Animating arrows along an arbitrary path. Basically a combination of Seamless animated dash and Animating along a path - tweens the stroke-dashoffset on a loop and computes the translate/rotation of the arrowheads at the same time. Performance is not great, especially in Firefox...
See also: Directional arrows
| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <style> | |
| path { | |
| fill: none; | |
| stroke: #d3008c; | |
| stroke-width: 2px; | |
| } | |
| #arrowhead { | |
| fill: #d3008c; | |
| stroke: none; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <svg version="1.1" xmlns="http://www.w3.org/2000/svg" width="960" height="500"> | |
| <path d="M636.5,315c-0.4-18.7,1.9-27.9-5.3-35.9 | |
| c-22.7-25-107.3-2.8-118.3,35.9c-7,24.4,20.6,37.2,16,71c-4,29.6-30.8,60.7-56.5,61.1c-30.8,0.4-32.9-43.8-81.7-70.2 | |
| c-50.9-27.6-110.1-12.9-125.2-9.2c-66.1,16.4-82.2,56.9-109.2,47.3c-38-13.6-55.9-112.1-19.8-143.5c39-34,121.2,27.7,148.1-3.8 | |
| c18-21.1,3.1-74.3-25.2-105.3c-31.1-34.1-70.1-32.4-105.3-76.3c-8.2-10.2-16.9-23.8-15.3-39.7c1.2-11.4,7.5-23.3,15.3-29 | |
| c33.8-25,101.6,62.6,193.1,59.5c40.1-1.3,38.7-18.5,99.2-38.9c126.2-42.6,242.4-4.9,297.7,13c54.7,17.7,105.4,35,129.8,82.4 | |
| c13,25.3,22.9,67.7,4.6,87c-11.6,12.3-25.1,5.1-46.6,20.6c-2.8,2-28.9,21.4-32.1,49.6c-3.1,27.4,18.7,35,29,70.2 | |
| c8.8,30.1,8.5,77.8-18.3,99.2c-32.3,25.8-87,0.6-100-5.3c-69.6-32-67.2-88.4-73.3-109.2z"/> | |
| <defs> | |
| <path id="arrowhead" d="M7,0 L-7,-5 L-7,5 Z" /> | |
| </defs> | |
| </svg> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| var path = document.querySelector("path"), | |
| totalLength = path.getTotalLength(), | |
| group = totalLength / 20, | |
| start; | |
| var arrowheads = d3.select("svg").selectAll("use") | |
| .data(d3.range(20).map(function(d){ return d * group + 50; })) | |
| .enter() | |
| .append("use") | |
| .attr("xlink:href", "#arrowhead"); | |
| path.style.strokeDasharray = "50," + (group - 50); | |
| requestAnimationFrame(update); | |
| function update(t) { | |
| if (!start) { | |
| start = t; | |
| } | |
| var offset = -group * ((t - start) % 900) / 900; | |
| path.style.strokeDashoffset = offset; | |
| arrowheads.attr("transform",function(d){ | |
| var l = d - offset; | |
| if (l < 0) { | |
| l = totalLength + l; | |
| } else if (l > totalLength) { | |
| l -= totalLength; | |
| } | |
| var p = pointAtLength(l); | |
| return "translate(" + p + ") rotate( " + angleAtLength(l) + ")"; | |
| }); | |
| requestAnimationFrame(update); | |
| } | |
| function pointAtLength(l) { | |
| var xy = path.getPointAtLength(l); | |
| return [xy.x, xy.y]; | |
| } | |
| // Approximate tangent | |
| function angleAtLength(l) { | |
| var a = pointAtLength(Math.max(l - 0.01,0)), // this could be slightly negative | |
| b = pointAtLength(l + 0.01); // browsers cap at total length | |
| return Math.atan2(b[1] - a[1], b[0] - a[0]) * 180 / Math.PI; | |
| } | |
| </script> |
