|obj||The object or instance to activate (the keyword all can also be used).|
With this function you can activate a single instance or all
instances of a specific object from all those that have been
instance_deactivate_region(view_xview - 64, view_yview - 64, view_wview + 128, view_hview + 128, false, false);
The above code activates all instances within the room and then deactivates those that are outside of the limits of the current view, except for the object "obj_Lights" which are re-activated again at the end.