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How to create a link programetically and attach to one of the link in the model?

asked 2018-06-13 08:35:45 -0500

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I am trying following code in model plugin to create and attach a new created link to the model.

void Load(physics::ModelPtr _parent, sdf::ElementPtr _sdf)

    // Store the pointer to the model
    this->model = _parent; 

    this->updateConnection = event::Events::ConnectWorldUpdateBegin(std::bind(&a_link_model::OnUpdate, this));

    hasLinkCreated = false;



if(true == hasLinkCreated)

this->a_link = this->model->CreateLink("link_a");

   ROS_ERROR("Link for %s not found in the world", "link_a");
// something wrong ??

hasLinkCreated = true;

However, the link is not existing in next line. Am I missing some conceptual stuff. I am coding for ODE (and Bullet later). The bool hasLinkCreated is making sure the createlink is attempted only once.

It prints

  ROS_ERROR("Link for %s not found in the world", "point_mass");

I am checking gazebo gui model link list to see if link was created. Please let me know if any more info is needed. This is my first question.

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answered 2018-06-15 17:20:30 -0500

From the documentation for CreateLink:

a LinkPtr to the new link created, returns NULL if link _name already exists.

You've said that this is in your OnUpdate function. Perhaps the first time it works, but on subsequent calls it is a duplicate so the function returns null?

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Oh I am updating the question if allowed. OnUpdate is updating the link only once conditioned by a bool variable. Also even if it was created once the Gazebo gui should have the link listed, which was not. Thank you for pointing that out.

rick2050 gravatar imagerick2050 ( 2018-06-18 01:04:08 -0500 )edit
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Asked: 2018-06-13 08:35:45 -0500

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Last updated: 2 days ago