[Hugo]

Ok thanks @xiaojuan , it’s closed
Note that you can always close the topic yourself by crossing the appropriate box near to the “Submit” button (when topic is open)

[Hugo]

Hi @hkomninos

To answer you first, it is strange indeed to get way smaller strain than FeBIO.
I know @Igorp and @Eleonora are discussing about such comparison and validation on another forum topic. Igor, Eleonora, any advice / info about Harris’ remark ?

Dear @outtt, you can find an example based on constraint solved with Penalty method in the repository examples/Components/collision:

• TriangleModel.scn
• SphereModel.scn

But notice that – as stated above – even if penalty method would not suffer from a decrease in performance due to increasing nb of contacts, but it would be way less stable, and the constraints might not be well respected. If you have specific questions regarding penalty methods, please open a dedicated topic.

Best,

Hugo

[Hugo]

Hmm ok it means this might have been fixed in master since then
I’ll investigate and let you know.

Best

Hugo

[Hugo]

Hi Harris

That’s exactly my point, the GS requires more iterations to converge.

Hugo

[Hugo]

Hi @outtt

which version are you using ? 18.06 ?
This should be fixed in 18.12. I will gather more info about this issue with the devs.

Best

Hugo

[Hugo]

Hi Harris

Good, that’s what I assumed.
When constraints (like contacts) based on the Lagrange multipliers appears in the simulation, a new term appears in the linear system : the H matrix, which includes the constraint directions. When the pressure applied on your soft body increases, the constraints becomes harder to respect. And the solver requires more iterations to converge and find a proper solution, respecting the constraints. This is why the frame rate decreases, while the number of constraints (contacts) remains the same.

With penalty methods, you would not have a significant decrease in performance but it would be way less stable, and the constraints might not be well respected.

Best

Hugo

[Hugo]

You are very welcome @rubab !
I close the topic then!

Hugo

[Hugo]

Hi @rubab

I guess using Python you can dynamically create and destroy OglLabel in your scene.
You can find an example of use in examples/Components/visualmodel/OglLabel.scn

Let me know if it helps.

Hugo

[Hugo]

Dear Harris,

How are you solving the constraint?
Using penalty or using Lagrange approach?

Best

Hugo

[Hugo]

Hi @xiaojuan

I never used it myself but the example scene helped me.
With the RecordedCamera, you define yourself the position of the camera where you will make the recording: using the position and rotationLookAt datafields.

With the scene NavigationRecordedCamera, you define a series of position/orientations that the camera will follow at specific time frames: using the cameraPosition (vector of positions) and cameraOrientations (vector of orientations) datafields. The motion of the camera is done between a starting time (startTime) and the end time (endTime).

Do never hesitate to have a short look in the C++ code for a better understanding.
Best wishes,

Hugo

[Hugo]

Good @hkomninos , and thanks @secretdevil.
Harris, do not hesitate to set yourself a forum status to “[SOLVED]” when the discussion is over.

[Hugo]

Hi @darynapanicheve

Could you please share the scene and associated files with us?
In case you do not want to make it public, send them to me in private. Thanks.

Hugo

[Hugo]

Dear Wong,

I will tell you more in details about the memberships in a private email. But most information is available online.

Regarding developer room, note that we recently setup a Gitter room. This room is dedicated to developers, for development questions. So if you have such developer questions, do not hesitate to join. For user question, the forum is the right place to be.
Note that scripting in Python is not really considered as SOFA development.

