[pax]

Если нужен поворот при выводе на экран, т.е. 2D то вот тут есть пример с форума unity3d.ru

public class RotateArrowScript : MonoBehaviour
{
    public float angle;
    public Rect mainRect;
    public Texture guiTextur;

    Vector3 centerRotateOfGUI;//center point of Rotate

    void Start()
    {
        centerRotateOfGUI = new Vector2(mainRect.x + mainRect.width / 2, mainRect.y + mainRect.height / 2);
    }

    void OnGUI()
    {
        Matrix4x4 iniMatrix = GUI.matrix;
        GUIUtility.RotateAroundPivot(angle, centerRotateOfGUI);//Change GUI matrix
        GUI.DrawTexture(mainRect, guiTextur);
        ///There restore the initial GUI.matrix for future elements from iniMatrix;
        GUI.matrix = iniMatrix;
    }
}