XL2, a developer well known in the Saturn homebrew scene for work on Sonic Z-Treme, has just achieved an impressive technical feat: implementing ray tracing on the Sega Saturn. While the term today brings to mind the most powerful graphics cards on the market like Nvidia’s GeForce RTX series, applying it to a 1994 console is a display of truly remarkable mathematical ingenuity.

A clever approach to ray tracing

Ray tracing is a graphics technique that simulates the path of light to create realistic shadows and reflections. On modern PCs, this requires enormous processing power. So how can it work on a 1994 console? XL2 found a smart workaround: instead of calculating light for every pixel on screen (which would be impossible), it only computes it for the corners of 3D objects.

To optimize things even further, a technique called BSP is used to divide the environment into zones. Picture a level map split into sections: the processor can quickly determine whether a light ray is blocked by a wall or an object. If it is, that area falls into shadow. Simple and effective!

Optimization and impressive results

To keep the game running smoothly, XL2 doesn’t recalculate every corner at once. With each displayed frame, only a quarter of the corners are updated. To prevent shadows from flickering unpleasantly, the transition between light and shadow is handled gradually and smoothly.

The video result is striking: lighting reacts in real time, especially when gunshots briefly illuminate the environment. For now, moving enemies don’t yet cast shadows, but the technical foundation is already working very well.

The Saturn pushed to its full potential

This demonstration proves that the Sega Saturn still has hidden capabilities. Its dual processors, often underused by developers at the time, can achieve impressive graphical feats when programmed properly.

Once again, this experiment shows that retro consoles still have many secrets left to uncover in the hands of passionate developers.

Sources: Le Mag MO5 / Retrogamer