If you don't already have a custom GDT, make one with "New GDT" in APE. I've named mine custom_t7. (This is because Treyarch's updates to the tools can overwrite any changes you make to the GDTs already provided.)
Click New Asset next to the GDT button. Give it a name, select type material, then your custom GDT if it isn't already selected. I've called mine mtl_tutorial and used this image:
- Give your material the appropriate settings for the texture you're making. Almost all common materials will use the material type lit. Here are my settings:
|Material Category||The material will have certain options and settings based on its category. Most materials will just have Geometry. Weapon materials go under Weapons.|
|Material Type||Similar to above, types will have certain options available specific to them for their respective contexts. Almost all common materials will have the type lit.|
|Surface Type||In-game mechanics, like sound (e.g. footsteps), need to know how to interact with materials. This is where you define that. Do not leave it as error. none is used when you don't want materials to interact with anything.|
|Gloss Range||Different gloss ranges will make the texture shine/reflect in different intensities in-game. Selecting custom means you can define specific values under the Specular and Gloss section. full means full gloss.|
|Usage||Which category the material will be sorted under in Radiant, if any.|
You can ignore the Asset Tags, Enemy Material and FrameBuffer Operations sections for almost everything.
Color map, normal map, etc.
The color map is the actual color texture you want. Click this button to add a new image to your material:
Click the three dots next to the Texture box and a dialog will pop up. Select the image you want to use. You probably don't need to tweak any settings, but do so if you need to.
Repeat this for the normal map. You can quickly generate normal maps for your images at: NormalMap-Online.
Save and use
Click Save All.
In Radiant, in the Texture Browser, look for the material name (i.e. mine was mtl_tutorial), and apply it to brushes as normal.