UV Tiling Question

VertexHazard

I have a question about UV tiling. I am working on a 3D prop in 3DS Max and wanted to understand UV tiling a bit better. I have seen some side effects from overlapping UVs when baking normal map so I wanted to know if what I did was OK for game ready models. In the prop I have about 14 bolts that are all the same so I overlapped the UVs to fix some issues I left 1 UV shell in the Original UV location and shifted all other 13 to the right by 1 UV space, so I wanted to know if leaving all other 13 bolts overlapping in the 2 UV space was OK or if it produces bad results when taken to engine or If I have to move each individual bolt by 1 UV space until they are not overlapping? 

poopipe

If they're outside the 0-1 space the bake will ignore them

So yes,  fine

VertexHazard

K Thx for the Help!

Creo_metus

Is that how this works? 

So if I had say a box and all 6 sides were identical textures/normals. I could put 5 sides 1 UV space over(outside the 0-1) overlapping and that's ok? 
Is this how a weapon could be made for a game engine to maximize detail? 

ant1fact

Creo_metus said:

Is that how this works? 

So if I had say a box and all 6 sides were identical textures/normals. I could put 5 sides 1 UV space over(outside the 0-1) overlapping and that's ok? 
Is this how a weapon could be made for a game engine to maximize detail? 

You only offset them for baking, then you move them back

Creo_metus

Do you then overlap them back in the 0-1 space? 

ant1fact

Creo_metus said:

Do you then overlap them back in the 0-1 space? 

Yep

janoshx

This may be stupid question but why you move them back to 0-1 space after baking? Isn't their location already in right place if they are exactly one UV offset outside of the 0-1 space?

Maybe i should just try this...

Ghogiel

janoshx said:

This may be stupid question but why you move them back to 0-1 space after baking? Isn't their location already in right place if they are exactly one UV offset outside of the 0-1 space? Maybe i should just try this...

I think generally it's fine to leave it offest. But it depends on where it's going.

I have seen, in the distant past, that mirrored and overlapped UVs break TS calculation along the seam. The tangents and binormals go weird and invert on the seam, regular stacked UV shells are unaffected but if any mirrored seam is stacked, it broke, the solution was to actually leave them offset outside the 0-1.

I think the opposite has also been truefor TS where shells outside 0-1 went wonky. Wasn't this the case in UE3, or was that also TS being wonked on mirroed UV seams?

I think Just being aware it could be a solution to weird lighting artifacts that either appear along mirrored seams or on parts of a mesh that corespond to parts that are offset UVs. Though  don't think you will run into too many issues either way these days.

ant1fact

Not a stupid question at all, I get what you mean. I think it's just good practice to be explicit about what you're doing. What if you turn off tiling for this material in engine for some reason, what if you accidentally offset the islands inaccurately, etc. - you could run into problems.

Creo_metus

So is this what Mirroring UV's is all about?