I've been working hard these past few days on coming up with a solution that allows for custom atlas textures with albedo, normal, and parallax mapping. This is the result:
Round studs by Kokonut & Pandan
Example stud atlas texture:
The bottom left of the image is information for the shader letting it know this is a custom atlas map.
The bottom right is the heightmap for parallax effect.
The top left is the albedo.
The tom right is the normal map.
