Add a function to get the kinetic and potential energy of a node from a python script

[aleblanc30]

As suggested by @alxbilger here

Also adapted from QEnergyStatWidget in Sofa.Qt.

I did not manage to build this yet on my machine, so I haven't tested it.

[alxbilger]

Great! Thanks

Does it work? Have you tested?

The problem is that not all the components implement the computation of the energies.

[aleblanc30]

I haven't tested it yet, I can't build the plugin for some reason. I opened a topic in the forum : sofa-framework/sofa#5554

[aleblanc30]

I have managed to build it in-tree. It works great for a simple scene with an object sliding on an incline. Do you happen to know which components may be a problem and need to be tested ?

[alxbilger]

I cannot be specific, but usually, there is a runtime warning such as Method getPotentialEnergy not implemented yet.

For example:

Targets
    Occurrences of 'Method getPotentialEnergy not implemented yet.' in Solution with mask '*.cpp,*.inl,*.h,*.cu'
Found usages  (28 usages found)
      TetrahedronDiffusionFEMForceField.inl  (1 usage found)
          232 msg_warning() <<"Method getPotentialEnergy not implemented yet." ;
      ConicalForceField.h  (1 usage found)
          111 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      EdgePressureForceField.inl  (1 usage found)
          132 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      EllipsoidForceField.inl  (1 usage found)
          189 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      OscillatingTorsionPressureForceField.inl  (1 usage found)
          200 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      PlaneForceField.inl  (1 usage found)
          152 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      QuadPressureForceField.h  (1 usage found)
          121 SReal getPotentialEnergy(const core::MechanicalParams* /*mparams*/, const DataVecCoord&  /* x */) const override { msg_warning() << "Method getPotentialEnergy not implemented yet."; return 0.0; }
      SphereForceField.inl  (1 usage found)
          236 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      SurfacePressureForceField.inl  (1 usage found)
          301 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TaitSurfacePressureForceField.inl  (1 usage found)
          330 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TorsionForceField.inl  (1 usage found)
          154 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TrianglePressureForceField.inl  (1 usage found)
          240 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      BeamFEMForceField.inl  (1 usage found)
          691 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      FastTetrahedralCorotationalForceField.h  (1 usage found)
          146 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      HexahedralFEMForceField.h  (1 usage found)
          151 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      HexahedralFEMForceFieldAndMass.h  (1 usage found)
          93 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      HexahedronFEMForceFieldAndMass.h  (2 usages found)
          102 msg_warning() << "Method getPotentialEnergy not implemented yet.";
          108 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TetrahedralCorotationalFEMForceField.h  (1 usage found)
          189 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TriangleFEMForceField.h  (1 usage found)
          109 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      StandardTetrahedralFEMForceField.h  (1 usage found)
          184 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TetrahedronHyperelasticityFEMForceField.inl  (1 usage found)
          501 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      AngularSpringForceField.h  (1 usage found)
          87 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      RestShapeSpringsForceField.h  (1 usage found)
          109 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TriangularBiquadraticSpringsForceField.h  (1 usage found)
          158 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TriangularQuadraticSpringsForceField.h  (1 usage found)
          142 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TetrahedralTensorMassForceField.h  (1 usage found)
          114 msg_warning() << "Method getPotentialEnergy not implemented yet.";
      TriangularTensorMassForceField.h  (1 usage found)
          143 msg_warning() << "Method getPotentialEnergy not implemented yet.";

[aleblanc30]

So from what I read, the methods that are not implemented actually just return 0. So the code will run, produce a warning, and a wrong result. I think this is fine ? Otherwise, I can change the not implemented method to return NaNs instead of 0.

[hugtalbot]

Sounds reasonable to me to return 0
What's your opinion @alxbilger ?

[alxbilger]

So from what I read, the methods that are not implemented actually just return 0. So the code will run, produce a warning, and a wrong result. I think this is fine ?

Yes, it's fine