DegustatoR
Legend
Oh look you've deleted my fully technical reply again calling it a "market share discussion".
That's what happens when a big mess is made and someone else has to step in to clean up the mess. One of the posts was restored after removing the baited content @ https://forum.beyond3d.com/threads/amd-rdna3-specifications-discussion-thread.63037/post-2276120
Please, everyone, learn how to self-moderate. Don't get drawn into pointless back-and-forth with some folks.
Silent_Buddha
Legend
And yet, that's the exact direction that UE5 is going. And if reports are to be believed roughly half of all AAA games in development now are on UE5 with most if not all of them using consoles as the primary development target.
And that is unlikely to change until the next generation of consoles arrive with more performant RT.
Regards,
SB
Frenetic Pony
Veteran
I mean, it pretty much has to go that way. Devs will be supporting the Series S until 2029 or more at this rate. Besides, RT is expensive, shading is cheap, may as well concentrate on the latter where possible.
I wonder if RDNA4 could see even more use of the multi-issue design? If they can split wavefronts, at least for RT instructions, why not split it into 4. Half the worst case scenario for ray bundles.
In absolute terms you’re right of course. RT usage will only increase. That’s a different point though. My comment was about the relative balance of ray casting vs shading workloads. As RT games get “smarter” it seems there will be less emphasis on casting rays and more emphasis on importance sampling, temporal and spatial reuse etc. This means Nvidia’s (and Intel’s) raw ray casting advantage could be mitigated in future RT titles.
DegustatoR
Legend
It is? Last time I've checked UE5 was in fact adding h/w RT features and not removing them.
They do improve their s/w Lumen path as well but that's expected - and the results are also expected with h/w path being either faster or resulting in higher quality.
So in a sense of this discussion you're likely looking at a hypothetical 2x faster non-RT GPU ending up at the same speed/quality in UE5 as a 1/2 as complex one with RT h/w would.
Which then means that it would again be 2x faster at the same complexity.
Sorry about the purely made up math of course but you get the idea.
Which means what for PC market and PC GPUs exactly? Some of the most demanding RT games on the market right now are using UE4 - while their console versions don't use RT at all.
The fact that UE5 will scale from non-RT all the way up to pure PT means that it will be easy for developers to make use of advanced RT h/w on PC in games using UE5, not the opposite which you seem to suggest.
I mean we already have some such titles and a) they don't really mitigate anything, just show a lower comparative advantage, b) it's not like AMD has a FLOPs advantage either and it's not clear why would they have it in the future, and c) these things could be a great fit for AI which, again, well...
Also as I've said I don't think that it will be less emphasis on casting rays - they'll just use RT for more than they do now, add a secondary bounce here and there, etc. The end game is still full path tracing after all.
Bondrewd
Veteran
Never gonna happen unless someone magically finds a way to revive moore's law (and fucks a hole in the memory wall while we're at it).
Nah. Your hypothetical calculations hold no weight. If the HW-RT mode could be faster by using lower quality similar to SW-Lumen, Epic sure as hell would've done that in high scalability mode, which targets 60 fps on consoles. But instead they are going to use SW-RT mode.
DegustatoR
Legend
We haven't really seen this "60 fps" mode in action though did we? Judging from the description in UE docs it will have severe quality cutbacks compared to both "30 fps s/w" mode and RT h/w mode so if it's cut back beyond what people would even expect from RT then there's little point in using h/w RT for it.
And we do have games with h/w RT doing Lumen like stuff on consoles running at 60 fps right now so it's not like console RT h/w can't do it. It's just Epic's choice, for reasons which we don't know yet in full.
Bold claims with nothing to back them up.
There are actually path tracing titles in works as well as already productized games.
The number of such games, mods, remasters can only grow up with all the SDKs and tools that are being developed.
DegustatoR
Legend
I'd say it's the exact opposite - because of scaling being "dead" the idea of putting 2/3/4X more FP32 SIMDs into a chip is what's "never gonna happen" while opting for a "smart" dedicated h/w doing the same thing for a fracture of complexity (and power likely) will.
Bondrewd
Veteran
Yea bro making 20yo titles shiny is surely the best application of very limited xtor budgets.
Show me PT in anything approaching modern day AAA and then we might talk (obvious we won't, rofl).
Tech demos. NV loves throwing those around (remember that car sim with SMP haha).
No one's seriously playing q2rtx.
That's like half your GPU already.
Again, each xtor gonna cost more now for every upcoming node.