Best regards,

Hugo

[Hugo]

Hi @fayad

I needed to investigate myself, here is a solution using the ArticulatedSystemMapping.
Scene:

<?xml version="1.0" ?>
<Node name="root" dt="0.02" gravity="0 0 0">
        <RequiredPlugin name="SofaPython" pluginName="SofaPython" />
        <PythonScriptController filename="ChangeOrientation.py" classname="Rotate" listening="true"/>

        <EulerImplicit />
        <CGLinearSolver iterations="100" threshold="1e-6" tolerance="1e-6" />
        
        <MechanicalObject name="bati" template="Rigid" position="0 0 0   0 0 0 1"  />
        <UniformMass />

        <Node name="Grasper">
         
            <MechanicalObject name="Articulations" template="Vec1d" position="0 0" /> <!-- rest_position="0 0.52" -->
            <RestShapeSpringsForceField points="0 1" stiffness="100000    100000" printLog="true"/>

            <Node name="Jaws">
                <MechanicalObject name="GrasperDOFs" template="Rigid" position="0 0 0  0 0 0 1    0.1 0 0  0 0 0 1    0.2 0 0  0 0 0 1" showObject="1" showObjectScale="1"/>
                        
                <Node name="visualization">
                        
                    <Node name="handle_VM"> 
                        <OglModel name="VM" filename="mesh/dental_instrument.obj" color="red"  />
                        <RigidMapping  input="@../../GrasperDOFs" output="@VM" index="0" isMechanical="false" />
                    </Node>

                    <Node name="grasper-bottom_VM">
                        <OglModel name="VM" filename="mesh/dental_instrument.obj" rx="90" color="green"  />
                        <RigidMapping  input="@../../GrasperDOFs" output="@VM" index="1" />
                    </Node>
                    
                    <Node name="grasper-top_VM">
                        <OglModel name="VM" filename="mesh/dental_instrument.obj" ry="90" color="blue" /> 
                        <RigidMapping  input="@../../GrasperDOFs" output="@VM" index="2" />
                    </Node>
                                   
                </Node>
                               
                <ArticulatedSystemMapping input1="@../Articulations" output="@GrasperDOFs" input2="@../../bati"/>
            </Node>
            
            <ArticulatedHierarchyContainer/>
            <Node name="articulationCenters">
            
                <Node name="articulationCenter2">
                    <ArticulationCenter parentIndex="0" childIndex="1" posOnParent="0 0 -13" posOnChild="0 0 -13"/>
                    <Node name="articulations">
                        <Articulation translation="0" rotation="1" rotationAxis="0 1 0" articulationIndex="0"/>
                    </Node>
                </Node>

                <Node name="articulationCenter3">
                    <ArticulationCenter parentIndex="0" childIndex="2" posOnParent="0 0 -13" posOnChild="0 0 -13"/>
                    <Node name="articulations">
                        <Articulation translation="0" rotation="1" rotationAxis="0 -1 0" articulationIndex="1"/>
                    </Node>
                </Node>
            </Node>
        </Node>
</Node>

with a python script:

import sys
import Sofa

class Rotate(Sofa.PythonScriptController):
    def initGraph(self,node):
        self.Articulations=node.getChild('Grasper').getObject('Articulations')
        return 0
        
    def onKeyPressed(self,k):
        
        if k=="M" :
            rotation = self.Articulations.findData('position').value
            rotation[1][0] = rotation[1][0] - 0.1
            self.Articulations.findData('position').value = rotation
            self.Articulations.findData('rest_position').value = rotation
            print ' M '

        if k=="L" :
            rotation = self.Articulations.findData('position').value
            rotation[1][0] = rotation[1][0] + 0.1
            self.Articulations.findData('position').value = rotation
            self.Articulations.findData('rest_position').value = rotation            
            print ' L '
        return 0

Do not hesitate to post us your resulting video 😉
Best wishes,

Hugo

[Hugo]

Hi PF,

How does this look into your simulation scene ?

[Hugo]

Hey @rubab,

I am no expert, but I noticed other devs about your issue. They should come back to you soon.

Hugo

[Hugo]

Dear PF,

after a quick check (SpringForceField.inl line 67), it appears that it is still possible to use “fileSprings” or “filename” to initialize Ks, Kd and the rest length with a Xsp file.
Can you share some examples /files ?

