Is there any downside?

Hey guys i got a quick question. For small random meshes/models can i just assign the material in the editor rather then having to map and unwrap the UVW? Is there any downsides to that because that would seem to save a lot of time on really small and simple meshes.

Basically to break it down:

  1. Create model in 3DS Max
  2. Assign various material slots to the model
  3. Modify UV layout so there are no overlapping edges
  4. Create second UV
  5. Export from Max and import into UE4
  6. Assign materials to various material slots
  7. profit?!!

Thanks again.

Hi there

I’m not sure I completely understand what you mean…Do you refer to the lighting UVs or do you mean it in a general way?

In case you mean it generally: Of course you can just apply a material to a selection set. You will need correct UVs (to get undistorted mappings) but you dont have to paint the texture based on the UV layout if thats not required by your asset. You can just apply the material and tile it using TextureCoordinate nodes.

Let me know if I got your question correctly :wink:

By the way, you don’t always need two UV sets.


If you want a solid color for an object then that’s perfectly fine if that’s easier than unwrapping UV’s and making texture maps–but, limit as much as possible how many materials you use, each material on a mesh means an additional draw call which slows performance. What I’ve done in cases where I have a bunch of things that use solid colors is to make a simple texture with my solid colors in it, then do a very quick UV mapping on the mesh so that each part is on the right color. You don’t need to do anything complicated with the UV’s you just select the part you want a color and move it onto the right color, they can be overlapping inverted or whatever they don’t need good mapping.
That way I’m able to use one material that has all the solid colors I want to use and it saves on the number of materials I need.

Thanks guy, you both helped a lot :smiley:

IMX, when do i not need two UV maps? whenever i try to import into UE4 with a single UV i always get an error. Thanks again good sir.

You don’t need a second UV channel if you aren’t using static lighting. Otherwise it needs a UV channel to use when it creates the lightmaps.

Most of the time, one UV channel is sufficient even for static (baked) lighting. UE just doesn’t like certain unwraps, but you will notice this with black areas on the mesh or wrong shadows.

Well there’s specific requirements for lightmap UV’s, but sometimes your first UV channel follows the guidelines already so if that’s the case then you don’t need another UV channel.

@Deathviper: I know of issues with UV islands that are too close to each other or too close to the borders of the UV space. Do you know of any other requirements that cause the artifacts?

The issue with things being too close can happen when you have too many UV islands, if you do automatic unwrapping like in 3ds Max then you can end up with lots of separated parts which doesn’t work well. It’s best to do it by hand where you can limit the number of seams and islands. If it still has issues after doing a good UV mapping then you can try increasing the lightmap resolution, if you have to increase it to a ridiculous amount to get a reasonable result then you might have too much geometry in the mesh and you should consider splitting it up so that it can then use multiple lightmaps.
The other standard requirements for lightmap UV’s is that it has to fit in the 1x1 UV space (otherwise it would be trying to tile the lightmap which it can’t do) and then make sure your UV’s aren’t overlapping or inverted. Sometimes you get an error about overlapping or inverted UV’s and it might not actually be a problem so just look at the result and if it’s OK then you can ignore that error.