Inspired by the Paper.js “tadpoles” example. Built with D3. Feeling inspired? Fork this example and incorporate the Boids flocking algorithm.
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January 12, 2022 07:40
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Spermatozoa
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| license: gpl-3.0 | |
| redirect: https://observablehq.com/@mbostock/tadpoles |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| background: #000; | |
| } | |
| ellipse { | |
| fill: #fff; | |
| } | |
| path { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-linecap: round; | |
| } | |
| .mid { | |
| stroke-width: 4px; | |
| } | |
| .tail { | |
| stroke-width: 2px; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var n = 100, | |
| m = 12, | |
| degrees = 180 / Math.PI; | |
| var spermatozoa = d3.range(n).map(function() { | |
| var x = Math.random() * width, | |
| y = Math.random() * height; | |
| return { | |
| vx: Math.random() * 2 - 1, | |
| vy: Math.random() * 2 - 1, | |
| path: d3.range(m).map(function() { return [x, y]; }), | |
| count: 0 | |
| }; | |
| }); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| var g = svg.selectAll("g") | |
| .data(spermatozoa) | |
| .enter().append("g"); | |
| var head = g.append("ellipse") | |
| .attr("rx", 6.5) | |
| .attr("ry", 4); | |
| g.append("path") | |
| .datum(function(d) { return d.path.slice(0, 3); }) | |
| .attr("class", "mid"); | |
| g.append("path") | |
| .datum(function(d) { return d.path; }) | |
| .attr("class", "tail"); | |
| var tail = g.selectAll("path"); | |
| d3.timer(function() { | |
| for (var i = -1; ++i < n;) { | |
| var spermatozoon = spermatozoa[i], | |
| path = spermatozoon.path, | |
| dx = spermatozoon.vx, | |
| dy = spermatozoon.vy, | |
| x = path[0][0] += dx, | |
| y = path[0][1] += dy, | |
| speed = Math.sqrt(dx * dx + dy * dy), | |
| count = speed * 10, | |
| k1 = -5 - speed / 3; | |
| // Bounce off the walls. | |
| if (x < 0 || x > width) spermatozoon.vx *= -1; | |
| if (y < 0 || y > height) spermatozoon.vy *= -1; | |
| // Swim! | |
| for (var j = 0; ++j < m;) { | |
| var vx = x - path[j][0], | |
| vy = y - path[j][1], | |
| k2 = Math.sin(((spermatozoon.count += count) + j * 3) / 300) / speed; | |
| path[j][0] = (x += dx / speed * k1) - dy * k2; | |
| path[j][1] = (y += dy / speed * k1) + dx * k2; | |
| speed = Math.sqrt((dx = vx) * dx + (dy = vy) * dy); | |
| } | |
| } | |
| head.attr("transform", headTransform); | |
| tail.attr("d", tailPath); | |
| }); | |
| function headTransform(d) { | |
| return "translate(" + d.path[0] + ")rotate(" + Math.atan2(d.vy, d.vx) * degrees + ")"; | |
| } | |
| function tailPath(d) { | |
| return "M" + d.join("L"); | |
| } | |
| </script> |
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Nice example, but I'm not sure why you would modify the sinusoid phase at each iteration in
k2 = Math.sin(((spermatozoon.count += count) + j * 3) / 300) / speed;rather than simply adding the count to the phase before the loop (spermatozoon.count += count-- note that you should probably add some higher value here likecount*10for more animation), and you don't really have to modify the phase depending on j (simply usek2 = sin(spermatozoon.count/300)/speed)