glDepthFunc — specify the value used for depth buffer comparisons
void glDepthFunc( | GLenum | func); |
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_NEVERNever passes.
GL_LESSPasses if the incoming depth value is less than the stored depth value.
GL_EQUALPasses if the incoming depth value is equal to the stored depth value.
GL_LEQUALPasses if the incoming depth value is less than or equal to the stored depth value.
GL_GREATERPasses if the incoming depth value is greater than the stored depth value.
GL_NOTEQUALPasses if the incoming depth value is not equal to the stored depth value.
GL_GEQUALPasses if the incoming depth value is greater than or equal to the stored depth value.
GL_ALWAYSAlways passes.
The initial value of func is GL_LESS.
Initially, depth testing is disabled. If depth testing is disabled or if no
depth buffer exists, it is as if the depth test always passes.
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.
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.
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