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<STRONG>NAME</STRONG>
<STRONG>glDepthFunc</STRONG> - specify the value used for depth buffer
comparisons
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>glDepthFunc</STRONG>( GLenum <EM>func</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>func</EM> Specifies the depth comparison function. Symbolic
constants <STRONG>GL_NEVER</STRONG>, <STRONG>GL_LESS</STRONG>, <STRONG>GL_EQUAL</STRONG>, <STRONG>GL_LEQUAL</STRONG>,
<STRONG>GL_GREATER</STRONG>, <STRONG>GL_NOTEQUAL</STRONG>, <STRONG>GL_GEQUAL</STRONG>, and <STRONG>GL_ALWAYS</STRONG> are
accepted. The initial value is <STRONG>GL_LESS</STRONG>.
<STRONG>DESCRIPTION</STRONG>
<STRONG>glDepthFunc</STRONG> 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 <STRONG>glEnable</STRONG> and <STRONG>glDisable</STRONG> of
<STRONG>GL_DEPTH_TEST</STRONG>.)
<EM>func</EM> specifies the conditions under which the pixel will be
drawn. The comparison functions are as follows:
<STRONG>GL_NEVER</STRONG> Never passes.
<STRONG>GL_LESS</STRONG> Passes if the incoming depth value is less
than the stored depth value.
<STRONG>GL_EQUAL</STRONG> Passes if the incoming depth value is equal
to the stored depth value.
<STRONG>GL_LEQUAL</STRONG> Passes if the incoming depth value is less
than or equal to the stored depth value.
<STRONG>GL_GREATER</STRONG> Passes if the incoming depth value is
greater than the stored depth value.
<STRONG>GL_NOTEQUAL</STRONG> Passes if the incoming depth value is not
equal to the stored depth value.
<STRONG>GL_GEQUAL</STRONG> Passes if the incoming depth value is
greater than or equal to the stored depth
value.
<STRONG>GL_ALWAYS</STRONG> Always passes.
The initial value of <EM>func</EM> is <STRONG>GL_LESS</STRONG>. 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.
<STRONG>ERRORS</STRONG>
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>func</EM> is not an accepted
value.
<STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glDepthFunc</STRONG> is executed
between the execution of <STRONG>glBegin</STRONG> and the corresponding
execution of <STRONG>glEnd</STRONG>.
<STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_DEPTH_FUNC</STRONG>
<STRONG>glIsEnabled</STRONG> with argument <STRONG>GL_DEPTH_TEST</STRONG>
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>glDepthRange</STRONG>, <STRONG>glEnable</STRONG>, <STRONG>glPolygonOffset</STRONG>
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