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Comment by sterlind | Hacker News Reader

All sorts of rendering tricks had to be played before RTX. Now that we have real-time ray tracing, models are becoming more important than shaders (see e.g. Minecraft. It looks like a real world made of Legos - the blocks make it look artificial.)

Maybe once real time photorealism is cracked, we'll move to a completely Newtonian global physics for some games, with some analogue of "atoms" the way RTX models "photons."

I'm not in the industry, this is just something I'm wondering about. What would Minecraft be like if blocks were the size of pixels and the physics were real?

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> Maybe once real time photorealism is cracked, we'll move to a completely Newtonian global physics for some games, with some analogue of "atoms" the way RTX models "photons."

There is an extreme amount of doubt about whether the tech is real (myself included). These people have promised the world, have incredible videos, but have nothing to show in terms of a demo you can download and run yourself. Still, they claim to do what you describe and have videos demonstrating it: https://www.youtube.com/watch?v=J62z_7JaYMw

Holy shit, wow! I hear you on the skepticism, but did you notice how the vehicles shimmer during some of the editing? I think think they're optimizing by joining adjacent voxels together until they're deleted, at which point they get replaced with new polys, and it causes a ripple effect.

That type of detail suggests to me that it's a real (clunky) demo, but maybe it's running slower than advertised.

I can also understand not releasing a demo.. the code would be too valuable to risk reverse engineers.

It's possible that it's an async compute task, which could potentially miss a frame and show old data (instead of the whole frame missing vsync).

Also this demo is supposed to be running on a PS5 devkit, which means that you'd need a devkit to run it, which means that you'd need to sign NDAs and join their developer programs and whatnot.

Having worked with current gen consoles (meaning I can't go into any amount of detail), it's not a trivial thing to get a demo like this running well on PCs. This demo is likely making use of every platform specific feature available to them.

That said, the demo might be accessible through some back channels if you're already a UE4 licensee and have a PS5 devkit.

The link I shared wasn't UE5, and their other videos specifically indicate that they are running on PC - unbelievably modest PC hardware at that.

> it's not a trivial thing to get a demo like this running well on PCs

This old tired argument.

The current theory for how the meshing is done is something similar to mesh shaders (available on commodity PC hardware since 2018)[1]. This "PS5 platform specific feature" running on PC in 2018[2].

As for the lighting, NVDIA have already had this "platform specific feature" on PCs for some time now. It's called RTX. In 2018[3] (using DLSS), in 2020[4] (no apparent DLSS usage, but it may have improved).

Both next-gen consoles are essentially PCs. Their primary advantage is tightly coupled hardware (e.g. memory latency, the absurdly fast PS5 SSD). While dedicated raytracing silicon on AMD is currently unique to PS5 (AMD claims they can emulate DXRT on Navi), it has been around for more than a year in consumer hands in the form RTX.

[1]: https://devblogs.nvidia.com/introduction-turing-mesh-shaders... [2]: https://www.youtube.com/watch?v=CRfZYJ_sk5E [3]: https://www.youtube.com/watch?v=jkhBlmKtEAk [4]: https://www.youtube.com/watch?v=2744rWPvNuE

I work in AAA. I'm talking lower level things like picking which "type" of GPU memory to allocate, access to specific registers in shaders, etc. PC didn't have real async compute capabilities until DX12, for example.

On the CPU side yeah it's 100% just a normal computer but nothing will be interrupting your threads. I think Windows 10 tries to do in it's new game mode too.

Sorry for assuming the link was the PS5 one. I have a UDN account and their login setup sometimes just dumps me to their homepage, so I made the assumption that it was the same video that I had seen everywhere else.

> PC didn't have real async compute capabilities until DX12

Indeed it didn't, and DX12 is extremely old tech. Consoles don't have async compute right now. (Edit: apart from the PS3).

AMD GCN absolutely supports async compute[1]. Radeon cards for years would only make use of the ACEs in pure compute contexts, as OpenGL and DX11 had no concept of a secondary command queue and could not make use of them. This is a big part of the reason why Vulkan/DX12 require so much boilerplate to get a triangle rendered.

The PS3's SPU definitely counts as async compute especially with how it was used later in the console lifecycle[2] once people had time to familiarize themselves with it.

However, in the current gen consoles, you don't have to deal with a different ISA, command queuing, and shared memory between the GPU and CELL processor. You are only writing HLSL/GLSL/PSSL and setting up an aggressive amount of fencing to transition resources between readable and writable states within the GPU.

[1]: https://www.anandtech.com/show/9124/amd-dives-deep-on-asynch... [2]: https://www.slideshare.net/DICEStudio/spubased-deferred-shad...

It's going to be at least a solid 3-5 years until one can say "now that we have real-time ray tracing" as far as most consumer devices are concerned, and even then it likely won't mean that all games will use raytracing for all rendering - more likely just for select special effects etc. I wouldn't give it less than at least a decade or two before we can have a mainstream fully raytraced game; and even then, I'd guess that good game artists will keep using smoke and mirrors to make effects even more stunning than what they can make by the brute force ray tracing approach.

There are a few indie devs trying to make "finer resolution" Minecraft; e.g. https://www.youtube.com/watch?v=VQv1OEm_www

You might be interested in the upcoming game, Teardown[0]. The voxels are definitely larger than pixels, but much smaller than in Minecraft. It definitely exploits the voxel geometry for really impressive physics (as well as optimized ray tracing).

[0]: https://youtu.be/GCuCQSyqeXM

What you are suggesting are called voxel engines, and there have been a lot of attempts at them, none close to success.

There is no way we can simulate physics at the level you suggest for real-time games, not even in a hundred years. Unless you achieve a breakthrough in fundamental physics which would have an impact in every aspect of life, not just games.

Thanks, I didn't know what they were called!

There must be some granularity at which voxel engines can work smoothly today. Let's say my room is a square with 320 pixels on each side. 320^3 = 32,768,000 voxels, which looks like a lot, but an RTX 2080 can render 17 billion triangles per second, which works out to 273 million per frame at 60fps.

Let's ignore gravity and focus on momentum vectors and collisions. Even if simulating physics for each voxel were 10x slower than rendering a triangle, you could do 320^3 voxels in 60fps on today's hardware.

And this is naive, assuming you can't merge neighboring voxels together! I think you're being unfairly pessimistic.

You’re welcome!

Current systems simulate about 30k simple bodies. So that is already off by 3 orders of magnitude.

And that is a basic simulation, nothing complex, no fancy physics simulated, just rigid collisions.

Even if you could simulate the numbers you propose, 320 voxels per side is really low. Each voxel would be around a centimeter wide, which would look very bad (compared to the usual way of doing things).

I think you need to discretize time very finely to have believable collisiom physics. So it’s orders of magnitude more than 10x.

not exactly what you are saying, but you might be interested in teardown https://youtu.be/Wc_QC25RM44

Almost exactly what I was looking for! I can't fathom how a single person manages to make a game like that. He mentions a physics solver in that video.. I wonder if he'll talk about how it works

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