gluUnProject()                                     gluUnProject()

NAME    [Toc]    [Back]

       gluUnProject  -  map  window coordinates to object coordinates

SYNOPSIS    [Toc]    [Back]

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

PARAMETERS    [Toc]    [Back]

       Specify the window coordinates to  be  mapped.   Specifies
       the  modelview  matrix  (as  from  a glGetDoublev() call).
       Specifies the projection matrix (as from a  glGetDoublev()
       call).   Specifies the viewport (as from a glGetIntegerv()
       call).  Returns the computed object coordinates.

DESCRIPTION    [Toc]    [Back]

       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:
                           (2(winX - view[0]) / view[2]) -1  objX
       (2(winY  -  view[1])  /  view[3])  -1 objY  = INV(PM) objZ
       2(winZ) -1 W                            1

       INV() denotes matrix inversion. W is an  unused  variable,
       included for consistent matrix notation.

SEE ALSO    [Toc]    [Back]

       glGet(3), gluProject(3)



                                                   gluUnProject()