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canvas实现爱心和彩虹雨效果

程序员文章站 2022-12-17 18:58:59
效果图: 代码如下:

效果图:

canvas实现爱心和彩虹雨效果

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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