Add earcut library to examples

examples/js/libs/earcut.js

@@ -0,0 +1,674 @@
+/**
+ *
+ * Earcut https://github.com/mapbox/earcut
+ *
+ * Copyright (c) 2015, 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.
+ */
+'use strict';
+
+module.exports = earcut;
+
+function earcut(data, holeIndices, dim) {
+
+    dim = dim || 2;
+
+    var hasHoles = holeIndices && holeIndices.length,
+        outerLen = hasHoles ? holeIndices[0] * dim : data.length,
+        outerNode = filterPoints(data, linkedList(data, 0, outerLen, dim, true)),
+        triangles = [];
+
+    if (!outerNode) return triangles;
+
+    var minX, minY, maxX, maxY, x, y, size;
+
+    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 size are later used to transform coords into integers for z-order calculation
+        size = Math.max(maxX - minX, maxY - minY);
+    }
+
+    earcutLinked(data, outerNode, triangles, dim, minX, minY, size);
+
+    return triangles;
+}
+
+// create a circular doubly linked list from polygon points in the specified winding order
+function linkedList(data, start, end, dim, clockwise) {
+    var sum = 0,
+        i, j, last;
+
+    // calculate original winding order of a polygon ring
+    for (i = start, j = end - dim; i < end; i += dim) {
+        sum += (data[j] - data[i]) * (data[i + 1] + data[j + 1]);
+        j = i;
+    }
+
+    // link points into circular doubly-linked list in the specified winding order
+    if (clockwise === (sum > 0)) {
+        for (i = start; i < end; i += dim) last = insertNode(i, last);
+    } else {
+        for (i = end - dim; i >= start; i -= dim) last = insertNode(i, last);
+    }
+
+    return last;
+}
+
+// eliminate colinear or duplicate points
+function filterPoints(data, start, end) {
+    if (!start) return start;
+    if (!end) end = start;
+
+    var node = start,
+        again;
+    do {
+        again = false;
+
+        if (!node.steiner && (equals(data, node.i, node.next.i) || orient(data, node.prev.i, node.i, node.next.i) === 0)) {
+            removeNode(node);
+            node = end = node.prev;
+            if (node === node.next) return null;
+            again = true;
+
+        } else {
+            node = node.next;
+        }
+    } while (again || node !== end);
+
+    return end;
+}
+
+// main ear slicing loop which triangulates a polygon (given as a linked list)
+function earcutLinked(data, ear, triangles, dim, minX, minY, size, pass) {
+    if (!ear) return;
+
+    // interlink polygon nodes in z-order
+    if (!pass && minX !== undefined) indexCurve(data, ear, minX, minY, size);
+
+    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 (isEar(data, ear, minX, minY, size)) {
+            // cut off the triangle
+            triangles.push(prev.i / dim);
+            triangles.push(ear.i / dim);
+            triangles.push(next.i / dim);
+
+            removeNode(ear);
+
+            // skipping the next vertice 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(data, filterPoints(data, ear), triangles, dim, minX, minY, size, 1);
+
+            // if this didn't work, try curing all small self-intersections locally
+            } else if (pass === 1) {
+                ear = cureLocalIntersections(data, ear, triangles, dim);
+                earcutLinked(data, ear, triangles, dim, minX, minY, size, 2);
+
+            // as a last resort, try splitting the remaining polygon into two
+            } else if (pass === 2) {
+                splitEarcut(data, ear, triangles, dim, minX, minY, size);
+            }
+
+            break;
+        }
+    }
+}
+
+// check whether a polygon node forms a valid ear with adjacent nodes
+function isEar(data, ear, minX, minY, size) {
+
+    var a = ear.prev.i,
+        b = ear.i,
+        c = ear.next.i,
+
+        ax = data[a], ay = data[a + 1],
+        bx = data[b], by = data[b + 1],
+        cx = data[c], cy = data[c + 1],
+
+        abd = ax * by - ay * bx,
+        acd = ax * cy - ay * cx,
+        cbd = cx * by - cy * bx,
+        A = abd - acd - cbd;
