[SOLVED] LMConstraints with Flexible simulation

[jjcasmar]

Hi,

I’m doing some experiments involving constraints. I have created a scene which contains a fixed torus simulated with the Flexible plugin components. The fixed constraint is added with a FixedLMConstraint in the master DOF level.

<?xml version="1.0"?>
<Node 	 name="Root"  gravity="0 -0.5 0"  dt="0.3"  >
	<RequiredPlugin name="requiredPlugin1"  printLog="1"  pluginName="Flexible" />
	<VisualStyle name="visualStyle1"  displayFlags="showBehaviorModels showForceFields" />
	<DefaultAnimationLoop name="defaultAnimationLoop1" />
	<DefaultVisualManagerLoop name="defaultVisualManagerLoop1" />
    <LMConstraintSolver name="lMConstraintSolver0"  listening="1" />
    <CGLinearSolver template="GraphScattered" name="cGLinearSolver2" />
    <EulerImplicitSolver name="eulerImplicitSolver2" />
	<Node 	 name="Flexible"  >
		
		
		<MeshGmshLoader name="loader"  filename="mesh/torus_low_res.msh"  edgesGroups="  -1 0 200"  trianglesGroups="  -1 0 408"  tetrahedraGroups="  -1 0 862" />
		<MeshTopology name="mesh"  position="@loader.position"  edges="@loader.edges"  triangles="@loader.triangles"  quads="@loader.quads"  tetrahedra="@loader.tetras"  hexahedra="@loader.hexas" />
		<MechanicalObject template="Vec3d" name="parent"  position="0 0 0"  velocity="0 0 0"  force="0 0 0"  externalForce="0 0 0"  restScale="1"  showObject="0"  showObjectScale="0.05" />
		<BoxROI template="Vec3d" name="FixedROI"  box="0 -2 0 5 2 5"  position="@mesh.position"  indices="0" />
		<BarycentricShapeFunction template="ShapeFunctiond" name="barycentricShapeFunction1" />
		
        <FixedLMConstraint template="Vec3d" name="fixedLMConstraint1"  indices="@FixedROI.indices" />
		<Node 	 name="behavior"  >
			<TopologyGaussPointSampler name="sampler"  method="0 - Gauss-Legendre"  order="1"  showSamplesScale="0"  inPosition="@../mesh.position" />
			<MechanicalObject template="F331" name="F"  position=" 0 0 0 0 0 0 0 0 0"  velocity=" 0 0 0 0 0 0 0 0 0"  force=" 0 0 0 0 0 0 0 0 0"  externalForce=" 0 0 0 0 0 0 0 0 0"  restScale="1"  showObject="0"  showObjectScale="0.05" />
			<LinearMapping template="Vec3d,F331" name="linearMap1"  showDeformationGradientStyle="0 - All axis"  showColorOnTopology="0 - None"  input="@../"  output="@./" />
			<Node 	 name="Strain"  >
				<MechanicalObject template="E331" name="E"  position="0 0 0 0 0 0"  velocity="0 0 0 0 0 0"  force="0 0 0 0 0 0"  externalForce="0 0 0 0 0 0"  restScale="1" />
				<CorotationalStrainMapping template="F331,E331" name="corotationalStrainMap1"  method="svd"  input="@../"  output="@./" />
				<HookeForceField template="E331" name="ff"  youngModulus="2000"  poissonRatio="0.2"  viscosity="0" />
			</Node>
		</Node>
		<Node 	 name="mass"  >
			<MechanicalObject template="Vec3d" name="mObject1"  position="@../mesh.position"  velocity="0 0 0"  force="0 0 0"  externalForce="0 0 0"  restScale="1" />
			<UniformMass template="Vec3d" name="uniformMass2"  totalmass="250" />
			<LinearMapping template="Vec3d,Vec3d" name="linearMap2"  showDeformationGradientStyle="0 - All axis"  showColorOnTopology="0 - None"  input="@../"  output="@./" />
		</Node>
		<Node 	 name="collision"  >
			<MeshObjLoader name="loader"  filename="mesh/torus.obj" />
			<MeshTopology name="meshTopology1"  position="@loader.position"  edges="@loader.edges"  triangles="@loader.triangles"  quads="@loader.quads"  tetrahedra="@loader.tetras"  hexahedra="@loader.hexas" />
			<MechanicalObject template="Vec3d" name="mObject2"  position="0 0 0"  velocity="0 0 0"  force="0 0 0"  externalForce="0 0 0"  restScale="1" />
			<TTriangleModel template="Vec3d" name="tTriangleModel1" />
			<LinearMapping template="Vec3d,Vec3d" name="linearMap3"  showDeformationGradientStyle="0 - All axis"  showColorOnTopology="0 - None"  input="@../"  output="@./" />
		</Node>
		<Node 	 name="visual"  >
			<MeshObjLoader name="loader"  filename="mesh/torus.obj" />
			<MeshTopology name="meshTopology1"  position="@loader.position"  edges="@loader.edges"  triangles="@loader.triangles"  quads="@loader.quads"  tetrahedra="@loader.tetras"  hexahedra="@loader.hexas" />
			<MechanicalObject template="Vec3d" name="mObject2"  position="0 0 0"  velocity="0 0 0"  force="0 0 0"  externalForce="0 0 0"  restScale="1" />
			<LinearMapping template="Vec3d,Vec3d" name="linearMap3"  showDeformationGradientStyle="0 - All axis"  showColorOnTopology="0 - None"  input="@../"  output="@./" />
			<Node 	 name="model"  >
				<OglModel template="ExtVec3f" name="oglModel0"  primitiveType="DEFAULT"  blendEquation="GL_FUNC_ADD"  sfactor="GL_SRC_ALPHA"  dfactor="GL_ONE_MINUS_SRC_ALPHA" />
				<BarycentricMapping template="Vec3d,ExtVec3f" name="barycentricMap1"  input="@../"  output="@./" />
			</Node>
		</Node>
	</Node>
	<Node 	 name="RigidFloor"  >
	</Node>
</Node>

The problem is that the constraint are not being satisfied. When I simulate this scene, the torus falls due to gravity and the constraint are violated. Any idea?

[Hugo]

Hi Juan,

This sounds redundant with the end of your thread about Floor as projective constraint. Just to get how both discussions are linked to each other.

Cheers,

Hugo

[jjcasmar]

Hi Hugo,

in fact it have some relationship as I’m simply trying to understand how constraints work.

The main issue I’m facing in this example is that the LMConstraints are not being applied, but the solver is added in the scene :-s

Thanks!

[Hugo]

Hi Juan,

As you noticed, the collision and constraints in SOFA are not well documented.
Any progress on your LMConstraints ?

Hugo

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