Initial

resources/app/node_modules/earcut/LICENSE

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+ISC License
+
+Copyright (c) 2016, Mapbox
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.

resources/app/node_modules/earcut/package.json

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+{
+  "name": "earcut",
+  "version": "2.2.4",
+  "description": "The fastest and smallest JavaScript polygon triangulation library for your WebGL apps",
+  "main": "src/earcut.js",
+  "unpkg": "dist/earcut.min.js",
+  "jsdelivr": "dist/earcut.min.js",
+  "files": [
+    "dist/earcut.min.js",
+    "dist/earcut.dev.js"
+  ],
+  "author": "Vladimir Agafonkin",
+  "license": "ISC",
+  "devDependencies": {
+    "benchmark": "^2.1.4",
+    "browserify": "^17.0.0",
+    "c8": "^7.11.3",
+    "coveralls": "^3.1.1",
+    "eslint": "^8.19.0",
+    "eslint-config-mourner": "^2.0.3",
+    "mkdirp": "^1.0.4",
+    "tape": "^5.5.3",
+    "uglify-js": "^3.16.2",
+    "watchify": "^4.0.0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/mapbox/earcut.git"
+  }
+}

resources/app/node_modules/earcut/src/earcut.js

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+'use strict';
+
+module.exports = earcut;
+module.exports.default = earcut;
+
+function earcut(data, holeIndices, dim) {
+
+    dim = dim || 2;
+
+    var hasHoles = holeIndices && holeIndices.length,
+        outerLen = hasHoles ? holeIndices[0] * dim : data.length,
+        outerNode = linkedList(data, 0, outerLen, dim, true),
+        triangles = [];
+
+    if (!outerNode || outerNode.next === outerNode.prev) return triangles;
+
+    var minX, minY, maxX, maxY, x, y, invSize;
+
+    if (hasHoles) outerNode = eliminateHoles(data, holeIndices, outerNode, dim);
+
+    // if the shape is not too simple, we'll use z-order curve hash later; calculate polygon bbox
+    if (data.length > 80 * dim) {
+        minX = maxX = data[0];
+        minY = maxY = data[1];
+
+        for (var i = dim; i < outerLen; i += dim) {
+            x = data[i];
+            y = data[i + 1];
+            if (x < minX) minX = x;
+            if (y < minY) minY = y;
+            if (x > maxX) maxX = x;
+            if (y > maxY) maxY = y;
+        }
+
+        // minX, minY and invSize are later used to transform coords into integers for z-order calculation
+        invSize = Math.max(maxX - minX, maxY - minY);
+        invSize = invSize !== 0 ? 32767 / invSize : 0;
+    }
+
+    earcutLinked(outerNode, triangles, dim, minX, minY, invSize, 0);
+
+    return triangles;
+}
+
+// create a circular doubly linked list from polygon points in the specified winding order
+function linkedList(data, start, end, dim, clockwise) {
+    var i, last;
+
+    if (clockwise === (signedArea(data, start, end, dim) > 0)) {
+        for (i = start; i < end; i += dim) last = insertNode(i, data[i], data[i + 1], last);
+    } else {
+        for (i = end - dim; i >= start; i -= dim) last = insertNode(i, data[i], data[i + 1], last);
+    }
+
+    if (last && equals(last, last.next)) {
+        removeNode(last);
+        last = last.next;
+    }
+
+    return last;
+}
+
+// eliminate colinear or duplicate points
+function filterPoints(start, end) {
+    if (!start) return start;
+    if (!end) end = start;
+
+    var p = start,
+        again;
+    do {
+        again = false;
+
+        if (!p.steiner && (equals(p, p.next) || area(p.prev, p, p.next) === 0)) {
+            removeNode(p);
+            p = end = p.prev;
+            if (p === p.next) break;
+            again = true;
+
+        } else {
+            p = p.next;
+        }
+    } while (again || p !== end);
+
+    return end;
+}
+
