Bradley Cooper On Set of Leonard Bernstein Movie Kissing Matt Bomer

Bradley Cooper is living life through the late Leonard Bernstein's eyes while he shoots a movie about the guy's life -- which translated to a kissing scene with Matt Bomer this week.

The two actors locked lips on set Monday in NYC, where they're shooting this new Netflix biopic about the legendary conductor -- titled "Maestro" -- and it seems the smooching went well ... 'cause BC was all smiles during the scene, as was Matt.

Of course, Bernstein was openly gay -- so it's no surprise/NBD the lead star is making out with a dude for the flick -- if anything, it was 100% expected. Bomer just happened to be the lucky man to land the role of romantic interest ... and fun fact, Matt's gay in real life.

What's been getting way more buzz as it pertains to the film is how unrecognizable Brad looks as Lenny ... it seems he'll be playing the Maestro at different life stages, including in old age, and some of the shots of Brad in costume and makeup have gotten double-takes.

There's also been some controversy ... it's been noted that Brad's using a prosthetic to make his nose look longer than it really is, which many have called anti-Semitic -- as they see this as clear "Jew face," as it's been dubbed by some.