How to get the center of an object?

[WrongAgain]

I want to let some objects in my scene rotate with its center. These objects
maybe be far from the origin. I can not use the 'model.worldposition', because
I found it is (0,0,0) when debug, not the coordinates of the objects. So I want
the shape centers of them, or barycenters, or some point like this. How to get
it? Which fuction?

When debug, I found the boundingbox center seems to satisfy my requirement,
but I tried and tried, and can not retrieve it at last.

[Ex Malterra]

boundingSphere returns a list with two elements, a vector representing the
position of the model and a float representing the radius of the bounding
sphere. you can use:

member("your3dWorld").model("yourModel").boundingS phere[1]

to get the entire position vector, or

member("your3dWorld").model("yourModel").boundingS phere[1][1].x
member("your3dWorld").model("yourModel").boundingS phere[1][1].y
member("your3dWorld").model("yourModel").boundingS phere[1][1].z

to get the x,y or z portion of the vector respectively.