ui/node_modules/@melt-ui/svelte/dist/internal/helpers/polygon/hull.js

/*
 * Convex hull algorithm - Library (TypeScript)
 *
 * Copyright (c) 2021 Project Nayuki
 * https://www.nayuki.io/page/convex-hull-algorithm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program (see COPYING.txt and COPYING.LESSER.txt).
 * If not, see <http://www.gnu.org/licenses/>.
 */
// Returns a new array of points representing the convex hull of
// the given set of points. The convex hull excludes collinear points.
// This algorithm runs in O(n log n) time.
export function makeHull(points) {
    const newPoints = points.slice();
    newPoints.sort(POINT_COMPARATOR);
    return makeHullPresorted(newPoints);
}
// Returns the convex hull, assuming that each points[i] <= points[i + 1]. Runs in O(n) time.
export function makeHullPresorted(points) {
    if (points.length <= 1)
        return points.slice();
    // Andrew's monotone chain algorithm. Positive y coordinates correspond to "up"
    // as per the mathematical convention, instead of "down" as per the computer
    // graphics convention. This doesn't affect the correctness of the result.
    const upperHull = [];
    for (let i = 0; i < points.length; i++) {
        const p = points[i];
        while (upperHull.length >= 2) {
            const q = upperHull[upperHull.length - 1];
            const r = upperHull[upperHull.length - 2];
            if ((q.x - r.x) * (p.y - r.y) >= (q.y - r.y) * (p.x - r.x))
                upperHull.pop();
            else
                break;
        }
        upperHull.push(p);
    }
    upperHull.pop();
    const lowerHull = [];
    for (let i = points.length - 1; i >= 0; i--) {
        const p = points[i];
        while (lowerHull.length >= 2) {
            const q = lowerHull[lowerHull.length - 1];
            const r = lowerHull[lowerHull.length - 2];
            if ((q.x - r.x) * (p.y - r.y) >= (q.y - r.y) * (p.x - r.x))
                lowerHull.pop();
            else
                break;
        }
        lowerHull.push(p);
    }
    lowerHull.pop();
    if (upperHull.length == 1 &&
        lowerHull.length == 1 &&
        upperHull[0].x == lowerHull[0].x &&
        upperHull[0].y == lowerHull[0].y)
        return upperHull;
    else
        return upperHull.concat(lowerHull);
}
export function POINT_COMPARATOR(a, b) {
    if (a.x < b.x)
        return -1;
    else if (a.x > b.x)
        return +1;
    else if (a.y < b.y)
        return -1;
    else if (a.y > b.y)
        return +1;
    else
        return 0;
}