I came across this problem with Shell today.
I made a surface object and extruded an edge from it, trimmed that and joined the two objects. When I do a shell on the resulting object it seems the normals of the joined surfaces point in the oposite directions, leading to a wonky shell.

Hi Linker, thanks for the bug report and example model.

It appears to be going wrong somewhere down in the guts of the sheller, so it may be a little while before I'm able to drill in there and figure out what has gone wrong with this one. I've added this to a stack of geometry library bugs to look at in a while.

I'm sure you have already figured this out, but to finish this particular model you can shell each part individually and then boolean union them together.

Getting these example models is really a big help, thank you!

- Michael

To Linker - I finally found out what was causing this normal-direction problem with shelling certain joined surfaces like this, it will be fixed for the next beta.

- Michael

Very nice, Michael! I think it's great that you take your time to follow up on reports like this. I really look forward to working a bit with Moi again soon, I haven't really had time to do much other that quickly trying the features of each released Beta lately. (I think the latest version of the poly-exporter is great, by the way. The only thing I can think of to make it even better would be the possibility to set an upper limit to the ammount of vertexes of an n-gon.)

> I think the latest version of the poly-exporter is great, by the way.

Great!


> The only thing I can think of to make it even better would be the possibility
> to set an upper limit to the ammount of vertexes of an n-gon.

What would you want to happen to n-gons that had more than that number? Would they be broken up into triangles, or are you thinking of breaking them into smaller n-gons until they satisfy that number?

The latter will take a different type of polygon processing mechanism than I currently have available, so it will be a while before I'll be able to tackle that, it will probably have to be a future version enhancement.

What about planar shapes, would you expect an ngon vertex limit to apply to those as well? Normally some simple things like the cap of a cylinder will create an ngon with a pretty high vertex count...

- Michael

Well, when I first thought about this I'd say breaking it down to several n-gons would be ideal, then you would have the advantages of quads/n-gons in apps that don't handle unlimited vertexes very well. With some closer thought I'm not sure how much use it would be. From a few years ago, when n-gons first started to become common, I remember quite a few softwares having problems in two distinkt areas, one would be polys with more than 8 or 10 vertexes, the other being non-convex polys. I don't know how much of an issue this is now, though, as the apps I use now (Maya and XSI) don't hve problems with n-gons at all.