Hugo

[Hugo]

Dear @zahra,

AdvancedTimer has time be placed in the c++ code to keep track/compute the time spent on specific part of the simulation. Not sure about python equivalent, but I guess their are dedicated libs. What I know is working is to set in your environment variable:

export SOFA_TIMER_ALL=1

this will activate all these timer computations. (set =0 to desactivate it)
Best

Hugo

[Hugo]

Hi @adamzhang

In case you need it, we are proposing training sessions soon.
Best,

Hugo

[Hugo]

Hey @outtt

I am fine with helping you, but you should learn coding in Python since it is extremely useful in SOFA. Here is what I would write to test if it works (do not forget to use the PythonScriptController in your xml scene).
XML (inspired from the example examples/Components/visualmodel/OglModel.scn)

<?xml version="1.0"?>
<Node name="root" dt="0.01">

    <RequiredPlugin name="SofaPython" pluginName="SofaPython" />
    <PythonScriptController filename="model.py" classname="ChangeTexture" listening="true"/>

    <OglModel name="VisualModel" fileMesh="mesh/raptor_8kp.obj" texturename="/data/Softwares/sofa/src/master/share/textures/bubble_skin.bmp" translation="30 0 0" useNormals="0"/>
    
    <MeshObjLoader name="loader" filename="mesh/raptor_8kp.obj" translation="0 0 0"/>    
    <OglModel name="VisualModel2"  src="@loader" color="red"/>

</Node>

Python:

import sys
import Sofa
class ChangeTexture(Sofa.PythonScriptController):
    def initGraph(self,node):
        print 'initGraph called (python side)'
        self.VM=node.getObject('VisualModel')
        return 0
        
    def onKeyPressed(self,k):
        
        if k=="M" :
            self.VM.findData('texturename').value='/data/Softwares/sofa/src/master/share/textures/brushed_metal.bmp'
            self.VM.init()
            self.VM.initVisual()

        return 0

Dear @outtt, do you know whether GDUT would be ready to support the open-source project SOFA? Many ways are available to support the open-source initiative : donations, memberships, projects.
And many non-profit ways also exist like feature contributions, communication about your plugins (conferences, youtube, linkedin, twitter) and setup collaborations with the community!

Best,

Hugo

[Hugo]

Hi @fayad

In order to consider them all as Rigid parts, you can :

1. define one master Rigid node, with only one point
2. create subnodes for each Rigid part, and map them on the above single point with a RigidRigidMapping

Thus it would be considered as one rigid object.

Best

Hugo

[Hugo]

Hi @zahra,

you can have a look at the AdvancedTimer.
It may help you

Best,

Hugo

[Hugo]

Hi Nassim,

Please find below a scene solving your issue. Two modifs:
1. put the fiber node as a child node from the cylinder (since they correspond to the same object)
2. decreasing the mass of the fiber, that was relatively to the cylinder very high.
3. Removing the TetraModel which is not needed, the collision node (with Point, Line etc) does the job !

<Node name="root" gravity="0 -1 0" dt="0.1">
    <!-- Basic Components to perform the collision detection -->
	<RequiredPlugin name="SofaPython" pluginName="SofaPython" />
	<RequiredPlugin pluginName='SofaMiscCollision'/>
    

    <GenericConstraintSolver tolerance="0.001" maxIterations="1000"/>
    <VisualStyle displayFlags="showBehaviorModels showForceFields showVisual showWireframe" />
    <DefaultMotionAnimationLoop />
    <DefaultPipeline name="DefaultCollisionPipeline" verbose="0" />
    <BruteForceDetection name="Detection" />
    <MinProximityIntersection name="Proximity" alarmDistance="0.8" contactDistance="0.5" />
    <DefaultContactManager name="Response" />
    <DefaultCollisionGroupManager name="Group" />
	<CollisionResponse name="Response" response="FrictionContact" responseParams="10"/>
	<CollisionGroup name="Group" />
    
