Hexagonal texture filtering in Brahma engine

A quick test of my new version of the hexagonal texture filter on a Duke3D level, with an animation that illustrates how square texels are turned into hexagons. This code is yet to be vectorized with SIMD intrinsics, thus the performance is not optimal, but the effect is enabled for all surfaces including the heightmaps. The texture filtering in Brahma comes in a variety of styles, normally picked by level designer's choice, which can be set up for every surface individually using engine's internal bytecod