OCC geometry STL export

Netgen
1

Hi there.
Just wondering if there is a way to export STL files, or get the triangulated data, from OCC geometry with the python api. Works fine from the interface but I can’t find the Python command.
Thanks
Ryan

2

with the netgen mesh:

ngmesh.Export("test.stl", "STL Format")

best

3

Hi.
Thank you, but is it possible to do it for the OCC geometry itself, without going through a meshing process, like the “File > Save Geometry - STL file type” interface menu?
Cheers
Ryan

4

For this there is no interface in netgen, but opencascade can be directly used for stuff like this.
Also the gui cannot do read occ → write stl without meshing step in between

5

In my experience on Arch linux, with the latest Netgen git, the interface does allow you to export a triangulated STL mesh directly from an OCC file. It will show an “Unknown target format error” window but the STL is still exported. I have attached a STEP file that I can load into Netgen and then just save as an STL.
I think it may work as I am currently working with STEP files that contain only faces, not curves. The Netgen Python API exposes an OCC face triangulation function but when I try and use it I get the error below. Looks like it returns a C construct of triangulated face data that Python cannot understand. I do not know enough about C to know how to follow the advice of the error message. Do you have any simple-to-follow ideas on how I can get Python to understand the triangulated output?
Cheers
Ryan

geo.shape.faces[0].Triangulation()
TypeError: Unregistered type : ngcore::Array<std::array<netgen::Point<3, double>, 3ul>, unsigned long>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File “”, line 1, in
geo.shape.faces[0].Triangulation()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
TypeError: Unable to convert function return value to a Python type! The signature was
(self: netgen.libngpy._NgOCC.TopoDS_Shape) → ngcore::Array<std::array<netgen::Point<3, double>, 3ul>, unsigned long>

Did you forget to #include <pybind11/stl.h>? Or <pybind11/complex.h>,
<pybind11/functional.h>, <pybind11/chrono.h>, etc. Some automatic
conversions are optional and require extra headers to be included
when compiling your pybind11 module.

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