Hello everyone, I have a question about UVs. If I have a model, such as a cube, and I only want a single face of that cube to be emissive or just have a single face display another texture from the other faces, how can I set up my material to do that?
So far what I have tried to do is cut the UV for the face in question completely out in the UV in Maya, and put that in its own uv Channel. This seems to allow me to fill the two different UVs with different materials in programs like Substance Pinter, but once I move my two sets of textures over to Unreal, I cannot hook both Base Colors into the single Base Color node on the master material. I have tried using the Texture Coordinate nodes to specifically target the different UV channels, but it only displays like a blend of both textures across the whole object.
I am positive at this point that it is user error, and I was wondering if anyone could link me to a video where someone creates a mesh with multiple UV channels, textures it, and then implements it in Unreal so that I can see the proper workflow for how this is done.
*Note: I know I could simply cut that face out of the cube, make it emissive, and then place it where it needs to sit in the engine, but if I made a more complicated model like a dragon and just wanted the horns to glow, I would still ned to know this workflow.
In most art pipelines, when a single face has totally different material properties, then you make that face have a different material ID, rather than different UV channels. This is the same for “horns of dragon” and so on. (And typically also for “eyes” or “semi translucent wings” or “hair” or whatnot – different materials, different material IDs.)
If you must have a single material ID on the entire mesh, then you still don’t need multiple UV channels, you just need multiple material maps. One map for albedo (diffuse), and another map for emissive, and the emissive map is black in all the places where it’s not emissive. (This is typically in addition to normal maps, gloss maps, etc – they all typically share the same UV coordinate set.)
You can have multiple UV sets (this is for example used for light mapping,) and use it in the material, but both of the UV sets will each cover the entire mesh, so you can’t make the entire material B be emissive – it still needs to be emissive only where it’s supposed to be. So just make it a special emissive map, similar to how a normal map is its own map, and go with that.
To Answer your question: In Maya’s UV Editor, go to UV Sets, and Create Empty UV Set.
Then, you can use the Auto create UV maps, from the UV option in the main window.
A Brief explanation, Of what I think youre really looking for.
Black and Whites are the most important thing someone whos texturing needs to understand. Black and Whites as I call them are alpha channels, and or a way of telling the computer what -1, 0, and 1 are. So, any value in your texture that you want can be done simply using black and white in your text instead of dialing in numbers.
Ill break it down for you like this. You have your texture of your dragon in PS or w.e, create a seperate layer for the horns that is white, and everything else is black. You can then save out that b&w image, plug it into your emissive and the only thing that will glow will be the horns. At that point, you multiply a 3 vector (color) on top of the black and white, then plug that multiply into another multply that has a scalar param into the bottom that you can use to control the strength of the glow. Use that method for metal, roughnes, spec, etc.
Last example ill leave with you:
Your albedo= color
Your metal = a b&w image of the eye cornea, various parts of wings etc
Your Rough= the same as your metal but inverted, or not. play with it
Your Emissive= a b&w of your horns. For Transluceny, it works the same way. Just remember, Pure grey will leave you in the middle. This is also how landscapes determine height, by using b&w. You learn that technique, you can separate a texture like a master.
