fglDepthFunc(3G) OpenGL Reference fglDepthFunc(3G)NAME
fglDepthFunc - specify the value used for depth buffer comparisons
FORTRAN SPECIFICATION
SUBROUTINE fglDepthFunc( INTEGER*4 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
fglDepthFunc 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 fglEnable
and fglDisable 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.
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fglDepthFunc(3G) OpenGL Reference fglDepthFunc(3G)ERRORS
GL_INVALID_ENUM is generated if func is not an accepted value.
GL_INVALID_OPERATION is generated if fglDepthFunc is executed between the
execution of fglBegin and the corresponding execution of fglEnd.
ASSOCIATED GETS
fglGet with argument GL_DEPTH_FUNC
fglIsEnabled with argument GL_DEPTH_TEST
SEE ALSO
fglDepthRange, fglEnable, fglPolygonOffset
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