lookat(3G)

NAME
     lookat - defines a viewing transformation

C SPECIFICATION
     void lookat(vx, vy, vz, px, py, pz, twist)
     Coord vx, vy, vz, px, py, pz;
     Angle twist;

PARAMETERS
     vx      expects the x coordinate of the viewing point.

     vy      expects the y coordinate of the viewing point.

     vz      expects the z coordinate of the viewing point.

     px      expects the x coordinate of the reference point.

     py      expects the y coordinate of the reference point.

     pz      expects the z coordinate of the reference point.

     twist   expects the angle of rotation.

DESCRIPTION
     lookat defines the viewpoint and a reference point on the line of sight
     in world coordinates.  The viewpoint is at (vx, vy, vz), and is the
     position from which you are looking. The reference point is at
     (px, py, pz), and is the location on which the viewpoint is centered.
     The viewpoint and reference point define the line of sight.  twist
     measures right-hand rotation about the line of sight.  A twist of 0
     corresponds to the world coordinate Y axis being aligned with the screen
     coordinate Y axis.

     The matrix computed by lookat premultiplies the current matrix, as
     specified by mmode.  lookat is typically called only while mmode is
     either MSINGLE or MVIEWING.

SEE ALSO
     mmode, polarview