How to approach UVs and lightmaps on a complex object?

NeonGold

Hey guys!

I have a bit of a convoluted question regarding using lightmaps when you want to duplicate an object and have their UVs overlapped. I know you can't overlap lightmap UVs (which makes sense) but I've run into a bit of a weird situation. I'm guessing my approach to the problem is way off as I'm still learning best practices for approaching complex objects, so I'll try to take you guys through my thought process to see if you can't point out where I'm going wrong.

So for reference here is the asset in full in Blender:


I'm struggling a bit to figure out how to break this up as I would like to texture it in substance which will involve splitting this into a couple of texture sets I'm sure, so if you guys have any suggestions on how to do that efficiently that would be super helpful! As it is, I've broken it down into its modular bits, UVed those, and then duplicated them. Where I've run into a snag in particular is here:



Each of those steps is made of two rectangles which I UVed (creating two channels; one for lightmaps), duplicated, and then joined, leaving their UVs overlapping. I then took that whole thing and duplicated that to make all of the steps. I have a feeling that something about this process is very wrong, but all those little bits taking up their own UV space doesn't seem very efficient either so I'm not quite sure what to do there. This is also where my lightmapping issue comes in, as the lightmaps will be overlapping which I know isn't going to work. 

So... thoughts? I'm sure there is a better way to approach this overall, but I just can't quite get my head around it without ending up with messy UVs.

throttlekitty

There's a few strategies here. For the standard UVs, you could have groups of overlapped steps where every Nth step is a duplicate, like 1/3/5, 2/4/6. Or the top and bottom of a step shares the same space, and find a similar scheme for the inner faces. Or use a generic tiled texture and totally randomize UV positions, overlapping and normal maps be damned!

For a 'proper' lightmap, you'll want everything unique, not much you can do about that really. If this was placed once in a level under controlled lighting, like you knew the landing would always be totally top lit and it's underside will be totally shrouded, you could get away with some strategic overlaps or groups of UVs severely scaled down.

Option C is to reconsider using modeled grating, replacing it with a transparent texture, but that's less fun.

NeonGold

throttlekitty said:

There's a few strategies here. For the standard UVs, you could have groups of overlapped steps where every Nth step is a duplicate, like 1/3/5, 2/4/6. Or the top and bottom of a step shares the same space, and find a similar scheme for the inner faces. Or use a generic tiled texture and totally randomize UV positions, overlapping and normal maps be damned!

For a 'proper' lightmap, you'll want everything unique, not much you can do about that really. If this was placed once in a level under controlled lighting, like you knew the landing would always be totally top lit and it's underside will be totally shrouded, you could get away with some strategic overlaps or groups of UVs severely scaled down.

Option C is to reconsider using modeled grating, replacing it with a transparent texture, but that's less fun.

Ah, that makes sense! It's always good to have options as I'm finding that there is no one right way to do everything.

Thankfully the scene this is going in is just being used once and is just a background prop so I suppose I can get away with fudging a bit. I did consider the alpha mask option, but you're right- where's the fun in that? haha

Thanks for your help!