So you want to find some new, unique textures to spice up your maps? Unfortunately for FAF, even though a lot of websites provide CC0 textures that are free for commercial use without attribution, their licenses can specifically prohibit rehosting, which means we can't add them to our repositories. Due to this, I have listed my favourite sites here, together with a tutorial on how to edit them.
Another excellent website with a decent library of procedural textures.
A bit less useful for ground textures, but good nonetheless.
Again, not so many ground textures but still very nice.
Be sure to read the licenses for these sites in full before using resources from them.
The source of the famous Frozen Firefight ice, you need to register to use the textures but they are free for commercial use.
Step 1: Download the texture you want to use.
Step 2: Unzip. Look for the 'Albedo' and 'Normal' textures.
Step 3: Navigate to your map's folder.
Step 4: Create a new folder tree called env/layers
Step 5: Paste the albedo and normal textures in
Step 6: Convert them to .dds BC3 (Linear, DXT5) using Paint .NET (see below) or similar program.
Step 7: Load the textures in the map editor from 'map folder'.
CC0 allows the free editing of all assets. This is how I personally edit textures.
Software: Paint dot NET, which you can get from https://www.dotpdn.com/downloads/pdn.html
Most useful tools:
Use brightness/contrast if a texture is showing up too dark or light.
Curves lets you edit luminosity and dip specific channels, I use it to dip red/green/blue for example.
Hue/saturation is extremely useful for changing the colours of a texture; I use it liberally to create grass textures like the dried out grass in Auburn Canyon.
This tutorial is a work in progress, check in regularly for updates and feel free to suggest things.