+// main ear slicing loop which triangulates a polygon (given as a linked list)
+function earcutLinked(ear, triangles, dim, minX, minY, invSize, pass) {
+    if (!ear) return;
+
+    // interlink polygon nodes in z-order
+    if (!pass && invSize) indexCurve(ear, minX, minY, invSize);
+
+    var stop = ear,
+        prev, next;
+
+    // iterate through ears, slicing them one by one
+    while (ear.prev !== ear.next) {
+        prev = ear.prev;
+        next = ear.next;
+
+        if (invSize ? isEarHashed(ear, minX, minY, invSize) : isEar(ear)) {
+            // cut off the triangle
+            triangles.push(prev.i / dim | 0);
+            triangles.push(ear.i / dim | 0);
+            triangles.push(next.i / dim | 0);
+
+            removeNode(ear);
+
+            // skipping the next vertex leads to less sliver triangles
+            ear = next.next;
+            stop = next.next;
+
+            continue;
+        }
+
+        ear = next;
+
+        // if we looped through the whole remaining polygon and can't find any more ears
+        if (ear === stop) {
+            // try filtering points and slicing again
+            if (!pass) {
+                earcutLinked(filterPoints(ear), triangles, dim, minX, minY, invSize, 1);
+
+            // if this didn't work, try curing all small self-intersections locally
+            } else if (pass === 1) {
+                ear = cureLocalIntersections(filterPoints(ear), triangles, dim);
+                earcutLinked(ear, triangles, dim, minX, minY, invSize, 2);
+
+            // as a last resort, try splitting the remaining polygon into two
+            } else if (pass === 2) {
+                splitEarcut(ear, triangles, dim, minX, minY, invSize);
+            }
+
+            break;
+        }
+    }
+}
+
+// check whether a polygon node forms a valid ear with adjacent nodes
+function isEar(ear) {
+    var a = ear.prev,
+        b = ear,
+        c = ear.next;
+
+    if (area(a, b, c) >= 0) return false; // reflex, can't be an ear
+
+    // now make sure we don't have other points inside the potential ear
+    var ax = a.x, bx = b.x, cx = c.x, ay = a.y, by = b.y, cy = c.y;
+
+    // triangle bbox; min & max are calculated like this for speed
+    var x0 = ax < bx ? (ax < cx ? ax : cx) : (bx < cx ? bx : cx),
+        y0 = ay < by ? (ay < cy ? ay : cy) : (by < cy ? by : cy),
+        x1 = ax > bx ? (ax > cx ? ax : cx) : (bx > cx ? bx : cx),
+        y1 = ay > by ? (ay > cy ? ay : cy) : (by > cy ? by : cy);
+
+    var p = c.next;
+    while (p !== a) {
+        if (p.x >= x0 && p.x <= x1 && p.y >= y0 && p.y <= y1 &&
+            pointInTriangle(ax, ay, bx, by, cx, cy, p.x, p.y) &&
+            area(p.prev, p, p.next) >= 0) return false;
+        p = p.next;
+    }
+
+    return true;
+}
+
+function isEarHashed(ear, minX, minY, invSize) {
+    var a = ear.prev,
+        b = ear,
+        c = ear.next;
+
+    if (area(a, b, c) >= 0) return false; // reflex, can't be an ear
+
+    var ax = a.x, bx = b.x, cx = c.x, ay = a.y, by = b.y, cy = c.y;
+
+    // triangle bbox; min & max are calculated like this for speed
+    var x0 = ax < bx ? (ax < cx ? ax : cx) : (bx < cx ? bx : cx),
+        y0 = ay < by ? (ay < cy ? ay : cy) : (by < cy ? by : cy),
+        x1 = ax > bx ? (ax > cx ? ax : cx) : (bx > cx ? bx : cx),
+        y1 = ay > by ? (ay > cy ? ay : cy) : (by > cy ? by : cy);
+
+    // z-order range for the current triangle bbox;
+    var minZ = zOrder(x0, y0, minX, minY, invSize),
+        maxZ = zOrder(x1, y1, minX, minY, invSize);
+
+    var p = ear.prevZ,
+        n = ear.nextZ;
+
+    // look for points inside the triangle in both directions
+    while (p && p.z >= minZ && n && n.z <= maxZ) {
