I'd like the game object to follow the mouse but I have trouble doing this when the object is in 3D and the camera has been rotated.
The only thing that seems to be true (and still it works only when camera isn't rotated) is :
The visible X for the camera is equal to
2 * Mathf.Abs(object.position.z - camera.position.z)
The visible Y for the camera is equal to
VisibleX * (camera.pixelHeight / (float)camera.pixelWidth)(casting to