Merge pull request #33 from mapbox/dateline

Date line handling
mapbox · Jun 15, 2015 · 770feee · 770feee
2 parents 5025d29 + 499a033
commit 770feee
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diff --git a/README.md b/README.md
@@ -70,6 +70,10 @@ npm run build-min # minified production build
 
 ### Changelog
 
+##### 2.1.0 (June 15, 2015)
+
+- Added proper handling for features crossing or near the date line.
+
 ##### 2.0.1 (June 9, 2015)
 
 - 10-20% faster tile indexing.

diff --git a/src/index.js b/src/index.js
@@ -4,6 +4,7 @@ module.exports = geojsonvt;
 
 var convert = require('./convert'), // GeoJSON conversion and preprocessing
     clip = require('./clip'),       // stripe clipping algorithm
+    wrap = require('./wrap'),       // date line processing
     createTile = require('./tile'); // final simplified tile generation
 
 
@@ -31,6 +32,8 @@ function GeoJSONVT(data, options) {
         this.total = 0;
     }
 
+    features = wrap(features, options.buffer / options.extent, intersectX);
+
     // start slicing from the top tile down
     this.splitTile(features, 0, 0, 0);
 
@@ -150,6 +153,9 @@ GeoJSONVT.prototype.getTile = function (z, x, y) {
         extent = options.extent,
         debug = options.debug;
 
+    var z2 = 1 << z;
+    x = ((x % z2) + z2) % z2; // wrap tile x coordinate
+
     var id = toID(z, x, y);
     if (this.tiles[id]) return transformTile(this.tiles[id], extent);
 