+        if (p.x >= x0 && p.x <= x1 && p.y >= y0 && p.y <= y1 && p !== a && p !== c &&
+            pointInTriangle(ax, ay, bx, by, cx, cy, p.x, p.y) && area(p.prev, p, p.next) >= 0) return false;
+        p = p.prevZ;
+
+        if (n.x >= x0 && n.x <= x1 && n.y >= y0 && n.y <= y1 && n !== a && n !== c &&
+            pointInTriangle(ax, ay, bx, by, cx, cy, n.x, n.y) && area(n.prev, n, n.next) >= 0) return false;
+        n = n.nextZ;
+    }
+
+    // look for remaining points in decreasing z-order
+    while (p && p.z >= minZ) {
+        if (p.x >= x0 && p.x <= x1 && p.y >= y0 && p.y <= y1 && p !== a && p !== c &&
+            pointInTriangle(ax, ay, bx, by, cx, cy, p.x, p.y) && area(p.prev, p, p.next) >= 0) return false;
+        p = p.prevZ;
+    }
+
+    // look for remaining points in increasing z-order
+    while (n && n.z <= maxZ) {
+        if (n.x >= x0 && n.x <= x1 && n.y >= y0 && n.y <= y1 && n !== a && n !== c &&
+            pointInTriangle(ax, ay, bx, by, cx, cy, n.x, n.y) && area(n.prev, n, n.next) >= 0) return false;
+        n = n.nextZ;
+    }
+
+    return true;
+}
+
+// go through all polygon nodes and cure small local self-intersections
+function cureLocalIntersections(start, triangles, dim) {
+    var p = start;
+    do {
+        var a = p.prev,
+            b = p.next.next;
+
+        if (!equals(a, b) && intersects(a, p, p.next, b) && locallyInside(a, b) && locallyInside(b, a)) {
+
+            triangles.push(a.i / dim | 0);
+            triangles.push(p.i / dim | 0);
+            triangles.push(b.i / dim | 0);
+
+            // remove two nodes involved
+            removeNode(p);
+            removeNode(p.next);
+
+            p = start = b;
+        }
+        p = p.next;
+    } while (p !== start);
+
+    return filterPoints(p);
+}
+
+// try splitting polygon into two and triangulate them independently
+function splitEarcut(start, triangles, dim, minX, minY, invSize) {
+    // look for a valid diagonal that divides the polygon into two
+    var a = start;
+    do {
+        var b = a.next.next;
+        while (b !== a.prev) {
+            if (a.i !== b.i && isValidDiagonal(a, b)) {
+                // split the polygon in two by the diagonal
+                var c = splitPolygon(a, b);
+
+                // filter colinear points around the cuts
+                a = filterPoints(a, a.next);
+                c = filterPoints(c, c.next);
+
+                // run earcut on each half
+                earcutLinked(a, triangles, dim, minX, minY, invSize, 0);
+                earcutLinked(c, triangles, dim, minX, minY, invSize, 0);
+                return;
+            }
+            b = b.next;
+        }
+        a = a.next;
+    } while (a !== start);
+}
+
+// link every hole into the outer loop, producing a single-ring polygon without holes
+function eliminateHoles(data, holeIndices, outerNode, dim) {
+    var queue = [],
+        i, len, start, end, list;
+
+    for (i = 0, len = holeIndices.length; i < len; i++) {
+        start = holeIndices[i] * dim;
+        end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
+        list = linkedList(data, start, end, dim, false);
+        if (list === list.next) list.steiner = true;
+        queue.push(getLeftmost(list));
+    }
+
+    queue.sort(compareX);
+
+    // process holes from left to right
+    for (i = 0; i < queue.length; i++) {
+        outerNode = eliminateHole(queue[i], outerNode);
+    }
+
+    return outerNode;
+}
+
+function compareX(a, b) {
+    return a.x - b.x;
+}
+
+// find a bridge between vertices that connects hole with an outer ring and and link it
+function eliminateHole(hole, outerNode) {
+    var bridge = findHoleBridge(hole, outerNode);
