WTF?! Real-time ray tracing is one of the most computationally demanding features in modern video games, significantly impacting frame rates on the latest consoles and most PC graphics cards. However, a retro homebrew developer recently proved that, with enough ingenuity, the technique is possible on a console released over three decades ago.
Recent videos from Sega Saturn homebrew specialist XL2 showcase a rudimentary implementation of ray tracing running on Sega's CD-ROM console, which launched in 1994. While the second demo uses an emulator, the first manages the feat on real hardware.
The initial clip (above) features a small room where all lights and shadows are dynamic, something unthinkable in Saturn games. As the player fires a weapon, the tech demo tests every vertex using a BSP – a system that divides the 3D world into planes – using the muzzle flash as a light source. As objects move through the room, their positions dynamically alter the shadows throughout the scene.
A second demonstration showcases optimizations that allow XL2 to apply ray tracing to a more complex environment. A hybrid approach with static lights creates dynamic, moving shadows that affect the characters in the scene.
The developer claims that the demo can achieve roughly 15-20 fps on a real Sega Saturn – very playable considering the standards for 3D console games of the era. Moreover, XL2 states that further optimization is possible. Digital Foundry explains that the technique, which enables developers to light environments in real time instead of using lightmaps and textures, could have saved a significant amount of memory and reduced disk access in real Saturn games.
XL2 has spent nearly a decade sharing videos of his experiments that push Sega's console beyond what its official software library achieved. His entry in the Sega Xtreme 2023 homebrew competition was a port of the first two levels of Unreal, which was never released for any console.
Instead of converting the Unreal Engine, XL2 remade Epic's famous shooter in his homebrew engine, similar to how Lobotomy Software ported Quake to the Saturn in 1997. However, the Unreal demo, along with XL2's in-development deathmatch shooter Hellslave, runs far more smoothly than the console's version of Quake. Other videos on XL2's channel demonstrate real-time reflections, transparencies, split-screen FPS multiplayer, and other features that should not run as smoothly on the Saturn as they do here.