Звёзды, летающие по экрану на HTML5 Canvas
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#stars { position: fixed; top: 0; right: 0; bottom: 0; left: 0; background-color: #ff2222; z-index: -1; } |
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<canvas id="stars"></canvas> <script> (function() { var ShootingStars, Star, debounce, extend, requestAnimationFrame; Star = function Star(size, rotate, points, outerRadius, innerRadius, borderColor, fillColor, x, y, starCanvas) { var self; self = this; self.x = x; self.y = y; self.size = size; self.color = fillColor; self.border = borderColor; self.outerRad = outerRadius; self.innerRad = innerRadius; self.rotation = rotate; self.points = points; self.opacity = 0; self.scale = 0; self.vx = Math.random() * 2 - 1; self.vy = Math.random() * 2 - 1; self.life = 0; self.ss = starCanvas; return self; }; Star.prototype.update = function() { var canvas, maxLife, particlePool, particles; this.x += this.vx; this.y += this.vy; canvas = this.ss.canvas; maxLife = this.ss.maxLife; particlePool = this.ss.particlePool; particles = this.ss.particles; if (this.opacity < 1 && this.life < maxLife / 6) { this.opacity += 100 / (maxLife / 6) / 100; this.scale += 100 / (maxLife / 6) / 100; } this.life++; if (maxLife - this.life < maxLife / 6) { this.scale -= 100 / (maxLife / 6) / 100; } if (maxLife - this.life < maxLife / 3) { this.vy *= 1.075; this.vx *= 1.075; this.opacity = (maxLife - this.life) / 100; } else if (this.life % 2 === 0) { this.rotation++; } if (this.life >= maxLife) { this.life = 0; this.scale = 0; this.x = Math.floor(Math.random() * canvas.width + 1); this.y = Math.floor(Math.random() * canvas.height + 1); this.vx = Math.random() - 0.5; this.vy = Math.random() - 0.5; self.vx = Math.random() * 2 - 1; self.vy = Math.random() * 2 - 1; particlePool.push(particles.shift()); } return this; }; Star.prototype.render = function(context) { var i, rad, rotation, star, starCanvas, starContext; star = this; starCanvas = document.createElement('canvas'); starCanvas.width = star.size; starCanvas.height = star.size; starContext = starCanvas.getContext('2d'); starContext.save(); starContext.fillStyle = star.color; starContext.strokeStyle = star.border; starContext.globalAlpha = star.opacity; starContext.translate(star.size / 2, star.size / 2); starContext.rotate(star.rotation * Math.PI / 180); starContext.translate(-(star.size / 2), -(star.size / 2)); starContext.scale(star.scale, star.scale); starContext.beginPath(); i = 0; while (i <= star.points * 2) { rotation = i * Math.PI / star.points; rad = i % 2 === 0 ? star.outerRad : star.innerRad; starContext.lineTo(star.size / 2 + rad * Math.cos(rotation), star.size / 2 + rad * Math.sin(rotation)); ++i; } starContext.fill(); starContext.stroke(); starContext.restore(); return context.drawImage(starCanvas, star.x, star.y); }; debounce = function debounce(func, delay) { var inDebounce; inDebounce = void 0; inDebounce = void 0; return function() { var args, context; args = void 0; context = void 0; context = this; args = arguments; clearTimeout(inDebounce); return inDebounce = setTimeout(function() { return func.apply(context, args); }, delay); }; }; extend = function extend(a, b) { var key; for (key in b) { if (b.hasOwnProperty(key) && b[key] !== void 0) { a[key] = b[key]; } } return a; }; requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.msRequestAnimationFrame || function(callback) { return setTimeout(callback, 1000 / 60); }; window.ShootingStars = ShootingStars = function ShootingStars(config) { var canvas, canvasId, defaults, self; self = this; canvasId = config.id; defaults = { particleLife: 300, particleRenderProbability: 0.05, amount: 5, resizePoll: 250, star: { size: { upper: 50, lower: 25 }, rotateLimit: 45, points: 5, innerRadius: 0.5, borderColor: '#000', fillColor: 'red' } }; self.options = extend(defaults, config); self.canvas = canvas = document.getElementById(canvasId); canvas.width = window.innerWidth; canvas.height = window.innerHeight; canvas.ctx = canvas.getContext('2d'); self.maxLife = self.options.particleLife; self.particles = []; self.particlePool = []; self.particleProbability = self.options.particleRenderProbability; self.poolSize = self.options.amount; window.addEventListener('resize', debounce(function() { self.canvas.width = window.innerWidth; self.canvas.height = window.innerHeight; self.flushPool(); }, self.options.resizePoll)); return self; }; ShootingStars.prototype.flushPool = function() { var canvas, getRandomFromRange, i, particlePool, particles, poolSize, results, rotation, size, that; that = this; canvas = that.canvas; particlePool = that.particlePool = []; particles = that.particles = []; poolSize = self.poolSize = that.options.amount; if (canvas.width < 450) { poolSize = self.poolSize = poolSize / 2; } i = 0; results = []; while (i < poolSize) { getRandomFromRange = function getRandomFromRange(max, min) { return Math.floor(Math.random() * (max - min + 1) + min); }; size = getRandomFromRange(that.options.star.size.upper, that.options.star.size.lower); rotation = getRandomFromRange(that.options.star.rotateLimit, 0); particlePool.push(new Star(size, rotation, 5, size / 2, size / 2 * that.options.star.innerRadius, this.options.star.borderColor, this.options.star.fillColor, Math.floor(Math.random() * canvas.width + 1), Math.floor(Math.random() * canvas.height + 1), that)); results.push(i++); } return results; }; ShootingStars.prototype.render = function() { var canvas, ctx, p, particlePool, particles, that; that = this; canvas = that.canvas; ctx = canvas.ctx; particlePool = that.particlePool; particles = that.particles; ctx.save(); ctx.clearRect(0, 0, canvas.width, canvas.height); if (Math.random() > that.particleProbability && particles.length < that.poolSize && particlePool.length > 0) { particles.push(particlePool.shift()); } p = 0; while (p < particles.length) { particles[p].update(); if (particles[p]) { particles[p].render(ctx); } p++; } /* FOR A TRIPPY EFFECT - If you render a star every frame in a different position and then wipe the canvas every frame you get a pretty trippy effect whereby the star will be blinking all over the canvas at close to 60 FPS. */ ctx.restore(); return requestAnimationFrame(function() { return that.render(); }); }; }).call(undefined); var config = { id: 'stars', particleLife: 300, particleRenderProbability: 0.95, amount: 50, star: { size: { upper: 50, lower: 25 }, rotateLimit: 90, points: 5, innerRadius: 0.5, borderColor: '#290f5a', fillColor: '#ffcc00' } }; var myCanvas = new ShootingStars(config); myCanvas.flushPool(); myCanvas.render(); </script> |
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