d3.js geoHealpix()用法及代码示例

d3.geoHealpix()函数返回2球面的等值分层等值纬度像素化。在该实现中，参数K固定为3。

注意：它需要裁剪到球体。

用法:

d3.geoHealpix()

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Healpix投影。

范例1：以下示例创建中心为(0，0)且不旋转的Healpix世界投影。

HTML

<!DOCTYPE html>  
<html lang="en">  
  
<head>  
    <meta charset="UTF-8" />  
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" />  
    <script src="https://d3js.org/d3.v4.js"> 
     </script>  
    <script src=  
     "https://d3js.org/d3-geo-projection.v2.min.js">  
    </script>  
</head>  
  
<body>  
    <div style="width:700px; height:600px;">  
        <svg width="700" height="550">  
        </svg>  
    </div>  
  
    <script>  
        var svg = d3.select("svg"),  
            width = +svg.attr("width"),  
            height = +svg.attr("height");  
  
        // Healpix projection  
        // Center(0, 0) and no rotation  
        var gfg = d3.geoHealpix()  
            .scale(width / 1.5 / Math.PI)  
            .rotate([0, 0])  
            .center([0, 0])  
            .translate([width / 2, height / 3])  
  
        // Loading the json data  
        // Used json file stored at  
        // https://raw.githubusercontent.com/epistler999/  
        // GeoLocation/master/world.json 
        d3.json("https://raw.githubusercontent.com/" 
            +"epistler999/GeoLocation/master/world.json",  
            function (data) {  
                // Draw 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>  
</html>

输出：

范例2：在下面的示例中，我们将创建以(30，0)为中心并相对于Y轴旋转30度anti-clockwise的世界的HealPix投影。

HTML

<!DOCTYPE html>  
<html lang="en">  
  
<head>  
    <meta charset="UTF-8" />  
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" />  
    <script src="https://d3js.org/d3.v4.js"> 
    </script>  
    <script src=  
       "https://d3js.org/d3-geo-projection.v2.min.js">  
    </script>  
</head>  
  
<body>  
    <div style="width:700px; height:600px;">  
        <svg width="700" height="550">  
        </svg>  
    </div>  
  
    <script>  
        var svg = d3.select("svg"),  
            width = +svg.attr("width"),  
            height = +svg.attr("height");  
  
        // Healpix projection  
        // Center(30, 0) and 30 degree rotation  
        var gfg = d3.geoHealpix()  
            .scale(width / 1.5 / Math.PI)  
            .rotate([-30, 0])  
            .center([30, 0])  
            .translate([width / 2, height / 2])  
  
        // Loading the json data  
        // Used json file stored at  
        // https://raw.githubusercontent.com/epistler999/  
        // GeoLocation/master/world.json 
        d3.json("https://raw.githubusercontent.com/" 
            +"epistler999/GeoLocation/master/world.json",  
            function (data) {  
                // Draw 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：

相关用法

注：本文由纯净天空筛选整理自epistler_999大神的英文原创作品 D3.js geoHealpix() 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。