just give him a subtle sign and see if he approaches
give him a eye (don't just glance at him give him a eye to eye stare, if he stares back give him a wink or other sign, see if he does it back)
or mingle with him, sit (go) next to him and say hi maybe (I think that one works for women better, gay guys gets offended lol )
women at least would say hi orΒ I'm sorry - blah - but gay guys .. I've seen people getting into a fight or cussing at each other just because he said hi and he wasn't his type.
see? sometime its worse.