Add layerName and layers options to ol.source.TopoJSON

examples/osm-vector-tiles.html

@@ -3,7 +3,7 @@ layout: example.html
 title: OSM Vector Tiles
 shortdesc: Using OpenStreetMap vector tiles.
 docs: >
-  A simple vector tiles map with Mapzen vector tiles. **Note**: TopoJSON vector tiles are not optimized for rendering - they might clip geometries exactly at the tile boundary instead of adding a buffer, and use geographic coordinates instead of tile relative pixel coordinates in view projection.
+  A simple vector tiles map with Mapzen vector tiles. This example uses the TopoJSON format's `layerName` option to determine the layer ("water", "roads", "buildings") for styling. **Note**: [`ol.format.MVT`](../apidoc/ol.format.MVT.html) is an even more efficient format for vector tiles.
 tags: "vector, tiles, osm, mapzen"
 cloak:
   vector-tiles-5eJz6JX: Your Mapzen API key from https://mapzen.com/developers

examples/osm-vector-tiles.js

@@ -1,4 +1,3 @@
-goog.require('ol.Attribution');
 goog.require('ol.Map');
 goog.require('ol.View');
 goog.require('ol.format.TopoJSON');
@@ -13,11 +12,6 @@ goog.require('ol.tilegrid');
 
 var key = 'vector-tiles-5eJz6JX';
 
-var attribution = [new ol.Attribution({
-  html: '© OpenStreetMap contributors, Who’s On First, Natural Earth, and openstreetmapdata.com'
-})];
-var format = new ol.format.TopoJSON();
-var tileGrid = ol.tilegrid.createXYZ({maxZoom: 19});
 var roadStyleCache = {};
 var roadColor = {
   'major_road': '#776',
@@ -34,65 +28,58 @@ var buildingStyle = new ol.style.Style({
     width: 1
   })
 });
+var waterStyle = new ol.style.Style({
+  fill: new ol.style.Fill({
+    color: '#9db9e8'
+  })
+});
+var roadStyle = function(feature) {
+  var kind = feature.get('kind');
+  var railway = feature.get('railway');
+  var sort_key = feature.get('sort_key');
+  var styleKey = kind + '/' + railway + '/' + sort_key;
+  var style = roadStyleCache[styleKey];
+  if (!style) {
+    var color, width;
+    if (railway) {
+      color = '#7de';
+      width = 1;
+    } else {
+      color = roadColor[kind];
+      width = kind == 'highway' ? 1.5 : 1;
+    }
+    style = new ol.style.Style({
+      stroke: new ol.style.Stroke({
+        color: color,
+        width: width
+      }),
+      zIndex: sort_key
+    });
+    roadStyleCache[styleKey] = style;
+  }
+  return style;
+};
 
 var map = new ol.Map({
   layers: [
     new ol.layer.VectorTile({
       source: new ol.source.VectorTile({
-        attributions: attribution,
-        format: format,
-        tileGrid: tileGrid,
-        url: 'https://tile.mapzen.com/mapzen/vector/v1/water/{z}/{x}/{y}.topojson?api_key=' + key
+        attributions: '© OpenStreetMap contributors, Who’s On First, ' +
+            'Natural Earth, and openstreetmapdata.com',
+        format: new ol.format.TopoJSON({
+          layerName: 'layer',
+          layers: ['water', 'roads', 'buildings']
+        }),
+        tileGrid: ol.tilegrid.createXYZ({maxZoom: 19}),
+        url: 'https://tile.mapzen.com/mapzen/vector/v1/all/{z}/{x}/{y}.topojson?api_key=' + key
       }),
-      style: new ol.style.Style({
-        fill: new ol.style.Fill({
-          color: '#9db9e8'
-        })
-      })
-    }),
-    new ol.layer.VectorTile({
-      source: new ol.source.VectorTile({
-        attributions: attribution,
-        format: format,
-        tileGrid: tileGrid,
-        url: 'https://tile.mapzen.com/mapzen/vector/v1/roads/{z}/{x}/{y}.topojson?api_key=' + key
-      }),
-      style: function(feature) {
-        var kind = feature.get('kind');
-        var railway = feature.get('railway');
-        var sort_key = feature.get('sort_key');
-        var styleKey = kind + '/' + railway + '/' + sort_key;
-        var style = roadStyleCache[styleKey];
-        if (!style) {
-          var color, width;
-          if (railway) {
-            color = '#7de';
-            width = 1;
-          } else {
-            color = roadColor[kind];
-            width = kind == 'highway' ? 1.5 : 1;
-          }
-          style = new ol.style.Style({
-            stroke: new ol.style.Stroke({
-              color: color,
-              width: width
-            }),
-            zIndex: sort_key
-          });
-          roadStyleCache[styleKey] = style;
+      style: function(feature, resolution) {
+        switch (feature.get('layer')) {
+          case 'water': return waterStyle;
+          case 'roads': return roadStyle(feature);
+          case 'buildings': return (resolution < 10) ? buildingStyle : null;
+          default: return null;
         }
-        return style;
-      }
-    }),
-    new ol.layer.VectorTile({
-      source: new ol.source.VectorTile({
-        attributions: attribution,
-        format: format,
-        tileGrid: tileGrid,
-        url: 'https://tile.mapzen.com/mapzen/vector/v1/buildings/{z}/{x}/{y}.topojson?api_key=' + key
-      }),
-      style: function(f, resolution) {
-        return (resolution < 10) ? buildingStyle : null;
       }
     })
   ],

examples/topojson.js

@@ -29,13 +29,14 @@ var style = new ol.style.Style({
 var vector = new ol.layer.Vector({
   source: new ol.source.Vector({
     url: 'data/topojson/world-110m.json',
-    format: new ol.format.TopoJSON(),
+    format: new ol.format.TopoJSON({
+      // don't want to render the full world polygon (stored as 'land' layer),
+      // which repeats all countries
+      layers: ['countries']
+    }),
     overlaps: false
   }),
-  style: function(feature) {
-    // don't want to render the full world polygon, which repeats all countries
-    return feature.getId() !== undefined ? style : null;
-  }
+  style: style
 });
 
 var map = new ol.Map({