+
+    if (A <= 0) return false; // reflex, can't be an ear
+
+    // now make sure we don't have other points inside the potential ear;
+    // the code below is a bit verbose and repetitive but this is done for performance
+
+    var cay = cy - ay,
+        acx = ax - cx,
+        aby = ay - by,
+        bax = bx - ax,
+        i, px, py, s, t, k, node;
+
+    // if we use z-order curve hashing, iterate through the curve
+    if (minX !== undefined) {
+
+        // triangle bbox; min & max are calculated like this for speed
+        var minTX = ax < bx ? (ax < cx ? ax : cx) : (bx < cx ? bx : cx),
+            minTY = ay < by ? (ay < cy ? ay : cy) : (by < cy ? by : cy),
+            maxTX = ax > bx ? (ax > cx ? ax : cx) : (bx > cx ? bx : cx),
+            maxTY = ay > by ? (ay > cy ? ay : cy) : (by > cy ? by : cy),
+
+            // z-order range for the current triangle bbox;
+            minZ = zOrder(minTX, minTY, minX, minY, size),
+            maxZ = zOrder(maxTX, maxTY, minX, minY, size);
+
+        // first look for points inside the triangle in increasing z-order
+        node = ear.nextZ;
+
+        while (node && node.z <= maxZ) {
+            i = node.i;
+            node = node.nextZ;
+            if (i === a || i === c) continue;
+
+            px = data[i];
+            py = data[i + 1];
+
+            s = cay * px + acx * py - acd;
+            if (s >= 0) {
+                t = aby * px + bax * py + abd;
+                if (t >= 0) {
+                    k = A - s - t;
+                    if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
+                }
+            }
+        }
+
+        // then look for points in decreasing z-order
+        node = ear.prevZ;
+
+        while (node && node.z >= minZ) {
+            i = node.i;
+            node = node.prevZ;
+            if (i === a || i === c) continue;
+
+            px = data[i];
+            py = data[i + 1];
+
+            s = cay * px + acx * py - acd;
+            if (s >= 0) {
+                t = aby * px + bax * py + abd;
+                if (t >= 0) {
+                    k = A - s - t;
+                    if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
+                }
+            }
+        }
+
+    // if we don't use z-order curve hash, simply iterate through all other points
+    } else {
+        node = ear.next.next;
+
+        while (node !== ear.prev) {
+            i = node.i;
+            node = node.next;
+
+            px = data[i];
+            py = data[i + 1];
+
+            s = cay * px + acx * py - acd;
+            if (s >= 0) {
+                t = aby * px + bax * py + abd;
+                if (t >= 0) {
+                    k = A - s - t;
+                    if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
+                }
+            }
+        }
+    }
+
+    return true;
+}
+
+// go through all polygon nodes and cure small local self-intersections
+function cureLocalIntersections(data, start, triangles, dim) {
+    var node = start;
+    do {
+        var a = node.prev,
+            b = node.next.next;
+
+        // a self-intersection where edge (v[i-1],v[i]) intersects (v[i+1],v[i+2])
+        if (a.i !== b.i && intersects(data, a.i, node.i, node.next.i, b.i) &&
+                locallyInside(data, a, b) && locallyInside(data, b, a) &&
+                orient(data, a.i, node.i, b.i) && orient(data, a.i, node.next.i, b.i)) {
+
+            triangles.push(a.i / dim);
+            triangles.push(node.i / dim);
+            triangles.push(b.i / dim);
+
+            // remove two nodes involved
+            removeNode(node);
+            removeNode(node.next);
+
+            node = start = b;
+        }
+        node = node.next;
+    } while (node !== start);
+
+    return node;
+}
+
+// try splitting polygon into two and triangulate them independently
+function splitEarcut(data, start, triangles, dim, minX, minY, size) {
+    // 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(data, a, b)) {
