openGL之API学习（五十四）glDepthFunc

指定深度测试比较的方法，如果满足深度测试条件则赢得深度测试并会被渲染出来。

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.

指定深度比较函数，可以取GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER, GL_NOTEQUAL, GL_GEQUAL, and GL_ALWAYS等。默认值是GL_LESS。

GL_NEVER

    Never passes.

总是不通过测试
GL_LESS

    Passes if the incoming depth value is less than the stored depth value.

较小的值通过测试
GL_EQUAL

    Passes if the incoming depth value is equal to the stored depth value.

相等的值通过测试
GL_LEQUAL

    Passes if the incoming depth value is less than or equal to the stored depth value.

小于等于的值通过测试
GL_GREATER

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

较大的值通过测试
GL_NOTEQUAL

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

不相等的值通过测试
GL_GEQUAL

    Passes if the incoming depth value is greater than or equal to the stored depth value.

大于等于的值通过测试
GL_ALWAYS

    Always passes.

总是通过测试