Fix layering issue with basemap tiles using order of 0

src/layer/tile/ImageTile.js

@@ -69,10 +69,10 @@ class ImageTile extends Tile {
     localMesh.rotation.x = -90 * Math.PI / 180;
 
     localMesh.receiveShadow = true;
-    localMesh.renderOrder = 0;
+    localMesh.renderOrder = -1;
 
     mesh.add(localMesh);
-    mesh.renderOrder = 0;
+    mesh.renderOrder = -1;
 
     mesh.position.x = this._center[0];
     mesh.position.z = this._center[1];

src/layer/tile/ImageTileLayer.js

@@ -83,7 +83,7 @@ class ImageTileLayer extends TileLayer {
         }
 
         var mesh = new THREE.Mesh(geom, baseMaterial);
-        mesh.renderOrder = -1;
+        mesh.renderOrder = -2;
         mesh.rotation.x = -90 * Math.PI / 180;
 
         // TODO: It might be overkill to receive a shadow on the base layer as it's