Alright, I think I've got this figured out. Even got a homebrew "fix" for custom textures for affected files.
1. The un-openable files are not all of the DDS assets, but a subset. I'm not sure there is any pattern, but the biome textures as a general thing are completely unaffected (contacted the guy who did those amazing mods).
2. They're unopenable because they're in DXT4. DXT4 is analogous with DXT2 in certain respects, and differs from DXT5 due to some alpha-blending techniques and other features.
Most common DDS converters handle DXT1, 3 and 5 (and not 2 and 4).
3. Windows, however, specifically Windows versions with DX11 support (Win8 and up? Could be on Win7 as well) can view DDS files natively in Windows Photo Viewer. This is
integral to the workaround.
4. Screencap the file at native resolution by viewing it in Photo Viewer. Paste into Paint or your editing program of choice, and save as whatever format you want (I prefer PNG). This is your base file to work with.
The bypasses the issue of converting using a typical DDS converter (assuming you have one that even works), as they force an incorrect version of DXT that causes visual artefacts.
5. The file will be lighter; as if you'd exported the normal diffuse map at 50% saturation or similar. This is how Beyond Earth uses DXT4 to handle specular (?) effects (or at least it seems to be). The lighter / more saturated the file, the greater the specular distortion ingame. Conversely, if you make the entire file completely black, once you get it ingame it basically disappears, leaving you with nothing but the diffuse layer (and no specular effects at all).
6. You should now have enough information to edit your file. Exporting the file as you screencapped it will lead to a huge mirror-effect ingame due to specular distortion. What you want to do is alter the levels of black across the image dependent on what areas you want to be specular (to take the Explorer as the example, black out everything but the metal areas and perhaps the visor).
I'm playing with this last step myself, and it's stupidly fiddly, but it's a way around the issue that shouldn't be a hurdle to actual graphics artists (obvious note: I'm not one of those
) and beats messing around with file headers and the like.
EDIT:
Almost damned-there. Hopefully Firaxis can resolve this at some point, DXT4 compression is virtually-impossible to deal with.
Just minor changes, preparing for Affinity re-texturing work. Red pants, reddish visor / goggles. Only thing off is the specular on the metal is still a bit too flashy compared to the vanilla textures.
Also, my sref.dds file (in a PNG format
), for comparison: