Forces in dynamically added nodes are not working

[PatrickDNeobird]

Hi guys,

i am currently working on a script where I load an xml file, remove some Box-Nodes and readd them later over time while the simulation is running. The script seems to be working correctly and the nodes are also added with all child elements, but netiher gravity nor the ConstantForceField are working when the nodes are added this way. I also do not get any error messages.
When I run the xml file by itself or just load the xml file without removing and readding the nodes it is working as expected.
I think I miss some kind of linking but I was not able to find anything.

The script:

import sys
import Sofa
import Sofa.Gui
import SofaRuntime
import Sofa.Simulation

class MyController(Sofa.Core.Controller):
    
    def __init__(self, nodesToLoad, *args, **kwargs):
        Sofa.Core.Controller.__init__(self, *args, *kwargs)
        self.elapsed_time = 0.0
        self.trigger_time = 0.1
        self.nodesToLoad = nodesToLoad
        self.currentNode = 0
                
    def onAnimateBeginEvent(self, event): # called at each begin of animation step            
        self.elapsed_time += event['dt']
        
        if self.elapsed_time >= self.trigger_time:
            self.elapsed_time = 0.0
            if self.currentNode < len(self.nodesToLoad):
                nodeToLoad = self.nodesToLoad[self.currentNode]
                print(f"Activating node {nodeToLoad.name.value}")
                self.currentNode += 1
                newNode = self.getContext().addChild(nodeToLoad)
                newNode.init()
                Sofa.Simulation.initVisual(newNode)
				

def createScene(filename):
    """ Loads XML file and adds the controller node """
    node = Sofa.Simulation.load(filename)
    
    nodesToLoad = []
    childrenNames = []
    for child in node.children:
        if not child.name.value == "Palette": 
            childrenNames.append(child.name.value)
            
    for childName in childrenNames:
        nodesToLoad.append(node.getChild(childName))
        node.removeChild(childName)
    
    node.addObject( MyController(nodesToLoad) )
    return node

if __name__ == "__main__":
    if len(sys.argv) != 2:
        """ checks if a scene filename was given """
        print("ERROR: invalid number of arguments")
        print("USAGE: python3 sp_launch_scene.py [scene-filename].xml")
        sys.exit(-1)

    filename = sys.argv[1]
    
    root = createScene(filename)

    # Lauch simulation
    Sofa.Simulation.initRoot(root)
    Sofa.Gui.GUIManager.Init("myscene", "qglviewer")
    Sofa.Gui.GUIManager.createGUI(root, __file__)
    Sofa.Gui.GUIManager.SetDimension(1080, 1080)
    Sofa.Gui.GUIManager.MainLoop(root)
    Sofa.Gui.GUIManager.closeGUI()

The XML-File:

<Node name="root" dt="0.001" gravity="0 -9.81 0">

    <RequiredPlugin name="Sofa.Component.AnimationLoop" />
    <RequiredPlugin name="Sofa.Component.Collision.Detection.Algorithm" />
    <RequiredPlugin name="Sofa.Component.Collision.Detection.Intersection" />
    <RequiredPlugin name="Sofa.Component.Collision.Geometry" />
    <RequiredPlugin name="Sofa.Component.Collision.Response.Contact" />
    <RequiredPlugin name="Sofa.Component.Constraint.Lagrangian.Correction" />
    <RequiredPlugin name="Sofa.Component.Constraint.Lagrangian.Solver" />
    <RequiredPlugin name="Sofa.Component.IO.Mesh" />
    <RequiredPlugin name="Sofa.Component.LinearSolver.Direct" />
    <RequiredPlugin name="Sofa.Component.LinearSolver.Iterative" />
    <RequiredPlugin name="Sofa.Component.Mapping.Linear" />
    <RequiredPlugin name="Sofa.Component.Mapping.NonLinear" />
    <RequiredPlugin name="Sofa.Component.Mass" />
    <RequiredPlugin name="Sofa.Component.ODESolver.Backward" />
    <RequiredPlugin name="Sofa.Component.SolidMechanics.FEM.Elastic" />
    <RequiredPlugin name="Sofa.Component.StateContainer" />
    <RequiredPlugin name="Sofa.Component.Topology.Container.Constant" />
    <RequiredPlugin name="Sofa.Component.Visual" />
    <RequiredPlugin name="Sofa.GL.Component.Rendering3D" />
    <RequiredPlugin name="Sofa.Component.Topology.Container.Grid" />
    <RequiredPlugin name="MultiThreading" />
    <RequiredPlugin name="Sofa.Component.SceneUtility" />
	<RequiredPlugin name='Sofa.Component.MechanicalLoad'/>

