C SPECIFICATION

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

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:


                           objX
                                         __w_i_n<I>v_X<I>i_<I>e_v<I>w_i_e_w_____-1














                          (    )=INV(PM)(                 )









                           objZ
                                             2(winZ)-1


















                            W
                                                 1
















































































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

       glGet, gluProject



                                                              GLUUNPROJECT(3G)