Hi,
In this example I applied a mass of 100 to the red sphere (head) and a mass of 10 to th body and joined them together using fixed joint. When falling, I assume a physically correct behavior would be the object will tilt and the red sphere will hit the ground first. Is it possible to achieve this?
You will probably need to simulate air resistance somehow if you want to achieve this - though I am uncertain if even that might get the behavior you are seeking. I would do a real world test, if you can make a similar object, and observe the behavior.
Absent air resistance or other forces, all objects fall at the same speed regardless of mass.
(See, for example: If You Drop A Feather And A Metal Cube In A Vacuum Chamber Will They Hit At The Same Time? - YouTube)
This could also be hacked by adding rotational velocity as well.
How do you add a joint? I have looked at the samples and not figured that out.
Select two rigid bodies, then Create->Physics->Joint
I did that, but they do not move together. If I move one the other stays where it is. I would think a joint would be connected.
I must not understand the Joint part.
OK, I got further, but now I get an error: Cannot create a joint between static bodies.
It worked fine with 1 then I made 20 copies and I got this error.
Looks like the bodies you are trying to connect are not dynamic bodies. The joint connects either two bodies where at least one has to be a dynamic body, or it is a joint to the world where only one body is provided. Then the body must be a dynamic body.
If you crate two dynamic bodies and connect them with a fixed joint then moving one of the bodies will make sure that the bodies stay connected. Like I am trying to do that in the attached video.
I don’t understand the term dynamic body. I know how to add physics - rigid body with colliders preset. Is that what you mean? I just tried what you did and it doesn’t work for me.
Edit: I just figured out it wasn’t working because I wasn’t running the simulation. So the joint is not active during design mode?
That is what was throwing me off I think.
Thank you
Ah yes, simulation must be running (play needs to be pressed). Without play physics is not active.
I wonder how to set or simulate air resistance force in Isaac gym or isaac sim ?