| license: gpl-3.0 |
Input a set of comma-delimited numbers, and press play to animate.
My quest to understand how transitions work under the hood, part 2: animate multiple elements with different ending x-positions using d3.interpolate and window.requestAnimationFrame.
Part 1 here: How D3 Transitions Work, Pt. 1: d3.interpolate
forked from sxywu's block: How D3 Transitions Work, Pt. 2: d3.interpolate with multiple elements
| <html> | |
| <head> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.js" charset="utf-8"></script> | |
| <style> | |
| * { | |
| font-family: Helvetica, Verdana, sans-serif; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <p> | |
| <input type="text" onkeyup="input(event)" placeholder="100, 200, 300, 400" /> | |
| <button onclick="play()">play</button> | |
| </p> | |
| <p> | |
| <strong>starting x-position</strong> 100 | <strong>ending x-position</strong> <span class="result">[100, 200, 300, 400]</span> | |
| </p> | |
| <svg width="1000" height="1000"></svg> | |
| <script> | |
| var startX = 100; | |
| var data = [100, 200, 300, 400]; // ending x positions | |
| var yPadding = 100; | |
| var svg = d3.select('svg'); | |
| var circle; | |
| var start = null; | |
| var duration = 1000; | |
| var interpolaters = []; | |
| update(); | |
| // enter and exit circles based on the new set of data | |
| function update() { | |
| circle = svg.selectAll('circle') | |
| .data(data); | |
| circle.enter().append('circle'); | |
| circle.exit().remove('circle'); | |
| circle.attr('cx', startX) | |
| .attr('cy', function(d, i) { | |
| return (i + 1) * yPadding; | |
| }).attr('r', 25) | |
| .attr('fill', '#3FB8AF'); | |
| } | |
| // every time user inputs new data | |
| // update data array and then update circles | |
| function input(e) { | |
| data = e.target.value.split(',').map(function(value) { | |
| return parseFloat(value) || 0; | |
| }); | |
| d3.select('.result').text(JSON.stringify(data)); | |
| update(); | |
| } | |
| // when user clicks play, reset the circles' x positions | |
| // create interpolaters based on the data, and animate | |
| function play() { | |
| start = null; | |
| circle.attr('cx', startX); | |
| // create interpolaters for all the elements | |
| interpolaters = data.map(function(endX) { | |
| return d3.interpolate(startX, endX); | |
| }); | |
| window.requestAnimationFrame(step); | |
| } | |
| // adapted from MDN example for requestAnimationFrame | |
| // (https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame) | |
| function step(timestamp) { | |
| if (!start) start = timestamp; | |
| var progress = timestamp - start; | |
| // use calculated interpolaters to calculate cx at time t | |
| // for each of the circles | |
| var t = progress / duration; | |
| circle.attr('cx', function(d, i) { | |
| return interpolaters[i](t); | |
| }); | |
| if (progress < duration) { | |
| window.requestAnimationFrame(step); | |
| } | |
| } | |
| </script> | |
| </body> | |
| </html> |