From b15016a0e45618087ec889c657dd2407541c2534 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Fri, 20 Feb 2015 21:07:06 -0800
Subject: [PATCH] Add feature.toGeoJSON(x, y, z)

---
 lib/vectortilefeature.js | 33 +++++++++++++++++++++++
 package.json             |  3 ++-
 test/parse.test.js       | 58 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/lib/vectortilefeature.js b/lib/vectortilefeature.js
index 667d5dd..4f30479 100644
--- a/lib/vectortilefeature.js
+++ b/lib/vectortilefeature.js
@@ -125,3 +125,36 @@ VectorTileFeature.prototype.bbox = function() {
 
     return [x1, y1, x2, y2];
 };
+
+var SphericalMercator = require('sphericalmercator');
+
+VectorTileFeature.prototype.toGeoJSON = function(x, y, z) {
+    var merc = new SphericalMercator({size: this.extent}),
+        x0 = this.extent * x,
+        y0 = this.extent * y,
+        coords = this.loadGeometry(),
+        type = VectorTileFeature.types[this.type];
+
+    for (var i = 0; i < coords.length; i++) {
+        var line = coords[i];
+        for (var j = 0; j < line.length; j++) {
+            var p = line[j];
+            line[j] = merc.ll([p.x + x0, p.y + y0], z);
+        }
+    }
+
+    if (type === 'Point') {
+        coords = coords[0][0];
+    } else if (type === 'LineString') {
+        coords = coords[0];
+    }
+
+    return {
+        type: "Feature",
+        geometry: {
+            type: type,
+            coordinates: coords
+        },
+        properties: this.properties
+    };
+};
diff --git a/package.json b/package.json
index 45764ec..161fed5 100644
--- a/package.json
+++ b/package.json
@@ -6,7 +6,8 @@
   "license": "BSD",
   "main": "index.js",
   "dependencies": {
-    "point-geometry": "0.0.0"
+    "point-geometry": "0.0.0",
+    "sphericalmercator": "^1.0.3"
   },
   "devDependencies": {
     "benchmark": "^1.0.0",
diff --git a/test/parse.test.js b/test/parse.test.js
index 3679604..2bc0ba5 100644
--- a/test/parse.test.js
+++ b/test/parse.test.js
@@ -55,6 +55,64 @@ test('parsing vector tiles', function(t) {
         t.deepEqual(building, [ [ { x: 1, y: 2 }, { x: 3, y: 4 }, { x: 2032, y: -31 }, { x: 2032, y: -32 }, { x: 2039, y: -32 } ] ]);
         t.end();
     });
+
+    t.test('toGeoJSON', function(t) {
+        var tile = new VectorTile(new Protobuf(data));
+
+        function close(actual, expected) {
+            t.equal(actual.length, expected.length);
+            for (var i = 0; i < actual.length; i++) {
+                if (actual[i].length) {
+                    close(actual[i], expected[i]);
+                } else {
+                    t.ok(Math.abs(actual[i] - expected[i]) < 1e-6);
+                }
+            }
+        }
+
+        var point = tile.layers.poi_label.feature(11).toGeoJSON(8801, 5371, 14);
+        t.deepEqual(point.type, 'Feature');
+        t.deepEqual(point.properties, {
+            localrank: 1,
+            maki: 'park',
+            name: 'Mauerpark',
+            name_de: 'Mauerpark',
+            name_en: 'Mauerpark',
+            name_es: 'Mauerpark',
+            name_fr: 'Mauerpark',
+            osm_id: 3000003150561,
+            ref: '',
+            scalerank: 2,
+            type: 'Park'
+        });
+        t.deepEqual(point.geometry.type, 'Point');
+        close(point.geometry.coordinates, [13.402258157730103, 52.54398925380624]);
+
+        var line = tile.layers.bridge.feature(0).toGeoJSON(8801, 5371, 14);
+        t.deepEqual(line.type, 'Feature');
+        t.deepEqual(line.properties, {
+            class: 'service',
+            oneway: 0,
+            osm_id: 238162948,
+            type: 'service'
+        });
+        t.deepEqual(line.geometry.type, 'LineString');
+        close(line.geometry.coordinates,
+            [[13.399457931518555, 52.546334844036416], [13.399441838264465, 52.546504478525016]]);
+
+        var poly = tile.layers.building.feature(0).toGeoJSON(8801, 5371, 14);
+        t.deepEqual(poly.type, 'Feature');
+        t.deepEqual(poly.properties, {
+            osm_id: 1000267229912
+        });
+        t.deepEqual(poly.geometry.type, 'Polygon');
+        close(poly.geometry.coordinates,
+            [[[13.392285704612732, 52.54974045706258], [13.392264246940613, 52.549737195107554],
+                [13.392248153686523, 52.549737195107554], [13.392248153686523, 52.54974045706258],
+                [13.392285704612732, 52.54974045706258]]]);
+
+        t.end();
+    })
 });
 
 test('VectorTileLayer', function(t) {