Quick Tip: Strange visible mesh edges (no UV Problem) on meshes with modelled interior.

[InsaneDruid]

So I was revisiting my proton to bring all the features to 1.0.5 level, and noticed some strange artefacts in the VAB on my second, and upon closer inspection also on the third stage and even on SQUAD parts. You can see them in the first image, the appear and relocate depending on camera position, but are not the known UV-padding problems, for they appear on real close-ups and well within the UV isles. The lines appeared on the edges of the outer skin and on triangles tessellated from quads by the game engine. After checking that no lost vertices cause the effect I tried widening the wall by resizing the inner parts of the hollow structure of the stages, with little to no effect.



The solution was simple: Just separate the inner walls from the mesh to be a single mesh of its own, independent from the outer skin solved the problem, like on the right tank in the first picture. The second picture in the small album shows the separated inner mesh in blender for clarity.

Edited January 29, 2016 by InsaneDruid
imgur adjustment for new forum

[NecroBones]

Yeah, there are some strange artifacts you can get with normals if you let Blender keep the entire mesh as one big manifold mesh object. Sometimes separating them out into separate mesh islands is all that's needed, rather than splitting it into a separate mesh object. Additional mesh objects don't hurt, except for slightly reducing performance by making an additional draw call in the game.

I'm in the habit of separating the outer wall of my tanks (and cylinders in general) into their own islands, as one of the last steps before exporting to Unity. Otherwise these cylindrical walls can sometimes get spherical (or otherwise incorrect) normals, and create some strange shadows in game.