glDepthFunc

Name

glDepthFunc â 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. +

Description

+ 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. If depth testing is disabled or if no + depth buffer exists, it is as if the depth test always passes. +

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. In order to + unconditionally write to the depth buffer, the depth test should be enabled + and set to GL_ALWAYS. +

Errors

+ GL_INVALID_ENUM is generated if func is not an accepted value. +

Associated Gets

+ glGet with argument GL_DEPTH_FUNC +

+ glIsEnabled with argument GL_DEPTH_TEST +