GLdouble winY,
                                       GLdouble winZ,
                                       GLdouble clipW,
                                       const GLdouble *model,
                                       const GLdouble *proj,
                                       const GLint *view,
                                       GLdouble nearVal,
                                       GLdouble farVal,
                                       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).

       nearVal, farVal 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 GL_4D_COLOR_TEXTURE is re‐
       turned.  This also handles the case where the nearVal and farVal  planes
       are  different  from the default, 0 and 1, respectively.  A return value
       of GL_TRUE indicates success; a return value of GL_FALSE 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:

                           objX
                          ⎝objY⎠=INV(PM)⎝_______________−1 ⎠
                           objZ          _______________−1
                           objW          ________________−1
                                                clipW