Smoothing problems when I try to triangulate my bread slice. (Imgur link.)
well, "Fixing"... is relative, in this context. I'm not trying to be cryptic, mate, its based upon a few considerations that I detail below, and there's also what you, as a modeler, would consider a proper result. So, to try and be more precise:
- Subdividing a polygon mesh, either with the Mesh menu >> Smooth command, or via it's "virtual" (my term), display equivalent of doing a smooth preview (by hitting '3' on the selected mesh) will always attempt to divide your edges by at least 2 (at one level of subdivision), 4 (at 2, maya's default), and so on. It's appreciatively predictable with a manifold geome(edit: much less non-)planar though, so in that regard yes: it's fixing this.
- but a mesh with non planar polygons (always quads or Ngon, since triangles are always planar, obviously), might not always subdivide as you'd prefer. Hopefullly this pics will prevent us both from suffering through more verbiage of mine, lol :
From a basic plane, I extruded up and scaled down its single face, but with two different geometry. On the left, the topology goes through, vertically and horizontally, making four non planar faces at the corner, while the rightest mesh hasn't this issue thanks to its diagonal corner (from a top point of view).
Check the '1' corners, showing the very typical issue with this non-planar geometry, at a certain camera angle, Maya (or any other software as I said) can't be sure how to render this stuff, showing a sort of caving in, or concavity. that you don't have at the '2' points on the other mesh.
Now, I duplicated and added subdivision/smooth preview levels: in all cases there is no non-plannar faces anymore, but the actual subdivision gives different results. see how there is still a bit of concavity at the corners of the left most, initial mesh, but how the "correct" triangles does affect the topolygy flows, rounding up the corners.
Generally speaking, it is good practice to avoid non planar faces: they deform less predictably making it particularly bad for animation, display/render in wonky ways as shown here, but also makes the UV unwrapping less easy. But it's a matter of degree, a tiny bit of non-planarity is not always a big deal. What is certain is that if you intent to subdivide a mesh, quads instead of triangles are better.
well, I made another wall of text. my bad. Hope this helps nevertheless.
Happy modeling!
- Fred.
The solution to non-planar faces is not triangulating your mesh. It's fixing the non-planar faces.
On the left object, the bottom two faces with points pushed down are non-planar. Depending on where your faces are on the model, the object on the right, is not necessarily the solution. I just added the edges to make the point that, the object on the right would not register as having non-planar faces.
When you rotate around, you can see the issue with geometry. The face is being contorted in unnatural ways and that can cause lighting issues later on.
A way to find you non-planar faces is, when you go to "Cleanup", under Operation, choose "Select matching polygons". That way, you can zoom in on those areas and start fixing the geometry. They may also be n-gons.