[SOLVED] usage of BaseData and SingleLink

Here are other connected questions, I put them in the same thread, but in a separate post for the sake of clarity.
I have some wrong behaviour when getting values using links, the problem is illustrated in the following minimal example, and the questions are listed as comments inside the code:

class  MyComponent : public BaseController

{
public:

    SOFA_CLASS(MyComponent, BaseController);
        
	typedef  sofa::core::loader::MeshLoader  TMeshSTLLoader;
    typedef  sofa::component::visualmodel::OglModel TOGLModel;
    typedef  sofa::helper::io::Mesh TMesh;

    typedef sofa::core::objectmodel::SingleLink< MyComponent, TMeshSTLLoader, BaseLink::FLAG_STOREPATH|BaseLink::FLAG_STRONGLINK> STLLink;
    typedef sofa::core::objectmodel::SingleLink< MyComponent, TOGLModel, BaseLink::FLAG_STOREPATH|BaseLink::FLAG_STRONGLINK> OGLLink; 
    typedef sofa::core::objectmodel::SingleLink< MyComponent, TMesh, BaseLink::FLAG_STOREPATH|BaseLink::FLAG_STRONGLINK> MeshLink; 

    OGLLink m_ogl_link;
    STLLink m_stl_link;
    //MeshLink m_mesh_link; 
  
}

MyComponent<DataTypes>::MyComponent():
						   m_stl_link(initLink("stl_link", "desc. of the link")), 
                           m_ogl_link(initLink("ogl_link", "desc. of the link"))
                           /* m_mesh_link(initLink("mesh_link", "desc. of the link")) */
  
{
...
}

template<class DataTypes>
void MyComponent<DataTypes>::updateOnBeginStep(){
	
	if(!m_stl_link.get())
    {
        std::cout << "Error getting link" << std::endl;
        return;
    }
    

    TMeshSTLLoader* ldr = m_stl_link.get();
  
    ldr->load();
    
    sofa::helper::vector < sofa::defaulttype::Vec< 3, SReal > >	my_vertices;
    my_vertices = ldr->d_positions.getValue(); 
    
    // First question concerning the size of the vertices 
    // I noticed that the my_vertices size increases by x(the initial size of the positions in the stl loader) at each updateOnBeginStep. 
    // Should I establish the link to the mesh instead of the the stlLoader? this brings me back to my first post 
    
    std::cout<<"number of vertices: "<<my_vertices<<std::endl;
    
    
    // Second question concerning the translation value
    Data<Vector3> myVec;
    myVec=ldr->getTranslation();
    std::cout<<myVec.getValue()[0]<<", "<<myVec.getValue()[1]<<", "<<myVec.getValue()[2]<<std::endl;
    // I was expecting to get the values dx="9,425276" dy="-36,149002" dz="4,296117" as they are set in the scene, but I get 0 0 0. Did I missed something?
    
    
    // Third question concerning the visual model
    if(!m_ogl_link.get())
    {
        std::cout << "Error getting link" << std::endl;
        return;
    }
        TOGLModel* ogl = m_ogl_link.get();

    ldr->applyTranslation(1,0.0,0.0);
    ogl->applyTranslation(1,0.0,0.0); // Is there another way to make the oglModel updates automatically with the corresponding mesh.
}

Again the scene node:

    <Node name="Lunatum" activated="1">
                <MeshSTLLoader name="loader" filename="Lunatum.stl"  dx="9,425276" dy="-36,149002" dz="4,296117" rx="0" ry="5" rz="0"/>
                <Mesh src="@loader"/>
                <MechanicalObject src="@loader" />
                <OglModel name="Visual" fileMesh="Lunatum.stl" color="blue"  />
                <MyComponent  ogl_link="@Visual" stl_link="@loader"  listening="1" />                

    </Node>

Thanks,

Noura

Hi Jean-Nico,

Yes, your explanation helped me a lot. Thank you!

1- The remark concerning the sofa::component::topology::MeshTopology was on point! I mistaked the type of the “Mesh” component in the scene. I linked the “mesh_link” attribute to a sofa::component::topology::MeshTopology and it works fine.

2- Concerning your remark that the linked object must inherit the Base class, I’m not quite sure about this because both the OGLLink and STLLink in the above code do not, and they are working fine.

Looking at the SingleLink class

class SingleLink : public TLink<TOwnerType,TDestType,TFlags&~BaseLink::FLAG_MULTILINK>

where

template<class TOwnerType, class TDestType, unsigned TFlags>
class TLink : public BaseLink

It isn’t clear enough to me which types TDestType is destinated to. But no problem! I did what I need using the link to the MeshTopology.

Before marking the topic as resolved, I would ask for some hints concerning the odd size values of the d_positions in my second post.

I’ll summarize the problem again:
The “Lunatum.stl” mesh file contains 1732 points.
It is the same value which I obtain using the “mesh_link” when calling the getNbPoints()

However, after the following code

    TMeshSTLLoader* ldr = m_stl_link.get();
    ldr->load();    
    sofa::helper::vector < sofa::defaulttype::Vec< 3, SReal > >	my_vertices;
    my_vertices = ldr->d_positions.getValue();  
    std::cout<<"number of vertices: "<<my_vertices<<std::endl;

I’m expecting that size of my_vertices should be equal the vertices number in the file loaded using the STLLoader(which is 1732) Right?

But, at the first simulation step the size of my_vertices is equal to 3464 which is (1732+1732)
at the second step the the size becomes 5196 which is (3464+1732)
then 6928 ( 5196+1732) and so on …

I should have missed some reinitializing for example? Any idea?

Thanks,

Noura

Exactly! the simulation will be slow and saturates after a while, this is why I worried about the increasing memory size. I placed the load function in the constructor and now it keeps the correct positions size ( My error was because I thought that since the ldr is declared at every simulation step, the positions should not be appended).

As for the TDestType, I agree it must inherit the base class 😉

Concerning the translation, still not correct, but I’ll manage to find out the reason.

Finally, the OglModel, now it is working fine. There was an error in the mapping I used which prevented it from updating correctly according to the correspondent mesh. This is why I was trying to reproduce the same positions change. Now, the behaviour is as it should be.

Thanks again Jean-Nico!

Noura