What is a workflow for Unreal Engine that doesn't use UV maps at all?

I am looking forward to learn Unreal Engine, once version 5 comes out this year. I am interested in creating simple 3D games to teach myself the software. I am already proficient at 3D modelling, but I might want to pick up a new 3D modelling software to learn as well.

I have no interest in UV mapping, and I am very aware “how easy” it has become. I am uninterested in hearing how difficult it is to manually paint all assets, because I prefer it to working in 2D. I don’t need to know the fastest, or most efficient way to texture a 3D model without a UV map, but I would like to know if it is possible in 2021.

What is a workflow that someone can use to create 3D models, and use them within Unreal Engine that doesn’t use UV maps, and can I provide any color or texture without them?

Is it still possible to have multi-colored or multi-textured models, or to apply a texture via 3D painting?

I would be happy with simple colors and “toon shading” if that was the only way.

Any ideas?

The way shader (in UE4 they are materials) works it let you apply texture using any coordinates as input, if you look on texture sample node it has UV pin that let you put your own UV coordinates (the pin simply say from what point of texture to read), so there lot of methods of applying textures on shader level without need to proper UV map on mesh. For example quite popular alternative is triplanar mapping that use vertices coordinates for texture cordinates:

Problem is those techniques are quite limited and work only on specific applications sometimes for very specific type of meshes. You can’t really replace proper UV mapping of mesh, UV map in technical sense is which position of texture goes where on the mesh. Even 3D paining requires UV map as that paint need to be stored on the texture and shaders needs to know which part goes where (or else you talk about vertex paint which is stores in vertices)

It will probably be easier to just to make proper UV map then finding way around it

You seem oddly hostile to UV mapping when you acknowledge there are easy ways to get around most cases of it. It comes across as an irrational dislike without any good reason. I’ll still suggest using the automapping and then painting tools in substance painter. Your fear of painting in 2d is irrelevant, there are plenty of packages that are based around a workflow of painting in 3d (Substance painter, quixel mixer)

Nevertheless, if you REALLY hate UV’s that much, you could just colour/paint using vertex colours, either in a 3d package or in Ue4 itself. The detail will be limited by the density of the mesh, but it will get you some of the way there (think zbrush polypaint). Your material will just be feeding vert col directly to Basecolour. You’d also be throwing normal maps, roughness variation and pretty much the whole PBR pipeline etc out the window for the sake of your stubbornness but you do you.

Theoretically Ptex could do what you want, but as far as I know no realtime engines support it.

Why do you “have no interest in UV mapping”?

The short answer is I think in the modern era it is dangerous and irresponsible to spend time and energy learning and mastering outdated and fading technologies. I design and think in 3D, and I would like to find a place in the 3D modelling industry for a future career, but I would like to eliminate the (in my opinion) relatively archaic methods of working in an unwrapped 2D format, saving me the time and strain of needless complexity when for a decade the technology has existed to get similar results without UV mapping such as with Ptex. I realize there are tradeoffs when it comes to output fidelity specifically with detail but I have always been gravitated toward more lose artistic expression than photorealism. Since Unreal Engine is so advanced, and has had years of improvements I figured there must be a way to drive the car without learning manual, so to speak. It seems I might be a few years too early. In the meantime it is a relief to know that learning UV mapping seems more/less mandatory, but I will continue to keep my eye out for methods that abstract out the tedious nature of 2D translations.

The most simple way, is just make your mesh separate with each individual color a separate material, this way each mesh will have a dedicated colour, thus you won’t need a UV. just Triplanar project every material that will have a tiling texture. This is the only none brain intensive workflow to get what you want, involves no baking out anything too.