Revolutionary PC game tech developers ignore

Variable rate shaders, or VRS, is a major part of graphics technology that PC gamers have largely ignored for the past three years. Works on all modern AMD and Nvidia devices screen cardsIt has a simple goal: to improve performance by up to 20% without any noticeable decrease in image quality.

It looks amazing, doesn’t it? Well, there’s a reason you probably haven’t heard much about it. The past two years have focused on Nvidia Deep Learning Ultra Sampling (DLSS) and AMD FidelityFX Ultra Precision (FSR) As champions providing performance in the era of modern graphics. And while it makes the best bang for the buck for a game developer, VRS is an equally impressive tool that is woefully unused.

Variable rate shader: not new

Visualize VRS in Gears 5.
Microsoft / Alliance

VRS is not new – Microsoft مدونة Blog Post The feature announcement in DirectX 12 is more than three years old. If you’re not familiar, VRS changes the resolution with which shading is applied within a scene. It does not change the accuracy of the game; VRS simply allows neighboring pixels to share shaders rather than making the GPU do more than redundant work.

If a corner of a scene is wrapped in shadow without much detail, for example, your graphics card won’t need to calculate the light, color, and texture values ​​for each pixel. It can save some hassle by grouping them together – four pixels in a 2×2 grid may have very similar shader values, so VRS starts to improve performance by calculating just one shader and applying it to the rest of the grid. The size of the grid is the shading rate, and more pixels in the grid means a lower shading rate.

This small change can make a big difference in performance. in gear tactics At 4K resolution, for example, VRS displayed a 22.9% increase in average frame rate. This is the best example, but Resident Evil Village It also showed a 9.8% increase in average frame rate, while Hitman 3 Offered a strong 8% boost. The idea behind VRS is that it should be indistinguishable when turned on, providing essentially free performance.

VRS performance in three video games.

There are only a few games that support VRS on PC, despite it being over three years old. I’ll address this issue later in the column, but the more pressing issue is how to use VRS among the few games that support it.

There are two buckets for VRS: one that makes it seem like a revolutionary suite that offers free performance, and one that makes it look like a feature that does more harm than helps.

Two worlds from VRS

Correction screen for VRS in Dirt 5.
Code Masters

Microsoft has two levels of VRS in the . format DirectX 12 Ultimate: Level 1 and Level 2. Level 1 Level 1 is the most common technique you’ll find in games, and it’s the crux of the problem. This level does not care about individual pixels, and instead applies different shaders to each pull call. When a call to draw background assets, for example, might have a 2×2 shading rate, while assets drawn in the foreground have a 1×1 shading rate.

Level 2 VRS is what you want. This is much more accurate, allowing the developer to shade inside Tie call. This means that one part of the model can have a 2×2 shading ratio, for example, while a more detailed area can be used in the same 1×1 model. Level 2 VRS is ideal, as it allows the developer to focus on the details that are important to press Every ounce of performance.

VRS comparison in Resident Evil Village.
Left: VRS Off, Right: VRS On

Problem: Even among the small group of games that support VRS, most only use level 1. resident evil village, The latest game I’ve looked at, uses Tier 1 VRS. You can see how this affects the image quality above, as you can create pixels in the snow as Level 1 VRS brings everything together just a few feet away from the camera.

Contrast with gear tactics Which supports Level 2 VRS. There is little difference in quality when zoomed in to about 200%, but it looks much nicer than at level 1. You can spot the difference when both frames are side by side with zoom, but put those two frames in the back. Blind test, and you won’t be able to tell any difference. I certainly can’t.

VRS comparison at Gears Tactics.
Left: VRS Off, Right: VRS On

Free performance with virtually no loss in image quality is huge, but on PC at least, VRS isn’t quite as much into the conversation as it should be (not to mention the discussion between Level 1 and Level 2). Even after moving gear tactics And the gears 5 to Level 2 VRSThe developers didn’t jump on the performance train. Instead, VRS has mostly focused on the limited power budgets of consoles, and there is one particular console that holds the feature back.

Console Siege

PS5 standing on a table with purple lights around it.
Martin Cutler / Unsplash

The reason why VRS comes out in two versions is that Level 2 requires certain hardware to work. Nvidia and . RTX graphics cards AMD RX 6000 GPUs You have hardware support, as with the Xbox Series X. Old graphics cards and Playstation 5 don’t do that. Instead, they use a software-based version of Tier 1 VRS, if it’s ever available in the game.

Developers working on multiplatform titles usually focus on the lowest common denominator, which is Tier 1 VRS. There are only a few developers who have done their best to support Tier 2 VRS on supported devices (ID Tier 2 VRS software is used on Eternal torment for Xbox Series X, for example), but the vast majority of modern AAA games either don’t support VRS or use this level 1 approach.

as such gear tactics It shows that proper Level 2 implementation from the developer provides the best image quality and performance. It is true that DLSS and FSR provide an easy solution for developers to improve performance in PC games. But a proper Level 2 VRS can represent about a 20% increase for any difference in image quality, which is too good to be ignored.

This article is part of risbeck – An ongoing biweekly column that includes in-depth discussions, tips, and reports on the technology behind computer games.

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