You most likely received’t be capable to run Portal RTX. I’ll simply get that out of the best way upfront. Based on the latest Steam {hardware} survey, I’d estimate lower than 10% of PCs are even able to working Portal RTX, and it’s nearer to 4% if we’re speaking about any affordable body fee and determination.
Portal RTX is essentially the most demanding recreation I’ve examined, and working it’s only doable with intelligent picture reconstruction strategies and the quickest GPUs available on the market immediately. Ray tracing is taxing, but it surely’s how Portal RTX is leveraging ray tracing that makes it the next-gen benchmark I’ve been ready for.
Way extra demanding than you suppose
Portal RTX is far more demanding than you most likely suppose. Even two years after launch, Cyberpunk 2077 is essentially the most demanding recreation in my GPU benchmark suite, each with ray tracing on and off. Even Metro Exodus Enhanced Edition, which makes use of full ray-traced world illumination, is leagues simpler to run than Cyberpunk 2077.
But Portal RTX is much more taxing. For reference, you’ll be able to see how the RTX 3070 held up with Nvidia’s Deep Learning Super Sampling (DLSS) set to Auto in Portal RTX under. In each Cyberpunk 2077 and Portal RTX, I used the identical DLSS mode and the very 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 specifically, 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), but it surely’s a great illustration that Portal RTX is likely to be essentially the most demanding ray tracing recreation we’ve seen thus far. Or at least, it’s essentially the most demanding ray tracing recreation you would possibly truly play.
The query is why? Portal is 15 years outdated at this level, and even with up to date belongings and rays bouncing round, certainly it couldn’t be extra demanding than the dense, vibrant open world filled with ray-traced lighting that’s accessible Cyberpunk 2077 (or numerous different video games with ray tracing).
But it’s, and there’s a great rationalization for why.
Why Portal RTX is so taxing
Portal RTX makes use of path tracing, which you would possibly see Nvidia discuss with as “full ray tracing.” That alone isn’t the explanation 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 digicam. It goes in a straight line till it hits an object, bounces, and continues on, finally going again to the sunshine supply. The issues provide you with how completely different objects deal with gentle. Some of that gentle is absorbed, different gentle 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 posh string of math that’d make anybody’s head spin.
Modern AAA video games with ray tracing don’t undergo all of that trouble. A first-rate instance is Dying Light 2‘s ray-traced flashlight. It traces rays where the flashlight hits a surface and bounces them around the room, creating a soft glow in dark areas where that lighting ends up. Critically, it doesn’t forged shadows, nor does it decide up the colour properties of objects the flashlight interacts with.
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These limitations are essential shortcuts for a recreation as grand as Dying Light 2. It’s utilizing ray tracing to boost sure options within the recreation. Portal RTX is utilizing ray tracing to simulate gentle. Path tracing brings all the disparate features of how gentle behaves in an surroundings below 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 a number of the knowledge from typical display screen area reflections (SSR) relying on what’s being mirrored. In addition, post-process parts like avenue fog don’t carry gentle additional into the scene. That’s not the case in Portal RTX, as you’ll be able to see within the screenshot under. The blue forged from the hallway travels all through the scene as a result of smooth fog and casts blue gentle far past the hallway.
Nvidia is not any stranger to path tracing, showcased by the Quake II RTX demo. But Nvidia says Portal RTX consists of 4 instances 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 accessible 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 gentle in a scene to forged path-traced gentle and shadows. In 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 crimson glow from the button, and the blue gentle from the window.
The different is — prepare for it — Reservoir Spatio-Temporal Importance Resampling Global 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 essential gentle paths as an alternative of tracing extra paths. Despite what the efficiency above might counsel, that is truly extra environment friendly and permits Portal RTX to hint extra bounces than it might’ve been capable of.
Put collectively, Portal RTX is a glimpse at what could also be doable in huge open-world video games like Cyberpunk 2077 and Dying Light 2 sooner or later. It takes shortcuts, but it surely nonetheless serves totally simulating gentle 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 intense ray tracing performs an essential 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 basic with overly reflective surfaces and nonsensical lighting like Quake II RTX did. It’s a wonderful recreation and the proper excuse to revisit Aperture Laboratories. It’s simply unlucky that so few will be capable 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 capable of hit 60 fps, and that was after bumping the decision all the way down to 1080p. There’s little question 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.
Unfortunately, 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 form sufficient to incorporate a temporal upscaler to make use of with non-RTX GPUs, however that’s not the primary challenge dealing with 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 ray tracing can be the one to problem the established order?
This article 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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