void GLAPIENTRY glDepthRange( GLclampd near_val,
                                     GLclampd far_val )

PARAMETERS
       near_val  Specifies the mapping of the near clipping plane to window co‐
                 ordinates.  The initial value is 0.

       far_val   Specifies  the mapping of the far clipping plane to window co‐
                 ordinates.  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 im‐
       plementation, window coordinate depth values are treated as though  they
       range  from  0  through 1 (like color components).  Thus, the values ac‐
       cepted 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, glPolygonOffset, glViewport

                                                               GLDEPTHRANGE(3G)