I did it in my old project (
)
if I remember well ( I don't have my project right now ) I set some variables inside the barrel that say the distance in pixel where the player have to go, the angle, etc... when the player jump on it, if I remember I disabled the platform behavior or I set the gravity 0 of the player, and made a new system to menage the movement of the player while fly (you can do it in different ways) , and when the player reach the distance, I activate the gravity or the platform player and simulate a movement from the platform behavior (right or left) it depends where the player is direct