H5炫酷特效系列2——canvas特效-炫酷的心

阿新 • • 發佈：2019-02-01

var settings = { particles: { length: 500, //最大粒子數 duration: 2, //粒子持續時間 velocity: 100, //粒子速度，畫素/秒 effect: -0.75, size: 30, //粒子大小 } }; (function() { var b = 0; var c = ["ms", "moz", "webkit", "o"]; for (var a = 0

; a < c.length && !window.requestAnimationFrame; ++a) { window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"]; window.cancelAnimationFrame = window[c[a] + "CancelAnimationFrame"] || window[c[a] + "CancelRequestAnimationFrame"] } if (!window.requestAnimationFrame) { window.requestAnimationFrame = function

(h, e) { var d = new Date().getTime(); var f = Math.max(0, 16 - (d - b)); var g = window.setTimeout(function() { h(d + f) }, f); b = d + f; return g } } if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function

(d) { clearTimeout(d) } } }()); var Point = (function() { function Point(x, y) { this.x = (typeof x !== 'undefined') ? x : 0; this.y = (typeof y !== 'undefined') ? y : 0; } Point.prototype.clone = function() { return new Point(this.x, this.y); }; Point.prototype.length = function(length) { if (typeof length == 'undefined') return Math.sqrt(this.x * this.x + this.y * this.y); this.normalize(); this.x *= length; this.y *= length; return this; }; Point.prototype.normalize = function() { var length = this.length(); this.x /= length; this.y /= length; return this; }; return Point; })(); var Particle = (function() { function Particle() { this.position = new Point(); this.velocity = new Point(); this.acceleration = new Point(); this.age = 0; } Particle.prototype.initialize = function(x, y, dx, dy) { this.position.x = x; this.position.y = y; this.velocity.x = dx; this.velocity.y = dy; this.acceleration.x = dx * settings.particles.effect; this.acceleration.y = dy * settings.particles.effect; this.age = 0; }; Particle.prototype.update = function(deltaTime) { this.position.x += this.velocity.x * deltaTime; this.position.y += this.velocity.y * deltaTime; this.velocity.x += this.acceleration.x * deltaTime; this.velocity.y += this.acceleration.y * deltaTime; this.age += deltaTime; }; Particle.prototype.draw = function(context, image) { function ease(t) { return (--t) * t * t + 1; } var size = image.width * ease(this.age / settings.particles.duration); context.globalAlpha = 1 - this.age / settings.particles.duration; context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size); }; return Particle; })(); var ParticlePool = (function() { var particles, firstActive = 0, firstFree = 0, duration = settings.particles.duration; function ParticlePool(length) { // 建立和填充粒子庫 particles = new Array(length); for (var i = 0; i < particles.length; i++) particles[i] = new Particle(); } ParticlePool.prototype.add = function(x, y, dx, dy) { particles[firstFree].initialize(x, y, dx, dy); // 處理迴圈佇列 firstFree++; if (firstFree == particles.length) firstFree = 0; if (firstActive == firstFree) firstActive++; if (firstActive == particles.length) firstActive = 0; }; ParticlePool.prototype.update = function(deltaTime) { var i; // 更新活動粒子 if (firstActive < firstFree) { for (i = firstActive; i < firstFree; i++) particles[i].update(deltaTime); } if (firstFree < firstActive) { for (i = firstActive; i < particles.length; i++) particles[i].update(deltaTime); for (i = 0; i < firstFree; i++) particles[i].update(deltaTime); } // 刪除不活動的粒子 while (particles[firstActive].age >= duration && firstActive != firstFree) { firstActive++; if (firstActive == particles.length) firstActive = 0; } }; ParticlePool.prototype.draw = function(context, image) { // 畫活動粒子 if (firstActive < firstFree) { for (i = firstActive; i < firstFree; i++) particles[i].draw(context, image); } if (firstFree < firstActive) { for (i = firstActive; i < particles.length; i++) particles[i].draw(context, image); for (i = 0; i < firstFree; i++) particles[i].draw(context, image); } }; return ParticlePool; })(); (function(canvas) { var context = canvas.getContext('2d'), particles = new ParticlePool(settings.particles.length), particleRate = settings.particles.length / settings.particles.duration, // particles/sec time; // 獲取heart點位 -PI <= t <= PI function pointOnHeart(t) { return new Point( 160 * Math.pow(Math.sin(t), 3), 130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25 ); } // 使用canvas建立粒子影象 var image = (function() { var canvas = document.createElement('canvas'), context = canvas.getContext('2d'); canvas.width = settings.particles.size; canvas.height = settings.particles.size; // 建立路徑的輔助函式 function to(t) { var point = pointOnHeart(t); point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350; point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350; return point; } // 建立路徑 context.beginPath(); var t = -Math.PI; var point = to(t); context.moveTo(point.x, point.y); while (t < Math.PI) { t += 0.01; point = to(t); context.lineTo(point.x, point.y); } context.closePath(); // 填充 context.fillStyle = '#ea80b0'; context.fill(); // 建立圖片 var image = new Image(); image.src = canvas.toDataURL(); return image; })(); // 渲染 function render() { requestAnimationFrame(render); // update time var newTime = new Date().getTime() / 1000, deltaTime = newTime - (time || newTime); time = newTime; // clear canvas context.clearRect(0, 0, canvas.width, canvas.height); // 建立新的粒子 var amount = particleRate * deltaTime; for (var i = 0; i < amount; i++) { var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random()); var dir = pos.clone().length(settings.particles.velocity); particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y); } // 更新並繪製 particles.update(deltaTime); particles.draw(context, image); } // 處理canvas大小 function onResize() { canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; } window.onresize = onResize; // 延遲渲染 setTimeout(function() { onResize(); render(); }, 10); })(document.getElementById('pinkboard'));

H5炫酷特效系列2——canvas特效-炫酷的心

H5炫酷特效系列2——canvas特效-炫酷的心

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H5炫酷特效系列2——canvas特效-炫酷的心

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