So you've created these truly amazing textures. And GZDoom recently added support for PBR and materials. This looks like a great opportunity to really show off how amazing your textures are. Your main texture package is several hundred textures, so I started with your Doom 1 override package. I optimized your PNG files, and then compressed them in DDS format (with pre-generated mipmaps). This should actually help performance as the DDS file can be loaded directly into your GPU without having to convert it, and mipmaps are pre-generated.
Then I created normal maps for all of your textures. This I did in batch with a tool.
I manually created bright maps and specular maps by hand for the 71 or so textures in this package.
Then I created a definition file that tells GZDoom to use these textures. I've never created a Doom map before in my life. I'm going to just test this in existing Doom 1 maps and see if I can see any of these 71 textures in use, but someone could perhaps make a test map to showcase these specific textures. If these are working as intended and look good, I may do all the other hundreds of textures as well.
The amazing thing is that your PK3 package was 280 MB to start. I added bright maps, normal maps and specular maps. It is more than 3 times the number of previous textures. But the new PK3 file is actually smaller at 256 MB.
https://drive.google.com/open?id=1_MYVB ... vtHYL8o5ih