Cyberpunk, Portal with RTX, Justice, Minecraft with RTX are all new games with modern content (yes, even minecraft when pushed to the limits), so nothing 20yo in the list.
RT scales logarithmically with triangles counts, so it's way easier to push it for billions of micro triangles in real-time, no need for complex LODs and other voodoo. IMO a way better investment of xtors than doing all the heavy lifting in compute that pushes power consumption ever higher)
Many play it, as well as myriads of other modded games out of nostalgia or for many other reasons.
Yes, because of Dennard scaling, and as long as it doesn't scale as good as the number of xtors there will always be extra xtors left for energy efficient stuff)
Bondrewd
Veteran
The what.
We don't have extra xtors left anymore since each one costs more now.
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Surely amd and others must see that working smarter is the only way forward. Even if we manage to scale smaller several nodes below 1nm, you approach an insurmountable problem of cooling. We are talking about generating power at watts per cm^2 that will be greater than nuclear power output.
Bondrewd
Veteran
Those are SIMD machines, there's only so much you can do to make em smarter.
Cooling isn't really the biggest issue (particularly for GPUs that, unlike, say, DC CPUs, spend relatively little power on driving their I/O) given we're making fairly huge dies or huge area MCPs those days.
It's the cost per transistor dilemma.
Sure, we have. 8nm Ampere will be as fast as RDNA3 on 5nm with Raytracing. That is basically twice the numbers of transistor useable to spend on other things - like L2 cache, higher clock rates, more Tensor Cores etc.
The logarithmic scaling is nice, but it does not change how expensive tracing is ragardless.
And, as said before, it only applies to the tracing, not to the cost of building BVH. You talk about billions of triangles, but you still ignore this is not possible without having LOD.
LOD is not voodoo, it is one of the primary problems in computer graphics we try to solve for a reason, and RT does not change those reasons.
How do you intend to stream open worlds without LOD? How should it fit into limited memory? How do you intend to build BVH for it?
If you resist to understand, i'm sure to know who's next with proudly announcing switching over to UE, because having no more idea about how to do it on his own.
Sorry, but the ignorance is tiring.
I think we do know those reasons quite well:
1. Epic does not choose - it's the dev who decides which path to use for what. Currently we just still need an alternative to HW RT anyway.
2. We know HW RT is slower with overlapping instances (natural scenes), but faster with non overlapping instances (technical scenes).
3. HW RT can't support Nanite or any other fine grained LOD solution due to API design flaws.
We have discussed this up and down, but still people use the Matrix demo as proof the HW RT path is 'generally faster or better'.
Yes, assuming end game means game over for the gaming industry, committing suicide by requesting unaffordable HW from anyone.
Otherwise, anyone with a brain will use at least a caching technique, which is harder to implement than PT, but gives speedups of multiple orders of magnitude for the same quality.
What will happen (and already did) is that game devs call their caching tech 'Path Tracing', just for the sake to use a marketing buzz word.
If at all, we could seriously discuss how the border blurs between traditional PT and realtime methods. Listing games like CP as PT examples would require such discussion, because RT CP still does not look realistic at all, while PT does.
Tiring, turning in circles, stubborn, and ignorant. It's like schoolboys arguing who's the best wrestler, but no technical discussion aiming to converge at serious way forward.
This goes on since years already, and there is no progress. Shame to all of us, really.
DegustatoR
Legend
We don't. You guessing is not us knowing.
Epic choose what they implement for what feature/performance level.
This is true and it will most likely be possible to still get 60 fps while using RT h/w on modern consoles in UE5 - with a different set of limitations than those of a 60 fps non-h/w RT mode. It will be interesting to see how many developers will end up choosing such option instead of going with Epic's "recommended" one.
Do we? UE5 needs it because it targets mobile platforms where RT is in its infancy and will remain so for some time most likely. On PC we really don't need a non-RT path for games coming out in 2024+. On consoles we don't need it right now already.
We know that it's slower in scenes designed as many overlapping instances and we also know that this is an engine world design issue, not a h/w RT issue.
Yep.
Neither can s/w RT in UE5 as it's using SDF simplification for that. And h/w RT likely can support Nanite but it should be implemented differently for that.
So most of what you've said is actually wrong.
Nowhere does a "marketing buzz word" imply the number of RPPs you need to be compatible with it. You can shoot one ray per scene for all anyone care and if your "caching scheme" will allow you to reconstruct the whole scene from that one ray in something which will be close to full detail - then it will still be PT.
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