glDepthFunc

glDepthFunc

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 default value is GL_LESS.

DESCRIPTION

glDepthFunc specifies the function used to compare each incoming pixel z value with the z 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 z value is less than the stored z value.

GL_EQUAL ? Passes if the incoming z value is equal to the stored z value.

GL_LEQUAL ? Passes if the incoming z value is less than or equal to the stored z value.

GL_GREATER ?

Passes if the incoming z value is greater than the stored z value.

GL_NOTEQUAL ?

Passes if the incoming z value is not equal to the stored z value.

GL_GEQUAL ? Passes if the incoming z value is greater than or equal to the stored z value.

GL_ALWAYS ? Always passes.

The default value of func is GL_LESS. Initially, depth testing is disabled.

ERRORS

GL_INVALID_ENUM is generated if func is not an accepted value.

GL_INVALID_OPERATION is generated if glDepthFunc is called between a call to glBegin and the corresponding call to glEnd.

ASSOCIATED GETS

glGet with argument GL_DEPTH_FUNC

glIsEnabled with argument GL_DEPTH_TEST

SEE ALSO

"glDepthRange" , "glEnable"