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Grand Theft Auto 5 on PC has finally received the RT upgrades to achieve feature parity with the current generation console versions, almost three years since they arrived on Xbox and PlayStation consoles. The wait was worth it as scalability is impressive and the game also includes the ability to toggle ray traced global illumination – which may well hint at the kind of RT features we can expect to see in the upcoming Grand Theft Auto 6.
To begin with though, let’s be realistic. GTA 5 is almost 12 years old now and as such, there are limits as to how much better the game can actually look. The original was built around the fundamental constraints of the Xbox 360 and PlayStation 3, after all, and that still shines through today, even in the maxed out PC experience. Character models are of their era, while material and texture quality is nowhere near as impressive as modern releases. GTA 5 comes from a time before the games industry switched to techniques like physically-based art pipelines and shading maths. Ray tracing can still transform the game in many respects, but not to the extent of making it comparable to a brand-new triple-A release.
Even so, the upgrades are welcome. Pre-RTGI GTA 5 is a game that suffers from a problem that many games without RTGI have – and especially ones from this era. Indirect lighting in the original is handled in an interesting way, however. According to investigations by Adrian Courrèges, the game generates a cubemap from the player camera position in real-time, similar to many racing games. This gives the game approximate real-time reflections on elements like cars, and for rougher surfaces the game appears to use a filtered version of that to make it so shadows are not pitch black. The problem is that lighting is only represented from one angle and as such, all shadowed areas in GTA 5 tend to look grey or overly dark. Everything not in sunlight tends to be shaded a greyish light or almost blue colour and where the edges of geometry are adorned with a thick halo of screen- space ambient occlusion.
Ray traced global illumination – not available in the current-gen console versions, remember – is a game-changer here, with light bounce around the environments of a far, far superior quality. To say it really lightens up the mood is almost an understatement: bounce lighting you get from the sun and the indirect shadows you get as a result dramatically alter the game’s look – and it is always for the better.
RT reflections are also part of the mix, dramatically changing the look of reflections on windows for example, turning them from potato-mode raster versions into per-pixel RT upgrades. However, unlike other games with a physically-based pipeline, these RT reflections do not universally apply to all materials depending on the angle. Rather, the RT reflections apply to select materials in the game that were either marked as ‘somewhat shiney’ or ‘full shiney’ or in the original release. Even so, on maxed out settings, the BVH structure for RT (the geometry against which rays are traced) is far more complex than the console versions – so even if the technique is selective, it can be far more detailed than Xbox or PS5.
In fact, the RT global illumination solution in particular is comprehensive that it can’t be termed as a mere bolt-on to the standard game. A lot of care and developmental work has gone into it, which perhaps makes little sense for a free upgrade for just one version of an old game. In fact, based on our analysis of GTA 6’s first trailer, there’s enough evidence here to suggest that this may well be tech for the upcoming Rockstar release backported to GTA 5 on PC. So, perhaps we are actually getting a preview of the lighting technology found in GTA 6 both in terms of features we can expect and even the level of performance we can expect.
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Let me ground my reasoning here with a number of points. Usually when an old game gets updated with some form of ray tracing limited to just a subset of the platforms that can play it, typically developers will make that ray tracing a bit more limited. For example, in Dying Light 2, the RTGI only works from the sun but not other lights. Similarly, in the The Witcher 3’s current-gen update, RTGI does not work on a per-pixel basis and instead is coarsely applied to the world with probes, with obvious artefacts as a result.
That’s not the case here – it’s far more comprehensive. Firstly, it applies to all and any light sources, not just the sun. This is not just limited to stationary lights, but even moving lights like those from cars. Getting bounce lighting from any random light in the world to work with stability and coherency is a difficult task, requiring lots of work but clearly, Rockstar has put in the effort. The RTGI is indeed per-pixel too, so very finely detailed shadows and light bounce are present with none of the artefacts seen in cheaper/easier implementations. And based on what we’ve seen in GTA 6’s first trailer, a per-pixel RTGI implementation is also present, which works great with emissive materials – surfaces within the game that are supposed to give off light.
As you’ll see in the video above, I put this through its paces with some tricky examples – and it works remarkably well.In summary, 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 newly RT-enhanced GTA 5 for PC. And that fidelity is such that it seems unlikely to have been a simple, bolt-on feature. Not only that, but it’s performant and optimised too. As an example, objects that use transparent cut-out textures like trees and vegetation are represented accurately in reflections where you can see the individual blades and other detail. That makes sense for quality reasons, but it’s very expensive for RTGI. In this scenario, Rockstar ensures that these textures never test transparency. This improves performance, but can result in some blocky shadows – a small concession in light of how fast it is.
How fast? An RTX 4060 at 1440p DLSS 3 quality mode using ultra RTGI and ultra RT reflections runs the game at a flawless 60fps while speeding through the city in dense traffic – and that’s with all other settings maxed. In this scenario, optimised settings aren’t really required. This level of RT optimisation bodes well for the current-gen consoles with GTA 6: RT apart, this game will be taxing the GPU hard, so the more performant and optimised the ray tracing is, the more GPU time will be available for the other cutting edge visuals we’ve seen. We still don’t think GTA 6 will be a 60fps game on consoles, however, and again, GTA 5 on PC indicates that the set-up costs for RT are too much for 60fps on console-equivalent CPUs. So while RTGI is relatively light on the GPU, it is far heavier on the CPU side and is more limiting as a result.
One more thing – I don’t think every aspect of GTA 5’s RTGI will transfer over to GTA 6, specifically in how extra light bounces work. Based on what I have seen in the game, there are a limited amount of bounces of light from the RTGI and you can see this readily by tweaking the game’s config file to add another bounce at the cost of some performance. It does add in a good deal more light so it would appear that the game might even just be using one bounce per default on ultra. For a game like GTA 6, I cannot imagine that would be the case. Typically, modern games do one real bounce per frame, but then use some sort of caching structure to get in additional bounces over time – that is pretty standard in the industry and I imagine Rockstar would do the same. However, In GTA 5’s case, that does not seem to be the case, and instead it looks like the cubemap lighting I mentioned earlier seems to apply at times like additional bounces of light.
Ultimately, while the RT reflections are a nice addition to Grand Theft Auto 4 – just as they were on the consoles – it’s the RTGI and the extended RT distance that really make a big difference up against PS5 and Xbox. There are certainly commonalities with GTA 6’s ray traced global illumination, but the CPU intensive nature of the implementation does lend more evidence to the idea that the console games will target 30fps, not 60fps.
