Question on UV In the game engine? Clarity on in engine mesh

Hi all. I have a noob question I believe which i cant get my mind around and it would be great if someone could answer. I tried to ask in Blender forums but I dont really think i got the answer, or they didnt get the question, so i thought it was best to ask in a game engine forum.

I have used many game engines to create custom levels for halflife, cod, mohaa, max payne etc etc.

In a game engine like the above games sdks…you can create tarrain, walls, floors, rooms, buildings with the game engine meshes. At no time do you UV them. You simply select a texture then place it on the mesh in the game engine. Simple. However all those mesh faces will add up and without UV wouldnt this cause high draw call and optimization issues?

In blender you create an asset (character, prop etc etc) it has to be UV so the mesh has one texture on it and so the engine only needs to read one texture not many textures on all the poly faces if not UV.

So question is…why do you have to UV map in a model editor to export it into a game engine if you dont have to UV map the tarrain, walls, floors, buildings you create in the game engine itself?

Second question is, if i create a building/room in blender and export it into a game engine like unity/UE do i have to UV that building/room or can i just create the building/house/room etc in blender and either texture it in blender or game engine and not have to UV it?

So when you all create levels…do you UV the level or not?

Do you just UV the characters and props or do you UV it all?

Just confused as i created levels in game engines with HL2, cod, mohaa, max payne editors in the past and never had to UV the levels i created and played the levels fine…yes the assets/props were already made and were from a model editor and would have been UV but not the level itself.

Hope this makes sense and you can support in the questions. Thank you all soo much. Sorry for a noob question haha.

To simplify the terrain answer: you don’t really need to generate UVs when you’re just applying a texture to what amounts to a dynamically subdivided quad. A heightmap-based terrain won’t really have to worry about this. In the case of walls, floors, and buildings in other engines, the UVs are being generated by the engine and then saved as needed. Unity’s ProBuilder does the same thing.

If you create these things in an external tool, you will have to do UV work. There are ways to do this relatively procedurally with addons in Blender, but when you’re dealing with relatively simple geometry like buildings and walls, you really aren’t going to be doing that much work once you get a handle on the workflow.

Hero assets, such as buildings where it’ll be a main focus and there’s lots of geometry, all get UV work done to them. For very simple tileable things like background buildings or roads and sidewalks, I’ll use either ProBuilder, RealtimeCSG, or Chisel depending on the version of Unity I’m using.

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Amazing thank you so much Murgilod. You have been so supportive on this and not judged me on my questions haha. Thank you, that does make it more understandable now with UVs importance and why in game engine it is basically already auto applied.

Question…if I had created a scene/room/building in blender/maya etc and removed all textures from it, then exported the geometry over to unity/ue then would this mean i could apply the textures in unity/ue thus not having to UV. Or would it be better to texture it in blender and UV finish it in blender and export it in. Basically what is the better choice…or would it benefit to modular that building/scene in blender and export it over and texture it in Unity/ue. Or make that scene directly in Unity/ue with the scene.

Sorry for the questions.

Generally speaking, if you want to do anything related to UVs and texturing, you should be doing that in dedicated software like Blender. If you’re using the basic Blender material setup, you should even be able to bring everything over fully textured without having to do much additional work.