gluUnProject4(3G)	       OpenGL Reference		     gluUnProject4(3G)

NAME    [Toc]    [Back]

     gluUnProject4 - map window	and clip coordinates to	object coordinates

C SPECIFICATION    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     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:



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gluUnProject4(3G)	       OpenGL Reference		     gluUnProject4(3G)


				      (			      )
				      |			      |
				      |_________________      |
		   (	   )	      |	    view[2]	 - 1  |
		   | objX  |	      |			      |
		   | objY  | = INV(PM)|_________________ - 1  |
		   |	   |	      |	    view[3]	      |
		   | objZ  |	      |	______________	      |
		   ( objW  )	      |	 (far -	near)  - 1    |
				      (			      )
					       clipW
     INV() denotes matrix inversion.

     gluUnProject4 is equivalent to gluUnProject when clipW is 1, near is 0
     and far is	1.

NOTES    [Toc]    [Back]

     gluUnProject4 is available	only if	the GLU	version	is 1.3 or greater.

SEE ALSO    [Toc]    [Back]

     glGet, glFeedbackBuffer, gluProject, gluUnProject


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