Create a new component from AttachConstraint

Hi @amit

No problem it’s always a pleasure, but I apologize for my delay.
As you just attended the SOFA training session, I guess you have got the answer.

Let me however give you some more input so that others can also benefit from your post.
The first step is to create your own plugin, as explained in the documentation and illustrated in the pluginExample.
Once your plugin created, to create a c++ class inheriting from AttachConstraint, here is an example to start from (TemplateAttachConstraint) I would use:

TemplateAttachConstraint.h

/******************************************************************************
*       SOFA, Simulation Open-Framework Architecture, development version     *
*                (c) 2006-2017 INRIA, USTL, UJF, CNRS, MGH                    *
*                                                                             *
* This program is free software; you can redistribute it and/or modify it     *
* under the terms of the GNU Lesser General Public License as published by    *
* the Free Software Foundation; either version 2.1 of the License, or (at     *
* your option) any later version.                                             *
*                                                                             *
* This program is distributed in the hope that it will be useful, but WITHOUT *
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or       *
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License *
* for more details.                                                           *
*                                                                             *
* You should have received a copy of the GNU Lesser General Public License    *
* along with this program. If not, see <http://www.gnu.org/licenses/>.        *
*******************************************************************************
* Authors: The SOFA Team and external contributors (see Authors.txt)          *
*                                                                             *
* Contact information: contact@sofa-framework.org                             *
******************************************************************************/
#ifndef SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_H
#define SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_H

#include "config.h"

#include <sofa/component/projectiveconstraintset/AttachConstraint.h>
#include <sofa/defaulttype/Vec3Types.h>

namespace sofa
{

namespace component
{

namespace projectiveconstraintset
{

template <class DataTypes>
class TemplateAttachConstraint : public sofa::component::projectiveconstraintset::AttachConstraint<DataTypes>
{
public:
    SOFA_CLASS(SOFA_TEMPLATE(TemplateAttachConstraint,DataTypes),SOFA_TEMPLATE(sofa::core::behavior::AttachConstraint,DataTypes));

    typedef typename DataTypes::VecCoord VecCoord;
    typedef typename DataTypes::VecDeriv VecDeriv;
    typedef typename DataTypes::Coord Coord;
    typedef typename DataTypes::Deriv Deriv;
    typedef typename DataTypes::Real Real;

    typedef core::objectmodel::Data<VecCoord> DataVecCoord;
    typedef core::objectmodel::Data<VecDeriv> DataVecDeriv;

protected:
    TemplateAttachConstraint(core::behavior::MechanicalState<DataTypes> *mm1, core::behavior::MechanicalState<DataTypes> *mm2);
    TemplateAttachConstraint();
    virtual ~TemplateAttachConstraint();
public:
    // -- Constraint interface
    void init() override  {};
    void projectJacobianMatrix(const core::MechanicalParams* /*mparams*/ /* PARAMS FIRST */, core::MultiMatrixDerivId /*cId*/) override  {};
    void projectResponse(const core::MechanicalParams *mparams, DataVecDeriv& dx1, DataVecDeriv& dx2) override  {};
    void projectVelocity(const core::MechanicalParams *mparams, DataVecDeriv& v1, DataVecDeriv& v2) override  {};
    void projectPosition(const core::MechanicalParams *mparams, DataVecCoord& x1, DataVecCoord& x2) override  {};

    /// Project the global Mechanical Matrix to constrained space using offset parameter
    void applyConstraint(const core::MechanicalParams *mparams, const sofa::core::behavior::MultiMatrixAccessor* matrix) override  {};

    /// Project the global Mechanical Vector to constrained space using offset parameter
    void applyConstraint(const core::MechanicalParams *mparams, defaulttype::BaseVector* vector, const sofa::core::behavior::MultiMatrixAccessor* matrix) override {};

    /// Define your internal functions and data
};

#if defined(SOFA_EXTERN_TEMPLATE) && !defined(SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_CPP)
extern template class SOFA_GENERAL_OBJECT_INTERACTION_API TemplateAttachConstraint<defaulttype::Vec3Types>;
extern template class SOFA_GENERAL_OBJECT_INTERACTION_API TemplateAttachConstraint<defaulttype::Vec2Types>;
extern template class SOFA_GENERAL_OBJECT_INTERACTION_API TemplateAttachConstraint<defaulttype::Vec1Types>;
#endif

