enhance and restructure FEM mesh handling and visualization

Added new functions attach_mesh_with_springs,
attach_3d_points_to_meca_with_barycentric_mapping, and
add_finger_mesh_force_field_Object to modularize and simplify FEM mesh
handling and visualization.
Introduced show_mecha_visual for toggling visibility of mechanical
objects and indices.
Replaced addFEMObject with add_finger_mesh_force_field_Object for
improved clarity and functionality.
Updated tuto_5.py to utilize new FEM mesh functions, enabling better
integration and enhanced visualization.
Removed redundant code and refactored solver and geometry attachment
logic for better maintainability.

examples/python3/useful/header.py

@@ -17,7 +17,9 @@
 import os
 from useful.params import ContactParameters as DefaultContactParams
 
-
+def show_mecha_visual(node, show=True):
+    node.showObject = show
+    node.showIndices = show
 def addHeader(parent_node, multithreading=False, inverse=False, is_constrained=False, is_contact=False,
               contact_params=None):
     """
@@ -152,44 +154,44 @@ def addSolverNode(parent_node, name='solverNode', template='CompressedRowSparseM
 
     return solver_node
 
+def attach_mesh_with_springs(mesh_node, _box='-18 -15 -8 2 -3 8'):
+    mesh_node.addObject('BoxROI', name='ROI1', box=_box, drawBoxes='true')
+    mesh_node.addObject('RestShapeSpringsForceField',
+                          points='@ROI1.indices', stiffness='1e12')
+
+def attach_3d_points_to_meca_with_barycentric_mapping(parent_node, name='node_name',
+                                                      list_of_points=[" 0.0 0 0 15 0 0 30 0 0 45 0 0 60 0 0 66 0 0 81 0.0 0.0"]):
+    points_node = parent_node.addChild(name)
+    points_node.addObject('MechanicalObject', name=name+"_mo", position=list_of_points)
+    points_node.addObject('BarycentricMapping')
+    return points_node
 
-def addFEMObject(parent_node, path, name='FEMFinger'):
-    finger_solver = addSolverNode(parent_node, name=name)
+def add_finger_mesh_force_field_Object(parent_node, path):
+    parent_node.addObject('VisualStyle', displayFlags='showForceFields')
+    #finger_solver = addSolverNode(parent_node, name=name)
 
     # Load a VTK tetrahedral mesh and expose the resulting topology in the scene .
-    loader = finger_solver.addObject('MeshVTKLoader', name='loader', filename=f'{path}finger.vtk',
+    loader = parent_node.addObject('MeshVTKLoader', name='loader', filename=f'{path}finger.vtk',
                                      translation="-17.5 -12.5 7.5",
                                      rotation="0 180 0")
-    finger_solver.addObject('TetrahedronSetTopologyContainer', position=loader.position.getLinkPath(),
+    parent_node.addObject('TetrahedronSetTopologyContainer', position=loader.position.getLinkPath(),
                             tetras=loader.tetras.getLinkPath(), name='container')
     # Create a MechanicalObject component to stores the DoFs of the model
-    finger_solver.addObject('MechanicalObject', template='Vec3', name='dofs')
+    parent_node.addObject('MechanicalObject', template='Vec3', name='dofs')
 
     # Gives a mass to the model
-    finger_solver.addObject('UniformMass', totalMass='0.075')
+    parent_node.addObject('UniformMass', totalMass='1.75')
     # Add a TetrahedronFEMForceField component which implement an elastic material model
     # solved using the Finite Element Method on
     # tetrahedrons.
-    finger_solver.addObject('TetrahedronFEMForceField', template='Vec3d', name='forceField', method='large',
+    parent_node.addObject('TetrahedronFEMForceField', template='Vec3d', name='forceField', method='large',
                             poissonRatio='0.45', youngModulus='500')
+    attach_mesh_with_springs(parent_node)
 
-    finger_solver.addObject('BoxROI', name='ROI1', box='-18 -15 -8 2 -3 8', drawBoxes='true')
-    finger_solver.addObject('RestShapeSpringsForceField',
-                            points='@ROI1.indices', stiffness='1e12')
-    ##########################################
-    # Cable points                           #
-    ##########################################
     # Mapped points inside the finger volume, these points attached to the FE model
     # are constrained to slide on the cable.
-
-    FEMpos = [" 0.0 0 0 15 0 0 30 0 0 45 0 0 60 0 0 66 0 0 81 0.0 0.0"]
-    fem_points = finger_solver.addChild('femPoints')
-    fem_points.addObject('MechanicalObject', name="pointsInFEM", position=FEMpos, showObject="1",
-                         showIndices="1")
-    fem_points.addObject('BarycentricMapping')
-
-    return finger_solver, fem_points
-
+    points_node = attach_3d_points_to_meca_with_barycentric_mapping(parent_node)
+    return points_node
 
 def addMappedPoints(parent_node, name="pointsInFEM", position=None, showObject="1",
                     showIndices="1", femPos="0.0 0 0 15 0 0 30 0 0 45 0 0 60 0 0 66 0 0 81 0.0 0.0"):

tutorial/tuto_scenes/tuto_5.py

@@ -9,7 +9,7 @@
 __copyright__ = "(c) 2021,Inria"
 __date__ = "October, 26 2021"
 
-from useful.header import addHeader, addSolverNode, addFEMObject
+from useful.header import addHeader, addSolverNode, add_finger_mesh_force_field_Object, show_mecha_visual
 from useful.params import BeamPhysicsParametersNoInertia, BeamGeometryParameters, SimulationParameters
 from useful.params import Parameters
 from cosserat.CosseratBase import CosseratBase
@@ -19,6 +19,7 @@
 import os
 from math import pi
 from controller import FingerController
+from geo_cosserat_cable_driven_cosserat_beam import show_mecha_visual
 
 _beam_radius = 0.5
 _beam_length = 81.
@@ -100,22 +101,31 @@ def onKeypressedEvent(self, event):
 
 
 def createScene(root_node):
-    addHeader(root_node, is_constrained=True)
+    addHeader(root_node, is_constrained=False)
     root_node.gravity = [0, -9.81, 0.]
 
+    # Add FEM finger node
+    finger_node = addSolverNode(root_node, name="finger_node")
+    # this function attach the geometry and force field to predefine solver node
+    # It also fixe finger regarding predefine box
+    attached_3d_points_fem_node = add_finger_mesh_force_field_Object(finger_node, path=path)
+    show_mecha_visual(attached_3d_points_fem_node, show=True)
+
+    return root_node
+
     solver_node = addSolverNode(root_node, name="cable_node", isConstrained=is_constrained)
 
     # create cosserat Beam
     cosserat_beam = solver_node.addChild(CosseratBase(parent=solver_node, params=Params))
     cosserat_frames_node = cosserat_beam.cosseratFrame
 
     # Finger node
-    femFingerNode = root_node.addChild('femFingerNode')
+    #femFingerNode = root_node.addChild('femFingerNode')
     """ Add FEM finger to the scene"""
     # finger_node, fem_points_node = Finger(femFingerNode, name="Finger", rotation=array([0.0, 180.0, 0.0]),
     #                                      translation=array([-17.5, -12.5, 7.5]), path=path)
 
-    finger_node, fem_points_node = addFEMObject(root_node, path=path, name="Finger")
+
 
     return root_node