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用D3js画爱心

2017.03.08 Cao LinJian

最近重新研究起D3，前些天刚好看到一个新的爱心函数，故拿来练练手

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<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalabel=no">
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>Heart</title>
        <style>
            svg {
                margin: auto;
                display: block;
                position: fixed;
                top:0;
                bottom:0;
                right: 0;
                left:0;
            }
            .axis--x {
                display: none;
            }
            .axis--y {
                display: none;
            }
            .axis path,
            .axis line {
                fill: none;
                stroke: #000;
                shape-rendering: crispEdges;
            }
            .line {
                fill: none;
                stroke: red;
                stroke-width: 1.5px;
            }
            .dot {
                fill: white;
                stroke: red;
                stroke-width: 1.5px;
            }
        </style>
    </head>
    <body>
        <script src="https://d3js.org/d3.v4.min.js"></script>
        <script>
            var heartData = d3.range(-1200, 1200).map(function(i) {
                let x = i / 400;
                let y = Math.sqrt(Math.abs(x)) - Math.sqrt(Math.cos(x)) * Math.cos(60 * x);
                return y && y > -0.9 ? {
                    x: x,
                    y: y
                } : null;
            });
            var lineData = heartData.map((item)=>{
                return item?{
                    x:item.x,
                    y:1
                }:null
            })
            var margin = {
                    top: 20,
                    right: 20,
                    bottom: 20,
                    left: 20
                },
                width = document.body.clientWidth*0.8 - margin.left - margin.right,
                height = document.body.clientWidth*0.625 - margin.top - margin.bottom;
            var x = d3.scaleLinear()
                .domain([-2, 2])
                .range([0, width]);
            var y = d3.scaleLinear()
                .domain([-1, 2])
                .range([height, 0]);
            var line = d3.line()
                 .defined(function(d) { return d; })
                .x(function(d) {
                    return x(d.x)
                })
                .y(function(d) {
                    return y(d.y)
                });
            var svg = d3.select("body").append("svg")
                .datum(lineData)
                .attr("width", width + margin.left + margin.right)
                .attr("height", height + margin.top + margin.bottom)
                .append("g")
                .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
            svg.append("g")
                .attr("class", "axis axis--x")
                .attr("transform", "translate(0," + height + ")")
                .call(d3.axisBottom().scale(x));
            svg.append("g")
                .attr("class", "axis axis--y")
                .call(d3.axisLeft().scale(y));
            svg.append("path")
                .attr("class", "line")
                .attr("translate", "all 0.5 ease-in-out")
                .attr("d", line)
                .transition()
                    .delay(1000)
                    .duration(800)
                    .attr("d", line(heartData));
            // setTimeout(() => {
            //     svg.selectAll(".dot").remove()
            //         .data(heartData.filter(function(d, index) {
            //             return index % 54 == 0 && d;
            //         }))
            //         .enter().append("circle")
            //         .attr("class", "dot")
            //         .attr("cx", line.x())
            //         .attr("cy", line.y())
            //         .attr("r", 3.5);
            // }, 2000)
        </script>
    </body>
</html>

演示地址 http://caolinjian.github.io/Heart.html