“Blade: Trinity” (New Line Cinema) has serious identity issues. Is this an action movie? A horror movie? A buddy comedy? A surreal blend of all three? Like a raging alcoholic at a Christmas party, the film staggers about, alternating between charming humor and harsh violence, always demanding your attention in the most garish way possible. Unless the idea of poorly constructed postmodern vampire pastiche makes you want to break out in song and dance, forming a gothic conga line to the nearest theater, you’d be better served watching the film’s earlier, more consistent iterations.

There’s really nothing here we haven’t seen before. Boy meets vampire. Boy slays vampire uses an array of neat weapons. Alliances are formed with like-minded vampire hunters, and for a period of time the vampires seem certain to triumph. But then there’s a big shootout at the vampire headquarters. The world is saved and everyone goes home happy.

The film’s title would have you believe that its formula was considerably shook up by the addition of new vampire hunters Hannibal King (Ryan Reynolds) and Abigail Whistler (Jessica Biel). But in truth, Blade’s always had sidekicks – this time around they’re simply better looking and armed with an array of snappy comebacks.

It’s a welcome addition though, because the humor is, oddly enough, the film’s strongest part. Off-color comebacks, sly digs at the commercialization of vampire lore and a few amusing scenes with a Pomeranian help the film’s ludicrous plot go down smoothly. It’s only when the film tries to ape motions of its overly-gothic predecessors that the franchise starts to show its age.

Perhaps writer/director David S. Goyer (who penned all three “Blade” films) was really sick of making these movies and wanted to open them up, explore their foibles and make a really fast, fresh action/comedy, but his plans were reigned in by overly cautious studio execs who demanded he “goth it up” to avoid alienating the base. The result is a tepid, if not exactly unpleasant film, that can’t really live up to the series’ potential.

“Blade: Trinity” opens Friday in Washington, D.C.