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+/**
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+ *
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+ * Earcut https://github.com/mapbox/earcut
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+ *
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+ * Copyright (c) 2015, Mapbox
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+ *
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+ * Permission to use, copy, modify, and/or distribute this software for any purpose
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+ * with or without fee is hereby granted, provided that the above copyright notice
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+ * and this permission notice appear in all copies.
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+ *
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+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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+ * FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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+ * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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+ * THIS SOFTWARE.
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+ */
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+'use strict';
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+
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+//module.exports = earcut;
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+
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+function earcut(data, holeIndices, dim) {
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+
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+ dim = dim || 2;
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+
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+ var hasHoles = holeIndices && holeIndices.length,
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+ outerLen = hasHoles ? holeIndices[0] * dim : data.length,
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+ outerNode = filterPoints(data, linkedList(data, 0, outerLen, dim, true)),
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+ triangles = [];
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+
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+ if (!outerNode) return triangles;
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+
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+ var minX, minY, maxX, maxY, x, y, size;
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+
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+ if (hasHoles) outerNode = eliminateHoles(data, holeIndices, outerNode, dim);
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+
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+ // if the shape is not too simple, we'll use z-order curve hash later; calculate polygon bbox
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+ if (data.length > 80 * dim) {
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+ minX = maxX = data[0];
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+ minY = maxY = data[1];
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+
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+ for (var i = dim; i < outerLen; i += dim) {
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+ x = data[i];
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+ y = data[i + 1];
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+ if (x < minX) minX = x;
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+ if (y < minY) minY = y;
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+ if (x > maxX) maxX = x;
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+ if (y > maxY) maxY = y;
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+ }
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+
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+ // minX, minY and size are later used to transform coords into integers for z-order calculation
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+ size = Math.max(maxX - minX, maxY - minY);
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+ }
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+
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+ earcutLinked(data, outerNode, triangles, dim, minX, minY, size);
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+
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+ return triangles;
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+}
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+
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+// create a circular doubly linked list from polygon points in the specified winding order
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+function linkedList(data, start, end, dim, clockwise) {
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+ var sum = 0,
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+ i, j, last;
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+
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+ // calculate original winding order of a polygon ring
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+ for (i = start, j = end - dim; i < end; i += dim) {
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+ sum += (data[j] - data[i]) * (data[i + 1] + data[j + 1]);
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+ j = i;
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+ }
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+
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+ // link points into circular doubly-linked list in the specified winding order
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+ if (clockwise === (sum > 0)) {
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+ for (i = start; i < end; i += dim) last = insertNode(i, last);
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+ } else {
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+ for (i = end - dim; i >= start; i -= dim) last = insertNode(i, last);
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+ }
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+
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+ return last;
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+}
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+
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+// eliminate colinear or duplicate points
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+function filterPoints(data, start, end) {
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+ if (!start) return start;
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+ if (!end) end = start;
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+
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+ var node = start,
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+ again;
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+ do {
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+ again = false;
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+
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+ if (!node.steiner && (equals(data, node.i, node.next.i) || orient(data, node.prev.i, node.i, node.next.i) === 0)) {
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+ removeNode(node);
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+ node = end = node.prev;
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+ if (node === node.next) return null;
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+ again = true;
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+
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+ } else {
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+ node = node.next;
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+ }
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+ } while (again || node !== end);
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+
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+ return end;
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+}
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+
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+// main ear slicing loop which triangulates a polygon (given as a linked list)
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+function earcutLinked(data, ear, triangles, dim, minX, minY, size, pass) {
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+ if (!ear) return;
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+
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+ // interlink polygon nodes in z-order
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+ if (!pass && minX !== undefined) indexCurve(data, ear, minX, minY, size);
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+
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+ var stop = ear,
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+ prev, next;
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+
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+ // iterate through ears, slicing them one by one
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+ while (ear.prev !== ear.next) {
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+ prev = ear.prev;
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+ next = ear.next;
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+
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+ if (isEar(data, ear, minX, minY, size)) {
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+ // cut off the triangle
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+ triangles.push(prev.i / dim);
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+ triangles.push(ear.i / dim);
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+ triangles.push(next.i / dim);
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+
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+ removeNode(ear);
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+
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+ // skipping the next vertice leads to less sliver triangles
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+ ear = next.next;
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+ stop = next.next;
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+
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+ continue;
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+ }
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+
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+ ear = next;
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+
