d3.js Delaunay.halfedges用法及代码示例

Delaunay.halfedges属性以 Int32Array [j0, j1, …] 形式返回半边索引。对于 0 到 half-edges 数组长度(不包括)之间的每个索引值，存在从三角形的一个顶点到另一个顶点的连接。

用法:

delaunay.halfedges

参数：

它不接受任何内容作为参数。

返回值：

此属性返回一个指向 half-edges 索引的数组。

示例 1：下面的代码示例显示了使用d3.delaunay.halfedges属性。

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.Delaunay.halfedges Property
    </h3>
    <p id="result"></p>
    <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 halfedges = 
            voronoi.delaunay.halfedges;
        document.querySelector("#result").innerHTML =
            `Halfedges: ${halfedges}
            Number of Halfedges: ${halfedges.length}`;
        document.querySelector("#app").
            appendChild(canvas);
    </script>
</body>
</html>

输出：

D3SS

示例 2：下面的代码使用d3.Delaunay.halfedges属性来渲染 Voronoi 图并突出显示边。

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 | Voronoi Diagram with Halfedges
    </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 voronoi = 
            delaunay.voronoi([0, 0, width, height]);
        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 = "gray";
        voronoi.renderBounds(context);
        context.stroke();
        const halfedges = delaunay.halfedges;
        for (let i = 0; i < halfedges.length; ++i) {
            const j = halfedges[i];
            if (j !== -1) {
                const p0 = 
                    points[delaunay.triangles[Math.floor(i / 3)]];
                const p1 = 
                    points[delaunay.triangles[Math.floor((i + 1) / 3)]];
                const p2 = 
                    points[delaunay.triangles[Math.floor((i + 2) / 3)]];
                const e = delaunay.edges[i];
                context.moveTo(p0[0], p0[1]);
                context.lineTo(p1[0], p1[1]);
                context.lineTo(p2[0], p2[1]);
                context.closePath();
                context.stroke();
            }
        }
    </script>
</body>
</html>

输出：

Screenshot-2024-03-04-205849

相关用法

注：本文由纯净天空筛选整理自taran910大神的英文原创作品 D3.js Delaunay.halfedges Property。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。