glDepthFunc

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.

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.

Notes

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