jakke-graphics-ts/dist/utils/convexHullUtils.js

My common graphics utils for building my aec apps.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.computeContexHull2d = computeContexHull2d;
function computeContexHull2d(vertices) {
    // Find anchor
    let min = vertices[0];
    const comparableVertices = [];
    for (const v of vertices) {
        if (v.y < min.y || (v.y === min.y && v.x < min.x)) {
            min = v;
        }
    }
    // Set comparable vertices
    for (const v of vertices) {
        if (v !== min)
            comparableVertices.push(v);
    }
    // Get parameterized comparables and sort
    const parameterizedVertices = vertices.map(v => {
        const vec = { x: v.x - min.x, y: v.y - min.y, z: 0 };
        return {
            vertex: v,
            param: Math.atan2(vec.y, vec.x)
        };
    });
    const sorted = parameterizedVertices.sort((a, b) => a.param === b.param
        ? getSquaredDistance(min, a.vertex) - getSquaredDistance(min, b.vertex)
        : a.param - b.param);
    // Compares
    const stack = [min, sorted[0].vertex];
    for (let i = 1; i < sorted.length; i++) {
        const pt = sorted[i].vertex;
        while (stack.length >= 2 &&
            !isCCW2d(stack[stack.length - 2], stack[stack.length - 1], pt)) {
            stack.pop();
        }
        stack.push(pt);
    }
    return stack;
}
function getSquaredDistance(v0, v1) {
    return Math.pow(v1.x - v0.x, 2) + Math.pow(v1.y - v0.y, 2) + Math.pow(v1.z - v0.z, 2);
}
function isCCW2d(p0, p1, p2) {
    const v1 = {
        x: p1.x - p0.x,
        y: p1.y - p0.y,
        z: p1.z - p0.z,
    };
    const v2 = {
        x: p2.x - p1.x,
        y: p2.y - p1.y,
        z: p2.z - p1.z,
    };
    return cross2d(v1, v2) > 0;
}
function cross2d(p0, p1) {
    return (p0.y * p1.z - p0.z * p1.y) - (p0.x * p1.z - p0.z * p1.x) + (p0.x * p1.y - p0.y * p1.x);
}
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