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You in all probability received’t have the ability to run Portal RTX. I’ll simply get that out of the way in which upfront. Based mostly on the newest Steam {hardware} survey, I’d estimate lower than 10% of PCs are even able to operating Portal RTX, and it’s nearer to 4% if we’re speaking about any affordable body fee and determination.
Portal RTX is probably the most demanding recreation I’ve examined, and operating it’s only doable with intelligent picture reconstruction strategies and the quickest GPUs available on the market at this time. Ray tracing is taxing, nevertheless it’s how Portal RTX is leveraging ray tracing that makes it the next-gen benchmark I’ve been ready for.
Far more demanding than you assume
Portal RTX is far more demanding than you in all probability assume. Even two years after launch, Cyberpunk 2077 is probably the most demanding recreation in my GPU benchmark suite, each with ray tracing on and off. Even Metro Exodus Enhanced Version, which makes use of full ray-traced international illumination, is leagues simpler to run than Cyberpunk 2077.
However Portal RTX is much more taxing. For reference, you possibly can see how the RTX 3070 held up with Nvidia’s Deep Studying Tremendous Sampling (DLSS) set to Auto in Portal RTX under. In each Cyberpunk 2077 and Portal RTX, I used the identical DLSS mode and the best ray tracing high quality preset.
Portal RTX is a showcase for Nvidia’s next-gen graphics playing cards just like the RTX 4090, and particularly, the distinctive frame-generation capabilities of those GPUs with DLSS 3. Even with free frames, Portal RTX taxes the RTX 4080 rather more than Cyberpunk 2077 does.
Cyberpunk 2077 and Portal RTX couldn’t be extra completely different (technically and thematically), nevertheless it’s illustration that Portal RTX is likely to be probably the most demanding ray tracing recreation we’ve seen thus far. Or as a minimum, it’s probably the most demanding ray tracing recreation you may truly play.
The query is why? Portal is 15 years previous at this level, and even with up to date belongings and rays bouncing round, absolutely it couldn’t be extra demanding than the dense, vibrant open world full of ray-traced lighting that’s out there Cyberpunk 2077 (or numerous different video games with ray tracing).
However it’s, and there’s clarification for why.
Why Portal RTX is so taxing
Portal RTX makes use of path tracing, which you may see Nvidia confer with as “full ray tracing.” That alone isn’t the rationale Portal RTX is so demanding — it’s how Nvidia is using path tracing to hint all the lights all through a scene, in addition to the shadows, reflections, and refractions these lights introduce.
Path tracing works by tracing a line out out of your digital camera. It goes in a straight line till it hits an object, bounces, and continues on, finally going again to the sunshine supply. The problems give you how completely different objects deal with mild. A few of that mild is absorbed, different mild is mirrored, and a few breaks off as a refraction. Multiply this throughout each pixel and introduce a number of bounces (which Portal RTX does), and every body turns into a fancy string of math that’d make anybody’s head spin.
Fashionable AAA video games with ray tracing don’t undergo all of that trouble. A chief instance is Dying Gentle 2‘s ray-traced flashlight. It traces rays the place the flashlight hits a floor and bounces them across the room, making a delicate glow in darkish areas the place that lighting finally ends up. Critically, it doesn’t forged shadows, nor does it choose up the colour properties of objects the flashlight interacts with.
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These limitations are needed shortcuts for a recreation as grand as Dying Gentle 2. It’s utilizing ray tracing to boost sure options within the recreation. Portal RTX is utilizing ray tracing to simulate mild. Path tracing brings all the disparate facets of how mild behaves in an surroundings beneath a single roof, and finally ends up rather more demanding within the course of.
Cyberpunk 2077 takes loads of shortcuts, too. In ray-traced reflections, for instance, the sport calculates among the information from typical display house reflections (SSR) relying on what’s being mirrored. As well as, post-process parts like road fog don’t carry mild additional into the scene. That’s not the case in Portal RTX, as you possibly can see within the screenshot under. The blue forged from the hallway travels all through the scene because of the delicate fog and casts blue mild far past the hallway.
Nvidia is not any stranger to path tracing, showcased by the Quake II RTX demo. However Nvidia says Portal RTX consists of 4 occasions as many bounces as Quake II RTX and Minecraft RTX, resulting in a way more demanding (and bodily correct) showcase of sunshine.
Portal RTX is constructed on Nvidia’s RTX Remix modding toolkit, too, permitting it entry to options that weren’t out there in earlier tech demos and that we don’t see in typical ray-traced video games. The characteristic you’ll discover first is RTX Direct Illumination (RTXDI), which permits any mild in a scene to forged path-traced mild and shadows. Within the scene under, I’ve highlighted 4 areas the place RTXDI is at play: the yellow change on the ground, the orange glow from the steps, the pink glow from the button, and the blue mild from the window.
The opposite is — prepare for it — Reservoir Spatio-Temporal Significance Resampling International Illumination, or ReSTIR GI. Nvidia has a analysis paper that goes into the gritty particulars, however the in need of it’s that ReSTIR GI takes a number of samples from crucial mild paths as an alternative of tracing extra paths. Regardless of what the efficiency above might recommend, that is truly extra environment friendly and permits Portal RTX to hint extra bounces than it could’ve been in a position to.
Put collectively, Portal RTX is a glimpse at what could also be doable in huge open-world video games like Cyberpunk 2077 and Dying Gentle 2 sooner or later. It takes shortcuts, nevertheless it nonetheless serves totally simulating mild in a scene.
A problem for next-gen GPUs
When the RTX 4090 was introduced, we criticized it for not having any video games to push the GPU to its restrict. Portal RTX is that recreation. The extreme ray tracing performs an vital function, after all, however the 2007 launch has additionally been overhauled with bodily based mostly rendering (PBR) supplies, new belongings, and some enjoyable Easter eggs.
Portal RTX doesn’t tarnish the traditional with overly reflective surfaces and nonsensical lighting like Quake II RTX did. It’s a lovely recreation and the proper excuse to revisit Aperture Laboratories. It’s simply unlucky that so few will have the ability to run the sport.
With the RTX 3070, I averaged 1.9 frames per second (fps) with DLSS turned off at 1440p. Even with DLSS on, I wasn’t in a position to hit 60 fps, and that was after bumping the decision all the way down to 1080p. There’s little doubt Portal RTX seems to be and runs nice with a brand new RTX 40-series GPU and DLSS 3 in full swing, however you’ll want a minimum of an RTX 3080 to push the sport above 60 fps with DLSS turned on.
Sadly, that leaves different GPUs out within the chilly. Portal RTX doesn’t at the moment work with Intel’s Arc A770 and A750, and AMD’s GPUs are too behind in ray tracing to carry up (even on the excessive finish). Nvidia was type sufficient to incorporate a temporal upscaler to make use of with non-RTX GPUs, however that’s not the primary concern going through Portal RTX. It’s how demanding the sport is even with upscaling on.
The excellent news is that Portal RTX is an unlikely showcase of what next-gen seems to be and performs like. We’ve had the identical batch of demanding titles for just a few years now. Who would’ve thought {that a} quaint, two-hour puzzle recreation with a bit of ray tracing could be the one to problem the established order?
This text is a part of ReSpec – an ongoing biweekly column that features discussions, recommendation, and in-depth reporting on the tech behind PC gaming.
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