fgluUnProject4(3G)

NAME
     fgluUnProject4 - map window and clip coordinates to object coordinates


FORTRAN SPECIFICATION
     INTEGER*4 fgluUnProject4( REAL*4 winX,
                               REAL*4 winY,
                               REAL*4 winZ,
                               REAL*4 clipW,
                               CHARACTER*8 model,
                               CHARACTER*8 proj,
                               CHARACTER*8 view,
                               REAL*4 near,
                               REAL*4 far,
                               CHARACTER*8 objX,
                               CHARACTER*8 objY,
                               CHARACTER*8 objZ,
                               CHARACTER*8 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
     fgluUnProject4 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), fgluUnProject4
     multiplies the normalized device coordinates by the inverse of model*proj
     as follows:
                   ( objX  ) = INV(PM)(_________________ - 1  )

     INV() denotes matrix inversion.

     fgluUnProject4 is equivalent to fgluUnProject when clipW is 1, near is 0
     and far is 1.

NOTES
     fgluUnProject4 is available only if the GLU version is 1.3 or greater.

SEE ALSO
     glGet, glFeedbackBuffer, fgluProject, fgluUnProject