How do I add up a total for all instances of a sprite in a given map zone?

Hello all,

Just starting out with Construct 3 and having a lot of fun learning the systems.

I have a question about making a total for all instances of a sprite.

To give a bit of an overview, in the game I'm currently working on, a player has to move all of a certain type of item into a zone. For example, all blue boxes need to be moved to the blue zone on the game screen. These instances of blue boxes spawn randomly and at the moment I would like to leave the total number of these to be open-ended if possible - although an upper limit can be set if that helps for solving my problem.

So, what I'd like is to be able to add up a "score" for how many blue boxes are in the blue zone (1 "point" per box). If the player moves a blue box out of the zone, the score would then reduce by 1.

I've tried playing with a few things but I can't seem to figure out how to do this!

Any help would be appreciated!

The condition would be 'bluebox overlapping bluezone' and then the action is to set a variable to bluebox.pickedcount

Thank you lionz! This is what I was looking for. However the variable never seems to go below 0 after the first box is placed in the zone, i.e. once I remove all boxes from the zone the variable stays at 1 instead of reducing to 0.

Do I need to add something to this?

Ah yeah that's because the event doesn't run if it can't find any instances that meet the condition, you can add underneath a system Else then set the variable to 0.

That worked perfectly.

Thanks again lionz!