Superhuman Hack Brings Real-Time 3D Ray Tracing to the SNES

Superhuman Hack Brings Real-Time 3D Ray Tracing to the SNES

With the help of an extra graphics processing chip inside the cartridge, Star Fox did the impossible by bringing 3D graphics to the 16-bit Super Nintendo. The decision to engineer the SNES’ hardware to allow for this upgrade was a clever one on Nintendo’s part, and 29 years after its debut, Ben Carter has used a similar trick to bring real-time ray tracing to the now antiquated console.

The Super FX chip, as it was known, wasn’t just a term cooked up by Nintendo’s marketing team to sell hardware like Sega’s claimed “blast processing” was. The chip, included in cartridges like Star Fox and lesser known games like Dirt Racer, was a coprocessor designed to boost the Super Nintendo’s rendering capabilities. The console would essentially provide a description of what was happening in a given frame, and the Super FX chip would render the visuals and pass them back to the console to display on a TV. That’s a gross simplification of the process, but unlike games like Donkey Kong Country that faked a 3D effect with pre-rendered sprites, Star Fox was the real deal.

As impressive as seeing 3D polygonal graphics in the era of 16-bit gaming was, looking back, Star Fox isn’t exactly easy on the eyes. The textures used on the 3D models were essentially solid colours, shadows were minimal, lighting effects were non-existent, and models didn’t visually interact with each other through reflections. These are all tricks modern 3D games use to look so hyper-realistic, but even the Super FX chip wasn’t capable of all that.

This is why Ben Carter, a “freelance game developer/software engineer based in Japan,” wondered if he could take inspiration from the Super FX and design his own graphics co-processing chip that worked alongside the Super Nintendo’s own hardware to create realtime 3D graphics with an advanced effect known as ray tracing. In the real world, as light particles bounce around a room and off objects they create shadows, reflections, and other visual interactions. Place your hand next to a red ball in a bright room and you’ll notice your hand looks a bit red too. Ray tracing can recreate this effect by tracing the path of light in a given scene and calculating the effects it has as it interacts with, and bounces off, simulated objects.

It’s a very processor-intensive process, which is why even older 3D consoles like the Sony PlayStation and Nintendo 64 lacked the feature, and why their graphics look so dated. Getting it to happen at all on the Super Nintendo sounds like an impossible task, but Carter managed to get it to work.

The demo he shared on YouTube can’t even begin to compare to the visuals of a game like Cyberpunk 2077 running on a PC with an Nvidia RTX 3080 under the hood. The graphics run at a resolution of 200 x 160 (slightly below the SNES’ native resolution of 256 x 224) and the ray tracing effects are limited to single-bounce reflections and directional light shadows, but compared to Star Fox, the 3D animations look like they’re running on a completely different console.

To pull it off Carter had to crack open a Super Famicom console (the Japanese version of the Super Nintendo) and sacrifice a bad Pachinko game cartridge. The game’s ROM hardware was removed and the cartridge was wired into a DE10-Nano FPGA dev board that was paired with a Cyclone V FPGA. If you’ve heard that term before it’s probably because the Cyclone V can also be found in the upcoming Analogue Pocket handheld.

Carter has shared photos of the wiring needed to pull this off on his website, and needless to say, it’s a rat’s nest that will scare away all but the most determined of hardware hackers. In its current form the real-time ray tracing demos only run at around 20 frames per second, but Carter’s optimistic this can be improved, although for what purpose exactly isn’t known. Even if they were able to upgrade the graphics on a game like Star Fox, Carter would be the only one able to enjoy it unless he found a way to create a mod chip for the original game carts — another herculean undertaking. But as it stands, and as console upgrades go, this is an impressive trick taught to a very old dog.