In Unity I have an object with a circle collider attached to it and when I apply a torque to this object's rigidbody2D, it rotates as expected. However, I have now attached a sub-object to this object with a polygon (trigger) collider which I am using to detect when something is in a cone in front of the ship. There is no rigid body (2D or 3D) attached to the child object. The only rigid body on the object is the one I am applying torque to.
However, when I do this, the centre of mass of the ship is moved to the centre of this collider, which produces totally the wrong effect. This happens even if I move this collider to the root node (so both it and the circle collider are attached).
I either need a way of getting the rigid body to ignore the child collider/allow me to set the centre of gravity, or else some other way of detecting objects inside a region.