Setting up a UV to mirror a texture onto a second face

[Bitsy Buccaneer]

My current project is a painted boxbed/daybed. The construction and geometry are simple, with the entire design interest coming from the painting. This is why I would like the textures to be as sharp and clear as possible while still being resource-friendly.

The daybed has full left/right symmetry so I thought I could divide it in half without adding many vertices or triangles and use the same texture for each half. (512x512 used twice rather than 1024x512.)

I've used Project from View for the UV so far. Had to tweak parts of the layout slightly to accommodate perspective, but that was straight forward when done as a single layout. (The 1024x512 set up.) Trying it as two halves doesn't because the only way I've come up with is to Project from View from the back/reverse side and then the perspective distorts size and placement greatly. The two halves need to match exactly so I'd rather not rely on having to reshape it manually.

My other thought it to rebuild as a half and use the mirror function, which is still a bit of a frightening mystery to me. :matte-motes-smile:

So I thought I would ask for advice here before I go wading back in and wracking my brain over things which might turn out to be dead ends. Can the UV be flipped simply? (I can't figure out what to call it to search for it.) If I UV the first half before I use the mirror function, will I still need to UV the second half separately? Will the added vertices matter enough on the lowest LoD that I should just scrap the idea? (This is my first piece of proper furniture.) In theory, I know about using hidden triangles and spare materials to get around some of that; will such an approach counteract my idea of reducing texture data?

Right now, with only the mattress edges beveled, it's reading Verts: 83, Faces: 64, Tris: 150. Haven't explored lowest LoD options too much, but it's a bed/couch so I don't have to chase the < 1 LI dream too hard. :matte-motes-wink:

[arton Rotaru]

Building only one half, and using a mirror modifier is the way to go. You will have to keep the edges/verts along the center throughout all LODs indeed, or the UVs will break badly. Which means slightly higher poly counts. To make it ultimately low LI you could create another material for the lowest LOD without the center edges. With a very small projected texture of the whole thing.

Even if I don't plan to mirror the texture, in 99 % of the models I use symmetry/mirror functions while modeling. Sometimes even on the x, y, and z axis at once, and deleting the center edges in a last step before unwrapping.

Mirroring is your friend in a lot of situations. :matte-motes-smile: You anly have to make sure you don't have any negative scaling, and flipped face normals afterwards. So I would recommend to use the Mirror modifier instead of the Mirror function.

[arton Rotaru]

The performance aspect of the single larger texture vs a 2 material version with 2 smaller textures is 2 fold.

2 smaller textures are preferable, because of the smaller memory footprint. (For example a 512x512 = 768 KB + a 256x256 = 192 = 960 KB versus a 1024x512 = 1500 KB).
Though having 2 materials splits the mesh into 2 meshes in the render pipeline. With 2 different textures there will have to be state changes as well, hence an increase in draw calls/state changes. Which is bad if there are too many to be issued by the CPU. Which is a common problem in Second Life, because of all the prims. Thinking of the default cube, which has 6 faces/materials by default, there are a lot of unnecessary draw calls. One reason why we see so many threads popping up from people on GTX 980Ti cards who complain about poor performance in SL. It's inefficient.

In SL there will be a 3rd factor which is Land Impact indeed. So it's not an easy decision to make here. Personally I would try to get away with the mirrored 512x512 with slightly increased poly counts. If that doesn't work well regarding land impact, I'd go for the 2 material version.

[Bitsy Buccaneer]

I am now a convert to mirror building. :matte-motes-smile: Sorry it's taken me so long to get back to you, had problems getting into beta grid when I was ready to test and then RL got in the way. Its schedule and mine weren't cooperating for awhile. Anyway, things seem to be proceeding apace though I haven't finished all of my LoD levels yet. Provisional LI is good too. Thanks for your help, arton. As always, it's much appreciated.

[arton Rotaru]

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Bitsy Buccaneer wrote:

...Sorry it's taken me so long to get back to you....

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