pub type PFNGLPASSTEXCOORDATIPROC = Option<unsafe extern "C" fn(dst: GLuint, coord: GLuint, swizzle: GLenum)>;
enum PFNGLPASSTEXCOORDATIPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: u32)), }
No value.
Some value of type T.
T