    <VisualStyle displayFlags="showBehaviorModels showForceFields"/>
    <FreeMotionAnimationLoop parallelCollisionDetectionAndFreeMotion="true" />

    <LCPConstraintSolver tolerance="1e-3" maxIt="1000"/>
    <CollisionPipeline depth="6" verbose="0" draw="0"/>
    <ParallelBruteForceBroadPhase />
    <ParallelBVHNarrowPhase />
    <LocalMinDistance alarmDistance="0.01" contactDistance="0.001" angleCone="0" />
    <CollisionResponse response="FrictionContactConstraint" responseParams="mu=0.001" />

    <Node name="Palette">
        <MeshSTLLoader name="Loader-Palette" filename="./Meshes\./cube1x1x1.stl" translation="0.02500001 -0.15 0.03000001" rotation="0 0 0" scale3d="0.95 0.15 1.14" />
        <MeshTopology src="@Loader-Palette" />
        <MechanicalObject src="@Loader-Palette" />
        <TriangleCollisionModel simulated="0" moving="0" />
        <LineCollisionModel simulated="0" moving="0" />
        <PointCollisionModel simulated="0" moving="0" />
        <OglModel src="@Loader-Palette" color="blue" />
    </Node>

    <Node name="Box-27-0-978">
        <MeshGmshLoader name="Loader-27-0-978" filename="./Meshes\cube1x1x1.msh" translation="0.0341 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
        <MeshTopology src="@Loader-27-0-978" />
        <EulerImplicitSolver rayleighMass="0.01" rayleighStiffness="0.001" />
        <SparseLDLSolver template="CompressedRowSparseMatrixMat3x3d" />
        <MechanicalObject name="MO-27-0-978" src="@Loader-27-0-978" />
        <UniformMass totalMass="1.5" />
        <ParallelTetrahedronFEMForceField youngModulus="100000" poissonRatio="0.4" computeGlobalMatrix="false" plasticYieldThreshold="0.01" plasticMaxThreshold="0.05" plasticCreep="0.5" />
        <LinearSolverConstraintCorrection />
        <Node name="Visual-27-0-978">
            <MeshSTLLoader name="Loader-Visual-27-0-978" filename="./Meshes\cube1x1x1.stl" translation="0.0341 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <OglModel name="Model-Visual-27-0-978" src="@Loader-Visual-27-0-978" color="red" />
            <BarycentricMapping input="@.." output="@Model-Visual-27-0-978" />
        </Node>
        <Node name="Surface-27-0-978">
            <MeshSTLLoader name="Loader-Surface-27-0-978" filename="./Meshes\cube1x1x1.stl" translation="0.0341 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <MeshTopology src="@Loader-Surface-27-0-978" />
            <MechanicalObject src="@Loader-Surface-27-0-978" />
            <TriangleCollisionModel />
            <LineCollisionModel />
            <PointCollisionModel />
            <BarycentricMapping />
        </Node>
    </Node>

    <Node name="Box-27-154-978">
        <MeshGmshLoader name="Loader-27-154-978" filename="./Meshes\cube1x1x1.msh" translation="0.0341 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
        <MeshTopology src="@Loader-27-154-978" />
        <EulerImplicitSolver rayleighMass="0.01" rayleighStiffness="0.001" />
        <SparseLDLSolver template="CompressedRowSparseMatrixMat3x3d" />
        <MechanicalObject name="MO-27-154-978" src="@Loader-27-154-978" />
        <UniformMass totalMass="1.5" />
        <ParallelTetrahedronFEMForceField youngModulus="100000" poissonRatio="0.4" computeGlobalMatrix="false" plasticYieldThreshold="0.01" plasticMaxThreshold="0.05" plasticCreep="0.5" />
        <LinearSolverConstraintCorrection />
		<ConstantForceField indices="0" forces="-50 0 50" showArrowSize="0.01"/>
        <Node name="Visual-27-154-978">
            <MeshSTLLoader name="Loader-Visual-27-154-978" filename="./Meshes\cube1x1x1.stl" translation="0.0341 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <OglModel name="Model-Visual-27-154-978" src="@Loader-Visual-27-154-978" color="red" />
            <BarycentricMapping input="@.." output="@Model-Visual-27-154-978" />
        </Node>
        <Node name="Surface-27-154-978">
            <MeshSTLLoader name="Loader-Surface-27-154-978" filename="./Meshes\cube1x1x1.stl" translation="0.0341 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <MeshTopology src="@Loader-Surface-27-154-978" />
            <MechanicalObject src="@Loader-Surface-27-154-978" />
            <TriangleCollisionModel />
            <LineCollisionModel />
            <PointCollisionModel />
            <BarycentricMapping />
        </Node>
    </Node>

