Change opacity to an actor

MarkOnTheIron

I want to make a rule that allow an actor (a wall) to become partially invisible when the main actor go behind it.
Is it possible?

MarkOnTheIron

Just to complicate it more I want the wall to partially disappear when the main actor pass over a certain area and then return to normal when he leaves it.

CodeMonkey

Make a rule in the wall actor that when the main actor collides with it, change attribute: self.Color.alpha = .5. Otherwise Change Attribute self.Color.alpha = 1
Similarly create a game attribute that when an actor is over an actor that covers your certain area in the game, that attribute is changed.

IN THE WALL ACTOR:
Rule: When actor receives event 'overlaps or collides' with (mainactor)
OR
--Change Attribute: self.Color.Alpha = .5
Otherwise:
--Change Attribute: self.Color.Alpha = 1

Rule: When Attribute game.InArea = true
OR
--Change Attribute: self.Color.Alpha = 0
Otherwise:
--Change Attribute: self.Color.Alpha = 1

IN THE AREA ACTOR:
Rule: When actor receives event 'overlaps or collides' with (mainactor)
OR
--Change Attribute: game.InArea = true
Otherwise:
--Change Attribute: game.InArea = false