} // namespace projectiveconstraintset

} // namespace component

} // namespace sofa

#endif

TemplateAttachConstraint.inl

/******************************************************************************
*       SOFA, Simulation Open-Framework Architecture, development version     *
*                (c) 2006-2017 INRIA, USTL, UJF, CNRS, MGH                    *
*                                                                             *
* This program is free software; you can redistribute it and/or modify it     *
* under the terms of the GNU Lesser General Public License as published by    *
* the Free Software Foundation; either version 2.1 of the License, or (at     *
* your option) any later version.                                             *
*                                                                             *
* This program is distributed in the hope that it will be useful, but WITHOUT *
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or       *
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License *
* for more details.                                                           *
*                                                                             *
* You should have received a copy of the GNU Lesser General Public License    *
* along with this program. If not, see <http://www.gnu.org/licenses/>.        *
*******************************************************************************
* Authors: The SOFA Team and external contributors (see Authors.txt)          *
*                                                                             *
* Contact information: contact@sofa-framework.org                             *
******************************************************************************/
#ifndef SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_INL
#define SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_INL

#include <SofaGeneralObjectInteraction/TemplateAttachConstraint.h>

namespace sofa
{

namespace component
{

namespace projectiveconstraintset
{

template <class DataTypes>
AttachConstraint<DataTypes>::AttachConstraint()
    : // INIT your data here
{
}

template <class DataTypes>
AttachConstraint<DataTypes>::AttachConstraint(core::behavior::MechanicalState<DataTypes> *mm1, core::behavior::MechanicalState<DataTypes> *mm2)
    : core::behavior::PairInteractionProjectiveConstraintSet<DataTypes>(mm1,mm2)
    , // INIT your data here
{
}

template <class DataTypes>
void AttachConstraint<DataTypes>::init()
{
    // To implement
}

template<class DataTypes>
void AttachConstraint<DataTypes>::projectJacobianMatrix(const core::MechanicalParams* /*mparams*/ /* PARAMS FIRST */, core::MultiMatrixDerivId /*cId*/)
{
    // To implement
}

template <class DataTypes>
void AttachConstraint<DataTypes>::projectPosition(const core::MechanicalParams * /*mparams*/, DataVecCoord& res1_d, DataVecCoord& res2_d)
{
    // To implement
}

template <class DataTypes>
void AttachConstraint<DataTypes>::projectVelocity(const core::MechanicalParams * /*mparams*/, DataVecDeriv& res1_d, DataVecDeriv& res2_d)
{
    // To implement
}

template <class DataTypes>
void AttachConstraint<DataTypes>::projectResponse(const core::MechanicalParams * /*mparams*/, DataVecDeriv& res1_d, DataVecDeriv& res2_d)
{
    // To implement
}

// Matrix Integration interface
template <class DataTypes>
void AttachConstraint<DataTypes>::applyConstraint(const core::MechanicalParams * /*mparams*/, const sofa::core::behavior::MultiMatrixAccessor* matrix)
{
    // To implement
}

template <class DataTypes>
void AttachConstraint<DataTypes>::applyConstraint(const core::MechanicalParams * /*mparams*/, defaulttype::BaseVector* vect, const sofa::core::behavior::MultiMatrixAccessor* matrix)
{
    // To implement
}

}

} // namespace constraint

} // namespace component

} // namespace sofa

#endif

TemplateAttachConstraint.cpp

/******************************************************************************
*       SOFA, Simulation Open-Framework Architecture, development version     *
*                (c) 2006-2017 INRIA, USTL, UJF, CNRS, MGH                    *
*                                                                             *
* This program is free software; you can redistribute it and/or modify it     *
* under the terms of the GNU Lesser General Public License as published by    *
* the Free Software Foundation; either version 2.1 of the License, or (at     *
* your option) any later version.                                             *
*                                                                             *
* This program is distributed in the hope that it will be useful, but WITHOUT *
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or       *
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License *
* for more details.                                                           *
*                                                                             *
* You should have received a copy of the GNU Lesser General Public License    *
* along with this program. If not, see <http://www.gnu.org/licenses/>.        *
*******************************************************************************
* Authors: The SOFA Team and external contributors (see Authors.txt)          *
*                                                                             *
* Contact information: contact@sofa-framework.org                             *
******************************************************************************/
#define SOFA_COMPONENT_PROJECTIVECONSTRAINTSET_TEMPLATEATTACHCONSTRAINT_CPP

