Cone surface cannot be triangulated

[ricdezen-euclid]

Description

I opened a thread on the dev.opencascade.org forum. I was asked to also open a github issue. I'll copy and paste the body of the post here for ease of access.

Good day, The attached step file contains a face made from a truncated Cone surface. It was originally part of a much larger and complex model. We are developing a software using OpenCascade 7.8.0, and when loading the model, we find that this face has a null triangulation. Our code loads the file using the STEPCAFControl_Reader class, because we wish to retain color information.

Further information:

• CAD Assistant (OCCT 7.6.0) loads and displays the shape correctly.
• FreeCAD 0.21.1 loads and displays the shape correctly.
• draw.bat (OCCT 7.8.0) loads the shape, and reports no issue using the "checkshape" command. When visualizing the shape in the 3D viewer, only a wireframe is shown. I have made sure the display is set to solid with "vsetdispmode 1" and by loading another shape that indeed displays as filled.
• draw.bat (OCCT 7.9.1) shows the same behaviour as the 7.8.0 version.
• Our code (C# wrapper of OCCT 7.8.0) using STEPCAFControl_Reader, as already explained, yields a null triangulation.

This is not the first time we find ourselves unable to triangulate Conical or Cylindrical surfaces, so any help in identifying the issue would be appreciated.

Expected Behavior

The provided file should be triangulated and displayed.

Actual Behavior

The provided file does not display and cannot be triangulated.

Sample Code or DRAW Tcl Script

stepread Sfacciata.step cone *
vinit
vdisplay cone_1
vfit
vsetdispmode 1

Operating System

Windows

Compiler

MSVC

Bitness

64-bit

OCCT Version

latest

Additional Files

Sfacciata.zip