With nigh-on 30 titles revealed at last week’s PlayStation 5 software showcase, there’s certainly plenty of material for Digital Foundry to mull over in its wake – but one of the biggest and most pleasant surprises was the range of games from both first and third party developers using the machine’s hardware accelerated ray tracing technology. But what was actually shown that we can say for sure was using hardware RT? What kind of effects were featured and how do they function? And perhaps most crucially, going forward, what does the software showcase tell us more generally about how ray tracing will be deployed in the next-gen console era?
To begin with, I think it’s important to give credit where it’s due. Hardware accelerated ray tracing only made its debut in a shipping video game in November 2020, when DICE updated Battlefield 5 with its sub-optimal but still impressive RT implementation. It was updated months later with radical performance upgrades and was just the first of many RT-supported titles. However, the point is that for consoles to embrace this emerging technology so quickly and to be deliver so many examples of hardware RT in an initial software reveal borders on the miraculous, especially given how computationally expensive and complex ray tracing is.
How expensive? We learned that quickly enough on PC two years ago with RTX-supported titles: a single full-resolution ray tracing effect like reflections at 4K on the most powerful GPU available can drop frame-rates by significant double digit percentages. Other effects like ray traced shadows can be less intensive, but still significant. The point is that console hardware design is based around bang for the buck, meaning that developers will need to be careful in how RT is used to keep resolutions and frame-rates reasonable. In the first wave of PlayStation 5 titles we saw, we got a few indications of how the developers are adapting to this new rendering paradigm.
Gran Turismo 7 is as good a place as any to begin. The use of hardware RT here is undeniable – with reflections deployed on a number of the game’s surfaces and on the car bodies themselves. Today’s reflection tech of choice – cube-mapped reflections, as seen on Forza Horizon 4, for example – capture facsimiles of the environment then map them onto the bodywork, missing self-reflections and presenting in a perspective-incorrect manner. GT7 is on another level: environment reflections are properly mapped onto bodywork, all cars and indeed the player’s car are also reflected, as are elements that are off-screen. It’s a significant upgrade to the materials work on the player vehicle, while materials like glass seem to receive ray traced reflections too. It’s also the first Gran Turismo game we’ve seen where the rear view mirror includes the car interior and indeed the driver – by comparison, GT Sport’s equivalent presents like a camera stuck to the back of the car.