diff --git a/src/wrap.js b/src/wrap.js
@@ -0,0 +1,61 @@
+'use strict';
+
+var clip = require('./clip');
+
+module.exports = wrap;
+
+function wrap(features, buffer, intersectX) {
+    var merged = features,
+        left  = clip(features, 1, -1 - buffer, buffer,     0, intersectX, -1, 2), // left world copy
+        right = clip(features, 1,  1 - buffer, 2 + buffer, 0, intersectX, -1, 2); // right world copy
+
+    if (left || right) {
+        merged = clip(features, 1, -buffer, 1 + buffer, 0, intersectX, -1, 2); // center world copy
+
+        if (left) merged = shiftFeatureCoords(left, 1).concat(merged); // merge left into center
+        if (right) merged = merged.concat(shiftFeatureCoords(right, -1)); // merge right into center
+    }
+
+    return merged;
+}
+
+function shiftFeatureCoords(features, offset) {
+    var newFeatures = [];
+
+    for (var i = 0; i < features.length; i++) {
+        var feature = features[i],
+            type = feature.type;
+
+        var newGeometry;
+
+        if (type === 1) {
+            newGeometry = shiftCoords(feature.geometry, offset);
+        } else {
+            newGeometry = [];
+            for (var j = 0; j < feature.geometry.length; j++) {
+                newGeometry.push(shiftCoords(feature.geometry[j], offset));
+            }
+        }
+
+        newFeatures.push({
+            geometry: newGeometry,
+            type: type,
+            tags: feature.tags,
+            min: [feature.min[0] + offset, feature.min[1]],
+            max: [feature.max[0] + offset, feature.max[1]]
+        });
+    }
+
+    return newFeatures;
+}
+
+function shiftCoords(points, offset) {
+    var newPoints = [];
+    newPoints.area = points.area;
+    newPoints.dist = points.dist;
+
+    for (var i = 0; i < points.length; i++) {
+        newPoints.push([points[i][0] + offset, points[i][1], points[i][2]]);
+    }
+    return newPoints;
+}
diff --git a/test/fixtures/dateline-tiles.json b/test/fixtures/dateline-tiles.json
@@ -0,0 +1 @@
+{"z0-0-0":[{"geometry":[[[4160,1532],[4088,1464],[3952,1456],[3984,896],[4160,1217],[4160,1532]]],"type":3,"tags":{}},{"geometry":[[3312,1168]],"type":1,"tags":{}},{"geometry":[[[3472,2792],[4160,2782]],[[4160,2953],[3800,3112],[4160,3087]]],"type":2,"tags":{}},{"geometry":[[[3472,1488],[3992,2216],[4160,2370],[4160,2495],[3856,2384],[3616,2064],[3384,1744],[2744,1448],[2200,1736],[1672,2032],[1152,2384],[992,1904],[952,1520],[1400,1608],[1480,1800],[1840,1696],[1656,1384],[1232,1168],[616,1272],[152,1616],[-8,1464],[-64,1461],[-64,983],[112,1304],[280,1112],[680,816],[2304,816],[2792,1000],[2168,992],[1560,976],[2008,1216],[2896,1232],[3280,1168],[3472,1488],[3472,1488]]],"type":3,"tags":{}},{"geometry":[[2248,2808]],"type":1,"tags":{}},{"geometry":[[2968,2272]],"type":1,"tags":{}},{"geometry":[[488,1736]],"type":1,"tags":{}},{"geometry":[[[3456,280],[4160,280]],[[4160,378],[3752,464],[4160,526]]],"type":2,"tags":{}},{"geometry":[[[-64,2784],[464,2776],[-64,3009]],[[-64,3096],[624,3048]]],"type":2,"tags":{}},{"geometry":[[[-64,2253],[288,2576],[-64,2448],[-64,2253]]],"type":3,"tags":{}},{"geometry":[[368,2176]],"type":1,"tags":{}},{"geometry":[[[-64,280],[528,280],[-64,405]],[[-64,506],[344,568]]],"type":2,"tags":{}}]}
diff --git a/test/fixtures/dateline.json b/test/fixtures/dateline.json
@@ -0,0 +1,257 @@
+{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Polygon",
+        "coordinates": [
+          [
+            [
+              125.15625000000001,
+              44.08758502824518
+            ],
+            [
+              170.859375,
+              -14.604847155053886
+            ],
+            [
+              205.3125,
+              -42.0329743324414
+            ],
+            [
+              158.90625,
+              -28.30438068296277
+            ],
+            [
+              137.8125,
+              -1.4061088354351468
+            ],
+            [
+              117.42187500000001,
+              25.799891182088334
+            ],
+            [
+              61.17187499999999,
+              46.55886030311719
+            ],
+            [
+              13.359375,
+              26.43122806450644
+            ],
+            [
+              -33.046875,
+              1.4061088354351594
+            ],
+            [
+              -78.75,
+              -28.30438068296277
+            ],
+            [
+              -92.8125,
+              12.554563528593656
+            ],
+            [
+              -96.328125,
+              42.032974332441405
+            ],
+            [
+              -56.953125,
+              36.03133177633189
+            ],
+            [
+              -49.92187499999999,
+              21.28937435586041
+            ],
+            [
+              -18.28125,
+              29.53522956294847
+            ],
+            [
+              -34.453125,
+              50.28933925329178
+            ],
+            [
+              -71.71875,
+              60.930432202923335
+            ],
+            [
+              -125.859375,
+              56.17002298293205
+            ],
+            [
+              -166.640625,
+              35.460669951495305
+            ],
+            [
+              -180.703125,
+              45.583289756006316
+            ],
+            [
+              -192.65625,
+              46.07323062540838
+            ],
+            [
+              -189.84375,
+              70.61261423801925
+            ],
+            [
+              -170.15625,
+              54.57206165565852
+            ],
+            [
+              -155.390625,
+              63.23362741232569
+            ],
+            [
+              -120.234375,
+              72.81607371878991
+            ],
+            [
+              -72.421875,
+              72.81607371878991
+            ],
+            [
+              22.5,
+              72.81607371878991
+            ],
+            [
+              65.390625,
+              67.33986082559095
+            ],
+            [
+              10.546875,
+              67.60922060496382
+            ],
+            [
+              -42.890625,
+              68.13885164925573
+            ],
+            [
+              -3.515625,
+              58.81374171570782
+            ],
+            [
+              74.53125,
+              58.07787626787517
+            ],
+            [
+              108.28125,
+              60.930432202923335
+            ],
+            [
+              125.15625000000001,
+              44.08758502824518
+            ]
+          ]
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Point",
+        "coordinates": [
+          17.578125,
+          -55.379110448010486
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Point",
+        "coordinates": [
+          80.85937499999999,
+          -19.31114335506463
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Point",
+        "coordinates": [
+          -137.109375,
+          26.43122806450644
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Point",
+        "coordinates": [
+          -248.90624999999997,
+          60.930432202923335
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Point",
+        "coordinates": [
+          212.34375,
+          -11.178401873711785
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "LineString",
+        "coordinates": [
+          [
+            123.74999999999999,
+            82.40242347938855
+          ],
+          [
+            226.40625,
+            82.40242347938855
+          ],
+          [
+            149.765625,
+            79.93591824625466
+          ],
+          [
+            210.234375,
+            78.20656311074711
+          ]
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "LineString",
+        "coordinates": [
+          [
+            -234.84375000000003,
+            -54.572061655658516
+          ],
+          [
+            -139.21874999999997,
+            -53.748710796898976
+          ],
+          [
+            -206.015625,
+            -67.87554134672943
+          ],
+          [
+            -125.15625000000001,
+            -65.6582745198266
+          ]
+        ]
+      }
+    }
+  ]
+}
diff --git a/test/fixtures/us-states-tiles.json b/test/fixtures/us-states-tiles.json
diff --git a/test/test-full.js b/test/test-full.js
@@ -6,6 +6,7 @@ var path = require('path');
 var genTiles = require('./gen-tiles');
 
 testTiles('us-states.json', 'us-states-tiles.json', 7, 200);
+testTiles('dateline.json', 'dateline-tiles.json', 7, 200);
 
 function testTiles(inputFile, expectedFile, maxZoom, maxPoints) {
     test('full tiling test: ' + inputFile, function (t) {