Add binding for dfree

Author: alxbilger

bindings/Modules/src/SofaPython3/SofaConstraintSolver/Binding_ConstraintSolver.cpp

@@ -56,6 +56,13 @@ void moduleAddConstraintSolver(py::module &m)
         return { lambda.ptr(), lambda.size()};
     }, sofapython3::doc::constraintsolver::constraintSolver_lambda);
 
+    c.def("dfree", [](ConstraintSolverImpl& self) -> Eigen::Map<Eigen::Matrix<SReal, Eigen::Dynamic, 1> >
+    {
+        assert(self.getConstraintProblem());
+        auto& dfree = self.getConstraintProblem()->dFree;
+        return { dfree.ptr(), dfree.size()};
+    }, sofapython3::doc::constraintsolver::constraintSolver_dfree);
+
     /// register the binding in the downcasting subsystem
     PythonFactory::registerType<ConstraintSolverImpl>([](sofa::core::objectmodel::Base* object)
     {

bindings/Modules/src/SofaPython3/SofaConstraintSolver/Binding_ConstraintSolver_doc.h

@@ -46,7 +46,18 @@ Returns the force resulting from the constraints
 ------------
 
 constraint_solver = root.addObject("GenericConstraintSolver", tolerance=1e-9, maxIterations=1000)
-matrix = constraint_solver.lambda_force()
+lambda = constraint_solver.lambda_force()
+)";
+
+static auto constraintSolver_dfree =
+R"(
+Returns the displacement computed without any constraint
+
+example:
+------------
+
+constraint_solver = root.addObject("GenericConstraintSolver", tolerance=1e-9, maxIterations=1000)
+dfree = constraint_solver.dfree()
 )";
 
 } // namespace sofapython3::doc::constraintsolver