3D Printer Contour Plot

A contour plot of the height of the bed of a 3d printer.

<!DOCTYPE html>
<meta charset="utf-8">
<title>3D Printer Contour Plot</title>

<body>
  <style>
    svg {
      font: 10px sans-serif;
    }
    
    path.line {
      fill: none;
      stroke: #666;
      stroke-width: 1.5px;
    }
    
    path.area {
      fill: #e7e7e7;
    }
    
    .axis {
      shape-rendering: crispEdges;
    }
    
    .x.axis line {
      stroke: #fff;
    }
    
    .x.axis .minor {
      stroke-opacity: .5;
    }
    
    .x.axis path {
      display: none;
    }
    
    .y.axis line,
    .y.axis path {
      fill: none;
      stroke: #000;
    }
  </style>

// Add a "cliff edge" to force contour lines to close along the border.
var cliff = -1000;
data.push(d3.range(data[0].length).map(function() { return cliff; }));
data.unshift(d3.range(data[0].length).map(function() { return cliff; }));
data.forEach(function(d) {
  d.push(cliff);
  d.unshift(cliff);
});

var margin = {top: 40, right: 40, bottom: 40, left: 40},
    width = 500 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var c = new Conrec,
    xs = d3.range(0, data.length),
    ys = d3.range(0, data[0].length),
    zs = d3.range(-2, 12, 1),
    x = d3.scale.linear().range([0, width]).domain([1, data.length - 2]),
    y = d3.scale.linear().range([height, 0]).domain([1, data[0].length - 2]),
    colours = d3.scale.linear().domain([0, data.length]).interpolate(d3.interpolateHcl).range([d3.rgb("#007AFF"), d3.rgb('#FFF500')]);

var xAxis = d3.svg.axis()
    .scale(x);

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("right");

c.contour(data, 0, xs.length - 1, 0, ys.length - 1, xs, ys, zs.length, zs);

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

svg.selectAll("path")
    .data(c.contourList())
  .enter().append("path")
    .style("fill",function(d) { return colours(d.level);})
    .style("stroke","black")
    .attr("d", d3.svg.line()
      .x(function(d) { return x(d.x); })
      .y(function(d) { return y(d.y); }));

svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

svg.append("g")
      .attr("class", "y axis")
      .attr("transform", "translate(" + width + ",0)")
      .call(yAxis);

</script>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js