Tiling Trim with 45 degree corners on the grid??

jschlotz

I'm working with a modular workflow on my current project and am lost on how to handle corners.  



If my main trim is 4m meters long, its UVs look like this...


Despite not understanding how to tile the corners, I don't understand how to make other sizes of the trim pieces continue to be seamless without stretching the texture. 

Any advice would help me enormously.

Also, if anyone suggests that its fine to have a seam at the corner, I know that is ok sometimes. I'm asking this because I need to know what to do when a seam doesn't belong at the corner...like in my current situation.

musashidan

I would approach this as it would be in real life. Those corbels would be jointed and would not be a continuous piece. This works to your advantage. For the corner I would attach the mitred sections to a single piece and map the 90 corner as a single island.

when baking trim sheets like this it's always a good idea to have a continuous seamless strip from 0-1 and a strip with beveled corners to create the joints(that would be there in real life) Also, using this technique stretching uvs are actually used to your advantage rather than being a problem. Sorry, I don't have time now to provide images/links to better demonstrate what I mean. I'll reply again with better help or I'm sure somebody else will have by that time.

zachagreg

Let me see if I understand this correctly. The over hang piece on the third image is the problem area because it does not fit within the 1m space that would allow it to be tiling correct? In a case like this and in many modular set pieces having pieces that extend beyond the 0-1 UV space is quite common especially when using tiling materials, like a trim sheet.

Think of your trim sheet as a never ending strip of normal map(or material), when you have an UV island that would extend beyond the 0-1 space its just going to be more of your same tiling endless strip.

The seam at the overhang corner is not a problem honestly, there should be seams however on what would be the top and bottom of that piece to allow for those faces to be scaled up to fit the tiling material. Basically the space within the green box should be its own island and scaled matching your kit's texel density. Example being if that is a 1m portion it could take up a 1k map so the part where the island is past that 1m mark would hang out of the 0-1 UV space. (Blue line on the UVs below)


Edit: In regards to the second image, this applies to pieces like walls where you would be butting one next to the other and needing a material tile properly across the surface as whole. If there are no seams in your trim sheet it will continue on tiling regardless of your UV space.

musashidan

Have a read of this. It should explain everything you need to know: https://polycount.com/discussion/144838/ue4-modular-building-set-breakdown/p1

jschlotz

musashidan and zachagreg, thank you for the quick reply. Its very generous of both of you. I think I understand what you're saying, I'll try some things out and reply here with more questions I'm sure.

jschlotz

the 2m piece tiles with the corner on top. And the 4m piece tiles with the corner in the 2nd image, but do I really have to change the UVs on every corner piece depending on the situation?

I read the modular breakdown a few times and something is not sinking in. So to move on the corners, I should leave the geo separate, duplicate and mirror it over? then every piece connected to that beyond will need reversing of the UVs to tile? 

musashidan

Sorry, I didn't realise you were using a unique pattern. I thought you were just baking bevels. So obviously intentional stretching is out. In that case you could lay all you uvs out in a long continuous horizontal strip, spanning multiple UV tiles if necessary. Once your texture is seamless from 0-1(which it is) and your islands are snapped end to end you should get a seamless continuity.

For the corner pieces you can just add a rotated symmetry(not sure what you'd use exactly in Maya. In Max I'd use a symmetry modifier rotated 45 degrees) on the already mapped straight piece. This way your UVs will automatically be mirrored and stacked.