fglDepthFunc(3G)

NAME
     fglDepthFunc - specify the value used for depth buffer comparisons


FORTRAN SPECIFICATION
     SUBROUTINE fglDepthFunc( INTEGER*4 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
     fglDepthFunc 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 fglEnable
     and fglDisable 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 fglDepthFunc is executed between the
     execution of fglBegin and the corresponding execution of fglEnd.

ASSOCIATED GETS
     fglGet with argument GL_DEPTH_FUNC
     fglIsEnabled with argument GL_DEPTH_TEST


SEE ALSO
     fglDepthRange, fglEnable, fglPolygonOffset