rooftop removal and restore script for roll20. WIP, probably awful in lots of ways. Didn't test much.

rooftops.js

// a script to remove rooftops if a player enters a building

on("ready", function() {
    "use strict";

    var allPlayerTokens = [];
    var allRoofTokens = [];

    function getPlayerTokens()
    {   
        var campaign = findObjs({type: "campaign"})[0];
        var allTokens = findObjs({type: 'graphic', pageid: campaign.get("playerpageid"), layer: "objects"});
        allPlayerTokens = [];
        for (var i = 0; i<allTokens.length; i++)
        {
            if (allTokens[i].get("controlledby") != "" || allTokens[i].get("represents"))
            {
                if (allTokens[i].get("represents"))
                {
                    if (getObj('character', allTokens[i].get("represents")).get("controlledby"))
                    {
                        allPlayerTokens.push(allTokens[i]);        
                    }

                }
                else
                {
                    allPlayerTokens.push(allTokens[i]);
                }
            }
        }
    }

    function getRoofTokens()
    {
        var campaign = findObjs({type: "campaign"})[0];
        var allMapTokens = findObjs({type: 'graphic', pageid: campaign.get("playerpageid")});
        allRoofTokens = [];
        for (var i = 0; i<allMapTokens.length; i++)
        {
            if (allMapTokens[i].get("name") == "roof")
            {
                allRoofTokens.push(allMapTokens[i]);
            }
        }
    }

    function roofInsideCheck(roofToken)
    {
        var anyoneInside = false;
        for (var i = 0; i < allPlayerTokens.length; i++)
        {
            if (roofToken.get("left") - roofToken.get("width")/2 < allPlayerTokens[i].get("left") &&
                roofToken.get("left") + roofToken.get("width")/2 > allPlayerTokens[i].get("left") &&
                roofToken.get("top") - roofToken.get("height")/2 < allPlayerTokens[i].get("top") &&
                roofToken.get("top") + roofToken.get("height")/2 > allPlayerTokens[i].get("top"))
                {
                    anyoneInside = true;
                }
        }
        return anyoneInside;
    }

    function removeRoof(roofID)
    {
        getObj('graphic', roofID).set("layer", "walls");
    }

    function restoreRoof(roofID)
    {
        getObj('graphic', roofID).set("layer", "map");
    }

    on("change:campaign:playerpageid", function() {
        getPlayerTokens();
        getRoofTokens();
        sendChat("", "/w gm &{template:default} {{name=Rooftops Ready}} {{Player Tokens=" + allPlayerTokens.length + 
        "}} {{Roof Tokens=" + allRoofTokens.length + "}}")
    });

    on("chat:message", function (msg) {
        if (msg.type === 'api' && msg.content === "!RoofReady"){
            getPlayerTokens();
            getRoofTokens();
            sendChat("", "/w gm &{template:default} {{name=Rooftops Ready}} {{Player Tokens=" + allPlayerTokens.length + 
            "}} {{Roof Tokens=" + allRoofTokens.length + "}}")
        }
    });

    on("change:graphic", function(obj){
        if (allPlayerTokens.includes(obj)) 
        { 
            for (var i = 0; i < allRoofTokens.length; i++)
            {
                if (roofInsideCheck(allRoofTokens[i])) { removeRoof(allRoofTokens[i].id);  }
                else                                   { restoreRoof(allRoofTokens[i].id); }
            }
        }
    });
});