[SOLVED] Extracting tetrahedron forcefield indices

[Lekan]

Hi everyone,

I have a forcefield which I have written in the framework of the native TatrahedronHyperelasticityFEMForceField. My addForce and addDForce implementations are quite different from the native ones.

What I would love to do is to apply internal pressurization to each tetrahedron index from my main SOFA C++ loop. I have the scene file similar to the following gist

https://gist.github.com/lakehanne/eb13b29b17e833112b0b83f40529851b

In my C++ file, I am accessing the dome ring node as follows:

    auto dome_ring = root->getChild("DomeRingNode");
    // auto dome_ring_tetras = dome_ring->getObject("dofs");
    using MechanicalObject = sofa::component::container::MechanicalObject<Vec3Types>;
    typename MechanicalObject::SPtr dome_ring_dofs = dome_ring->get<MechanicalObject>(groot->SearchDown);
    auto dome_ring_pos_ = dome_ring_dofs.get()->read(sofa::core::ConstVecCoordId::position());
 sofa::helper::ReadAccessor<Data<Vec3Types::VecCoord>>dr_pos_vecs(dome_ring_dofs.get()->read(sofa::core::ConstVecCoordId::position()));

What I am not sure of is if dr_pos_vecs contain the dofs for the tetras only or for just the Vec3d templated mechanical object. It appears that the size of this vector is different from that of the ones I created with CGAL. Would appreciate your help.

[Hugo]

Dear @lakehanne

Your variable dr_pos_vecs will contain the field ‘position’ of your Vec3 MechanicalObject. It will therefore be a vector with a size corresponding to the number of nodes in your mesh, with 3 reals (x,y,z) for each node.
How many points does your mesh include?
What is the size returned by the MechanicalObject position vector?

Best wishes,

Hugo

PS: short question, why not using Python to script interactive features in your simulation?

[Lekan]

Thanks @Hugo. I think the error came from me. I was confusing the number of points with the total number of cells. My question is now moot, sorry.

Thanks for your SOFAPython interactive simulation suggestion. I wasn’t sure if I had to write the python bindings for my new TetrahedronMooneyRivlinFEMForceField class. I wouldn’t, would I?

[Lekan]

Specifically, can I just load my XML scene in python without having to explicitly rewrite my whole python scene in pyscn?

[Hugo]

Dear @lakehanne

Yes the new SOFAPython plugin (using Python3 instead of Python2) allows such an implementation, you can see an example for a forcefield here.

You might have to rewrite the entire scene. We had a script translating a *.scn into a *.py (see scn2python.py script) but this was compatible for Python2.

Best,

Hugo

[Lekan]

Thanks @Hugo!

[Hugo]

Hi @lakehanne

I’m glad if it helped. Can we close the topic?
Anyway, keep us posted from your progress (papers, video, pull-requests etc.)!

Best,

Hugo

[Lekan]

Thanks again, I’ve only just now had a chance to test the python2 scene generator. Thank you to you and the whole Sofa team for all the awesome work that you do.

[Author]

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