glDepthRange(3)

NAME

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

C SPECIFICATION

       void glDepthRange( GLclampd near_val,
                          GLclampd far_val )

       delim $$

PARAMETERS

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

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

DESCRIPTION

       After clipping and division by w, depth coordinates range from -1 to 1,
       corresponding to the near and far clipping planes.  glDepthRange speci-
       fies 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

       It is not necessary that near_val be less than far_val.   Reverse  map-
       pings such as $"near_val" ~=~ 1$, and $"far_val" ~=~ 0$ are acceptable.

ERRORS

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

ASSOCIATED GETS

       glGet with argument GL_DEPTH_RANGE

SEE ALSO

       glDepthFunc(3G), glPolygonOffset(3G), glViewport(3G)

                                                              GLDEPTHRANGE(3G)