glDepthRange(3G)	       OpenGL Reference		      glDepthRange(3G)

NAME    [Toc]    [Back]

     glDepthRange - specify mapping of depth values from normalized device
     coordinates to window coordinates

C SPECIFICATION    [Toc]    [Back]

     void glDepthRange(	GLclampd near,
			GLclampd far )

PARAMETERS    [Toc]    [Back]

     near  Specifies the mapping of the	near clipping plane to window
	   coordinates.	 The initial value is 0.

     far   Specifies the mapping of the	far clipping plane to window
	   coordinates.	 The initial value is 1.

DESCRIPTION    [Toc]    [Back]

     After clipping and	division by w, depth coordinates range from -1 to 1,
     corresponding to the near and far clipping	planes.	 glDepthRange
     specifies a linear	mapping	of the normalized depth	coordinates in this
     range to window depth coordinates.	 Regardless of the actual depth	buffer
     implementation, window coordinate depth values are	treated	as though they
     range from	0 through 1 (like color	components).  Thus, the	values
     accepted by glDepthRange are both clamped to this range before they are
     accepted.

     The setting of (0,1) maps the near	plane to 0 and the far plane to	1.
     With this mapping,	the depth buffer range is fully	utilized.

NOTES    [Toc]    [Back]

     It	is not necessary that near be less than	far.  Reverse mappings such as
     near = 1, and far = 0 are acceptable.

ERRORS    [Toc]    [Back]

     GL_INVALID_OPERATION is generated if glDepthRange is executed between the
     execution of glBegin and the corresponding	execution of glEnd.

ASSOCIATED GETS    [Toc]    [Back]

     glGet with	argument GL_DEPTH_RANGE


MACHINE	DEPENDENCIES
     Although it is possible to	reverse	the depth mapping so that near is 1
     and far is	0, doing so may	cause severe depth-buffering artifacts on
     InfiniteReality systems.  (This is	particularly true for 15-bit depth
     buffers.)	Therefore this practice	is strongly discouraged.








									Page 1






glDepthRange(3G)	       OpenGL Reference		      glDepthRange(3G)



SEE ALSO
     glDepthFunc, glPolygonOffset, glViewport


									PPPPaaaaggggeeee 2222