convert stl crash

[Mike Vivaldi]

Hi,

More google group issues for me. Long posts not allowed. I'm trying to import an STL from blender using ASCII with Y fwd, z up. I'm on Windows using version 3.45.4. Convert to Ngon crash.

Mike

[Mike Vivaldi]

primatives attached

[Mike Vivaldi]

On Monday, September 1, 2025 at 10:17:45 PM UTC-7 Mike Vivaldi wrote:

primatives attached

[Rob McDonald]

I've been having some struggles with Google Groups as well.  Not much we can do about it, we don't have any control over how it works.

What are you trying to achieve by converting to NGon here?

The convert to NGon functionality only works on surfaces that OpenVSP tessellates itself -- it 'knows' which quads were split into triangles.  An imported STL file does not have this information, so it has no hope of working.

The 'Convert to NGon' button is really just meant as a debugging feature.  I had planned on removing it before releasing 3.45, but I left it in just in case.  There really is no user-centric use case for it.

If you want it to 'work' though, there is a workaround.  Import the STL.  Then run CompGeom.  This will create a new MeshGeom that is essentially identical to the imported one -- but with some internal variables set (that currently are not set in the import).  Then, you can run Convert to NGon on that MeshGeom.  Of course, since OpenVSP doesn't know about the original structure, the converted NGon mesh will still be triangles.

Rob

[Mike Vivaldi]

Hi Rob,

The documentation I have for the Boeing 707 includes lots of points which I process using blender and parametric analysis as well as resampling, it is easier to work Blender than the OpenVSP modeler due to the nature of the input data. The process is also useful for generating a visual model for later use which is consistent with the aerodynamic model. Initially I wanted to do this in FreeCad or Fusion 360 but they lacked the ability to resample the input points on the lower fuselage and the lofting was generating less than optimal results. The goal is to include the fuselage into the aero analysis.

I just tried the work around and it appears that the process does not work on imported STL files, Image attached. I ran comp geom and then convert to Ngon but they appear the same.
Thanks,
Mike