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:
                   ( objX  ) = INV(PM)(_________________ - 1  )

     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