How can I add a second material as a decal?
I am needing to export to collada with 2 materials. The first material is a base texture build up with the principle shader. The second texture is a decal. I need the decal to be in the 2nd material as when I export it into scenekit. I would like to swap-out material 2 with anybitmap the user chooses in the app. But I will me ensuring that user material is always at the correct UVmap.
So I have created two UVmap as per this answer.
Texture mapping with multiple UV maps
in blender 2.8 the only texture properties I am seeing is a brush. So I've made the decal a brush but I'm not able to apply it.
As you see in the image above, there are two canvas pictures. The one in the back has the "painting" material applied before creating a 2nd UVmap. The canvase in the front has it applied but there isn't a decal.
I have seen the cycles/node editor where you use a 2nd texture and mix the color and alpha fracture into the base texture, resulting in a decal. mixing textures, same material But that is all in the same material. I need 2 separate materials.
I've created 2 shaders, each shader is using the appropriate UVmap.


