I'm making a puzzle map for L4D2 with one of the puzzles involving 3 people riding a lift.
My problem is making the lift work when exactly 3 people are on it.
At the moment I have a trigger_multiple adding and subtracting 1 to and from a math_counter whenever a player enters or leaves the trigger volume.
The counters max is set to 3, so when the HitMax output fires, a button unlocks allowing the lift to be operated. However, the problem with this is that 3 people can enter the trigger, exit, then operate the lift with no one on it.
How can I go about preventing the lift from working whenever anything other than 3 people are stood on it?