lookat(3G)							    lookat(3G)

NAME    [Toc]    [Back]

     lookat - defines a	viewing	transformation

C SPECIFICATION    [Toc]    [Back]

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

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     mmode, polarview


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