	<Node name="Floor">
        <MeshTopology name="Topology Floor" filename="mesh/floorFlat.obj" />
        <MechanicalObject name="Particles Floor" />
		<UncoupledConstraintCorrection />
		<PointModel name="FrictionCoeff" contactFriction="100" />
		<TetrahedronModel name="FrictionCoeff4" contactFriction="1" />
        <TriangleModel name="Triangle For Collision Floor" moving="0" simulated="0"  />
		<LineModel name="Lines For Collision" moving="0" simulated="0" />
        <PointModel name="Points For Collision" moving="0" simulated="0"/>
    </Node>
	<!--Test de cylindre 2 -->
	<Node name="Cylinder" activated="1">
        <MeshGmshLoader name="loader" filename="mesh/cylinder.msh" />
        <EulerImplicitSolver name="cg_odesolver" printLog="0" />
        <CGLinearSolver name="linear solver" template="GraphScattered" iterations="25" tolerance="1e-09" threshold="1e-09" />
        <TetrahedronSetTopologyContainer src="@loader" name="Topology Container" fileTopology="mesh/cylinder.msh" />
        <TetrahedronSetTopologyModifier name="Topology Modifier" />
        <TetrahedronSetTopologyAlgorithms name="Topology Algorithms" template="Vec3d" />
        <TetrahedronSetGeometryAlgorithms name="Geometry Algorithms" template="Vec3d" />
		<MechanicalObject src="@loader" name="Cylinder" template="Vec3d" translation="0 16 0" rotation="90 0 0" scale="12" />
		<TetrahedronFEMForceField name="FEM" template="Vec3d" method="polar" poissonRatio="0.3" youngModulus="1500" assembling="0" />
        <UniformMass name="Mass" template="Vec3d" totalMass="300" />

        <Node name="Visual Model">
            <OglModel name="Visual" template="ExtVec3f" color="green" />
            <IdentityMapping name="Mapping" template="Vec3d,ExtVec3f" input="@.." output="@Visual" />
        </Node>

		<Node name="Collision Model">
            <Mesh name="Cylinder Mesh" filename="mesh/cylinder.obj" />
            <MechanicalObject name="Collision" />
            <Triangle name="Cube Triangle For Collision" />
            <Line name="Cube Edge For Collision" />
            <Point name="Cube Point For Collision" />
            <IdentityMapping name="RigidMapping Collision-RigidDOF" input="@../Cylinder" output="@Collision" />
        </Node>

        <Node name="Wire2">
            <EulerImplicitSolver name="cg_odesolver" printLog="0" />
            <CGLinearSolver name="linear solver" template="GraphScattered" iterations="25" tolerance="1e-09" threshold="1e-09" />
            <CylinderGridTopology name="Regular Mesh2" n="5 5 5" axis="0 1 0" radius="0.5" length="12" />
            <MechanicalObject name="DOFs" template="Vec3d" translation="0 4 0" rotation="0 0 0" />
            <TetrahedronFEMForceField name="FEM2" template="Vec3d" method="polar" poissonRatio="0.1" youngModulus="130" assembling="0" />
            <UniformMass name="Mass2" template="Vec3d" totalMass="30" />
            <BarycentricMapping name="Mapping-fiber2" output="@." input="@.." />

            <PythonScriptController filename="ForceControl.py" classname="KeyboardControl" listening="true"/>

            <Node name="Visual Model">
                <OglModel name="Visual2" template="ExtVec3f" color="blue" />
                <IdentityMapping name="Mapping2" template="Vec3d,ExtVec3f" input="@.." output="@Visual2" />
            </Node>
        </Node>
    </Node>	
</Node>

Best

Hugo

[Hugo]

Dear @secretdevil @fayad

Note that @epernod is actively working in the current version of SOFA on topological changes (also needed in Carving). You can follow pull requests over here. Stay tuned.

Hugo

[Hugo]

Dear @outtt

I don’t think the OglModel can handle changes in its input texture.
Would you like to script this change of texture in Python, or code it in cpp ?

Hugo

[Author]

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