[SOLVED] ContactListener error on SofaPython3

[chiarasapo]

Hi, I am working with sofapython3 and I would like to implement the following:
As soon as a contact between body1 and body2 is detected, a spring should be added between the two bodies. Then, when the bodies move apart again, after a certain threshold distance, the spring should be removed.
Right now I am trying to create the first step: detecting the contact. I am using the ContactListener as:
Listener=name.addObject('ContactListener', name="Listener”, collsionModel1=Skin.SkinColl.TriangleCollisionSkin.getLinkPath(), collisionModel2 = Scalpel.InstrumentColl.SphereCollisionInstrument.getLinkPath())
And the listener is created. However when I try using the ContactListener method getNumberOfContacts() I receive this error:
[ERROR] [SofaPython3::SceneLoader] KeyError: 'getNumberOfContacts'
Should I do something differently?
Any help on this step or any of the other steps would be very appreciated!

[Scheikl]

Hi @chiarasapo,
as you can see in the bindings for ContactListener, the method getNumberOfContacts is commented out. Could you try uncommenting and recompile it?

Cheers,
Paul

[chiarasapo]

Hi First of all thank you for your answer! But unfortunately I uncommented it and recompiled but I get the same error

[Scheikl]

Hi @chiarasapo,
are you using SofaPython3 out-of-tree?

Also try removing the build folder to start clean.

What may also help is doing a separate install step after building.
cmake --install <sofa target folder>/external_directories/sofapython3/bindings

Cheers,
Paul

[chiarasapo]

It worked perfectly, thanks a lot! Now it checks for collisions but it only does it once when I load the project on sofa. Do you know how I can activate it only during animation time?

[Scheikl]

Hi @chiarasapo,
glad I could help!

I would suggest using a Sofa.Core.Controller to call the function on a specified event, such as AnimateEndEvent.
There is a nice example in the SofaPython3 repo.

Just delete all the functions that you do not need. 🙂
For example

class PrintContactController(Sofa.Core.Controller):

    def __init__(self, *args, **kwargs):
        Sofa.Core.Controller.__init__(self, *args, **kwargs)

    def init(self, contact_listener):
        self.contact_listener = contact_listener

    def onAnimateBeginEvent(self, event): # called at each begin of animation step
        print(self.contact_listener.getNumberOfContacts())

Cheers,
Paul

[chiarasapo]

Thank you very much! I will mark this as resolved.
Have a nice day,
Chiara

[Scheikl]

You’re very welcome! 🙂

Thanks, you too!

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