canvas实现爱心和彩虹雨的效果

互联网 18-7-3

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('canvas'),  ctx = canvas.getContext('2d'),  canvasW = canvas.width = window.innerWidth,  canvasH = canvas.height = window.innerHeight,  canvasWHalf = canvasW / 2,  canvasHHalf = canvasH / 2,  xoff = canvasWHalf - 306,  yoff = 50,  bg = '00061a',  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 = '';  hex.match(/.{2}/g).forEach(function(n) {   rgb += (parseInt(n, 16)) + ',';  });  return 'rgba(' + rgb + opacity + ')';  }  function draw() {  // Heart  ctx.fillStyle = hexToRGB(bg, '0.1');  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 = 'hsl(' + random(minHue, maxHue) + ',100%,55%)';  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, '#fff');  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 = '#' + 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 = 'overlay';  ctx.fillStyle = 'rgba(255,255,255,0.1)';  ctx.arc(x, y, 50, 0, Math.PI * 2);  ctx.fill();  ctx.restore();  }  window.addEventListener('mousemove', function(cursor) {  mouseTrail(cursor.x, cursor.y);  });  </script>  </body> </html>

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canvas实现爱心和彩虹雨的效果

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