3D DNA Helix

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js" charset="utf-8"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
    <script type="text/javascript">

var fills   = ['#00779C', '#00465C', '#54B8B1', '#377874', '#455560', '#7C99AC', '#F5CC49', '#F5CC9C', '#A8353D', '#682126'],
            h       = 150,
            w       = 800,
            numX    = 40,
            numY    = 30,
            speed   = 0.02,
            torsion = 0.2,
            x = d3.scale.linear().range([10, w - 10]),
            y = d3.scale.linear().range([h - 10, 10]),
            z = d3.scale.linear().range([10, 2]);

var svg = d3.select("body")
            .append("svg")
            .attr("width", w)
            .attr("height", h)

svg.append("rect")
            .attr("width", w)
            .attr("height", h)
            .attr("fill", "white")
            .on("mousemove", function () { torsion = 0.5 * d3.mouse(this)[0] / w; });

var container = svg.append("g");

return data
        }

function draw() {
            var cont = container.selectAll("g").data(generateData());
            cont.exit().remove();

var enter = cont.enter()
                .append("g")
                .each(function (d, index) {

d3.select(this)
                        .selectAll("circle")
                        .data(d)
                        .enter()
                        .append("circle")
                        .attr("fill", "black");

d3.select(this).append('line')
                        .attr("stroke", function (d, i) { return fills[index%7] })
                        .attr("stroke-width", 2)
                });
                
            cont.each(function (d, index) {

var inverted = (d[0].y < d[1].y) ? 1 : -1;

d3.select(this)
                    .selectAll("circle")
                    .data(d)
                    .attr("cx", function (d) { return x(d.x) })
                    .attr("cy", function (d) { return y(d.y) })
                    .attr("r",  function (d) { return z(d.z) })
                    .attr("fill-opacity", function (d) { return z(d.z) / 10 })
                    .attr("fill", function (d, i) { return fills[index%7]; });

d3.select(this)
                    .select('line')
                    .attr("x2", x(d[0].x))
                    .attr("x1", x(d[0].x))
                    .attr("y2", y(d[0].y) - inverted * z(d[0].z))
                    .attr("y1", y(d[1].y) + inverted * z(d[1].z))
                    .attr("opacity", 0.3 * inverted * (d[1].y - d[0].y))
            })
        }

setInterval(draw, 25);
    </script>
</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js

https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js