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Comment by wtallis | Hacker News Reader

> Sure fully pathtraced graphics might not be 100% usable currently, but the fact that they're even 70% usable is amazing!

Aside from Cyberpunk 2077 and a handful of ancient games with NVIDIA-sponsored remakes, what even offers fully path traced lighting as an option? The way it went for CP2077 makes your "70% usable" claim seem like quite an exaggeration: performance is only good if you have a current-generation GPU that cost at least $1k, the path tracing option didn't get added until years after the game originally shipped, and they had to fix a bunch of glitches resulting from the game world being built without path tracing in mind. We're clearly still years away from path tracing being broadly available among AAA games, let alone playable on any large portion of gaming PCs.

For the foreseeable future, games will still need to look good without fully path traced lighting.

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> performance is only good if you have a current-generation GPU that cost at least $1k

That's why I said games aren't currently designed with only pathtracing in mind, but in 3-5 years with faster hardware and better algorithms, we'll probably start to see it be more widespread. That's typically how graphics usually develop; something that's only for high end GPUs eventually becomes accessible to everyone. SSAO used to be considered extremely demanding, and now it's accessible to even the weakest phone GPU with good enough quality.

Again the fact that it's feasible at all, even if it requires a $1000 GPU, is amazing! 5 years ago real time path tracing would've been seen as impossible.

> The way it went for CP2077 makes your "70% usable" claim seem like quite an exaggeration

Based on the raw frame timing numbers and temporal stability, I don't think it is. RT GI is currently usually around ~4ms, which is at the upper edge of usable. However the temporal stability is usually the bigger issue - at current ray counts, with current algorithms, either noise or slow response times is an inevitable tradeoff. Hence, 70% usable. But with another few years of improvements, we'll probably get to the point where we can get it down to ~2.5ms with the current stability, or 4ms and much more stable. Which would be perfectly usable.

> RT GI is currently usually around ~4ms, which is at the upper edge of usable. However the temporal stability is usually the bigger issue - at current ray counts, with current algorithms, either noise or slow response times is an inevitable tradeoff. Hence, 70% usable. But with another few years of improvements, we'll probably get to the point where we can get it down to ~2.5ms with the current stability, or 4ms and much more stable. Which would be perfectly usable.

Maybe you should be saying 70% feasible rather than 70% usable. And you seem to be very optimistic about what kind of improvements we can expect for affordable, low-power GPU hardware over a mere 3-5 years. I don't think algorithmic improvements to denoisers and upscalers can get us much further unless we're using very wrong image quality metrics to give their blurriness a passing grade. Two rays per pixel is simply never going to suffice.

Right now, an RTX 4090 ($1700+) runs at less than 50 fps at 2560x1440, unless you lie to yourself about resolution using an upscaler. So the best consumer GPU at the moment is about 70-80% of what's necessary to use path tracing and hit resolution and refresh rate targets typical of high-end gaming in 2012.

Having better-than-4090 performance trickle down to a more mainstream price point of $300-400 is going to take at least two more generations of GPU hardware improvements even with the most optimistic expectations for Moore's Law, and that's the minimum necessary to do path tracing well at a modest resolution on a game that will be approaching a decade old by then. It'll take another hardware generation for that level of performance to fit in the price and power budgets of consoles and laptops.

UE5 supports fully path traced lighting and Black Myth Wukong is a recent example.

Alan Wake 2 has had path tracing from day 1, and it looks excellent with (and without) it.

> For the foreseeable future, games will still need to look good without fully path traced lighting.

And in 7-10 years when the software stack is matured, we'll be thanking ourselves for doing this in hardware the right way. I don't understand why planning for the future is considered so wasteful - this is an architecture Apple can re-use for future hardware and scale to larger GPUs. Maybe it doesn't make sense for Macs today, but in 5 years that may no longer be the case. Now people don't have to throw away a perfectly good computer made in these twilight years of Moore's law.

For non-games applications like Blender or Cinema4D, having hardware-accelerated ray tracing and denoising is already a game-changer. Instead of switching between preview and render layers, you can interact with a production-quality render in real time. Materials are properly emissive and transmissive, PBR and normal maps composite naturally instead of needing different settings, and you can count the time it takes before getting an acceptable frame in milliseconds, not minutes.

I don't often give Apple the benefit of the doubt, but hardware-accelerated ray tracing is a no-brainer here. If they aren't going to abandon Metal, and they intend to maintain their minuscule foothold in PC gaming, they have to lay the groundwork for future titles to get developed on. They have the hardware investment, they have the capital to invest in their software, and their competitors like Khronos (apparently) and Microsoft both had ray tracing APIs for years when Apple finally released theirs.

I think you have the wrong impression. Apple M2 does not have hw ray tracing. M3 and M4 do.

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