Fix fill update

Author: dy

src/traces/scattergl/index.js

@@ -781,9 +781,9 @@ function plot(container, subplot, cdata) {
         }
         // fill requires linked traces, so we generate it's positions here
         if(scene.fill2d) {
-            scene.fillOptions.forEach(function(fillOptions, i) {
+            var fillOptions = scene.fillOptions.map(function(fillOptions, i) {
                 var cdscatter = cdata[i];
-                if(!fillOptions || !cdscatter || !cdscatter[0] || !cdscatter[0].trace) return;
+                if(!fillOptions || !cdscatter || !cdscatter[0] || !cdscatter[0].trace) return {positions: []};
                 var cd = cdscatter[0];
                 var trace = cd.trace;
                 var stash = cd.t;
@@ -863,9 +863,11 @@ function plot(container, subplot, cdata) {
 
                 fillOptions.opacity = trace.opacity;
                 fillOptions.positions = pos;
+
+                return fillOptions;
             });
 
-            scene.fill2d.update(scene.fillOptions);
+            scene.fill2d.update(fillOptions);
         }
     }