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canvas实现爱心和彩虹雨的效果

发布时间:2020-06-03   编辑:jiaochengji.com
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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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