    <Node name="Box-358-0-978">
        <MeshGmshLoader name="Loader-358-0-978" filename="./Meshes\cube1x1x1.msh" translation="0.3651 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
        <MeshTopology src="@Loader-358-0-978" />
        <EulerImplicitSolver rayleighMass="0.01" rayleighStiffness="0.001" />
        <SparseLDLSolver template="CompressedRowSparseMatrixMat3x3d" />
        <MechanicalObject name="MO-358-0-978" src="@Loader-358-0-978" />
        <UniformMass totalMass="1.5" />
        <ParallelTetrahedronFEMForceField youngModulus="100000" poissonRatio="0.4" computeGlobalMatrix="false" plasticYieldThreshold="0.01" plasticMaxThreshold="0.05" plasticCreep="0.5" />
        <LinearSolverConstraintCorrection />
        <Node name="Visual-358-0-978">
            <MeshSTLLoader name="Loader-Visual-358-0-978" filename="./Meshes\cube1x1x1.stl" translation="0.3651 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <OglModel name="Model-Visual-358-0-978" src="@Loader-Visual-358-0-978" color="red" />
            <BarycentricMapping input="@.." output="@Model-Visual-358-0-978" />
        </Node>
        <Node name="Surface-358-0-978">
            <MeshSTLLoader name="Loader-Surface-358-0-978" filename="./Meshes\cube1x1x1.stl" translation="0.3651 0.003850001 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <MeshTopology src="@Loader-Surface-358-0-978" />
            <MechanicalObject src="@Loader-Surface-358-0-978" />
            <TriangleCollisionModel />
            <LineCollisionModel />
            <PointCollisionModel />
            <BarycentricMapping />
        </Node>
    </Node>

    <Node name="Box-358-154-978">
        <MeshGmshLoader name="Loader-358-154-978" filename="./Meshes\cube1x1x1.msh" translation="0.3651 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
        <MeshTopology src="@Loader-358-154-978" />
        <EulerImplicitSolver rayleighMass="0.01" rayleighStiffness="0.001" />
        <SparseLDLSolver template="CompressedRowSparseMatrixMat3x3d" />
        <MechanicalObject name="MO-358-154-978" src="@Loader-358-154-978" />
        <UniformMass totalMass="1.5" />
        <ParallelTetrahedronFEMForceField youngModulus="100000" poissonRatio="0.4" computeGlobalMatrix="false" plasticYieldThreshold="0.01" plasticMaxThreshold="0.05" plasticCreep="0.5" />
        <LinearSolverConstraintCorrection />
        <Node name="Visual-358-154-978">
            <MeshSTLLoader name="Loader-Visual-358-154-978" filename="./Meshes\cube1x1x1.stl" translation="0.3651 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <OglModel name="Model-Visual-358-154-978" src="@Loader-Visual-358-154-978" color="red" />
            <BarycentricMapping input="@.." output="@Model-Visual-358-154-978" />
        </Node>
        <Node name="Surface-358-154-978">
            <MeshSTLLoader name="Loader-Surface-358-154-978" filename="./Meshes\cube1x1x1.stl" translation="0.3651 0.15785 0.982725" rotation="0 0 0" scale3d="0.2698 0.1463 0.17955" />
            <MeshTopology src="@Loader-Surface-358-154-978" />
            <MechanicalObject src="@Loader-Surface-358-154-978" />
            <TriangleCollisionModel />
            <LineCollisionModel />
            <PointCollisionModel />
            <BarycentricMapping />
        </Node>
    </Node>
</Node>

[PatrickDNeobird]

I got it working now. instead of removing and readding the nodes, I call setActive(False) and setSleeping(True) one time in onAnimateBeginEvent and then I can call later in my loop setActive(True) and setSleeping(False).