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GLUUNPROJECT4(3G)                                                                          GLUUNPROJECT4(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 glGetDoublev 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 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 GL_TRUE indicates success; a return value of GL_FALSE indicates failure.

       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(3G), glFeedbackBuffer(3G), gluProject(3G), gluUnProject(3G)




                                                                                           GLUUNPROJECT4(3G)