Environment: Trimsheet + variation texturing

goekbenjamin

lets say i need a long wall ingame (unreal engine)
i would generate a square (one face only) with default 01 uv and would apply trimsheet. i now could  copypaste the one many times, then i would have a long wall.
now when i want some variation like moss, i could use vertexpaint after tesselation/subdividing the mesh, but that would increase the vertex count. 
are there some other ways we could apply variations? 
like using a second uv channel, and painting on that one per mesh??

gnoop

Yeah, vertex paint  makes you issues with lods .        So   it could be a  second  uv channel or   maybe  low res  automatically baked  textures for distant lods ( works quite well with hierarchical lod system and on terrains) .  

     It also could be a mix  of a macro mask that use a texel size  multiplied from same UV and  multiplied itself on  another mask having same texel size that regular textures ( like curvature mask) .  But that way  you have no direct control over  where your moss wold appear exactly.

icegodofhungary

If you're using lightmaps in Unreal and are making a long wall, it would be better to not use small squares. You don't have to worry about fitting in the 0-1 space unless you're going to bake something other than lighting. It should have a tiling texture which means it tiles outside of 0-1. So there's no reason you have to make a square that fits into that space. Nor do you need a square to maintain density. Baking lightmaps can create artifacts at the seams between meshes so you don't want to make a long flat wall a bunch of squares jammed together. You make stuff as big as you need it to be, and in the shape you need it to be. Plus it saves you time from having to copy/paste all those meshes. If you need sever 4m squares to make a all, consider a solid 12m wall. Just UV it so that 0-1 takes up 1/3 of the mesh.

You can also not worry about UVs at all and just use a triplanar material. Since walls are usually flat and stationary, that's a good fit.

You can take two tiling textures and blend them with a mask that also tiles. You can use vertex coloring and blending for several effects. You can use decals. You can use detail meshes like caps, columns, or whatever else one might find along or on a wall. It doesn't have to be all in the textures.