turf/proximity_platform
    var
        //This is the icon and icon state for the image that
        //will be created.
        proximity_icon
        proximity_icon_state

        //The offset of the platform from the turf's layer.
        proximity_layer_offset = 0.5

        //The distance the player has to be from the
        //platform to see it.
        proximity_distance = 5

        //The image for the platform.
        image/image

    New()
        image = new(proximity_icon, proximity_icon_state)
        image.layer = src.layer + proximity_layer_offset
        image.loc = src

mob
    Move()
        if(client)
            //If the mob has a client (it's a player), then
            //search for platforms.
            ProximityCheck()

        //Call the parent proc.
        ..()

    proc/ProximityCheck()
        //A list of everything in view.
        var/list/view = view(src, client.view)

        for(var/turf/proximity_platform/p in view)
            if(get_dist(src, p) <= p.proximity_distance)
                //If the platform is in view, add it to the
                //client's images.
                client.AddProximityPlatform(p)

            else
                //If not, remove it.
                client.RemoveProximityPlatform(p)

client/proc
    //These are in their own procs so that you can modify
    //them to perform special actions, if you need to.
    AddProximityPlatform(turf/proximity_platform/p)
        //Returns true if p wasn't in images. See below.
        . = !(p in images)
        images += p

    RemoveProximityPlatform(turf/proximity_platform/p)
        //Returns true is p was in images. See below. 
        . = (p in images)

        images -= p

/*
The assignment of the . value is to check whether the image
was or wasn't already in the list, depending on the proc.
This allows you do do . = ..() and then check the value of
. to determine whether a specific action should be carried
out. You may not want to do something if something was
already removed from the list.
*/