Multiple uvmaps for single object for texturing blender 2.9


i am trying to texture my object (a single object) with multiple different textures.

suppose my object has 3 different textures, i plan to map faces which have a particular type of texture to a single uvmap (so eventually i should have 3 uvmaps with different sets of vertices and faces on different uvmaps).

i know how to assign multiple uvmaps to an object. however the issue is when i switch between maps, the faces i selected for the previous uvmap are lost. and if i hit the uv sync key (in uv editor mode), all the faces of my object show up in uvmap!

i wanted to know -

  1. how to ensure the faces i selected and unwrapped for a particular uvmap remain on that uvmap and are not lost (even if i switch maps)? exporting the uvmap (as png etc.) is not an option as i may need to reorient the faces later for texturing.

  2. perhaps my workflow is the issue - if i want to assign different textures to different faces - is it better to split the mesh into seperate smaller objects and then assign textures to them?
    or is there some other better work flow for this? the issue with splitting the object into smaller objects is that if i later decide to apply subsurf mod to my objects (for higher poly count), the smaller object will deform seperately and so the objects wont line up!!!

  3. is it possible to render the different uvmaps for different faces (of the same object) all at the same time? in blender 2.9, in the uvmaps tab, i only able to enable one uvmap at a time for rendering!

what is the better approach/workflow here?

please help! :frowning:

  1. You can’t. UV map is for the whole mesh. So when you switch it, you’re seeing another map where verts of those faces have different UV coordinates.

  2. You can use different materials for different faces, and keep just one UV map (though you can use multiple if you so wish). Although if you do plan on using subsurf, you need to be aware that the generated geometry may stretch or pinch material boundaries (just as it does all other boundaries).

  3. It is possible. In the shader tree you simply connect different UV maps to texture inputs.

That said, what I think you’re looking for is either option (2) with just a single UV map and different materials, or even one material and a mask texture (or textures) that would let you blend between different image textures.