NAME

glDepthFunc - specify the value used for depth buffer comparisons

C SPECIFICATION

void ggllDDeepptthhFFuunncc( GLenum _f_u_n_c )

        

PARAMETERS

_f_u_n_c
Specifies the depth comparison function. Symbolic constants GGLL__NNEEVVEERR, GGLL__LLEESSSS, GGLL__EEQQUUAALL, GGLL__LLEEQQUUAALL, GGLL__GGRREEAATTEERR, GGLL__NNOOTTEEQQUUAALL, GGLL__GGEEQQUUAALL, and GGLL__AALLWWAAYYSS are accepted. The initial value is GGLL__LLEESSSS.

DESCRIPTION

ggllDDeepptthhFFuunncc 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 ggllEEnnaabbllee and ggllDDiissaabbllee of GGLL__DDEEPPTTHH__TTEESSTT.)

_f_u_n_c specifies the conditions under which the pixel will be drawn. The comparison functions are as follows:

GGLL__NNEEVVEERR
Never passes.
GGLL__LLEESSSS
Passes if the incoming depth value is less than the stored depth value.
GGLL__EEQQUUAALL
Passes if the incoming depth value is equal to the stored depth value.
GGLL__LLEEQQUUAALL
Passes if the incoming depth value is less than or equal to the stored depth value.
GGLL__GGRREEAATTEERR
Passes if the incoming depth value is greater than the stored depth value.
GGLL__NNOOTTEEQQUUAALL
Passes if the incoming depth value is not equal to the stored depth value.
GGLL__GGEEQQUUAALL
Passes if the incoming depth value is greater than or equal to the stored depth value.
GGLL__AALLWWAAYYSS
Always passes.

The initial value of _f_u_n_c is GGLL__LLEESSSS. 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

GGLL__IINNVVAALLIIDD__EENNUUMM is generated if _f_u_n_c is not an accepted value.

GGLL__IINNVVAALLIIDD__OOPPEERRAATTIIOONN is generated if ggllDDeepptthhFFuunncc is executed between the execution of ggllBBeeggiinn and the corresponding execution of ggllEEnndd.

ASSOCIATED GETS

ggllGGeett with argument GGLL__DDEEPPTTHH__FFUUNNCC
ggllIIssEEnnaabblleedd with argument GGLL__DDEEPPTTHH__TTEESSTT

SEE ALSO

ggllDDeepptthhRRaannggee((33GG)), ggllEEnnaabbllee((33GG)), ggllPPoollyyggoonnOOffffsseett((33GG))