[SOLVED] Visual Problem Tutorial SOFA v.18.06

[Nassim]

Hello,
I’m using the binaries of SOFA v18.06 on windows, but when i’m doing some tutorials, i have some visualisation problems.
First, by doing the step by step tutorial, ( you can see it in the video on youtube at 11.12min: https://www.youtube.com/watch?time_continue=250&v=YWC9kcHhzBE), while i’m creating the torus, in the last part, with the fixed box, a problem appeared. The torus, made by points ( not as in the video, and i also don’t understand why the appeareance is different), just fall down ( saw the pictures in the google drive link). I have followed the code put in the video, and I think it is correct, so I don’t understand why the torus doesn’t stay stucked on the box.
link : https://drive.google.com/drive/folders/1VrbP0xModPrSJpPyJIcVKIjnLH1puhBS?usp=sharing

Same problem of visualisation in the tutorial BasicCube (pictures in the drive). When i open the scn file with the runSofa.exe, the cube doesn’t appeared, there is only 4 red points, which is totally not what it is supposed to be (look picture of the tutorial in the folder examples/Tutorial/Basic:)

So, do you know why theses problem of visualisation are here and how to solve it?

Thank you very much.

Code for the fixed Torus :

<Node name=”root” dt=”0.01″ gravity=”0 -9.81 0″ >
	<VisualStyle displayFlags=”showForceFields showBehaviorModels”/>
	<DefaultAnimationLoop/>
	<Node name=”TorusSpring”>
		<EulerImplicitSolver rayleighStiffness=”0.01″/>
		<CGLinearSolver iterations=”20″ tolerance=”1e-06″ threshold=”1e-08″/>
		<MeshObjLoader name=”meshLoader” filename=”mesh/torus.obj”/>
		<Mesh src=”@meshLoader”/>
		<MechanicalObject template=”Vec3d” src=”@meshLoader” showObject=1/>
		<MeshSpringForceField name=”Springs” tetrasStiffness=”2000″ tetrasDamping=”5″/>
		<UniformMass totalmass=”4″/>
		<BoxROI name=”ROI” box=”-5 -2 -10 -1 2 10″ drawBoxes=”true” />
		<FixedConstraint indices=”@ROI.indices” />
	</Node>
</Node>

[Hugo]

Hi @nassim

it’s a bit tricky to notice here:
– the mesh you are loading only contains triangles (you can show them by setting the data drawTriangles=”1″ in the Mesh)
– the stiffness you defined in the MeshSpringForceField is on tetrahedra, but no tetrahedron exists. Therefore your object has not stiffness, i.e. no constitutive law. Points are just falling

To correct this, just change tetrasStiffness=”2000″ into trianglesStiffness=”2000″

Cheers,

Hugo

[yul131]

I suppose that :MeshSpringForceField is to add an internal force field to the mesh object, however, when adding this force field, I fould that the torus will fall down slower than its counterpart that are only under the gravity force field.

I wonder why this would happen, thanks!

[Author]

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