GLUNPROJECT4(3G)                                            GLUNPROJECT4(3G)



NAME
       gluUnProject4 - map window and clip coordinates to object coordinates


C SPECIFICATION
       GLint gluUnProject4( GLdouble winX,
                            GLdouble winY,
                            GLdouble winZ,
                            GLdouble clipW,
                            const GLdouble *model,
                            const GLdouble *proj,
                            const GLint *view,
                            GLdouble near,
                            GLdouble far,
                            GLdouble* objX,
                            GLdouble* objY,
                            GLdouble* objZ,
                            GLdouble* objW )


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

       clipW           Specify the clip w coordinate 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).

       near, far       Specifies the near and far planes (as from a  glGetDou-
                       blev call).

       objX, objY, objZ, objW
                       Returns the computed object coordinates.

DESCRIPTION
       gluUnProject4 maps the specified window coordinates winX, winY and winZ
       and its clip w coordinate clipW into object  coordinates  (objX,  objY,
       objZ,  objW)  using  model, proj and view. clipW can be other than 1 as
       for vertices in glFeedbackBuffer when data type GL4DCOLORTEXTURE  is
       returned.  This also handles the case where the near and far planes are
       different from the default, 0 and 1, respectively.  A return  value  of
       GLTRUE  indicates  success; a return value of GLFALSE indicates fail-
       ure.

       To compute the coordinates (objX, objY, objZ and  objW),  gluUnProject4
       multiplies   the  normalized  device  coordinates  by  the  inverse  of
       model*proj as follows:

                                2(winX - view[0])
                                -----------------  - 1
                                     view[2]

           objX                 2(winY - view[1])
           objY   =  INV(PM)    -----------------  - 1
           objZ                      view[3]
            W
                                  2(winZ - near)
                                -----------------  - 1
                                    (far - near)

                                      clipW


       INV() denotes matrix inversion.

       gluUnProject4 is equivalent to gluUnProject when clipW is 1, near is  0
       and far is 1.

NOTES
       gluUnProject4 is available only if the GLU version is 1.3 or greater.

SEE ALSO
       glGet, glFeedbackBuffer, gluProject, gluUnProject



                                                             GLUNPROJECT4(3G)