The Polymost renderer features some awful hackery to make non-power-of-two textures work and I've been trying to find out how to do the job without this hack, but so far to no avail.

Polymer just glitches - it has no handling whatsoever for this case and fails miserably, and the math routines in Polymost are just like the rest of it: Hideously dirty code doing black magic that is virtually impossible to derive any formula from.

Therefore my question: What precisely are the rules? Does anybody know? The math present in both renderers does not deal with this case in a way that makes sense to me, but I cannot say if this is because of a flaw in the math or a screw-up by Redneck Rampage's makers - because it seems to be the only game running afoul of the problem.

I cannot make much sense of the motivation for the shader-based solution, to me it looks like it is intended to reproduce a behavior that can only be the cause of poor mapping that abuses an engine glitch.