A test of the d3-timer module.
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April 5, 2018 02:20
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Connected Particles
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| license: gpl-3.0 | |
| redirect: https://beta.observablehq.com/@mbostock/connected-particles-iii |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <canvas width="960" height="500"></canvas> | |
| <script src="https://d3js.org/d3-timer.v1.min.js"></script> | |
| <script> | |
| var canvas = document.querySelector("canvas"), | |
| context = canvas.getContext("2d"), | |
| width = canvas.width, | |
| height = canvas.height, | |
| radius = 2.5, | |
| minDistance = 80, | |
| maxDistance = 100, | |
| minDistance2 = minDistance * minDistance, | |
| maxDistance2 = maxDistance * maxDistance; | |
| var tau = 2 * Math.PI, | |
| n = 100, | |
| particles = new Array(n); | |
| for (var i = 0; i < n; ++i) { | |
| particles[i] = { | |
| x: width * Math.random(), | |
| y0: height * Math.random(), | |
| v: 0.1 * (Math.random() - 0.5) | |
| }; | |
| } | |
| d3.timer(function(elapsed) { | |
| context.clearRect(0, 0, width, height); | |
| for (var i = 0; i < n; ++i) { | |
| for (var j = i + 1; j < n; ++j) { | |
| var pi = particles[i], | |
| pj = particles[j], | |
| dx = pi.x - pj.x, | |
| dy = pi.y - pj.y, | |
| d2 = dx * dx + dy * dy; | |
| if (d2 < maxDistance2) { | |
| context.globalAlpha = d2 > minDistance2 ? (maxDistance2 - d2) / (maxDistance2 - minDistance2) : 1; | |
| context.beginPath(); | |
| context.moveTo(pi.x, pi.y); | |
| context.lineTo(pj.x, pj.y); | |
| context.stroke(); | |
| } | |
| } | |
| } | |
| context.globalAlpha = 1; | |
| for (var i = 0; i < n; ++i) { | |
| var p = particles[i]; | |
| p.y = p.y0 + elapsed * p.v; | |
| if (p.y > height + maxDistance) p.x = width * Math.random(), p.y0 -= height + 2 * maxDistance; | |
| else if (p.y < -maxDistance) p.x = width * Math.random(), p.y0 += height + 2 * maxDistance; | |
| context.beginPath(); | |
| context.arc(p.x, p.y, radius, 0, tau); | |
| context.fill(); | |
| } | |
| }); | |
| </script> |
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