| license: gpl-3.0 |
This example is the third of three in the Path Transitions tutorial; see the previous example for context.
When transitioning a transform on a path using basis interpolation, you must clip the path by two additional control points so that the change in tangent is not visible while the path slides left.
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| svg { | |
| font: 10px sans-serif; | |
| } | |
| .line { | |
| fill: none; | |
| stroke: #000; | |
| stroke-width: 1.5px; | |
| } | |
| .axis path, | |
| .axis line { | |
| fill: none; | |
| stroke: #000; | |
| shape-rendering: crispEdges; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var n = 40, | |
| random = d3.random.normal(0, .2), | |
| data = d3.range(n).map(random); | |
| var margin = {top: 20, right: 20, bottom: 20, left: 40}, | |
| width = 960 - margin.left - margin.right, | |
| height = 500 - margin.top - margin.bottom; | |
| var x = d3.scale.linear() | |
| .domain([1, n - 2]) | |
| .range([0, width]); | |
| var y = d3.scale.linear() | |
| .domain([-1, 1]) | |
| .range([height, 0]); | |
| var line = d3.svg.line() | |
| .interpolate("basis") | |
| .x(function(d, i) { return x(i); }) | |
| .y(function(d, i) { return y(d); }); | |
| 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.append("defs").append("clipPath") | |
| .attr("id", "clip") | |
| .append("rect") | |
| .attr("width", width) | |
| .attr("height", height); | |
| svg.append("g") | |
| .attr("class", "x axis") | |
| .attr("transform", "translate(0," + y(0) + ")") | |
| .call(d3.svg.axis().scale(x).orient("bottom")); | |
| svg.append("g") | |
| .attr("class", "y axis") | |
| .call(d3.svg.axis().scale(y).orient("left")); | |
| var path = svg.append("g") | |
| .attr("clip-path", "url(#clip)") | |
| .append("path") | |
| .datum(data) | |
| .attr("class", "line") | |
| .attr("d", line); | |
| tick(); | |
| function tick() { | |
| // push a new data point onto the back | |
| data.push(random()); | |
| // redraw the line, and slide it to the left | |
| path | |
| .attr("d", line) | |
| .attr("transform", null) | |
| .transition() | |
| .duration(500) | |
| .ease("linear") | |
| .attr("transform", "translate(" + x(0) + ",0)") | |
| .each("end", tick); | |
| // pop the old data point off the front | |
| data.shift(); | |
| } | |
| </script> |
