An Overview of Ray Tracing
Ah, ray tracing. It’s been multiple decades since its invention, nearly 20 years since it became commonplace in CGI films (Monster House (2006) and Cloudy With A Chance of Meatballs (2009), among the earliest examples). Now we’re well into the first generation of real-time RT in video games such as Control (2019) and Marvel’s Spider-Man Remastered (2022), with Nvidia releasing their first RTX graphics cards in 2018, and Sony and Microsoft bringing out the PS5 and Xbox Series in 2020.
The PS5 Pro has just been released with improvements to the console RT hardware since in the base models, and the Switch’s successor should soon finally arrive with an interesting mix of the most advanced RT acceleration in consoles and a level of overall power possibly matching the Xbox Series S (in docked mode, anyway).
RT vs Traditional Lighting
It’s been called the latest revolution in-game graphics, but some people disagree and prefer to ignore it in favour of better performance. And indeed, it can be hard to spot, depending on the technique used. Ray-traced reflections are more accurate than screen-space reflections (which are limited to showing only parts of the game that are already rendered outside of the reflections) and are often seen in the marketing of the technology, while something like ray-traced global illumination can be much more subtle. Ray-traced shadows can initially look blurrier than some traditional techniques until you recall that real shadows do in fact diffuse as they get further away from the source, making the RT shadows legitimately more realistic despite not being ‘sharper’. These examples show why there’s such contention on the value of RT – yet it continues to be pushed. Why is that?
RT in Games, Now and Beyond
I’m not an expert on the subject, but I know enough to say this: the current state of ray tracing in games is still in its early stages. Currently, it’s used purely for its considerable visual impact and in conjunction with traditional baked-in lighting techniques that are ray-traced on the development side and then fixed into the game, saved in the files, and made to work in the states where the game environment is programmed. Those techniques work great when the game is designed around them, but they don’t work as well when more dynamism is needed. Specific RT lighting options can replace certain baked lighting options for the user, hopefully making for a more appealing view. But it’s still early days, much like how the Super Nintendo Entertainment System offered an early look at 3D with games like Star Fox (although RT has stepped beyond this).
Path-Tracing, or “Full Ray Tracing”
Firstly, there’s path tracing, or “Full Ray Tracing” as Nvidia has taken to calling it. This is where almost all of the lighting is swapped out with RT – everything is dynamic, everything ends up looking like “real” lighting, and you gaze upon its beauty to distract yourself from the price you paid for that RTX 4090 in your PC. But even this option that enhances games like Cyberpunk 2077, Alan Wake 2 and Indiana Jones and the Great Circle, is still just an option. It’s a box you can tick in the settings on the PC version. The game is not built around it, and that, I believe, is what we should really be looking forward to – a future where baked lighting is abandoned entirely in favour of full path tracing in every version of every game. Indiana Jones has already taken a step towards this with every version – even the Xbox Series S file – using ray-traced global illumination.
The Benefits of Required Ray Tracing
Ray tracing as a fundamental part of games will – at least, to my knowledge, have several major benefits. There’s the visual impact, of course, and possibly even superior performance, given how well Indiana Jones runs with its RT. But also:
Saving development time
Baked lighting is wonderfully light on the power/performance budget of your gaming machine, but not only is it inaccurate to real lighting, it also takes up development time, with the actual baking process taking as much time as actual baking. The result is a real hit to the time taken to make environments, with significant changes requiring new baked lighting – imagine cutting this down with games and machines that generate all their own lighting in real time.
Install sizes
We all know the annoyance of needing to delete games to save space, and games always seem to get bigger. Paths to reducing install sizes need to be taken advantage of, and one of those is removing baked lighting. All that lighting data is just that – data – and it needs to be stored. However, with a PC or console that could handle all the lighting in real-time, this problem has also been removed.
Design and gameplay advancements
This is where I, a non-expert, am going into more wild theorising, but bear with me.
We’ve seen how games like Spider-Man were held back by the limitations of hard drives, with traversal speeds and environment changes tamped down until consoles started guaranteeing SSD, allowing for follow-ups that broke previous limits. I believe that baked lighting is having a similar effect on some games, enforcing a certain level of ‘static-ness’ on games and their environments. They can only be allowed to change so much, given how every state an environment can be in needs its own baked lighting pass and data. Imagine what developers could do in the way of destructible environments, time skips, etc. Once those shackles are thrown off them? Could our gaming machines adapt the lighting automatically to any possible situation?
The Next Generation
This is why I think you should be looking forward to the future, even if you’re not a fan of RT right now. Imagine if the PS6, Xbox Next and Switch 3 made full path tracing a possible standard. Imagine a future where game install sizes remained in place – or even shrunk, given advances in compression techniques? Where development times saw cuts, even if they only went from 4 to 6 years to 3 to 4? Or if games included more interaction and realistic environment change than ever before? All because developers could make their games secure in the knowledge that path tracing is all they’d need for their lighting? Honestly, if that was the only Big New Thing of the next generation… I’d be happy with that.
