GLDEPTHFUNC() MachTen Programmer’s Manual GLDEPTHFUNC()

NAME
glDepthFunc - specify the value used for depth buffer com-
parisons

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. 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.

ERRORS
GL_INVALID_ENUM is generated if func is not an accepted
value.

GL_INVALID_OPERATION is generated if glDepthFunc is exe-
cuted between the execution of glBegin and the correspond-
ing execution of glEnd.

ASSOCIATED GETS
glGet with argument GL_DEPTH_FUNC
glIsEnabled with argument GL_DEPTH_TEST

SEE ALSO
glDepthRange, glEnable, glPolygonOffset

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