Anisotropic Filtering (Patreon)

Retroquad's "anisotropic texturemapping" is not a filter, because it does not filter the texture's coordinates while drawing to the screen. Instead, it just applies the same level of anisotropy to the whole surface.

Now I'm working on a true anisotropic filter, which will compute both the anisotropy and the trilinear filtering during the perspective correction. Hopefully the performance impact will be very small, since the current implementations of trilinear mipmapping and anisotropic texturemapping (which is a huge brute force hack) will be completely eliminated.

True anisotropic filtering is needed because the current implementation looks too sharp on the farthest parts of the surfaces and too blurry on the nearest parts, which in turn also makes the surfaces' seams noticeable. With true anisotropic filtering, the visuals will be significantly more consistent.