[pzingg]

Found out that my meshes were fine, but two of the elements were initialized with a poissonRatio of 0.5.

By using gdb and a debug version of SOFA, I found out that in the TetrahedronFEMForceField::computeMaterialStiffness() function that sets up the material stiffnesses for the force field, there is a calculation with a denominator of

((1+poissonRatio)*(1-2*poissonRatio))

This results in setting nan values for the DoF stiffnesses, which propogates to nan values for the forces, etc.

I am now using Poisson ratio values of 0.4 and 0.45, not 0.5, and everything is working as expected.

[pzingg]

From looking at the source code I think the issue is that the default constructor (in UncoupledConstraintCorrection.inl) sets the default for the attribute d_useOdeSolverIntegrationFactors to be “true”, which means that an ODE solver must be set in the attribute m_pOdeSolver in the constructor (it is instead set to nullptr). At runtime the code spits out the “Can’t find any odeSolver” message, sets the attribute to false, and carries on with default integration factors after that. Anyway I’m moving on to other problems, now, thanks!

[pzingg]

I got it working. Didn’t realize you have to enable pligin shared libraries in the Plugin Manager. I also had to add a file to build/etc/python.d so that SofaPythom3 would add the location of the stlib3 package to the Python sys.path.

Now I am trying to understand API scene and object changes between the stlib and stlib3 Python modules. I’m stuck at the moment because of missing declarations for ODE solver and constraint modules.

[pzingg]

Just to be clear, in v20.12 is it possible to load .pyscn files with SofaPython3? Or must I disable SofaPython3 and rebuild SOFA with SofaPython?

FYI, This is what I’m getting if I point SOFA to the FirstSteps/firststeps-tuto.pyscn file contained in the SoftRobots plugin source tree:

[ERROR] [DAGSimulation(Simulation)] extension (pyscn) not handled

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