. Honestly yet to see what the big deal is regarding it.

For me techs like DLSS and Checkerboarding are far more useful techs going forward.

You know ray tracing isn't just reflections right? Ray traced shadows are miles better than Shadow mapped ones, ray traced global illumination is mind blowing, even audio can be ray traced
 
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Armorian

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RT has got to be the most Over rated and useless tech I have seen in some time. Honestly yet to see what the big deal is regarding it.

For me techs like DLSS and Checkerboarding are far more useful techs going forward.

RT is the future of real time graphics. RT GI alone can fix lighting in open word games with dynamic TOD, no need to bake anything.
 

Alphagear

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You know ray tracing isn't just reflections right? Ray traced shadows are miles better than Shadow mapped ones, ray traced global illumination is mind blowing, even audio can be ray traced

Yes I do.

Add RT Audio and Shadows and it makes matters worse.

GPU resources can be better spent elsewhere.
 

Alphagear

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Which is why NVIDIA is smart to add ML and DLSS 2.0. Recreate the resolution, basically imperceptible to the eye from native resolutions, yet pretty decent gains in performance, which can be used by, I dunno, RT?

Agree but I rather see those gains from DLSS etc. be used elsewhere. Better textures, Framerates and Physics come to mind.
 

NullZ3r0

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RT has got to be the most Over rated and useless tech I have seen in some time. Honestly yet to see what the big deal is regarding it.

For me techs like DLSS and Checkerboarding are far more useful techs going forward.
It sucks this gen because both consoles can barely handle it. Next gen we should see games with both RT shadows and reflections.
 
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BeardGawd

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It's weird he mentioned DXR... should have just said the PC platform as a whole. As any api has to be vendor agnostic.
 
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Panajev2001a

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Let's extrapolate that to DirectX as a whole, shall we?
It holds back gaming, right?

There are APIs that suck and APIs that don't.

DXR is a half baked thought pushed out as API.

The best API that achieves the goals of abstracting HW differences well will almost always lose in optimisation potential / extracting 100% of the HW capabilities and/or flexibility (likely both) compared to lower level API’s.

Abstraction layers are designed for a purpose that is antithetical to what is generally needed in consoles and what having a fixed HW in all consoles for years and clear generation boundaries (and BC modes rather than forward compatibility). The high level abstracted API is designed to allow your source code to remain relatively unchanged as you move it across HW designs while lower level API’s might force source code changes on top of recompiles.

Higher level well abstracted API’s succeeded on PC’s / are needed because it is an open platform with tons of HW vendors and multiple variations per vendors and software developers have a wide, semi formed, fast moving target for their software. Consoles are designed to provide a well integrated SW+HW combination where each is customised to perform better when paired with the other... then since the specs are fixed for a few years, unless you are trying to unify all in a glorious universal gaming platform due to a company strategy, you can allow developers to get to know and use the HW unique capabilities more directly and leave older generation software more to an enhanced BC layer.

I wonder what MS did to customise DXR and DirectX for the XSX... it will be more efficient but how much lower level will it be in exposing the raw HW?

We've been doing a lot of work to remove a lot of the overhead in terms of the implementation and for a console we can go and make it so that when you call a D3D API it writes directly to the command buffer to update the GPU registers right there in that API function without making any other function calls.

"[Series X] goes even further than the PC standard in offering more power and flexibility to developers," reveals Goossen. "In grand console tradition, we also support direct to the metal programming including support for offline BVH construction and optimisation. With these building blocks, we expect ray tracing to be an area of incredible visuals and great innovation by developers over the course of the console's lifetime."

There is to hope that XSX has similar RT HW access level to PS5, the second quote is promising.
 

Azurro

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Their hardware allows much more than the plastic white and black box could do.

You didn't understand the point of my post. You can't optimise a black box, you have no access to what it does, you just throw it inputs and receive an output and that's it, that's a black box. That's the point, how can something be "poorly optimised" if it literally can't be optimised? His/her statement was nonsensical, as is yours.
 
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TearInto5th

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To be honest, Ray tracing at some levels can be amazing. But really, it seems all they're being used for is amazing reflections...

Who gives a shit? Demons souls has no ray tracing in it... a game can be made with other forms lighting, like global illumination and still look incredible...

If you need to use Ray Tracing, do it. But it doesn't seem like its the be all end all to make an amazing looking game.

If you can make your game look amazing and Ray tracing isn't necessary, why even bother?
 

VFXVeteran

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He actually goes more in depth about the advantages of being able to have low level access to the RT HW and the BVH accelerator structure (in terms of fine grain updates and data streaming in and out) that DXR does not give devs. Why? BC issues across GPU’ vendors and generations of GPU’s from the same vendor too which console developers normally do not take for granted and thus are able to optimise more.

Then again with the HotChips presentation hearing from the Xbox engineers, again, that console environments allowing much more optimisation than an equivalently specced Windows desktop was yet another reminder of why having a universal abstracted interface leaves a lot of untapped potential (as if people did need such a reminder really, but maybe some do...).

I have not worked with DXR to judge one way or the other. DXR being considered a "black box" is a bit odd to me considering I'd think that Vulkan was also a black box and it gives enormous low-level access beyond the typical OpenGL.

I've asked him to elaborate on what he thinks he can extract out of low level access when you are bandwidth starved anyway while using RT. I'd be curious to see what his response is.
 
