View Full Version : Linking two rigid bodies with constrains

05 May 2007, 01:38 PM

A while ago I had a question about how to link to active rigid bodies “Linking two active rigid bodies”

OK, it somehow worked for that moment, but now I need a more precise solution. I am trying to make it simple. What I am looking for is a way to constrain two spherical active rigid bodies with pin constrains. A smaller body is constrained inside a big one, to fix its position. Both of them are connected to gravity as well. Because the smaller one is not in the center of the bigger one, the bigger one starts to roll on a surface whereas the smaller one is following the movement.
But now, I would like to key frame the rotation of the smaller one a long its Z axis (360°). So when it starts to rotate, it drags the whole thing into a certain direction.
The problem is, that the rotate x y z attribute of the smaller one is already connected to the pin constrains. That means I can not add a key framed rotation to it. Even when I group them I can not add a rotation.

Does anybody of you have an idea how to combine/add two rotations on one object, without breaking the connection to a rigid body? Perhaps with an expression? I tried it with driven keys, but without success.

Thanks a lot


05 May 2007, 12:18 PM
Hi stussy....
U need to link twoo rigid bodies.....Larger sphere and smaller sphere...u need to control the larger one with smaller one .....rt...
if what i mentioned above is rt....
then to control the rotation...u dont need translate or rotate of smaller it is rigid body..u can use rigid body contol it....

if it is not correct let me know....

05 May 2007, 01:30 PM
Hello, for the first part of your assumption you are right :)
I like to control the bigger sphere with the smaller one. The smaller one should therefore rotate along its z-axis (see image, the pivot is where the megenta axis is). So when it starts to rotate, the whole object starts to roll/tumble over a surface. Basically I need two smaller spheres inside the bigger one. I skipped that part for now :/

What do you mean by ..u can use rigid body attributes..? I don’t want to give the smaller sphere an initial spin or so. I like to control its rotation along an axis. Perhaps I missed something in the attributes of that sphere. Would be to great



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05 May 2007, 01:30 PM
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