pub type PFNGLTEXTURERENDERBUFFEREXTPROC = Option<unsafe extern "C" fn(texture: GLuint, target: GLenum, renderbuffer: GLuint)>;
enum PFNGLTEXTURERENDERBUFFEREXTPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: u32)), }
No value.
Some value of type T.
T