[Gmsh] Access to full line or surface information

[Pieter Reumers]

Dear all,

I'm trying to get access to the full geometry of a certain model created using gmsh. For example, consider the following *.geo file:

Point(1)={0, 0, 0};
Point(2)={1, 0, 0};
Point(3)={0, 1, 0};
Circle(1)={2,1,3};
Line(2)={2,3};

This *.geo file creates a quarter circle and a straight line. When using the Mesh.SaveTopology option, all entities are saved in the $Entities ... $EndEntities section:

$Entities
3 2 0 0
1 0                          // Point 1
2 0                          // Point 2
3 0                          // Point 3
1 2 2 3 0               // Line 1 (=circle)
2 2 2 3 0               // Line 2
$EndEntities

As you can see, lines 1 and 2 seem to be identical entities, while in reality they are not. Line 1 is a quarter circle, while line 2 is a straight line. Is there a way to export the full geometry/topology information from gmsh at the moment? Thus, for a circle, this would be three points (the input points provided to the Circle command). My goal is to use gmsh as a mesh generator and couple it to an existing MATLAB finite element solver. Extracting the precise topology from gmsh allows for the easy definition of boundary conditions (e.g. distributed load on a circular line segment or pressure on a curved surface).


Thanks in advance.

Kind regards,
Pieter Reumers
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