+    if (!bridge) {
+        return outerNode;
+    }
+
+    var bridgeReverse = splitPolygon(bridge, hole);
+
+    // filter collinear points around the cuts
+    filterPoints(bridgeReverse, bridgeReverse.next);
+    return filterPoints(bridge, bridge.next);
+}
+
+// David Eberly's algorithm for finding a bridge between hole and outer polygon
+function findHoleBridge(hole, outerNode) {
+    var p = outerNode,
+        hx = hole.x,
+        hy = hole.y,
+        qx = -Infinity,
+        m;
+
+    // find a segment intersected by a ray from the hole's leftmost point to the left;
+    // segment's endpoint with lesser x will be potential connection point
+    do {
+        if (hy <= p.y && hy >= p.next.y && p.next.y !== p.y) {
+            var x = p.x + (hy - p.y) * (p.next.x - p.x) / (p.next.y - p.y);
+            if (x <= hx && x > qx) {
+                qx = x;
+                m = p.x < p.next.x ? p : p.next;
+                if (x === hx) return m; // hole touches outer segment; pick leftmost endpoint
+            }
+        }
+        p = p.next;
+    } while (p !== outerNode);
+
+    if (!m) return null;
+
+    // look for points inside the triangle of hole point, segment intersection and endpoint;
+    // if there are no points found, we have a valid connection;
+    // otherwise choose the point of the minimum angle with the ray as connection point
+
+    var stop = m,
+        mx = m.x,
+        my = m.y,
+        tanMin = Infinity,
+        tan;
+
+    p = m;
+
+    do {
+        if (hx >= p.x && p.x >= mx && hx !== p.x &&
+                pointInTriangle(hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy, p.x, p.y)) {
+
+            tan = Math.abs(hy - p.y) / (hx - p.x); // tangential
+
+            if (locallyInside(p, hole) &&
+                (tan < tanMin || (tan === tanMin && (p.x > m.x || (p.x === m.x && sectorContainsSector(m, p)))))) {
+                m = p;
+                tanMin = tan;
+            }
+        }
+
+        p = p.next;
+    } while (p !== stop);
+
+    return m;
+}
+
+// whether sector in vertex m contains sector in vertex p in the same coordinates
+function sectorContainsSector(m, p) {
+    return area(m.prev, m, p.prev) < 0 && area(p.next, m, m.next) < 0;
+}
+
+// interlink polygon nodes in z-order
+function indexCurve(start, minX, minY, invSize) {
+    var p = start;
+    do {
+        if (p.z === 0) p.z = zOrder(p.x, p.y, minX, minY, invSize);
+        p.prevZ = p.prev;
+        p.nextZ = p.next;
+        p = p.next;
+    } while (p !== start);
+
+    p.prevZ.nextZ = null;
+    p.prevZ = null;
+
+    sortLinked(p);
+}
+
+// Simon Tatham's linked list merge sort algorithm
+// http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
+function sortLinked(list) {
+    var i, p, q, e, tail, numMerges, pSize, qSize,
+        inSize = 1;
+
+    do {
+        p = list;
+        list = null;
+        tail = null;
+        numMerges = 0;
+
+        while (p) {
+            numMerges++;
+            q = p;
+            pSize = 0;
+            for (i = 0; i < inSize; i++) {
+                pSize++;
+                q = q.nextZ;
+                if (!q) break;
+            }
+            qSize = inSize;
+
+            while (pSize > 0 || (qSize > 0 && q)) {
+
+                if (pSize !== 0 && (qSize === 0 || !q || p.z <= q.z)) {
+                    e = p;
+                    p = p.nextZ;
+                    pSize--;
+                } else {
+                    e = q;
+                    q = q.nextZ;
+                    qSize--;
+                }
+
+                if (tail) tail.nextZ = e;
+                else list = e;
+
+                e.prevZ = tail;
+                tail = e;
