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. 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 executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS
glGet with argument GL_DEPTH_FUNC
glIsEnabled with argument GL_DEPTH_TEST

SEE ALSO
glDepthRange(3G), glEnable(3G), glPolygonOffset(3G)