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+ // if we looped through the whole remaining polygon and can't find any more ears
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+ if (ear === stop) {
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+ // try filtering points and slicing again
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+ if (!pass) {
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+ earcutLinked(data, filterPoints(data, ear), triangles, dim, minX, minY, size, 1);
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+
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+ // if this didn't work, try curing all small self-intersections locally
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+ } else if (pass === 1) {
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+ ear = cureLocalIntersections(data, ear, triangles, dim);
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+ earcutLinked(data, ear, triangles, dim, minX, minY, size, 2);
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+
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+ // as a last resort, try splitting the remaining polygon into two
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+ } else if (pass === 2) {
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+ splitEarcut(data, ear, triangles, dim, minX, minY, size);
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+ }
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+
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+ break;
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+ }
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+ }
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+}
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+
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+// check whether a polygon node forms a valid ear with adjacent nodes
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+function isEar(data, ear, minX, minY, size) {
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+
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+ var a = ear.prev.i,
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+ b = ear.i,
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+ c = ear.next.i,
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+
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+ ax = data[a], ay = data[a + 1],
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+ bx = data[b], by = data[b + 1],
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+ cx = data[c], cy = data[c + 1],
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+
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+ abd = ax * by - ay * bx,
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+ acd = ax * cy - ay * cx,
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+ cbd = cx * by - cy * bx,
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+ A = abd - acd - cbd;
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+
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+ if (A <= 0) return false; // reflex, can't be an ear
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+
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+ // now make sure we don't have other points inside the potential ear;
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+ // the code below is a bit verbose and repetitive but this is done for performance
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+
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+ var cay = cy - ay,
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+ acx = ax - cx,
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+ aby = ay - by,
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+ bax = bx - ax,
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+ i, px, py, s, t, k, node;
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+
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+ // if we use z-order curve hashing, iterate through the curve
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+ if (minX !== undefined) {
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+
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+ // triangle bbox; min & max are calculated like this for speed
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+ var minTX = ax < bx ? (ax < cx ? ax : cx) : (bx < cx ? bx : cx),
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+ minTY = ay < by ? (ay < cy ? ay : cy) : (by < cy ? by : cy),
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+ maxTX = ax > bx ? (ax > cx ? ax : cx) : (bx > cx ? bx : cx),
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+ maxTY = ay > by ? (ay > cy ? ay : cy) : (by > cy ? by : cy),
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+
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+ // z-order range for the current triangle bbox;
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+ minZ = zOrder(minTX, minTY, minX, minY, size),
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+ maxZ = zOrder(maxTX, maxTY, minX, minY, size);
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+
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+ // first look for points inside the triangle in increasing z-order
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+ node = ear.nextZ;
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+
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+ while (node && node.z <= maxZ) {
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+ i = node.i;
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+ node = node.nextZ;
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+ if (i === a || i === c) continue;
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+
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+ px = data[i];
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+ py = data[i + 1];
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+
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+ s = cay * px + acx * py - acd;
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+ if (s >= 0) {
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+ t = aby * px + bax * py + abd;
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+ if (t >= 0) {
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+ k = A - s - t;
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+ if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
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+ }
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+ }
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+ }
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+
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+ // then look for points in decreasing z-order
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+ node = ear.prevZ;
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+
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+ while (node && node.z >= minZ) {
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+ i = node.i;
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+ node = node.prevZ;
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+ if (i === a || i === c) continue;
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+
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+ px = data[i];
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+ py = data[i + 1];
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+
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+ s = cay * px + acx * py - acd;
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+ if (s >= 0) {
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+ t = aby * px + bax * py + abd;
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+ if (t >= 0) {
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+ k = A - s - t;
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+ if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
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+ }
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+ }
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+ }
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+
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+ // if we don't use z-order curve hash, simply iterate through all other points
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+ } else {
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+ node = ear.next.next;
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+
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+ while (node !== ear.prev) {
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+ i = node.i;
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+ node = node.next;
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+
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+ px = data[i];
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+ py = data[i + 1];
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+
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+ s = cay * px + acx * py - acd;
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+ if (s >= 0) {
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+ t = aby * px + bax * py + abd;
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+ if (t >= 0) {
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+ k = A - s - t;
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+ if ((k >= 0) && ((s && t) || (s && k) || (t && k))) return false;
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+ }
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+ }
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+ }
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+ }
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+
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+ return true;
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+}
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+
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+// go through all polygon nodes and cure small local self-intersections
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+function cureLocalIntersections(data, start, triangles, dim) {
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+ var node = start;
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+ do {
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+ var a = node.prev,
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+ b = node.next.next;
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+
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+ // a self-intersection where edge (v[i-1],v[i]) intersects (v[i+1],v[i+2])