+                // split the polygon in two by the diagonal
+                var c = splitPolygon(a, b);
+
+                // filter colinear points around the cuts
+                a = filterPoints(data, a, a.next);
+                c = filterPoints(data, c, c.next);
+
+                // run earcut on each half
+                earcutLinked(data, a, triangles, dim, minX, minY, size);
+                earcutLinked(data, c, triangles, dim, minX, minY, size);
+                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;
+        list = filterPoints(data, list);
+        if (list) queue.push(getLeftmost(data, list));
+    }
+
+    queue.sort(function (a, b) {
+        return data[a.i] - data[b.i];
+    });
+
+    // process holes from left to right
+    for (i = 0; i < queue.length; i++) {
+        eliminateHole(data, queue[i], outerNode);
+        outerNode = filterPoints(data, outerNode, outerNode.next);
+    }
+
+    return outerNode;
+}
+
+// find a bridge between vertices that connects hole with an outer ring and and link it
+function eliminateHole(data, holeNode, outerNode) {
+    outerNode = findHoleBridge(data, holeNode, outerNode);
+    if (outerNode) {
+        var b = splitPolygon(outerNode, holeNode);
+        filterPoints(data, b, b.next);
+    }
+}
+
+// David Eberly's algorithm for finding a bridge between hole and outer polygon
+function findHoleBridge(data, holeNode, outerNode) {
+    var node = outerNode,
+        i = holeNode.i,
+        px = data[i],
+        py = data[i + 1],
+        qMax = -Infinity,
+        mNode, a, b;
+
+    // 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 {
+        a = node.i;
+        b = node.next.i;
+
+        if (py <= data[a + 1] && py >= data[b + 1]) {
+            var qx = data[a] + (py - data[a + 1]) * (data[b] - data[a]) / (data[b + 1] - data[a + 1]);
+            if (qx <= px && qx > qMax) {
+                qMax = qx;
+                mNode = data[a] < data[b] ? node : node.next;
+            }
+        }
+        node = node.next;
+    } while (node !== outerNode);
+
+    if (!mNode) return null;
+
+    // look for points strictly 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 bx = data[mNode.i],
+        by = data[mNode.i + 1],
+        pbd = px * by - py * bx,
+        pcd = px * py - py * qMax,
+        cpy = py - py,
+        pcx = px - qMax,
+        pby = py - by,
+        bpx = bx - px,
+        A = pbd - pcd - (qMax * by - py * bx),
+        sign = A <= 0 ? -1 : 1,
+        stop = mNode,
+        tanMin = Infinity,
+        mx, my, amx, s, t, tan;
+
+    node = mNode.next;
+
+    while (node !== stop) {
+
+        mx = data[node.i];
+        my = data[node.i + 1];
+        amx = px - mx;
+
+        if (amx >= 0 && mx >= bx) {
+            s = (cpy * mx + pcx * my - pcd) * sign;
+            if (s >= 0) {
+                t = (pby * mx + bpx * my + pbd) * sign;
+
+                if (t >= 0 && A * sign - s - t >= 0) {
+                    tan = Math.abs(py - my) / amx; // tangential
+                    if ((tan < tanMin || (tan === tanMin && mx > bx)) &&
+                            locallyInside(data, node, holeNode)) {
+                        mNode = node;
+                        tanMin = tan;
+                    }
+                }
+            }
+        }
+
+        node = node.next;
+    }
+
+    return mNode;
+}
+
+// interlink polygon nodes in z-order
+function indexCurve(data, start, minX, minY, size) {
+    var node = start;
+
+    do {
+        if (node.z === null) node.z = zOrder(data[node.i], data[node.i + 1], minX, minY, size);
+        node.prevZ = node.prev;
+        node.nextZ = node.next;
+        node = node.next;
+    } while (node !== start);
+
+    node.prevZ.nextZ = null;
+    node.prevZ = null;
+
+    sortLinked(node);
+}
+
+// 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) {
+                    e = q;
+                    q = q.nextZ;
+                    qSize--;
+                } else if (qSize === 0 || !q) {
