I have unity 3.0 free license.
I got this message in console :
Actor::updateMassFromShapes: Compute mesh inertia tensor failed for one of the actor's mesh shapes! Please change mesh geometry or supply a tensor manually!
Error in file[....\Physics\src\NpActor.cpp line 134]
1- Is there anything that I can do to fix it? a. Do I have to reinstall unity?
This generally happens when you have a rigidbody on an object and the attached collider is not a closed shape-- only with a mesh collider. You have multiple ways to solve the problem:
You can remove the rigidbody. This would remove the error, but is likely the wrong answer because you added the rigidbody for a reason, so removing it is useless.
You can mark the rigidbody kinematic. Then it would still send collision messages, it would only move by scripting though.
You could remove the collider, and or change the type of collider. Not sure what you are doing, but it is a possibility.
This method is a little hard. You can enclose the mesh collider by marking it convex (that is a solution in itself), then add a basic script that prints the inertia tensor of the rigidbody i.e. `Debug.Log(rigidbody.inertiaTensor);`. Copy that value, uncheck the convex box, and set the value of the inertiaTensor to that. `rigidbody.inertiaTensor = new Vector3(value, value, value);` This would give you very similar, not necessarily identical behavior to an enclosed object like it. It is hard to tell what an object without volume would behave like in real life, because they don't exist.
Those are the only solutions that I have come across. The first and second methods will solve the problem, but they often compromised the reason for the rigidbody, a physics simulation. The third method is how I solved this problem when I came across it, but it isn't particularly clean.
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