canvas实现爱心和彩虹雨的效果

百变鹏仔 2个月前 (10-18) #H5教程

文章标签彩虹

本文主要介绍了canvas实现爱心和彩虹雨效果的实例，具有很好的参考价值。下面一起来看下吧

效果图：

代码如下：

<!doctype html> <html> <head> <meta charset="utf-8"> <title></title> </head> <body> <canvas id="canvas"></canvas> <script> var canvas = document.getElementById(&#39;canvas&#39;), ctx = canvas.getContext(&#39;2d&#39;), canvasW = canvas.width = window.innerWidth, canvasH = canvas.height = window.innerHeight, canvasWHalf = canvasW / 2, canvasHHalf = canvasH / 2, xoff = canvasWHalf - 306, yoff = 50, bg = &#39;00061a&#39;, id = 0, raindrops = [], minSize = 1, maxSize = 4, minSpeed = 5, maxSpeed = 20, minHue = 0, maxHue = 360, maxAmount = 50; function random(min, max) { if (arguments.length < 2) {  max = min;  min = 0; } return Math.floor(Math.random() * (max - min) + min); } function hexToRGB(hex, opacity) { var rgb = &#39;&#39;; hex.match(/.{2}/g).forEach(function(n) {  rgb += (parseInt(n, 16)) + &#39;,&#39;; }); return &#39;rgba(&#39; + rgb + opacity + &#39;)&#39;; } function draw() { // Heart ctx.fillStyle = hexToRGB(bg, &#39;0.1&#39;); ctx.beginPath(); // Left half ctx.moveTo(0, 0); ctx.lineTo(canvasWHalf, 0); ctx.lineTo(304 + xoff, 97 + yoff); ctx.bezierCurveTo(282 + xoff, -5 + yoff, 80 + xoff, -6 + yoff, 76 + xoff, 165 + yoff); ctx.bezierCurveTo(74 + xoff, 251 + yoff, 184 + xoff, 300 + yoff, 304 + xoff, 447 + yoff); ctx.lineTo(canvasWHalf, canvasH); ctx.lineTo(0, canvasH); // Right half ctx.moveTo(canvasW, 0); ctx.lineTo(canvasWHalf, 0); ctx.lineTo(304 + xoff, 97 + yoff); ctx.bezierCurveTo(326 + xoff, 5 + yoff, 528 + xoff, 6 + yoff, 532 + xoff, 165 + yoff); ctx.bezierCurveTo(534 + xoff, 251 + yoff, 424 + xoff, 300 + yoff, 304 + xoff, 447 + yoff); ctx.lineTo(canvasWHalf, canvasH); ctx.lineTo(canvasW, canvasH); ctx.closePath(); ctx.fill(); // Raindrops for (var i = 1; i < id; i++) {  raindrops[i].fall(); }; } var Raindrop = function() { id++; this.y = random(-canvasH); this.x = random(canvasW); this.size = random(minSize, maxSize); this.speed = random(minSpeed, maxSpeed); this.color = &#39;hsl(&#39; + random(minHue, maxHue) + &#39;,100%,55%)&#39;; this.origColor = this.color; this.id = id; raindrops[id] = this; }; Raindrop.prototype.fall = function() { this.y += this.speed; if (this.y >= canvasH) {  this.y = random(-canvasH);  this.x = random(canvasW); } ctx.save(); ctx.beginPath(); var gradient = ctx.createRadialGradient(this.x, this.y, 0, this.x, this.y, this.size); gradient.addColorStop(0, &#39;#fff&#39;); gradient.addColorStop(0.5, this.color); gradient.addColorStop(1, hexToRGB(bg, 0)); ctx.rect(this.x, this.y, this.size, maxSpeed); ctx.fillStyle = gradient; ctx.fill(); ctx.closePath(); ctx.restore(); }; (function init() { ctx.fillStyle = &#39;#&#39; + bg; ctx.fillRect(0, 0, canvasW, canvasH); for (var i = 0; i < maxAmount; i++) {  new Raindrop(); } }()); function animate() { draw(); window.requestAnimationFrame(animate); } window.requestAnimationFrame(animate); function mouseTrail(x, y) { ctx.save(); ctx.globalCompositeOperation = &#39;overlay&#39;; ctx.fillStyle = &#39;rgba(255,255,255,0.1)&#39;; ctx.arc(x, y, 50, 0, Math.PI * 2); ctx.fill(); ctx.restore(); } window.addEventListener(&#39;mousemove&#39;, function(cursor) { mouseTrail(cursor.x, cursor.y); }); </script> </body></html>

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