How to make limited ammo

I made a variable for every attack type which decays every time you shoot with that specific weapon type.

My code line for shooting is "On key pressed.... player spawns X on image point 1"

1) How do I make it impossible to shoot again when the variable equals zero? I want this object to not be able to spawn again if you have no ammunition.

2) Also, how do I make my shots move at the opposite direction when my character is mirrored? (Without affecting the bullets already in air)

Thank you.

If you already have an ammo number variable, right click the 'On key pressed' condition, add another condition :

System -> Compare variable -> "Ammo > 0". This will mean the object will only spawn if you press the key AND ammo > 0.

To mirror the shots, I would change "player spawns X on image point 1" to "player spawns X on image point 1 at angle X" where X is a variable that changes depending on a Boolean that is true or false depending on wether the character is mirrored or not.