I always used to do my textures on a bunch of different images, because the model is in different parts. I’m wondering if it is supposed to be on one image, or if it is OK to do it on multiple images?
It’s fine, just means more materials and more draw calls.
If I were to get a job in the industry (Which I am going for), do they want them on one image, or does it not matter?
I just want to start using one image if that’s what they like.
Thanks!
Get good at doing it on one image. Thats common for the industry. The one image technique is called an “atlas”.
What they will require on one image changes depending on a) the purpose of it (usually particle systems and characters) and b) the target hardware (nearly everything on one image for mobiles etc).
Thanks, exactly the answer I needed!
Yep, even if you use different shaders you can use the same atlas. If you are using the same texture file for multiple objects it can help save precious VRAM by using the otherwise unused “white space” of the main texture. This is mainly for character models as tiled textures use all the space they have. Although you can put tiled textures together on a texture atlas. Minecraft uses this approach. I am not sure if this is correct, but I think tiled texture atlases would reduce the number of times the GPU would need to perform tasks in RAM and thus allow greater efficiency with less fetch operations.
It is less intensive if you do it on one texture. Don’t know why, probably said above me somewhere, or below me soon.
Any more information on how to use this “atlas” system in Unity? sounds interesting
Put it on one texture, use different uv coordinates.
(removed double post)
I see. Thanks you 
As mentioned above, polygons using the same conditions (texture+shader+params) can be drawn with one draw call. There’s some overhead with each draw call (API texture selects, vertex buffer and index buffer setup etc.) and keeping it down is a good idea.
As usual though, the best way is still to profile your draw calls, as the way your model is setup/used might force the different parts to use separate draw calls anyway resulting in negligible performance gains from atlasing.
Don’t forget tiling textures which make atlases impossible but save on time and memory space, particularly in large environments where the same tiling texture can be used on multiple objects. In practice you end up using both techniques depending on the situation.
I typically use tiling textures for broad strokes and atlases for the details.