gluUnProject(3)

NAME

       gluUnProject - map window coordinates to object coordinates

C SPECIFICATION

       GLint gluUnProject( GLdouble winX,
                           GLdouble winY,
                           GLdouble winZ,
                           const GLdouble *model,
                           const GLdouble *proj,
                           const GLint *view,
                           GLdouble* objX,
                           GLdouble* objY,
                           GLdouble* objZ )

       delim $$

PARAMETERS

       winX, winY, winZ
                       Specify the window coordinates to be mapped.

       model           Specifies  the modelview matrix (as from a glGetDoublev
                       call).

       proj            Specifies the projection matrix (as from a glGetDoublev
                       call).

       view            Specifies  the viewport (as from a glGetIntegerv call).

       objX, objY, objZ
                       Returns the computed object coordinates.

DESCRIPTION

       gluUnProject maps the specified window coordinates into object  coordi-
       nates using model, proj, and view.  The result is stored in objX, objY,
       and objZ. A return value of GL_TRUE indicates success; a  return  value
       of GL_FALSE indicates failure.

       To  compute the coordinates (objX, objY, and objZ), gluUnProject multi-
       plies the normalized device coordinates by the inverse of model*proj as
       follows:

             left ( down 70 {cpile { ~"objX" above ~"objY" above ~"objZ"
       above ~W}} ~~ right ) ~=~ INV(P M) left ( down 140 {cpile { { {2("winX"
       ~-~ "view"[0])} over {"view"  [2]}  ~-~  1  }  above  {  {2("winY"  ~-~
       "view"[1])}  over  {"view"[3]}  ~-~ 1 } above { 2("winZ") ~-~ 1 } above
       1}} ~~ right )

       $INV()$ denotes matrix inversion.  W is an  unused  variable,  included
       for consistent matrix notation.

SEE ALSO

       glGet(3G), gluProject(3G)

                                                              GLUUNPROJECT(3G)