glDepthFunc(3)

NAME

       glDepthFunc - specify the value used for depth buffer comparisons

C SPECIFICATION

       void glDepthFunc( GLenum func )

PARAMETERS

       func  Specifies  the  depth  comparison  function.   Symbolic constants
             GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER,  GL_NOTEQUAL,
             GL_GEQUAL,  and  GL_ALWAYS  are  accepted.   The initial value is
             GL_LESS.

DESCRIPTION

       glDepthFunc specifies the function used to compare each incoming  pixel
       depth value with the depth value present in the depth buffer.  The com-
       parison is performed only if depth testing is enabled.   (See  glEnable
       and glDisable of GL_DEPTH_TEST.)

       func specifies the conditions under which the pixel will be drawn.  The
       comparison functions are as follows:

       GL_NEVER        Never passes.

       GL_LESS         Passes if the incoming depth value  is  less  than  the
                       stored depth value.

       GL_EQUAL        Passes  if  the  incoming  depth  value is equal to the
                       stored depth value.

       GL_LEQUAL       Passes if the incoming depth  value  is  less  than  or
                       equal to the stored depth value.

       GL_GREATER      Passes  if the incoming depth value is greater than the
                       stored depth value.

       GL_NOTEQUAL     Passes if the incoming depth value is not equal to  the
                       stored depth value.

       GL_GEQUAL       Passes  if  the incoming depth value is greater than or
                       equal to the stored depth value.

       GL_ALWAYS       Always passes.

       The initial value of func is GL_LESS.  Initially, depth testing is dis-
       abled.  Even if the depth buffer exists and the depth mask is non-zero,
       the depth buffer is not updated if the depth test is disabled.

ERRORS

       GL_INVALID_ENUM is generated if func is not an accepted value.

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

ASSOCIATED GETS

       glGet with argument GL_DEPTH_FUNC
       glIsEnabled with argument GL_DEPTH_TEST

SEE ALSO

       glDepthRange(3G), glEnable(3G), glPolygonOffset(3G)

                                                               GLDEPTHFUNC(3G)