gluUnProject(3G)

NAME
     gluUnProject - map window coordinates to object coordinates


C SPECIFICATION
     GLint gluUnProject( GLdouble winX,
                         GLdouble winY,
                         GLdouble winZ,
                         const GLdouble *model,
                         const GLdouble *proj,
                         const GLint *view,
                         GLdouble* objX,
                         GLdouble* objY,
                         GLdouble* objZ )


PARAMETERS
     winX, winY, winZ
                     Specify the window coordinates 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).

     objX, objY, objZ
                     Returns the computed object coordinates.

DESCRIPTION
     gluUnProject maps the specified window coordinates into object
     coordinates using model, proj, and view.  The result is stored in objX,
     objY, and objZ. A return value of GL_TRUE indicates success; a return
     value of GL_FALSE indicates failure.

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






                   ( objX  ) = INV(PM)(_________________ - 1  )
     INV() denotes matrix inversion. W is an unused variable, included for
     consistent matrix notation.

SEE ALSO
     glGet, gluProject