Grand Theft Auto 5 on PC has finally received RT enhancements to achieve feature parity with the last-gen console versions! 🎮 It’s been almost three years since they arrived on Xbox and PlayStation consoles. The wait was worth it, as the scalability is impressive and the game now includes the option to enable Ray Traced Global Illumination (RTGI), which could hint at the RT features we hope to see in the upcoming Grand Theft Auto 6.

Let's be real, though. GTA 5 is almost 12 years old, and therefore, there are limits to how much better the game can actually look. The original version was built with the fundamental limitations of the Xbox 360 and PlayStation 3 in mind, and that's still evident even in the maxed-out PC experience. The character models are of their time, and the quality of materials and textures is nowhere near as impressive as in modern releases.

GTA 5 comes from a time before the video game industry embraced techniques like physics-based art pipelines and shader math. Ray tracing can transform the game in many ways, but not to the point of comparing it to a new triple-A release. 🚀

Still, the improvements are welcome. The pre-RTGI GTA 5 suffered from a problem that many games of its era suffered from, especially those without RTGI. Indirect lighting in the original version was handled in an interesting way. According to research by Adrian Courrèges, the game generates a cubemap from the player's camera position in real time, similar to many racing games.

This provides approximate, real-time reflections on objects like cars, and on rougher surfaces, the game seems to use a filtered version of this to prevent shadows from being completely black. The problem is that lighting is only rendered from one angle, so all shadowed areas in GTA 5 tend to look gray or too dark. no is in sunlight tends to have a grayish or almost blue shade, and where the edges of the geometry are adorned with a thick halo of ambient occlusion on screen.

Ray-traced global illumination, which isn't available in the last-gen console versions! 🌟, is a game-changer here, with light bounce in environments of a far superior quality. To say it really brightens up the environment would be an understatement: the bounce lighting you get from the sun and the resulting indirect shadows drastically alter the look of the game, and always for the better! 🎉

Ray-traced reflections are also part of the package, drastically changing window reflections, for example, transforming them from low-quality versions to pixel-by-pixel RT updates. However, unlike other games with a physics-based pipeline, these RT reflections don't apply universally to all materials depending on the angle.

Rather, RT reflections are applied to select materials in the game that were marked as 'somewhat shiny' or 'fully shiny' in the original release. Still, at maximum settings, the BVH structure for RT (the geometry against which rays are traced) is much more complex than in the console versions, so while the technique is selective, it can be much more detailed than on Xbox or PS5.

In fact, the global illumination solution with RT is so comprehensive that it can't be considered simply an add-on to the standard game. A lot of care and development work has gone into it, which might not make much sense for a free update to just one version of an older game.

In fact, based on our analysis of the first GTA 6 trailer, there's enough evidence to suggest that this may be the technology from Rockstar's next release that's been ported to GTA 5 on PC. So, we may be getting a sneak peek at the lighting tech we'll find in GTA 6, both in terms of the features we can expect and the level of performance we might anticipate. 🔍

Let me anchor my reasoning here with several points. Typically, when an older game receives updates with some form of ray tracing limited to only a portion of the platforms that can play it, the developers usually make that ray tracing a bit more limited. For example, in Dying Light 2, RTGI only works in sunlight, but not in other light sources. Similarly, in the current-gen update of The Witcher 3, RTGI doesn't work on a per-pixel basis and is applied crudely to the world with probes, resulting in obvious artifacts.

That's not the case here: it's much more comprehensive. First, it applies to all light sources, not just the sun. This isn't limited to stationary lights, but also moving lights, like those on cars. Making bounce lighting work consistently and consistently with any random light in the world is a difficult task that requires a lot of work, but Rockstar has clearly put in the effort.

RTGI is also pixel-based, so shadows and light bounces are very detailed, without any of the artifacts seen in cheaper or easier implementations. And, based on what we've seen in the first GTA 6 trailer, it looks like a pixel-based RTGI implementation is also present, which works great with emissive materials—in-game surfaces that are supposed to emit light. 💡

As you'll see in the video above, I put it through its paces with some complicated examples, and it works surprisingly well! In short, it's clear from the GTA 6 trailer that RTGI is present, with a similar level of fidelity to the same effect found in the recently improved GTA 5 for PC. And that fidelity is such that it seems unlikely it was a simple, add-on feature. Not only that, it's also optimal in performance.

For example, objects that use transparent clipping textures, such as trees and vegetation, are accurately rendered in reflections, where you can see individual blades and other details. This makes sense for quality reasons, but it's very costly for RTGI. In this scenario, Rockstar ensures that these textures never test transparency. This improves performance, but may result in somewhat blocky shadows—a small concession to the speed it offers. 🏎️

How fast? An RTX 4060 running at 1440p DLSS 3, using Ultra RTGI and Ultra RT Reflections, runs the game at a flawless 60fps while zipping through the city in heavy traffic—and that's with all other settings maxed out! In this scenario, no optimized settings are required. This level of RT optimization bodes well for next-gen consoles running GTA 6: RT aside, this game will be quite demanding on the GPU.

The more optimal the ray tracing, the more GPU time is available for the other cutting-edge visuals we've seen. However, we still believe GTA 6 won't be a 60fps game on consoles, as, again, GTA 5 on PC indicates that the setup costs for RTGI are too high for 60fps on console-equivalent CPUs. So while RTGI is relatively light on the GPU, it's much heavier on the CPU and therefore more limiting. ⚖️

One more thing: I don't think every aspect of GTA 5's RTGI will carry over to GTA 6, especially with how the extra light bounce works. Based on what I've seen in-game, there's a limited amount of light bounce from RTGI, and this can be clearly seen by tweaking the game's config file to add another bounce at the expense of some performance. This adds quite a bit more light, so it would appear that the game might be using a default bounce on ultra.

For a game like GTA 6, I don't imagine that would be the case. Typically, modern games do one actual bounce per frame, but then use some sort of storage structure to get additional bounces over time; that's pretty standard in the industry, and I'm guessing Rockstar would do the same. However, in GTA 5's case, that doesn't appear to be the case, and it seems like the cubemap lighting I mentioned earlier is occasionally applied as additional light bounces. 🌐

Ultimately, while RT reflections are a nice addition to Grand Theft Auto 5—just as they were on consoles—it’s the RTGI and extended RT distance that really make a difference compared to PS5 and Xbox. There are some similarities to the ray-traced global illumination in GTA 6, but the CPU-intensive nature of the implementation further reinforces the idea that console games They will target 30 fps, not 60 fps. 📉