Add Element2d.SetGeomInfo() Python API for external mesh curving

[ksugahar]

Summary

Add a SetGeomInfo method to Element2d that allows setting the UV parametric coordinates (geominfo) for surface element vertices.

Motivation

This is essential for high-order curving of externally imported meshes (e.g., from Gmsh, Cubit, or other mesh generators). When meshes are imported without geometry, the geominfo is not set automatically, which prevents mesh.Curve(order) from working correctly.

Usage

from netgen.meshing import *

# After importing mesh and setting up geometry
for el in mesh.Elements2D():
    for i in range(len(el.vertices)):
        # Get UV coordinates from geometry for this vertex
        u, v = compute_uv_for_vertex(el.vertices[i])
        el.SetGeomInfo(i, u, v)

# Now curving works correctly
mesh.Curve(order)

API

Element2d.SetGeomInfo(vertex_index, u, v, trignum=0)

Parameters:

• vertex_index: 0-based index of the vertex within the element
• u, v: Surface parametric coordinates
• trignum: Triangle number for STL meshing (default: 0)

Related

• Feature request: https://forum.ngsolve.org/t/feature-request-python-api-for-high-order-curving-of-externally-imported-meshes/3810
• Complements existing Element2d.IsValid(), Element2d.IsDeleted(), and Element2d.geominfo (read-only) methods

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