+                    e = p;
+                    p = p.nextZ;
+                    pSize--;
+                } else if (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 size of the data bounding box
+function zOrder(x, y, minX, minY, size) {
+    // coords are transformed into non-negative 15-bit integer range
+    x = 32767 * (x - minX) / size;
+    y = 32767 * (y - minY) / size;
+
+    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(data, start) {
+    var node = start,
+        leftmost = start;
+    do {
+        if (data[node.i] < data[leftmost.i]) leftmost = node;
+        node = node.next;
+    } while (node !== start);
+
+    return leftmost;
+}
+
+// check if a diagonal between two polygon nodes is valid (lies in polygon interior)
+function isValidDiagonal(data, a, b) {
+    return a.next.i !== b.i && a.prev.i !== b.i &&
+           !intersectsPolygon(data, a, a.i, b.i) &&
+           locallyInside(data, a, b) && locallyInside(data, b, a) &&
+           middleInside(data, a, a.i, b.i);
+}
+
+// winding order of triangle formed by 3 given points
+function orient(data, p, q, r) {
+    var o = (data[q + 1] - data[p + 1]) * (data[r] - data[q]) - (data[q] - data[p]) * (data[r + 1] - data[q + 1]);
+    return o > 0 ? 1 :
+           o < 0 ? -1 : 0;
+}
+
+// check if two points are equal
+function equals(data, p1, p2) {
+    return data[p1] === data[p2] && data[p1 + 1] === data[p2 + 1];
+}
+
+// check if two segments intersect
+function intersects(data, p1, q1, p2, q2) {
+    return orient(data, p1, q1, p2) !== orient(data, p1, q1, q2) &&
+           orient(data, p2, q2, p1) !== orient(data, p2, q2, q1);
+}
+
+// check if a polygon diagonal intersects any polygon segments
+function intersectsPolygon(data, start, a, b) {
+    var node = start;
+    do {
+        var p1 = node.i,
+            p2 = node.next.i;
+
+        if (p1 !== a && p2 !== a && p1 !== b && p2 !== b && intersects(data, p1, p2, a, b)) return true;
+
+        node = node.next;
+    } while (node !== start);
+
+    return false;
+}
+
+// check if a polygon diagonal is locally inside the polygon
+function locallyInside(data, a, b) {
+    return orient(data, a.prev.i, a.i, a.next.i) === -1 ?
+        orient(data, a.i, b.i, a.next.i) !== -1 && orient(data, a.i, a.prev.i, b.i) !== -1 :
+        orient(data, a.i, b.i, a.prev.i) === -1 || orient(data, a.i, a.next.i, b.i) === -1;
+}
+
+// check if the middle point of a polygon diagonal is inside the polygon
+function middleInside(data, start, a, b) {
+    var node = start,
+        inside = false,
+        px = (data[a] + data[b]) / 2,
+        py = (data[a + 1] + data[b + 1]) / 2;
+    do {
+        var p1 = node.i,
+            p2 = node.next.i;
+
+        if (((data[p1 + 1] > py) !== (data[p2 + 1] > py)) &&
+                (px < (data[p2] - data[p1]) * (py - data[p1 + 1]) / (data[p2 + 1] - data[p1 + 1]) + data[p1]))
+            inside = !inside;
+
+        node = node.next;
+    } while (node !== start);
+
+    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),
+        b2 = new Node(b.i),
+        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, last) {
+    var node = new Node(i);
+
+    if (!last) {
+        node.prev = node;
+        node.next = node;
+
+    } else {
+        node.next = last.next;
+        node.prev = last;
+        last.next.prev = node;
+        last.next = node;
+    }
+    return node;
+}
+
+function removeNode(node) {
+    node.next.prev = node.prev;
+    node.prev.next = node.next;
+
+    if (node.prevZ) node.prevZ.nextZ = node.nextZ;
+    if (node.nextZ) node.nextZ.prevZ = node.prevZ;
+}
+
+function Node(i) {
+    // vertex coordinates
+    this.i = i;
+
+    // previous and next vertice nodes in a polygon ring
+    this.prev = null;
+    this.next = null;
+
+    // z-order curve value
+    this.z = null;
+
+    // previous and next nodes in z-order
+    this.prevZ = null;
+    this.nextZ = null;
+
+    // indicates whether this is a steiner point
+    this.steiner = false;
+}