d3.js geoLoximuthal()用法及代码示例

D3.js是一个JavaScript库，用于在Web浏览器中生成动态的交互式数据可视化。它利用可伸缩矢量图形，HTML5和级联样式表标准。
d3.js中的geoLoximuthal()函数用于绘制水平投影。

用法:

d3.geoLoximuthal()

参数：此方法不接受任何参数。

返回值：此方法根据给定的json数据创建Loximuthal投影。

范例1：下面的示例绘制以(0，0)为中心且旋转为0的世界的水平投影。

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" /> 
</head> 
  
<body> 
    <div style="width:700px; height:500px;"> 
        <center> 
            <h3 style="color:black;"></h3> 
        </center> 
  
        <svg width="600" height="450"></svg> 
    </div> 
    <script src="https://d3js.org/d3.v4.js"></script> 
    <script src= 
    "https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Loximuthal projection 
        // Center(0, 0) with 0 rotation 
        var gfg = d3 
            .geoLoximuthal() 
            .scale(width / 2.0 / Math.PI) 
            .rotate([0, 0]) 
            .center([0, 0]) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        // Used json file stored at  
        /*https://raw.githubusercontent.com/janasayantan 
                    /datageojson/master/world.json*/ 
        d3.json("https://raw.githubusercontent.com/" 
            + "janasayantan/datageojson/master/world.json", 
            function (data) { 
                // Drawing the map 
                svg.append("g").selectAll("path") 
                    .data(data.features).enter() 
                    .append("path").attr("fill", "black") 
                    .attr("d", d3.geoPath().projection(gfg)) 
                    .style("stroke", "#ffff"); 
            }); 
    </script> 
</body> 
  
</html>

输出：

无自旋且以(0，0)为中心的世界的投影投影

范例2：下面的示例在更改中心和旋转后绘制世界的Loximuthal投影。

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" /> 
</head> 
  
<body> 
    <div style="width:700px; height:600px;"> 
        <center> 
            <h3 style="color:black;"></h3> 
        </center> 
  
        <svg width="500" height="450"></svg> 
    </div> 
    <script src="https://d3js.org/d3.v4.js"></script> 
    <script src= 
    "https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Loximuthal  projection 
        // Center(0, 20) and 90 degree 
        // rotation w.r.t Y axis 
        var gfg = d3 
            .geoLoximuthal() 
            .scale(width / 2.0 / Math.PI) 
            .rotate([90, 0]) 
            .center([20, 20]) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        // Used json file stored at  
        /*https://raw.githubusercontent.com/janasayantan 
                    /datageojson/master/world.json*/ 
        d3.json("https://raw.githubusercontent.com/" 
            + "janasayantan/datageojson/master/world.json", 
            function (data) { 
                // Draw the map 
                svg.append("g").selectAll("path") 
                    .data(data.features).enter() 
                    .append("path").attr("fill", "Turquoise") 
                    .attr("d", d3.geoPath().projection(gfg)) 
                    .style("stroke", "#ffff"); 
            }); 
    </script> 
</body> 
  
</html>

输出：

Y轴旋转90度，以(20，20)为中心的水平投影

相关用法

注：本文由纯净天空筛选整理自jana_sayantan大神的英文原创作品 D3.js geoLoximuthal() Function。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。