Access stress in TriangularFEMForceField

Hi everyone,

I would like to use SOFA v21.12 to simulate the tearing of a membrane, using a TriangularFEMForceField. For that purpose, I would like to access the stress in each triangle and compare it to a threshold, and after that apply different tearing approaches to elements where the threshold is exceeded (similar to this forum topic, but with a TriangularFEMForceField: https://www.sofa-framework.org/community/forum/topic/how-to-break-the-spring-between-mesh/).

Now, as far as I understand the source code, the stress in each triangle and other data that could be interesting for me is already computed and stored in an attribute called triangleInfo, which is implemented as a nested class in TriangularFEMForceField.h:

/// Class to store FEM information on each triangle, for topology modification handling
    class TriangleInformation
    {
    public:
        ...
        // strain vector
        type::Vec<3,Real> strain;
        // stress vector
        type::Vec<3,Real> stress;
        Transformation initialTransformation;
        Coord principalStressDirection;
        Real maxStress;
        Coord principalStrainDirection;
        Real maxStrain;
...

Now, my issue is that I cannot access the attributes of this triangleInfo object from Python. I have access to the object itself, so TriangularFEMForceField.triangleInfo is working. But `TriangularFEMForceField.triangleInfo.stress’ gives me an error, as Python does not know about the attributes of the triangleInfo object. I assume that this is the case because there are no bindings explictly written for TriangularFEMForceField. Is that true?

In general, I can only use the attributes of TriangularFEMForceField that are initialized in the constructor, see TriangularFEMForceField.inl. So that means I also don’t have access to all the other public methods (like computeStressAlongDirection(), …). But it would be great if I could use them with Python.

To sum up my questions: How can I get access to the stress in each element using Python, and to the public methods of TriangularFEMForceField? Do I have to write my own bindings? Or should I create my scene with C++ and go without Python? Or is there another way or technique to get the stress in each element?

Thanks in advance!

Best regards,
Ludwig