glDepthFunc(3G)		       OpenGL Reference		       glDepthFunc(3G)

NAME    [Toc]    [Back]

     glDepthFunc - specify the value used for depth buffer comparisons

C SPECIFICATION    [Toc]    [Back]

     void glDepthFunc( GLenum func )

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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 nonzero,
 the depth buffer is not updated if the depth	test is	disabled.







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glDepthFunc(3G)		       OpenGL Reference		       glDepthFunc(3G)



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    [Toc]    [Back]

     glGet with	argument GL_DEPTH_FUNC
     glIsEnabled with argument GL_DEPTH_TEST

SEE ALSO    [Toc]    [Back]

     glDepthRange, glEnable, glPolygonOffset


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