GLDEPTHFUNC(3G) 						   OpenGL Manual						   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. If depth testing is disabled or if no depth buffer exists, it
       is as if the depth test always passes.

NOTES

       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. In order to
       unconditionally write to the depth buffer, the depth test should be enabled and set to GL_ALWAYS.

ERRORS

       GL_INVALID_ENUM is generated if func is not an accepted value.

ASSOCIATED GETS

       glGet() with argument GL_DEPTH_FUNC

       glIsEnabled() with argument GL_DEPTH_TEST

SEE ALSO

       glDepthRange(), glEnable(), glPolygonOffset()

COPYRIGHT

       Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

AUTHORS

       opengl.org

opengl.org							    06/10/2014							   GLDEPTHFUNC(3G)