Set Smooth bug - Repeatable

[mjl1966]

After having a problem with renders using the Set Smooth button and reading the many posts about it on the site, I finally found a specific way to reproduce the results that seem to indicate this is a bug.
First off, although I’d love to upload the blend, I can’t. But the procedure is fairly simple.
Second of all, let’s get the usual suspects out of the way. Recalculating normals, Y, “hidden” faces, etc. are not the problem. I start with 4 vertices, so my mesh is super simple.
Third, the problem seems to be specifically related to duplicated and rotated planar meshes.
Procedure:
Add any mesh and go to edit mode. Create 4 vertexes that create one side of a hexagon. (4 vertexes, 3 edges) Select and delete the original mesh just to get it out of the way. What you have left is one side of a hexagon.
Now, select all and duplicate, then rotate 180 so you have the other half of the hexagon. I did not use mirror rotation or anything fancy, just straight dup and rotate around the cursor.
Extrude hexagon. Enough so you have some faces to look at. These are the ones that will get fubar.
Set Smooth and render. At this point, all looks well.

Now, manually create faces on the side of the hexagon you originally started with. I did this with triangles, quads, border select, bb select, right click, clockwise, counter clockwise and with pink slippers on. How the vertexes are selected does not matter.
Once you’ve manually created faces, render and behold the mess that has become of your mesh using set smooth.

Turn on view normals, flip the ones that are incorrect. Render again, and you still get a blotchy render.
I made this procedure as simple as possible to reproduce these results. I can’t think of any part of the procedure that should cause the problem. This looks like a bug to me. And a pretty important one. Being able to create faces is kind of important.
I would be happy to post the blend file if somebody has a place I can upload it to.
P.S. just for good measure, I did just half the hexagon, without duplicating and rotating and the results are just fine. This is why I think it has to do with duplicatet/rotated planar meshes.

-MJL

[Orinoco]

I’ve had that problem, so I tried this.

Add a plane, select two adjascent vertices, scale apart.
Snap cursor to selection, delete edge.
Set rotation pivot to 3D cursor
Duplicate and rotate 180 degrees
[You didn’t say how you connected the two separate pieces, so I used remove doubles]
Select the hexagon, extrude edges, set smooth.

Now, manually create faces on the side of the hexagon you originally started with

Re-select the hexagon, extrude edges in the other direction.
Render.
No problem.

I’m using the Windows 2.42 build from 2006-07-15.
I wonder if I used the same method you did. If not, what should I do differently to create the problem?

[AndyD]

Firstly it’s worth mentioning that SetSmooth on a flat-surfaced mesh is prone to visual errors (because SetSmooth doesn’t actually do anything physical, it’s purely visual) but I guess you’re just using this to make the point. Anyway, does Auto Smooth give the same result?

Secondly, I can’t reproduce it in 2.42a (Nov 06) OS X Blender. The only time I came close to producing a strange effect it turned out I did have concurrent faces (from doubles) - presumably created from prior extrusions that I’d I’d failed to undo properly.

Mind you, I couldn’t follow your step by step guide. First you say to extrude the hexagon (you don’t mention if you joined the verts or if you still have two halves) then you say “Now, manually create faces on the side of the hexagon you originally started with. I did this with triangles, quads, border select, bb select, right click, clockwise, counter clockwise and with pink slippers on.” - Well I don’t have pink slippers but that doesn’t matter since I can’t actually figure out what you were creating faces from? If you only have half a hexagon (4 verts) - where are these faces going from and to? And since you already extruded that half so there’s three faces there anyway (you say these will get messed up), where are you putting all these extra faces you’re creating??? Sorry, but I just don’t follow you at all. Maybe you need to post step-by-step screenshots of the screwed up process for simpletons like me to follow

[RamboBaby]

He’s talking about the mostly black faces that are visible on the side of his second image. I’ve had the same thing happen when manually joining meshes that were created independently. In my case the problem turned out to be that the faces of one mesh were set smooth and the faces of the other were set solid. My results looked identical to what I see in your image.

[AndyD]

Yep, I can see what result he’s talking about, I just can’t follow the procedure - I don’t understand the instructions.

As for your joining problem, SetSmooth is per face so, unlike SubSurf, it is possible to SetSmooth part of a mesh if you apply it to selected faces in Edit Mode. Therefore, it is possible to join smooth and solid meshes for a mixed result.

[dudewithasock]

I’m having this same problem with a project I’m working…the shading of the main body is way off from the extruded Bezier curves. Anyone know what to do to fix this?