2:35 PM PT -- The judge just decided there's enough to take Rocky's case to trial. He'll answer to two counts of first-degree assault with a firearm ... arraignment on January 8.

Potentially huge development in the A$AP Rocky assault case ... prosecutors just showed what they claim is video of him holding a gun before allegedly shooting former fellow Mob member A$AP Relli.

The video was played in an L.A. courtroom Monday afternoon, and prosecutors say that's Rocky in the clip holding a gun during a physical altercation with Relli.

LAPD detective Frank Flores took the stand, and testified cops obtained the video during the course of their investigation. The prosecution also showed still photos from the footage to bolster their claim it's A$AP Rocky with a gun.

Rihanna's baby daddy was in court as prosecutors made their case against him ... wearing a dark blue suit, black glasses and black facemask, remaining stoic throughout the explosive testimony against him.

Prosecutors also played a separate clip of what they say are 2 gunshots ... though there's been no video of the alleged shooting itself. Relli claims Rocky shot his hand.

Police body cam video was also shown in court ... and it shows at least 7 officers arriving at the scene of the alleged shooting and canvassing for evidence ... they never find the weapon.

As we reported... Relli claims he had beef with Rocky leading up to the alleged incident, and he testified Rocky put a gun to his stomach during a heated exchange.

Relli previously testified Rocky didn't shoot right then and there, instead claiming the bullets started flying shortly after they separated. He says Rocky took off running and left him on the street after firing about 4 shots.

While cops say they didn't find any shell casings, Relli claims he came back to the scene later that night and recovered a pair of 9mm shells. Rocky's lawyers grilled him over the claim, asking how he could easily find casings when the cops could not.