+            }
+
+            p = q;
+        }
+
+        tail.nextZ = null;
+        inSize *= 2;
+
+    } while (numMerges > 1);
+
+    return list;
+}
+
+// z-order of a point given coords and inverse of the longer side of data bbox
+function zOrder(x, y, minX, minY, invSize) {
+    // coords are transformed into non-negative 15-bit integer range
+    x = (x - minX) * invSize | 0;
+    y = (y - minY) * invSize | 0;
+
+    x = (x | (x << 8)) & 0x00FF00FF;
+    x = (x | (x << 4)) & 0x0F0F0F0F;
+    x = (x | (x << 2)) & 0x33333333;
+    x = (x | (x << 1)) & 0x55555555;
+
+    y = (y | (y << 8)) & 0x00FF00FF;
+    y = (y | (y << 4)) & 0x0F0F0F0F;
+    y = (y | (y << 2)) & 0x33333333;
+    y = (y | (y << 1)) & 0x55555555;
+
+    return x | (y << 1);
+}
+
+// find the leftmost node of a polygon ring
+function getLeftmost(start) {
+    var p = start,
+        leftmost = start;
+    do {
+        if (p.x < leftmost.x || (p.x === leftmost.x && p.y < leftmost.y)) leftmost = p;
+        p = p.next;
+    } while (p !== start);
+
+    return leftmost;
+}
+
+// check if a point lies within a convex triangle
+function pointInTriangle(ax, ay, bx, by, cx, cy, px, py) {
+    return (cx - px) * (ay - py) >= (ax - px) * (cy - py) &&
+           (ax - px) * (by - py) >= (bx - px) * (ay - py) &&
+           (bx - px) * (cy - py) >= (cx - px) * (by - py);
+}
+
+// check if a diagonal between two polygon nodes is valid (lies in polygon interior)
+function isValidDiagonal(a, b) {
+    return a.next.i !== b.i && a.prev.i !== b.i && !intersectsPolygon(a, b) && // dones't intersect other edges
+           (locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b) && // locally visible
+            (area(a.prev, a, b.prev) || area(a, b.prev, b)) || // does not create opposite-facing sectors
+            equals(a, b) && area(a.prev, a, a.next) > 0 && area(b.prev, b, b.next) > 0); // special zero-length case
+}
+
+// signed area of a triangle
+function area(p, q, r) {
+    return (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
+}
+
+// check if two points are equal
+function equals(p1, p2) {
+    return p1.x === p2.x && p1.y === p2.y;
+}
+
+// check if two segments intersect
+function intersects(p1, q1, p2, q2) {
+    var o1 = sign(area(p1, q1, p2));
+    var o2 = sign(area(p1, q1, q2));
+    var o3 = sign(area(p2, q2, p1));
+    var o4 = sign(area(p2, q2, q1));
+
+    if (o1 !== o2 && o3 !== o4) return true; // general case
+
+    if (o1 === 0 && onSegment(p1, p2, q1)) return true; // p1, q1 and p2 are collinear and p2 lies on p1q1
+    if (o2 === 0 && onSegment(p1, q2, q1)) return true; // p1, q1 and q2 are collinear and q2 lies on p1q1
+    if (o3 === 0 && onSegment(p2, p1, q2)) return true; // p2, q2 and p1 are collinear and p1 lies on p2q2
+    if (o4 === 0 && onSegment(p2, q1, q2)) return true; // p2, q2 and q1 are collinear and q1 lies on p2q2
+
+    return false;
+}
+
+// for collinear points p, q, r, check if point q lies on segment pr
+function onSegment(p, q, r) {
+    return q.x <= Math.max(p.x, r.x) && q.x >= Math.min(p.x, r.x) && q.y <= Math.max(p.y, r.y) && q.y >= Math.min(p.y, r.y);
+}
+
+function sign(num) {
+    return num > 0 ? 1 : num < 0 ? -1 : 0;
+}
+
+// check if a polygon diagonal intersects any polygon segments
+function intersectsPolygon(a, b) {
+    var p = a;
+    do {
+        if (p.i !== a.i && p.next.i !== a.i && p.i !== b.i && p.next.i !== b.i &&
+                intersects(p, p.next, a, b)) return true;
+        p = p.next;
+    } while (p !== a);
+
+    return false;
+}
+
+// check if a polygon diagonal is locally inside the polygon
+function locallyInside(a, b) {
+    return area(a.prev, a, a.next) < 0 ?
