With buffer: 0, geometry coincident with a tile edge is clipped incon…

…sistently (#102)

* Update esm

* Add tests showing inconsistency in bufferless clipping on tile edges

* clip consistently (inclusively on top/left and exclusively on bottom/right)

package.json

@@ -23,7 +23,7 @@
     "coveralls": "^3.0.0",
     "eslint": "^4.18.2",
     "eslint-config-mourner": "^2.0.3",
-    "esm": "^3.0.11",
+    "esm": "^3.0.19",
     "nyc": "^11.4.1",
     "rollup": "^0.57.1",
     "rollup-plugin-uglify": "^3.0.0",

src/clip.js

@@ -13,8 +13,8 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti
     k1 /= scale;
     k2 /= scale;
 
-    if (minAll >= k1 && maxAll <= k2) return features; // trivial accept
-    else if (minAll > k2 || maxAll < k1) return null; // trivial reject
+    if (minAll >= k1 && maxAll < k2) return features; // trivial accept
+    else if (maxAll < k1 || minAll >= k2) return null; // trivial reject
 
     var clipped = [];
 
@@ -27,10 +27,10 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti
         var min = axis === 0 ? feature.minX : feature.minY;
         var max = axis === 0 ? feature.maxX : feature.maxY;
 
-        if (min >= k1 && max <= k2) { // trivial accept
+        if (min >= k1 && max < k2) { // trivial accept
             clipped.push(feature);
             continue;
-        } else if (min > k2 || max < k1) { // trivial reject
+        } else if (max < k1 || min >= k2) { // trivial reject
             continue;
         }
 
@@ -122,9 +122,9 @@ function clipLine(geom, newGeom, k1, k2, axis, isPolygon, trackMetrics) {
                 t = intersect(slice, ax, ay, bx, by, k1);
                 if (trackMetrics) slice.start = len + segLen * t;
             }
-        } else if (a > k2) {
+        } else if (a >= k2) {
             // |  <--|--- (line enters the clip region from the right)
-            if (b <= k2) {
+            if (b < k2) {
                 t = intersect(slice, ax, ay, bx, by, k2);
                 if (trackMetrics) slice.start = len + segLen * t;
             }

test/test-get-tile.js

@@ -17,8 +17,6 @@ test('getTile: us-states.json', function (t) {
     console.log = function () {};
     var index = geojsonvt(getJSON('us-states.json'), {debug: 2});
 
-    console.log = log;
-
     t.same(index.getTile(7, 37, 48).features, getJSON('us-states-z7-37-48.json'), 'z7-37-48');
 
     t.same(index.getTile(9, 148, 192).features, square, 'z9-148-192 (clipped square)');
@@ -28,11 +26,39 @@ test('getTile: us-states.json', function (t) {
     t.equal(index.getTile(-5, 123.25, 400.25), null, 'invalid tile');
     t.equal(index.getTile(25, 200, 200), null, 'invalid tile');
 
+    console.log = log;
+
     t.equal(index.total, 37);
 
     t.end();
 });
 
+test('getTile: unbuffered tile left/right edges', function (t) {
+    var index = geojsonvt({
+        type: 'LineString',
+        coordinates: [[0, 90], [0, -90]]
+    }, {
+        buffer: 0
+    });
+
+    t.same(index.getTile(2, 1, 1), null);
+    t.same(index.getTile(2, 2, 1).features, [{geometry: [[[0, 0], [0, 4096]]], type: 2, tags: null}]);
+    t.end();
+});
+
+test('getTile: unbuffered tile top/bottom edges', function (t) {
+    var index = geojsonvt({
+        type: 'LineString',
+        coordinates: [[-90, 66.51326044311188], [90, 66.51326044311188]]
+    }, {
+        buffer: 0
+    });
+
+    t.same(index.getTile(2, 1, 0).features, [{geometry: [[[0, 4096], [4096, 4096]]], type: 2, tags: null}]);
+    t.same(index.getTile(2, 1, 1).features, []);
+    t.end();
+});
+
 function getJSON(name) {
     return JSON.parse(fs.readFileSync(path.join(__dirname, '/fixtures/' + name)));
 }

yarn.lock

@@ -1171,9 +1171,9 @@ eslint@^4.18.2:
     table "4.0.2"
     text-table "~0.2.0"
 
-esm@^3.0.11:
-  version "3.0.11"
-  resolved "https://registry.yarnpkg.com/esm/-/esm-3.0.11.tgz#223baf6b5ab6956efbec6e554e8af1824145d160"
+esm@^3.0.19:
+  version "3.0.25"
+  resolved "https://registry.yarnpkg.com/esm/-/esm-3.0.25.tgz#d374e714c07abe0b8a7e80d18819e5823e491dbd"
 
 espree@^3.5.4:
   version "3.5.4"