| int num; | 
      Number of vertices in the clipping polygon. | 
    
    
      | float *px; | 
      Pointer to an array containing the X coordinate of each vertex. | 
    
    
      | float *py; | 
      Pointer to an array containing the Y coordinate of each vertex. | 
    
    
      | int *t; | 
      Pointer to an array containing the type proto for the line segment joined to each vertex. |