#include "TemplateAttachConstraint.inl"
#include <sofa/core/ObjectFactory.h>
#include <sofa/defaulttype/VecTypes.h>

namespace sofa
{

namespace component
{

namespace projectiveconstraintset
{

using namespace sofa::defaulttype;

int TemplateAttachConstraintClass = core::RegisterObject("A specific constraint inheriting from AttachConstraint")
        .add< TemplateAttachConstraint<Vec3Types> >();
        .add< TemplateAttachConstraint<Vec2Types> >();
        .add< TemplateAttachConstraint<Vec1Types> >();

template class TemplateAttachConstraint<Vec3Types>;
template class TemplateAttachConstraint<Vec2Types>;
template class TemplateAttachConstraint<Vec1Types>;

} // namespace projectiveconstraintset

} // namespace component

} // namespace sofa

NB: this kind of dev question is more dedicated on the Dev part of the forum.

Hope this helps, do not hesitate to close the topic if this explanation is fine for you.
Best,

Hugo

Dear @amit

Your CMakeList seems perfect! Good work!!

The error is mine.
In the TemplateAttachConstraint.h, you should have #include <SofaGeneralObjectInteraction/AttachConstraint.h> instead of #include <sofa/component/projectiveconstraintset/AttachConstraint.h>

In the TemplateAttachConstraint.h, you should have #include "TemplateAttachConstraint.h" instead of #include <SofaGeneralObjectInteraction/TemplateAttachConstraint.h>

Let me know if this works.

Hugo

Hi @amit

Sorry for the delay, I’ve been away for several days.
AttachConstraint is computing/enforcing two objects that are really attach, connected together.

If you want to mimic the interaction / collision of two objects, you should better use the collision pipeline for this. See an example in examples/Components/animationloop/FreeAnimationLoop.scn showing different objects interacting. At each collision, it creates a constraint solved using the Lagrange multiplier method.

If you want to model two objects that can be torn apart, using an AttachConstraint which can remove the constraints when the object are detached from another, your approach is a good one.

I hope this helps

Hugo

Hi @amit

Thank you for re-detailing everything. It helps.
You can forget about my remark concerning the FreeAnimationLoop, the AttachConstraint seems to be well respected using the usual DefaultAL.

The approach based on AttachConstraint in order to model the fatty tissue linking the two organs can work but I think this won’t look very really realistic. If you decrease/update the radius of the NearestROI you can see that the objects will suddenly detach (I tested changing radius from 0.5 to 0.000005).

Another approach that could look more physically realistic would be to go for springs (not necessarily linear!) linking the two objects. You could implement the stiffness law you wish and when the elongation exceeds a threshold, set the stiffness to zero. This would really give the feeling to tear the fatty tissue and detach the organs step by step.
To do so, you could inherit from SpringForceField, define the law you want and the threshold regarding the elongation as a Data.

I hope this helps.
Best wishes,

Hugo

Hey @amit,

To know which are the indices, you can see these point indices in SOFA by setting in the MechanicalObject: showIndices="1" and showIndicesScale="3.0" (set the scale you want).

If you want to automatically select points in a region of interest (ROI), you can still use Box/Sphere/NearestPointROI.

This could help. If this is not what you are looking for, please let me know.
Best

Hugo

Hey @amit,

There is no such option in the BoxROI. However, this could be added in the draw() function of the BoxROI class by getting inspired of the draw() in the MechanicalObject.
Let us know if you struggle with this part.

