Subdivide the result of a boolean. Issues.

[Gio SP]

(Hello! first post, been learning H for a month, this forum is amazing)

What I'm doing: a boolean between two polygonal circles produces a flat ring, I polyextrude it into a solid ring (Fig. 2), then polybevel the side edges (Fig. 3).

1) Problem is, when I try to subdivide it I get weird meshes like the one in Fig 4. It looks like the mesh coming from the boolean SOP is not 'joined/consolidated'.

2) How can I end up with edges where I drew the red lines on the beveled ring screenshot? 

I tried many combinations of join/fuse and other nodes, checked forums and docs but I can't figure out how to avoid ending up with a cheese wheel shape.

Hip attached.

cheers

boolean issues.hipnc

[Atom]

Try choosing another Subdivision Algorithm, like OpenSubdivLoop.

[vicvvsh]

Hi,

yes this happened because geo didn't have enough support edges on the sides of the ring. You can set parameter Arc Type - Sliced Arc on both circle sop and after boolean sop place fuse sop.

[Gio SP]

wow. both solutions work. thanks, this was so helpful! 

Saving here here screenshots of the two solutions in case anyone bumps into similar problems.

@Atom
the OpenSubdivLoop Subdivide option works without further workarounds, it does generate messy topology 

@vicvvsh
topology is perfect by setting Sliced arc on the Circle sop and fusing post Boolean
 

[AntoineSfx]

Also:

circle --- polyextrude: Distance 0, inset some value -- polyextrude --  polybevel 

Set some value greater than 1 in the divisions in the polyextrude SOP so that the quads have roughly the same size.

It will result in a correctly quadrangulated geometry that will be subdivided as expected, and the subdivided result will have a nice topology, which you will appreciate downstream.

[Gio SP]

Thanks @AntoineSfx, I just tried your method and it's quite neat. Haven't thought about it. 

Here I am with the noob frustration of the day, I can't possibly figure out a way to procedurally generate a mesh that will behave nicely while beveling the outer edges, in the gif you see the issue.
Any suggestion would be greatly appreciated!
 

[vicvvsh]

Here is not fully procedural approach but it is one of the ways to do that

boolean_issues_01.hipnc

[Librarian]

Combine! I Have this solution.
 

 

HavingFun.hipnc

[AntoineSfx]

On 9/23/2020 at 2:13 AM, Gio SP said:

Thanks @AntoineSfx, I just tried your method and it's quite neat. Haven't thought about it. 

Here I am with the noob frustration of the day, I can't possibly figure out a way to procedurally generate a mesh that will behave nicely while beveling the outer edges, in the gif you see the issue.
Any suggestion would be greatly appreciated!
 

If you can't design the mesh for polybeveling that specific edge, i.e get rid of the edges between the adjacent planar primitives, then do one of those:

group the ring primitives and the larger primitive together, the do a divide / uncheck convex polygons, check remove shared edges. This will be much more polybevel friendly.

or: group the larger primitive, then group expand SOP it with: flood fill + restrict by normal = 0 

The trick is .. polybevel can somehow slide on ring edges to hide small asymmetry problems in meshes, but it can't do magic. It doesn't somehow recursively slide on adjacent primitives until the target curvature radius is reached.

So it's up to you to make sure there is no other edge too close to the edge you're trying to polybevel. At least that's how I see it.

 

Edited September 24, 2020 by AntoineSfx

[Gio SP]

thanks @AntoineSfx that helped. 

@vicvvsh thanks, it makes sense, your post made me think about another possible, procedural solution, beveling first the individual elements and only afterwards running the boolean operations. It can generate quite a clean mesh.