Another Try At Perspective Correction Optimizations (Patreon)

Perspective correction is the slowest part of the Retroquad rasterizer right now.

Sure, that's debatable due to the complexity of the per-pixel drawing operations when most effects are used together, but the perspective correction is the least efficient step; it computes the same data up to dozens of thousands of times, even when the results are going to be identical.

And despite its obvious inefficiencies, eliminating all of its redundant computations is extremely tricky due to the nature of 3D rendering and Retroquad's precomputed dithering.

Anyway, now I'm having some ideas of another method for optimizing it through a somewhat complex Perspective Correction Caching System. Balancing the overhead of this caching system in a way that does not negate most speed gains is crucial for it to work, but I've got a feeling that it's possible. I wouldn't be surprised to see it making the framerate around 20% faster.

And on the plus side, it would give the rasterizer a per-pixel perspective correction that doesn't need interpolation at all. Per-pixel anisotropic texturemapping could also be possible, but that's not the focus yet.