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+ if (a.i !== b.i && intersects(data, a.i, node.i, node.next.i, b.i) &&
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+ locallyInside(data, a, b) && locallyInside(data, b, a) &&
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+ orient(data, a.i, node.i, b.i) && orient(data, a.i, node.next.i, b.i)) {
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+
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+ triangles.push(a.i / dim);
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+ triangles.push(node.i / dim);
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+ triangles.push(b.i / dim);
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+
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+ // remove two nodes involved
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+ removeNode(node);
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+ removeNode(node.next);
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+
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+ node = start = b;
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+ }
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+ node = node.next;
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+ } while (node !== start);
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+
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+ return node;
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+}
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+
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+// try splitting polygon into two and triangulate them independently
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+function splitEarcut(data, start, triangles, dim, minX, minY, size) {
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+ // look for a valid diagonal that divides the polygon into two
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+ var a = start;
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+ do {
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+ var b = a.next.next;
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+ while (b !== a.prev) {
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+ if (a.i !== b.i && isValidDiagonal(data, a, b)) {
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+ // split the polygon in two by the diagonal
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+ var c = splitPolygon(a, b);
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+
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+ // filter colinear points around the cuts
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+ a = filterPoints(data, a, a.next);
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+ c = filterPoints(data, c, c.next);
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+
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+ // run earcut on each half
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+ earcutLinked(data, a, triangles, dim, minX, minY, size);
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+ earcutLinked(data, c, triangles, dim, minX, minY, size);
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+ return;
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+ }
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+ b = b.next;
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+ }
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+ a = a.next;
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+ } while (a !== start);
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+}
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+
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+// link every hole into the outer loop, producing a single-ring polygon without holes
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+function eliminateHoles(data, holeIndices, outerNode, dim) {
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+ var queue = [],
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+ i, len, start, end, list;
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+
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+ for (i = 0, len = holeIndices.length; i < len; i++) {
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+ start = holeIndices[i] * dim;
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+ end = i < len - 1 ? holeIndices[i + 1] * dim : data.length;
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+ list = linkedList(data, start, end, dim, false);
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+ if (list === list.next) list.steiner = true;
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+ list = filterPoints(data, list);
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+ if (list) queue.push(getLeftmost(data, list));
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+ }
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+
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+ queue.sort(function (a, b) {
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+ return data[a.i] - data[b.i];
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+ });
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+
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+ // process holes from left to right
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+ for (i = 0; i < queue.length; i++) {
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+ eliminateHole(data, queue[i], outerNode);
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+ outerNode = filterPoints(data, outerNode, outerNode.next);
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+ }
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+
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+ return outerNode;
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+}
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+
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+// find a bridge between vertices that connects hole with an outer ring and and link it
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+function eliminateHole(data, holeNode, outerNode) {
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+ outerNode = findHoleBridge(data, holeNode, outerNode);
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+ if (outerNode) {
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+ var b = splitPolygon(outerNode, holeNode);
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+ filterPoints(data, b, b.next);
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+ }
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+}
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+
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+// David Eberly's algorithm for finding a bridge between hole and outer polygon
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+function findHoleBridge(data, holeNode, outerNode) {
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+ var node = outerNode,
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+ i = holeNode.i,
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+ px = data[i],
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+ py = data[i + 1],
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+ qMax = -Infinity,
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+ mNode, a, b;
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+
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+ // find a segment intersected by a ray from the hole's leftmost point to the left;
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+ // segment's endpoint with lesser x will be potential connection point
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+ do {
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+ a = node.i;
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+ b = node.next.i;
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+
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+ if (py <= data[a + 1] && py >= data[b + 1]) {
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+ var qx = data[a] + (py - data[a + 1]) * (data[b] - data[a]) / (data[b + 1] - data[a + 1]);
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+ if (qx <= px && qx > qMax) {
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+ qMax = qx;
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+ mNode = data[a] < data[b] ? node : node.next;
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+ }
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+ }
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+ node = node.next;
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+ } while (node !== outerNode);
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+
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+ if (!mNode) return null;
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+
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+ // look for points strictly inside the triangle of hole point, segment intersection and endpoint;
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+ // if there are no points found, we have a valid connection;
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+ // otherwise choose the point of the minimum angle with the ray as connection point
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+
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+ var bx = data[mNode.i],
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+ by = data[mNode.i + 1],
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+ pbd = px * by - py * bx,
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+ pcd = px * py - py * qMax,
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+ cpy = py - py,
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+ pcx = px - qMax,
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+ pby = py - by,
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+ bpx = bx - px,
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+ A = pbd - pcd - (qMax * by - py * bx),
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+ sign = A <= 0 ? -1 : 1,
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+ stop = mNode,
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+ tanMin = Infinity,
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+ mx, my, amx, s, t, tan;
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+
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+ node = mNode.next;
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+
|
|
|
+ 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;
|
|
|
+}
|