+        area(a, b, a.next) >= 0 && area(a, a.prev, b) >= 0 :
+        area(a, b, a.prev) < 0 || area(a, a.next, b) < 0;
+}
+
+// check if the middle point of a polygon diagonal is inside the polygon
+function middleInside(a, b) {
+    var p = a,
+        inside = false,
+        px = (a.x + b.x) / 2,
+        py = (a.y + b.y) / 2;
+    do {
+        if (((p.y > py) !== (p.next.y > py)) && p.next.y !== p.y &&
+                (px < (p.next.x - p.x) * (py - p.y) / (p.next.y - p.y) + p.x))
+            inside = !inside;
+        p = p.next;
+    } while (p !== a);
+
+    return inside;
+}
+
+// link two polygon vertices with a bridge; if the vertices belong to the same ring, it splits polygon into two;
+// if one belongs to the outer ring and another to a hole, it merges it into a single ring
+function splitPolygon(a, b) {
+    var a2 = new Node(a.i, a.x, a.y),
+        b2 = new Node(b.i, b.x, b.y),
+        an = a.next,
+        bp = b.prev;
+
+    a.next = b;
+    b.prev = a;
+
+    a2.next = an;
+    an.prev = a2;
+
+    b2.next = a2;
+    a2.prev = b2;
+
+    bp.next = b2;
+    b2.prev = bp;
+
+    return b2;
+}
+
+// create a node and optionally link it with previous one (in a circular doubly linked list)
+function insertNode(i, x, y, last) {
+    var p = new Node(i, x, y);
+
+    if (!last) {
+        p.prev = p;
+        p.next = p;
+
+    } else {
+        p.next = last.next;
+        p.prev = last;
+        last.next.prev = p;
+        last.next = p;
+    }
+    return p;
+}
+
+function removeNode(p) {
+    p.next.prev = p.prev;
+    p.prev.next = p.next;
+
+    if (p.prevZ) p.prevZ.nextZ = p.nextZ;
+    if (p.nextZ) p.nextZ.prevZ = p.prevZ;
+}
+
+function Node(i, x, y) {
+    // vertex index in coordinates array
+    this.i = i;
+
+    // vertex coordinates
+    this.x = x;
+    this.y = y;
+
+    // previous and next vertex nodes in a polygon ring
+    this.prev = null;
+    this.next = null;
+
+    // z-order curve value
+    this.z = 0;
+
+    // previous and next nodes in z-order
+    this.prevZ = null;
+    this.nextZ = null;
+
+    // indicates whether this is a steiner point
+    this.steiner = false;
+}
+
+// return a percentage difference between the polygon area and its triangulation area;
+// used to verify correctness of triangulation
+earcut.deviation = function (data, holeIndices, dim, triangles) {
+    var hasHoles = holeIndices && holeIndices.length;
+    var outerLen = hasHoles ? holeIndices[0] * dim : data.length;
+
+    var polygonArea = Math.abs(signedArea(data, 0, outerLen, dim));
+    if (hasHoles) {
+        for (var i = 0, len = holeIndices.length; i < len; i++) {
+            var start = holeIndices[i] * dim;
+            var end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
+            polygonArea -= Math.abs(signedArea(data, start, end, dim));
+        }
+    }
+
+    var trianglesArea = 0;
+    for (i = 0; i < triangles.length; i += 3) {
+        var a = triangles[i] * dim;
+        var b = triangles[i + 1] * dim;
+        var c = triangles[i + 2] * dim;
+        trianglesArea += Math.abs(
+            (data[a] - data[c]) * (data[b + 1] - data[a + 1]) -
+            (data[a] - data[b]) * (data[c + 1] - data[a + 1]));
+    }
+
+    return polygonArea === 0 && trianglesArea === 0 ? 0 :
+        Math.abs((trianglesArea - polygonArea) / polygonArea);
+};
+
+function signedArea(data, start, end, dim) {
+    var sum = 0;
+    for (var i = start, j = end - dim; i < end; i += dim) {
+        sum += (data[j] - data[i]) * (data[i + 1] + data[j + 1]);
+        j = i;
+    }
+    return sum;
+}
+
+// turn a polygon in a multi-dimensional array form (e.g. as in GeoJSON) into a form Earcut accepts
+earcut.flatten = function (data) {
+    var dim = data[0][0].length,
+        result = {vertices: [], holes: [], dimensions: dim},
+        holeIndex = 0;
+
+    for (var i = 0; i < data.length; i++) {
+        for (var j = 0; j < data[i].length; j++) {
+            for (var d = 0; d < dim; d++) result.vertices.push(data[i][j][d]);
+        }
+        if (i > 0) {
+            holeIndex += data[i - 1].length;
+            result.holes.push(holeIndex);
+        }
+    }
+    return result;
+};