d3.js Delaunay.hullPolygon()用法及代码示例

德劳奈.hullPolygon()方法返回表示凸包的闭合多边形 [[x0, y0], [x1, y1], …, [x0, y0]]。

用法:

Delaunay.hullPolygon()

参数：

该方法不带参数。

返回值：

此方法返回表示凸包的多边形数组。

示例 1：下面的代码示例显示了使用d3.德劳奈.hullPolygon()方法。

HTML


<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <script src="https://d3js.org/d3.v5.min.js"></script>
</head>
<body style="text-align: center;">
    <h1 style="text-align: center; color: green;">
        GeeksforGeeks
    </h1>
    <h3 style="text-align: center;">
        D3.js | d3.hullPolygon() Method
    </h3>
    <div id="app" style=
        "text-align: center; 
        margin-top: 20px; 
        font-size: 18px;">
    </div>
    <script type="module">
        import * as d3 from "https://cdn.skypack.dev/d3@7";
        const canvasWidth = 400;
        const canvasHeight = 300;
        const canvas = 
            document.createElement("canvas");
        const context = canvas.getContext("2d");
        canvas.width = canvasWidth;
        canvas.height = canvasHeight;
        const data = Array(50).fill()
            .map((_, i) => ({
                x: (i * canvasWidth) / 50,
                y: Math.random() * canvasHeight
            }));
        const voronoi = d3.Delaunay.from(data,
            (d) => d.x,
            (d) => d.y
        ).voronoi([0, 0, canvasWidth, canvasHeight]);
        context.clearRect(0, 0, canvasWidth, canvasHeight);
        context.fillStyle = "black";
        context.beginPath();
        voronoi.delaunay.renderPoints(context, 1);
        context.fill();
        context.lineWidth = 1.5;
        const segments = 
            voronoi.render().split(/M/).slice(1);
        for (const e of segments) {
            context.beginPath();
            context.strokeStyle = 
                d3.hsl(360 * Math.random(), 0.7, 0.5);
            context.stroke(new Path2D("M" + e));
        }
        const hull = voronoi.delaunay.hullPolygon();
        document.querySelector("#app").innerHTML =
            `Convex Hull: ${JSON.stringify(hull)}`;
        document.querySelector("#app").
            appendChild(canvas);
    </script>
</body>
</html>

输出：

Screenshot-2024-03-03-184851-(1)

示例 2：下面的代码演示了D3.js的使用HullPloygon()计算一组点的凸包的方法。

HTML


<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <script src="https://d3js.org/d3.v7.min.js"></script>
</head>
<body style="text-align: center;">
    <h1 style="text-align: center; color: green;">
        GeeksforGeeks
    </h1>
    <h3 style="text-align: center;">
        D3.js | hullPolygon() Method
    </h3>
    <div id="app" style=
        "text-align: center; 
        margin-top: 20px;">
    </div>
    <script type="module">
        import * as d3 from "https://cdn.skypack.dev/d3@7";
        const width = 600;
        const height = 400;
        const points = Array.from({ length: 50 }, 
            () => [Math.random() * width, 
                Math.random() * height]);
        const delaunay = d3.Delaunay.from(points);
        const hull = delaunay.hullPolygon();
        const canvas = d3.select("#app")
            .append("canvas")
            .attr("width", width)
            .attr("height", height);
        const context = 
            canvas.node().getContext("2d");
        context.beginPath();
        delaunay.renderPoints(context);
        context.fillStyle = "black";
        context.fill();
        context.beginPath();
        context.strokeStyle = "blue";
        context.lineWidth = 2;
        context.moveTo(hull[0][0], hull[0][1]);
        for (const point of hull) {
            context.lineTo(point[0], point[1]);
        }
        context.closePath();
        context.stroke();
    </script>
</body>
</html>

输出：

Screenshot-2024-03-04-214448

相关用法

注：本文由纯净天空筛选整理自kirandeepkaurguler大神的英文原创作品 D3.js Delaunay.hullPolygon() Method。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。