Best

Hugo

Hey @amit,

What you can do in the draw() function of BoxROI is to use the function:

vparams->drawTool()->draw3DText(pv, size, color, indice);

I tried it on my side, it worked. Here is a diff file:

diff --git a/SofaKernel/modules/SofaEngine/BoxROI.h b/SofaKernel/modules/SofaEngine/BoxROI.h
index c1896c2..4bad42e 100644
--- a/SofaKernel/modules/SofaEngine/BoxROI.h
+++ b/SofaKernel/modules/SofaEngine/BoxROI.h
@@ -166,6 +166,7 @@ public:
     //Parameter
     Data<bool> d_drawBoxes; ///< Draw Boxes. (default = false)
     Data<bool> d_drawPoints; ///< Draw Points. (default = false)
+    Data<bool> d_drawPointIndices; ///< Draw Points indices. (default = false)
     Data<bool> d_drawEdges; ///< Draw Edges. (default = false)
     Data<bool> d_drawTriangles; ///< Draw Triangles. (default = false)
     Data<bool> d_drawTetrahedra; ///< Draw Tetrahedra. (default = false)
diff --git a/SofaKernel/modules/SofaEngine/BoxROI.inl b/SofaKernel/modules/SofaEngine/BoxROI.inl
index 776307e..43bd206 100644
--- a/SofaKernel/modules/SofaEngine/BoxROI.inl
+++ b/SofaKernel/modules/SofaEngine/BoxROI.inl
@@ -91,6 +91,7 @@ BoxROI<DataTypes>::BoxROI()
     , d_nbIndices( initData(&d_nbIndices,"nbIndices", "Number of selected indices") )
     , d_drawBoxes( initData(&d_drawBoxes,false,"drawBoxes","Draw Boxes. (default = false)") )
     , d_drawPoints( initData(&d_drawPoints,false,"drawPoints","Draw Points. (default = false)") )
+    , d_drawPointIndices( initData(&d_drawPointIndices,false,"drawPointIndices","Draw Points indices in ROI. (default = false)") )
     , d_drawEdges( initData(&d_drawEdges,false,"drawEdges","Draw Edges. (default = false)") )
     , d_drawTriangles( initData(&d_drawTriangles,false,"drawTriangles","Draw Triangles. (default = false)") )
     , d_drawTetrahedra( initData(&d_drawTetrahedra,false,"drawTetrahedra","Draw Tetrahedra. (default = false)") )
@@ -810,6 +811,29 @@ void BoxROI<DataTypes>::draw(const core::visual::VisualParams* vparams)
         vparams->drawTool()->drawLines(vertices, linesWidth, color);
     }
 
+    ///draw points indices in ROI
+    if( d_drawPointIndices.getValue())
+    {
+        float size = d_drawSize.getValue() ? (float)d_drawSize.getValue() : 1;
+        vparams->drawTool()->setLightingEnabled(false);
+        std::vector<Vector3> vertices;
+        ReadAccessor< Data<VecCoord > > pointsInROI = d_pointsInROI;
+        ReadAccessor< Data<SetIndex > > indices = d_indices;
+
+        for (unsigned int i=0; i<pointsInROI.size() ; ++i)
+        {
+            CPos p = DataTypes::getCPos(pointsInROI[i]);
+            Vector3 pv;
+            for( unsigned int j=0 ; j<max_spatial_dimensions ; ++j )
+                pv[j] = p[j];
+
+            std::ostringstream oss;
+            oss << indices[i];
+            const char* indice = oss.str().c_str();
+            vparams->drawTool()->draw3DText(pv, size, color, indice);
+        }
+    }
+
     ///draw triangles in ROI
     if( d_drawTriangles.getValue())
     {

Events are described here. Using the listening option, you will activate the c++ function handleEvent() handling all SOFA events.

Best,

Hugo

Hi @amit

I forgot to mention, but do not hesitate to pull-request this improvement of BoxROI in SOFA! To do so, the documentation is here.

Right now I am struggling with collision detection in sofa. When I set my models for collision(triangle/sphere or any model) the frame rate drops and the simulation becomes unusable.

Performances will depend on your mesh refinement for the collision model, as well as on the numerical properties. I would advise to first try using a slightly coarser mesh for the collision detection. Do not hesitate to share your scene with me (in private if necessary).

However, once everything is optimized, if the simulation is still not efficient enough there is (always!) solutions. We have independent developers in the community working on a multithreaded and GPU collision detection. I could put you in contact with these guys if you need it.

Best

Hugo