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：

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);

});

以上就是本文的全部内容，希望对大家的学习有所帮助，更多相关内容请关注jquery中文网！

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