[SOLVED] How to create my own contact class?

[yupeng]

As I mentioned in this topic

I want to create a needle insertion application. I’ve talked with @hugo about this. We reach a consensus about the implementation.

Needle insertion step:

1. Before insertion, the soft tissue resists the insertion of the needle by creating unilateralInteractionConstraint
2. When the contact force computed from unilateralInteractionConstraintbeyond some threshold, we should create a slidingConstraint other than unilateralInteractionConstraint.

The creation of this kind of constraint is implemented in a contact class (for example frictionContact class). Thus, I create my own plugin which could create my own contact class: NeedleContactand sliding constraint: NSlidingConstraint.

Then I start to use this scene to test my needle insertion plugin. When the tool has contacts with the soft tissue, I get the errors as below:

[INFO]    [LCPcalc] dim should be dividable by 3 in nlcp_gaussseidel
[ERROR]   [DefaultContactManager(response)] Contact NeedleContact between SphereCollisionModel and PointCollisionModel creation failed
Supported models for contact NeedleContact:
   NeedleContact<PointCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,PointCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >
   NeedleContact<PointCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,SphereCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >
   NeedleContact<LineCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,SphereCollisionModel<StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >,StdVectorTypes<Vec<3,double>,Vec<3,double>,double> >
[ERROR]   [DefaultContactManager(response)] Contact NeedleContact between SphereCollisionModel and PointCollisionModel creation failed
[ERROR]   [DefaultContactManager(response)] Contact NeedleContact between SphereCollisionModel and PointCollisionModel creation failed
[ERROR]   [DefaultContactManager(response)] Contact NeedleContact between SphereCollisionModel and PointCollisionModel creation failed
further messages suppressed.
[INFO]    [LCPcalc] dim should be dividable by 3 in nlcp_gaussseidel
[INFO]    [LCPcalc] dim should be dividable by 3 in nlcp_gaussseidel

The error messages show that I failed to create the contacts in NeedleContact.cpp. How should I correct this?

Creator<sofa::core::collision::Contact::Factory, NeedleContact<
	PointCollisionModel<sofa::defaulttype::Vec3Types>, PointCollisionModel<sofa::defaulttype::Vec3Types>> > PointPointNeedleContactClass("NeedleContact",true);
Creator<sofa::core::collision::Contact::Factory, NeedleContact<
	PointCollisionModel<sofa::defaulttype::Vec3Types>, SphereCollisionModel<sofa::defaulttype::Vec3Types>> > SpherePointNeedleContactClass("NeedleContact", true);
Creator<sofa::core::collision::Contact::Factory, NeedleContact<
	LineCollisionModel<sofa::defaulttype::Vec3Types>, SphereCollisionModel<sofa::defaulttype::Vec3Types>> > SphereLineNeedleContactClass("NeedleContact", true);

[yupeng]

The error didn’t reappear anymore when I using SphereCollsionModelas the first template parameter in NeedleContact.cpp.

Creator<sofa::core::collision::Contact::Factory, NeedleContact<
	SphereCollisionModel<sofa::defaulttype::Vec3Types>, PointCollisionModel<sofa::defaulttype::Vec3Types>> > PointSphereNeedleContactClass("NeedleContact", true);
Creator<sofa::core::collision::Contact::Factory, NeedleContact<
	SphereCollisionModel<sofa::defaulttype::Vec3Types>, LineCollisionModel<sofa::defaulttype::Vec3Types>> > LineSphereNeedleContactClass("NeedleContact", true);

But the haptic force is too large and not stable.
LCPConstraintSolver.cpp Function nlcp_gaussseidel_unbuild spites out msg_error()<< " WARNING dim should be dividable by 3 in nlcp_gaussseidel"

[Hugo]

Let’s close this topic since this one is already open on the topic.

Hugo

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