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| <!doctype html> | |
| <title>fireflies</title> | |
| <style> | |
| #canvas { | |
| width: 600px; | |
| height: 450px; | |
| border: 1px solid grey; | |
| margin: 0 auto; | |
| position:relative; | |
| } | |
| .firefly{ | |
| position: absolute; | |
| width: 9px; | |
| height: 9px; | |
| } | |
| </style> | |
| <div id="canvas"></div> | |
| <script> | |
| // The MIT License (MIT) | |
| // Copyright (c) 2016 Pierre-Yves Gérardy py@py.gy | |
| // Permission is hereby granted, free of charge, to any person obtaining a copy | |
| // of this software and associated documentation files (the "Software"), to deal | |
| // in the Software without restriction, including without limitation the rights | |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| // copies of the Software, and to permit persons to whom the Software is | |
| // furnished to do so, subject to the following conditions: | |
| // The above copyright notice and this permission notice shall be included in | |
| // all copies or substantial portions of the Software. | |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
| // SOFTWARE. | |
| function color() { | |
| return ( | |
| '#' + | |
| (0|256*Math.random()).toString(16) + | |
| (0|256*Math.random()).toString(16) + | |
| '00' | |
| ) | |
| } | |
| function Firefly(parent, resolution) { | |
| this.resolution = resolution | |
| this.max = { | |
| x: parent.offsetWidth - resolution, | |
| y: parent.offsetHeight - resolution | |
| } | |
| this.end = { | |
| x:Math.random() * this.max.x, | |
| y:(1+Math.random()) / 2 * this.max.y, | |
| time: + new Date() | |
| } | |
| var el = document.createElement('div') | |
| el.className = 'firefly' | |
| el.style.backgroundColor = color() | |
| this.element = el | |
| parent.appendChild(el) | |
| this.setDestination(+new Date()) | |
| } | |
| p = Firefly.prototype | |
| p.setDestination = function (t) { | |
| this.start = this.end | |
| this.start.time = t | |
| var maxDistance = Math.min(this.max.x, this.max.y) / 4; | |
| do { | |
| var d = (0.5 - Math.random()) * maxDistance | |
| var angle = Math.asin(1) * (0.5 - Math.random()) // move mostly horizontally | |
| this.end = { | |
| x: this.start.x + (Math.cos(angle) * d), | |
| y: this.start.y + (Math.sin(angle) * d), | |
| time: t + (1 + Math.random()) * Math.abs(d) / this.resolution * 200 //100ms per tick | |
| } | |
| } while (!this.withinBounds()) | |
| } | |
| p.tick = function (t) { | |
| var soFar = t - this.start.time; | |
| var duration = this.end.time - this.start.time; | |
| if (soFar < duration) { | |
| progress = soFar/duration; | |
| this.element.style.left = this.quantize(this.start.x + (progress * (this.end.x - this.start.x))) | |
| this.element.style.top = this.quantize(this.start.y + (progress * (this.end.y - this.start.y))) | |
| } else { | |
| this.setDestination(t) | |
| } | |
| } | |
| p.quantize = function(n) { | |
| return Math.floor(n/this.resolution) * this.resolution + 'px' | |
| } | |
| p.withinBounds = function () { | |
| return 0 < this.end.x && 0 < this.end.y && this.end.x <= this.max.x && this.end.y <= this.max.y | |
| } | |
| fireflies = [] | |
| for (var i = 0; i < 10; i ++) { | |
| fireflies.push(new Firefly(canvas, 3)) | |
| } | |
| function update() { | |
| var t = +new Date() | |
| fireflies.forEach(function(frfl) {frfl.tick(t)}) | |
| } | |
| update() // position the fireflies | |
| setInterval(update, 200) | |
| </script> |
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