bgfx_sys::BGFX_STATE_ALPHA_REF!

macro_rules! BGFX_STATE_ALPHA_REF {
    ($aref:expr) => ((($aref as u64) << bgfx_sys::BGFX_STATE_ALPHA_REF_SHIFT) & bgfx_sys::BGFX_STATE_ALPHA_REF_MASK)
}