1GLDEPTHFUNC(3G)                                                GLDEPTHFUNC(3G)
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NAME

6       glDepthFunc - specify the value used for depth buffer comparisons
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C SPECIFICATION

10       void glDepthFunc( GLenum func )
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PARAMETERS

14       func  Specifies  the  depth  comparison  function.   Symbolic constants
15             GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER,  GL_NOTEQUAL,
16             GL_GEQUAL,  and  GL_ALWAYS  are  accepted.   The initial value is
17             GL_LESS.
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DESCRIPTION

20       glDepthFunc specifies the function used to compare each incoming  pixel
21       depth value with the depth value present in the depth buffer.  The com‐
22       parison is performed only if depth testing is enabled.   (See  glEnable
23       and glDisable of GL_DEPTH_TEST.)
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25       func specifies the conditions under which the pixel will be drawn.  The
26       comparison functions are as follows:
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28       GL_NEVER        Never passes.
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30       GL_LESS         Passes if the incoming depth value  is  less  than  the
31                       stored depth value.
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33       GL_EQUAL        Passes  if  the  incoming  depth  value is equal to the
34                       stored depth value.
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36       GL_LEQUAL       Passes if the incoming depth  value  is  less  than  or
37                       equal to the stored depth value.
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39       GL_GREATER      Passes  if the incoming depth value is greater than the
40                       stored depth value.
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42       GL_NOTEQUAL     Passes if the incoming depth value is not equal to  the
43                       stored depth value.
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45       GL_GEQUAL       Passes  if  the incoming depth value is greater than or
46                       equal to the stored depth value.
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48       GL_ALWAYS       Always passes.
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50       The initial value of func is GL_LESS.  Initially, depth testing is dis‐
51       abled.  Even if the depth buffer exists and the depth mask is non-zero,
52       the depth buffer is not updated if the depth test is disabled.
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ERRORS

55       GL_INVALID_ENUM is generated if func is not an accepted value.
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57       GL_INVALID_OPERATION is generated if glDepthFunc  is  executed  between
58       the execution of glBegin and the corresponding execution of glEnd.
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ASSOCIATED GETS

61       glGet with argument GL_DEPTH_FUNC
62       glIsEnabled with argument GL_DEPTH_TEST
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SEE ALSO

65       glDepthRange(3G), glEnable(3G), glPolygonOffset(3G)
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69                                                               GLDEPTHFUNC(3G)