Comment by crote

Comment by crote 3 days ago

16 replies

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Consoles are the perfect platform for a proper pure ray tracing revolution.

Ray tracing is the obvious path towards perfect photorealistic graphics. The problem is that ray tracing is really expensive, and you can't stuff enough ray tracing hardware into a GPU which can also run traditional graphics for older games. This means games are forced to take a hybrid approach, with ray tracing used to augment traditional graphics.

However, full-scene ray tracing has essentially a fixed cost: the hardware needed depends primarily on the resolution and framerate, not the complexity of the scene. Rendering a million photorealistic objects is not much more compute-intensive than rendering a hundred cartoon objects, and without all the complicated tricks needed to fake things in a traditional pipeline any indie dev could make games with AAA graphics. And if you have the hardware for proper full-scene raytracing, you no longer need the whole AI upscaling and framegen to fake it...

Ideally you'd want a GPU which is 100% focused on ray tracing and ditches the entire legacy triangle pipeline - but that's a very hard sell in the PC market. Consoles don't have that problem, because not providing perfect backwards compatibility for 20+ years of games isn't a dealbreaker there.

Aurornis 3 days ago

> Rendering a million photorealistic objects is not much more compute-intensive than rendering a hundred cartoon objects

Increasing the object count by that many orders of magnitude is definitely much more compute intensive.

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  • reactordev 3 days ago

    Only if you have more than 1 bounce. Otherwise it’s the same. You’ll cast a ray and get a result.

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    • pclmulqdq 3 days ago

      No, searching the set of triangles in the scene to find an intersection takes non-constant time.

      Reply View 5 replies
      • cubefox 3 days ago

        I believe with an existing BVH acceleration structure, the average case time complexity is O(log n) for n triangles. So not constant, but logarithmic. Though for animated geometry the BVH needs to be rebuilt for each frame, which might be significantly more expensive depending on the time complexity of BVH builds.

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khalladay 3 days ago

> Rendering a million photorealistic objects is not much more compute-intensive than rendering a hundred cartoon objects

Surely ray/triangle intersection tests, brdf evaluation, acceleration structure rebuilds (when things move/animate) all would cost more in your photorealistic scenario than the cartoon scenario?

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  • reactordev 3 days ago

    Matrix multiplication is all that is and GPUs are really good at doing that in parallel already.

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    • oivey 3 days ago

      So I guess there is no need to change any of the hardware, then? I think it might be more complicated than waving your hands around linear algebra.

      Reply View 1 reply
thfuran 2 days ago

>Consoles don't have that problem, because not providing perfect backwards compatibility for 20+ years of games isn't a dealbreaker there.

I'm not sure that's actually true for Sony. You can currently play several generations of games on the PS5, and I think losing that on PS6 would be a big deal to a lot of people.

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  • kevincox 2 days ago

    Maybe they can pull the old console trick of just including a copy of the old hardware inside the new console.

    However I suspect that this isn't as cost and space effective as it used to be.

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cubefox 3 days ago

Combining both ray tracing (including path tracing, which is a form of ray tracing) and rasterization is the most effective approach. The way it is currently done is that primary visibility is calculated using triangle rasterization, which produces perfectly sharp and noise free textures, and then the ray traced lighting (slightly blurry due to low sample count and denoising) is layered on top.

> However, full-scene ray tracing has essentially a fixed cost: the hardware needed depends primarily on the resolution and framerate, not the complexity of the scene.

That's also true for modern rasterization with virtual geometry. Virtual geometry keeps the number of rendered triangles roughly proportional to the screen resolution, not to the scene complexity. Moreover, virtual textures also keep the amount of texture detail in memory roughly proportional to the screen resolution.

The real advantage of modern ray tracing (ReSTIR path tracing) is that it is independent of the number of light sources in the scene.

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newsclues 3 days ago

So create a system RT only GPU plus a legacy one for the best of both worlds?

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