Expose filtered field

lib/carto/renderer_js.js

@@ -229,6 +229,8 @@ CartoCSS.prototype = {
           // serach the max index to know rendering order
           lyr.index = _.max(props[v].map(function(a) { return a.index; }).concat(lyr.index));
           lyr.constant = !_.any(props[v].map(function(a) { return !a.constant; }));
+          // True when the property is filtered.
+          lyr.filtered = props[v][0].filtered;
         }
       }
 

lib/carto/tree/definition.js

@@ -236,7 +236,11 @@ tree.Definition.prototype.toJS = function(env) {
         }
 
         r.constant = rule.value.ev(env).is !== 'field';
-        r.filtered = !!_if;
+        var DEFAULT_FILTER = "(8388607 & (1 << ctx.zoom))";
+        r.filtered = false;
+        if (_if && _if !== DEFAULT_FILTER){
+            r.filtered = true;
+        }
 
         shaderAttrs[rule.name].push(r);
       } else {