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GLDEPTHFUNC(3G)                                                                              GLDEPTHFUNC(3G)



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 comparison 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 disabled.  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)