Regarding the issue of combining the MSH software model and the OBJ model

[CherryJGit]

Here,
I will introduce my problem in three steps: 1. Background; 2. Expected effect; 3. Problem description.

1. Background: I have two models. One is an MSH model used to eliminate elements, and the other is an OBJ model connected to it. Originally, these two models could be integrated into one. Through local filling and encryption, the part where the elements are eliminated below and the part above would become a single entity. Moreover, due to the elimination of the lower part, the force caused by gravity would decrease, and the upper part could move upward a little bit.

2. Expected effect: However, considering performance issues now, I plan to use a spring at the top of the OBJ model of the upper part to give it the effect of having a tendency to move up and down. And I plan to let the lower MSH model support the OBJ model. When the MSH model disappears, the OBJ model won't drop too much due to the pull of the spring.

3. Problems: 1. How can the OBJ model be pulled by the spring? I have browsed through some questions on the forum. They are similar but still can't solve my problem. Maybe it's my cognitive problem that prevents me from finding the answer on the forum. 2. How can the MSH model support the OBJ model?

The description is a bit long, but I just hope I've described it clearly enough. I hope to get some help.
Thank you.

[hugtalbot]

Hi @CherryJGit

Have you already followed the introduction course of SOFA? This would be most helpful in building your SOFA simulation

To be pulled, you firstly need to define the mechanics of your object (solvers, mass, mechanical properties etc).
Since you are referring to an obj file, it means your mesh is only a surface mesh. Make sure to define your mechanics accordingly.

I do not get the second question "How can the MSH model support the OBJ model?"
Do you want to connect both models?

[CherryJGit]

Thank you very much for answering my questions.I skimmed through the course briefly and didn't think deeply about it. The second problem is that I want the MSH model to serve as the base to support the OBJ model. In other words, the OBJ model will be blocked, just like a cup placed on a table. So, do you mean that the surface mesh of my OBJ model can also be dragged?

[hugtalbot]

I really advise you to take the course and follow it thoroughly.
Regarding the second problem, I would say:

• either these are two separate objects and you would define them as is in SOFA, with the possibility to collide and get in contact
• or they can be considered as one single object and I would suggest to import them as one single mesh in SOFA

[CherryJGit]

Thank you for your advice. I will follow your suggestion and study carefully. Regarding the situation of a single mesh you mentioned, can a model be divided into two parts? One part is responsible for eliminating elements, and the other part is not affected but they are still considered as one entity. Is this approach achievable, or did I misunderstand something?

[hugtalbot]

Hi @CherryJGit

How are things going?
I would like to better understand your simulation case. Could you explain what your simulation is supposed to replicate? It would definitely help in advising the best simulation strategies.
Cheers