With instance_count_region, you can count the number of (specific) instances in a specific region, e.g. in a circle. It's really easy to use, you just need to use the scripts.
Actually you can use:
Maybe i will add some more region shapes, like a star or something like that.
Example:
instance_count_rectangle(x1,y1,x2,y2,prec,notme);
count = instance_count_rectangle(0,0,128,128,0,0);
instance_count_circle_object(x1,y1,x2,y2,obj,prec,notme);
count = instance_count_circle_object(0,0,128,128,obj_test,0,0);
End User Licence Agreement (EULA).
Added instance_count_(region)_object.
With instance_count_(region)_object, you can count the number of an specific instance in a specific region.