A useful debug tool. Invert the normal of your object, plain and simply.
    
                  
                
                
                Parameters
                
                  - 
                    Invert Normals (On/off option) : Invert normals of the object
                  
- 
                    Invert Tangents (On/off option) : Invert tangents of the object
                  
- 
                    Invert Bitangents (On/off option) : Invert bi-tangents of the object