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Connected Particles III
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <canvas width="960" height="500"></canvas> | |
| <script> | |
| /* https://github.com/d3/d3-timer Copyright 2015 Mike Bostock */ | |
| "undefined"==typeof requestAnimationFrame&&(requestAnimationFrame="undefined"!=typeof window&&(window.msRequestAnimationFrame||window.mozRequestAnimationFrame||window.webkitRequestAnimationFrame||window.oRequestAnimationFrame)||function(e){return setTimeout(e,17)}),function(e,n){"object"==typeof exports&&"undefined"!=typeof module?n(exports):"function"==typeof define&&define.amd?define(["exports"],n):n(e.timer={})}(this,function(e){"use strict";function n(){r=m=0,c=1/0,t(u())}function t(e){if(!r){var t=e-Date.now();t>24?c>e&&(m&&clearTimeout(m),m=setTimeout(n,t),c=e):(m&&(m=clearTimeout(m),c=1/0),r=requestAnimationFrame(n))}}function i(e,n,i){i=null==i?Date.now():+i,null!=n&&(i+=+n);var o={callback:e,time:i,flush:!1,next:null};a?a.next=o:f=o,a=o,t(i)}function o(e,n,t){t=null==t?Date.now():+t,null!=n&&(t+=+n),l.callback=e,l.time=t}function u(e){e=null==e?Date.now():+e;var n=l;for(l=f;l;)e>=l.time&&(l.flush=l.callback(e-l.time,e)),l=l.next;l=n,e=1/0;for(var t,i=f;i;)i.flush?i=t?t.next=i.next:f=i.next:(i.time<e&&(e=i.time),i=(t=i).next);return a=t,e}var a,m,r,f,l,c=1/0;e.timer=i,e.timerReplace=o,e.timerFlush=u}); | |
| var canvas = document.querySelector("canvas"), | |
| context = canvas.getContext("2d"), | |
| width = canvas.width, | |
| height = canvas.height, | |
| radius = 2.5, | |
| minDistance = 40, | |
| maxDistance = 60, | |
| minDistance2 = minDistance * minDistance, | |
| maxDistance2 = maxDistance * maxDistance; | |
| var tau = 2 * Math.PI, | |
| n = 200, | |
| particles = new Array(n); | |
| for (var i = 0; i < n; ++i) { | |
| particles[i] = { | |
| x: Math.random() * width, | |
| y: Math.random() * height, | |
| vx: 0, | |
| vy: 0 | |
| }; | |
| } | |
| timer.timer(function(elapsed) { | |
| context.save(); | |
| context.clearRect(0, 0, width, height); | |
| for (var i = 0; i < n; ++i) { | |
| var p = particles[i]; | |
| p.x += p.vx; if (p.x < -maxDistance) p.x += width + maxDistance * 2; else if (p.x > width + maxDistance) p.x -= width + maxDistance * 2; | |
| p.y += p.vy; if (p.y < -maxDistance) p.y += height + maxDistance * 2; else if (p.y > height + maxDistance) p.y -= height + maxDistance * 2; | |
| p.vx += 0.2 * (Math.random() - .5) - 0.01 * p.vx; | |
| p.vy += 0.2 * (Math.random() - .5) - 0.01 * p.vy; | |
| context.beginPath(); | |
| context.arc(p.x, p.y, radius, 0, tau); | |
| context.fill(); | |
| } | |
| 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.restore(); | |
| }); | |
| </script> |
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