IGES (.igs, .iges)

The Initial Graphics Exchange Specification, read through the optional OpenCASCADE backend: the twin of the STEP reader for the older CAD exchange format many tools still write. Read-only.

Format name	iges
Extensions	.igs, .iges
Read / Write	✓ (with OpenCASCADE) / —
Extra dependencies	OpenCASCADE 7.6 or later (-DMESHIOPLUSPLUS_WITH_OCCT=ON, LGPL-2.1 with the OCCT exception, bring your own)

import meshioplusplus as mp

mesh = mp.read("part.igs")                         # triangles at 1e-3 of the diagonal
mesh = mp.iges.read("part.igs", deflection=0.01)       # a chordal deflection of your own
mp.write("part.cad.json", mesh)                    # the NURBS faces as Kratos CAD JSON

IGESControl_Reader transfers the file's shape, which is then handled exactly as a STEP file's is: converted to NURBS throughout, triangulated by BRepMesh into one triangle block with the cad:* cell data, and kept as faces, trimming loops and edges in mesh.info["brep"] (C++ BrepInfo); see STEP: reading for the details and the options. Without the backend, reading raises NotImplementedError (C++ Unsupported) naming -DMESHIOPLUSPLUS_WITH_OCCT=ON; there is no Python twin of a CAD kernel. Writing IGES is not planned: STEP is the exchange format meshio++ writes (see conformance).