I haven't looked into it in detail, but didn't Bender use a single cloud image in the clouds4X4.tga, where the game seems to expect an array of 16? (Even if in the .mat file one specifies two values of "1" where for a 4x4 array they are "0.25", it seems.) If a single cloud graphic gets chopped into smaller bits, most of the sub-images resulting therefrom will have some or all edges with cloud right to those edges. Hence the square clouds.
Jiggly clouds, and other weird artifacts, particularly near the screen edge at wider FOVs, are ever more exacerbated the larger the texture size on screen. In no small measure is this due to the disparity in image scale resulting from distortion. At wider FOVs the gnomonic projection induces stretching, more strongly in the radial direction. Polygons present no problem, for their construction from 3-point triangles will always fit with no gaps or overlap between those immediately adjacent. And all polygon-based elements will seamlessly fit, no matter the severity of the distortion.But "sprite" -like textures not mapped to polygons will suffer varying gaps/overlap as their position on screen changes. Compared to the texture-mapped scenery (including high clouds), the relative size varies and the shape does not stretch the way polygons do.
I'm surprised to hear of a 3,000m limit to cloud tops. I get mine piling up to 10,000m and higher (in v4.08)
Unless there are game-version differences in the way clouds are generated, I think all mods using the same DENSITY value in DATA.cld make the same number of cloud elements and resultant clouds. I suspect no small amount of 'hard coding' which limits the degree of control we can exert. Until TD goes into the cloud generating module, we're stuck and cannot expect to see a 'perfect' cloud mod.
I'd like to see a smarter allocation of precious texture resources. The tinier clouds are too often made up of a veritable rat's nets of up to about a dozen textures, while many BIG clouds are made up of just one or two (!!). That's crazy. Furthermore, some of those big clouds are made to have an almost invisible opacity, appearing as very ghost-like veils you almost have to strain to see. Why is that?.
The more I poke around, the more I see which needs changing. Listening, TD?