Mouse Manager: Attach an Object to the Mouse is unrealistic

[giuliadinardo1]

Hi there,

I created a scene in sofa using a tetrahedron mesh. I want to be able to play with the model with my mouse, however, using the "Attach an Object to the Mouse" does not produce a realistic result. It seems to create a point load. Is there a way for the mouse to interact more realistically with the model, such as attaching to multiple nodes?

Thanks!
Giulia

[bakpaul]

Hello !

Your question is interesting: there is no such thing as 'realistic' attachment to a mouse cursor which is not a real object. The attachment is currently performed this way:

1. You are looking at the 3D scene through a 2D projective camera. So your click corresponds to a ray coming from the center of projection of your camera and passing through the pixel you clicked on
2. A collision detection is then performed between this ray and the closest collision model in the scene.
3. The collision detection output is simply a collision element id and the position of the closest point on it -> so by design you'll always get a point.

If you want this force to be more distributed you could either :

1. Make sure you are not using only 'PointCollisionModel' but also 'Triangle' and/or 'Line'. Using higher order elements distributes the force on more points of the model.
2. Use a collision model that is more sparse than your mechanical model, so the resulting picking point will be in reality distributed amongs points on your mechanical model thank's to the mapping
3. Code your own collision model that perform a local distribution of the forces.

Hope that helped !

[giuliadinardo1]

Thank you very much for your response!

I was wondering how I can make the collision model more sparse than the mechanical model using the triangle model. I tried to use a sparse sphere collision model but it does not seem to distribute the force among multiple mechanical points.

Thanks again!

[hugtalbot]

Hi @giuliadinardo1

To make the collision model more sparse than the mechanical model using the triangle model, you need to adapt your meshes. Making sure that the mesh you generate for the collision is sparser than the one used for the mechanical model.

[giuliadinardo1]

Thanks Hugo! Is there a way to do this with spheres? When I try to use the sphere collision model it still looks like only one node is attached to the mouse

[hugtalbot]

you will not have the same "distributed" effect if you use SphereCollisionModel

[github-actions[bot]]

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@giuliadinardo1
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding

[github-actions[bot]]

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@giuliadinardo1
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