The Sega Saturn has always been the console that gives emulator developers nightmares (with the Nintendo 64 being no slouch either). Not for lack of love — quite the opposite — but because its architecture is a true engineering puzzle. Some good news has just dropped, though: Yaba Sanshiro has reached a significant milestone in the way it reproduces the console’s graphics rendering.

The issue is as old as Saturn emulation itself. The console’s VDP1 graphics chip rendered its sprites and polygons as quadrilaterals — four-sided shapes. Modern GPUs, meanwhile, only understand triangles. To convert one into the other, emulators have traditionally split those quads into increasingly smaller fragments, a technique known as tessellation. It worked… more or less. But once games were upscaled to high definition, the flaws became visible: warped textures, missing pixels along the edges, gaps between polygons. The kind of detail that goes completely unnoticed on a CRT, but quickly becomes annoying at higher resolutions.

A completely new approach

With version 1.20.5, developer devMiyax is changing the paradigm entirely. Instead of continuing to force Saturn rendering into the triangular mold of modern GPUs, Yaba Sanshiro now uses compute shaders — a type of GPU program that bypasses the traditional graphics pipeline to work directly at the pixel level. In practical terms, instead of starting from a texture and projecting it onto the screen, the emulator now works backward: for every displayed pixel, it traces back to the original VDP1 coordinates and calculates what the real Saturn would have shown at that exact spot. The result is visually cleaner, more accurate, and — surprisingly enough — still runs at 60 frames per second in tests performed on mobile devices.

What about Recalbox?

The Saturn is a console we follow very closely. Recalbox currently offers four dedicated cores to emulate it (Mednafen, Yabause, YabaSanshiro — the one discussed here — and Kronos), and we are actively testing Ymir — an emulator that is also making waves in the scene thanks to its ambitious approach to Saturn rendering. The progress of Yaba Sanshiro and the rise of Ymir are two encouraging signs for a console long considered almost impossible to emulate properly. The ecosystem is evolving, and we love to see it.

A work in progress

It would be an exaggeration to say Saturn emulation is now “solved” — the console remains one of the most complex systems to reproduce faithfully, with its eight processors and highly unconventional graphics logic. But the trajectory is clear: where people were still talking a few years ago about hacks and compromises, we’re now discussing carefully considered technical choices and measurable on-screen results. For fans of Panzer Dragoon Saga, Radiant Silvergun, Sega Rally, or NiGHTS, that’s very good news indeed.

Sources: Time Extension, yabasanshiro.com, GenerationAmiga, rom-game.fr, Sega Saturn Shiro

Enjoying the work of the Recalbox team? Support the project by becoming a Patron!