void
       swf_lookat
       (double 
       view_x, double 
       view_y, double 
       view_z, double 
       reference_x, double 
       reference_y, double 
       reference_z, double 
       twist)
The swf_lookat() function defines a viewing transformation by giving the viewing position (the parameters view_x, view_y, and view_z) and the coordinates of a reference point in the scene, the reference point is defined by the reference_x, reference_y , and reference_z parameters. The twist controls the rotation along with viewer's z axis.