Texture Skew?

[Gez]

At the very most, you'll want four flags, tops:

• align lower texture with floor slope
• align midtexture with floor slope
• align upper texture with ceiling slope
• align midtexture with ceiling slope

I don't see a need for more. Just need perhaps to define what happens if both the align midtexture flags are set, perhaps a warning message at map load.

I guess technically you could want to differentiate between front and back sector slopes for when they're on two-sided lines. So that could be an added "use back sector for slope aligning" flag, with front sector being the assumed default.

[Graf Zahl]

The actual problem was that in the end the engine cannot do anything with this information. What it needs is a skew angle, nothing more, nothing less. My attempts always failed because I tried to put the skew calculation into the renderer instead of the map loader. If the renderer only needs to check a single value it would be a lot easier.

BTW, you forgot four more cases: "Align top/middle texture with backside ceiling" and "Align bottom/middle texture with backside floor". In any case, these should only calculate a skew angle and afterwards just act like slope definitions - whatever happens next is no longer their business.

And of course there should also be the option to directly set the skew angle instead of aligning it to a plane.
Where it will get tricky is to align skewed textures properly. That's something the engine cannot really solve. The only idea I have is to set a skew offset that adds the needed skew based on a horizontal offset.