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VFXVeteran

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Feel like I remember a certain Veteran constantly screaming that low level optimization is a thing of the past and consoles will not get benefits because of it and thus are just PC's.

You speak in "general" terms. Low level access can always give you advantages over an agnostic API like DX. However, that doesn't mean it's going to make your hardware "king of the hill" and it still has hardware limitations that can't be optimized (i.e. you are NOT going to see 4k/30 with a PC game showing that same game running 4k/60 on a console like the PS5). The way you guys throw around optimization is a sin. You put it up on a pedestal without actually knowing how or what would be needed to describe such optimization. A guy like Yuriy can give me a proper explanation instead of just throwing it out there in a void. He also said "That’s quite presumptuous about my opinion on DXR. " which most people will ignore why he said that and just go with what they want to hear.
 
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Sejan

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To be honest, Ray tracing at some levels can be amazing. But really, it seems all they're being used for is amazing reflections...

Who gives a shit? Demons souls has no ray tracing in it... a game can be made with other forms lighting, like global illumination and still look incredible...

If you need to use Ray Tracing, do it. But it doesn't seem like its the be all end all to make an amazing looking game.

If you can make your game look amazing and Ray tracing isn't necessary, why even bother?

RT is just one tool that can be used to improve a game in a number of different ways. It certainly isn’t necessary for every game to use it in every implementation, but it can be a tool that can push a good looking game to being great looking. It’s silly to suggest that all games need to use it in the same way, though.

More tools for developers can only be a good thing.
 

Lethal01

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You speak in "general" terms. Low level access can always give you advantages over an agnostic API like DX. However, that doesn't mean it's going to make your hardware "king of the hill" and it still has hardware limitations that can't be optimized (i.e. you are NOT going to see 4k/30 with a PC game showing that same game running 4k/60 on a console like the PS5).

You speak in general terms when you say things like "you won't see benefits due to optimization, optimization these days just means lowering the resolution". The way you jump to acting like optimization whenever someone mentions it is a a sin.. I assume because you continue to treat people you disagree with as some kind of fanboy hivemind.
 

VFXVeteran

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You speak in general terms when you say things like "you won't see benefits due to optimization, optimization these days just means lowering the resolution". The way you jump to acting like optimization whenever someone mentions it is a a sin.. I assume because you continue to treat people you disagree with as some kind of fanboy hivemind.

When you can objectively prove me wrong with optimization NOT being lowering resolution and incorporating a 'ray switch' to filter out things from the scene like in Spiderman MM/WDL, you can't really say shit about me being wrong. So far what you've seen coming out of these consoles is exactly what I've proposed. And even worse, they can't even play games with non-RT at a true native 4k/60FPS.
 
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Lethal01

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RT has got to be the most Over rated and useless tech I have seen in some time. Honestly yet to see what the big deal is regarding it.

For me techs like DLSS and Checkerboarding are far more useful techs going forward.

If you don't care about games improving visuals then sure. If all you want is to play ps4 games at 240fps then it won't appeal to you.
If you like having realistic light shadows and reflections and games actually looking more realistic then it's totally indispensible.



I have been waiting decades for games to have consistently good shadows. I want them to actually have a proper solution to the game looking good, they can make it looks smooth once that is solved.
 
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VFXVeteran

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here's some more.

So he wants access to the BVH structure. I was not aware that you don't have access to it. And if you can only access it when it's at the triangular level, that would suck. I would, however, stay away from trying to mess with that structure if it was built by the API itself. That would take a LOT of work to keep it in sync and continue to extract/inject data into it.
 

VFXVeteran

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Why isn’t Vulcan mentioned in the title of this thread?

I don't think VulkanRT is ready yet. I'm most certain that a lot of vendors will adopt it. DXR probably needs to go through it's iterations again like DX11/DX12. It's a slow burning process with new things like everything else.
 

draliko

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except abstraction layer on a console is not a big black box as someone thinks, because on consolle hw is fixed and so the functions can be optimized to the metal if you want. It's not the same code on pc and xbox, you call a function to get a result, how it get that results can be totally different. A standardized api doesn't mean you have to leave performance on the way. the abstraction layer ms uses is porting friendly, that doesn't mean you simply press the port to xbox button and it's done (could be for easy and simpler projects). And as every generation UE showed a nice demo, that's all, every gen is the same, nice shiny demo in the beginning and then you wait years for the engine and games that could have similar visual to that demo, it's just how the industry moves, a modern game requires big time investment. Naturally you need to have good software engi, but i don't think this is the problem at MS, even if they're always pointed at the evil they have pretty much created the modern pc environment and market
 
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Lethal01

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So he wants access to the BVH structure. I was not aware that you don't have access to it. And if you can only access it when it's at the triangular level, that would suck. I would, however, stay away from trying to mess with that structure if it was built by the API itself. That would take a LOT of work to keep it in sync and continue to extract/inject data into it.

Yes, he thinks that would be a good start. Assuming there is a lot more that he doesn't wanna flood his twitter with.
 
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mr.dilya

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RT has got to be the most Over rated and useless tech I have seen in some time. Honestly yet to see what the big deal is regarding it.

For me techs like DLSS and Checkerboarding are far more useful techs going forward.

It really is but you’ll never convince the cult otherwise.
 
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