glDepthFunc(3G) OpenGL Reference 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
GLNEVER, GLLESS, GLEQUAL, GLLEQUAL, GLGREATER, GLNOTEQUAL,
GLGEQUAL, and GLALWAYS are accepted. The initial value is
GLLESS.
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 GLDEPTHTEST.)
func specifies the conditions under which the pixel will be drawn. The
comparison functions are as follows:
GLNEVER Never passes.
GLLESS Passes if the incoming depth value is less than the
stored depth value.
GLEQUAL Passes if the incoming depth value is equal to the stored
depth value.
GLLEQUAL Passes if the incoming depth value is less than or equal
to the stored depth value.
GLGREATER Passes if the incoming depth value is greater than the
stored depth value.
GLNOTEQUAL Passes if the incoming depth value is not equal to the
stored depth value.
GLGEQUAL Passes if the incoming depth value is greater than or
equal to the stored depth value.
GLALWAYS Always passes.
The initial value of func is GLLESS. 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.
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glDepthFunc(3G) OpenGL Reference glDepthFunc(3G)
ERRORS
GLINVALIDENUM is generated if func is not an accepted value.
GLINVALIDOPERATION is generated if glDepthFunc is executed between the
execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGet with argument GLDEPTHFUNC
glIsEnabled with argument GLDEPTHTEST
SEE ALSO
glDepthRange, glEnable, glPolygonOffset
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