问题遇到的现象和发生背景
在此基础上，增加一段背景音乐
用代码块功能插入代码，请勿粘贴截图
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>爱你</title>
<style>
.box{
margin-top: 1cm;
text-align: center;
}
</style>
</head>
<style>
*{
padding: 0;
margin: 0;
}
html, body {
height: 100%;
padding: 0;
margin: 0;
background: #000;
}
canvas {
position: absolute;
width: 100%;
height: 100%;
}
.aa{
position: fixed;
left: 50%;
bottom: 10px;
color: #ccc
}
</style>
<body>
<canvas id="pinkBoard"></canvas>
<script>
var settings = {
particles: {
length: 500,
duration: 2,
velocity: 100,
effect: -0.75,
size: 30,
},
};
(function(){
var b=0;
var c=["ms","moz","webkit","o"];
for(var a=0;a<c.length&&!window.requestAnimationFrame;++a){
window.requestAnimationFrame=window[c[a]+"RequestAnimationFrame"];
window.cancelAnimationFrame=window[c[a]+"CancelAnimationFrame"]||window[c[a]+"CancelRequestAnimationFrame"]
}
if(!window.requestAnimationFrame){
window.requestAnimationFrame=function(h,e){
var d=new Date().getTime();
var f=Math.max(0,16-(d-b));
var g=window.setTimeout(function(){h(d+f)},f);
b=d+f;
return g
}
}
if(!window.cancelAnimationFrame){
window.cancelAnimationFrame=function(d){
clearTimeout(d)
}
}
}());
var Point = (function() {
function Point(x, y) {
this.x = (typeof x !== 'undefined') ? x : 0;
this.y = (typeof y !== 'undefined') ? y : 0;
}
Point.prototype.clone = function() {
return new Point(this.x, this.y);
};
Point.prototype.length = function(length) {
if (typeof length == 'undefined')
return Math.sqrt(this.x * this.x + this.y * this.y);
this.normalize();
this.x *= length;
this.y *= length;
return this;
};
Point.prototype.normalize = function() {
var length = this.length();
this.x /= length;
this.y /= length;
return this;
};
return Point;
})();
var Particle = (function() {
function Particle() {
this.position = new Point();
this.velocity = new Point();
this.acceleration = new Point();
this.age = 0;
}
Particle.prototype.initialize = function(x, y, dx, dy) {
this.position.x = x;
this.position.y = y;
this.velocity.x = dx;
this.velocity.y = dy;
this.acceleration.x = dx * settings.particles.effect;
this.acceleration.y = dy * settings.particles.effect;
this.age = 0;
};
Particle.prototype.update = function(deltaTime) {
this.position.x += this.velocity.x * deltaTime;
this.position.y += this.velocity.y * deltaTime;
this.velocity.x += this.acceleration.x * deltaTime;
this.velocity.y += this.acceleration.y * deltaTime;
this.age += deltaTime;
};
Particle.prototype.draw = function(context, image) {
function ease(t) {
return (--t) * t * t + 1;
}
var size = image.width * ease(this.age / settings.particles.duration);
context.globalAlpha = 1 - this.age / settings.particles.duration;
context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);
};
return Particle;
})();
var ParticlePool = (function() {
var particles,
firstActive = 0,
firstFree = 0,
duration = settings.particles.duration;
function ParticlePool(length) {
// create and populate particle pool
particles = new Array(length);
for (var i = 0; i < particles.length; i++)
particles[i] = new Particle();
}
ParticlePool.prototype.add = function(x, y, dx, dy) {
particles[firstFree].initialize(x, y, dx, dy);
// handle circular queue
firstFree++;
if (firstFree == particles.length) firstFree = 0;
if (firstActive == firstFree ) firstActive++;
if (firstActive == particles.length) firstActive = 0;
};
ParticlePool.prototype.update = function(deltaTime) {
var i;
// update active particles
if (firstActive < firstFree) {
for (i = firstActive; i < firstFree; i++)
particles[i].update(deltaTime);
}
if (firstFree < firstActive) {
for (i = firstActive; i < particles.length; i++)
particles[i].update(deltaTime);
for (i = 0; i < firstFree; i++)
particles[i].update(deltaTime);
}
// remove inactive particles
while (particles[firstActive].age >= duration && firstActive != firstFree) {
firstActive++;
if (firstActive == particles.length) firstActive = 0;
}
};
ParticlePool.prototype.draw = function(context, image) {
// draw active particles
if (firstActive < firstFree) {
for (i = firstActive; i < firstFree; i++)
particles[i].draw(context, image);
}
if (firstFree < firstActive) {
for (i = firstActive; i < particles.length; i++)
particles[i].draw(context, image);
for (i = 0; i < firstFree; i++)
particles[i].draw(context, image);
}
};
return ParticlePool;
})();
(function(canvas) {
var context = canvas.getContext('2d'),
particles = new ParticlePool(settings.particles.length),
particleRate = settings.particles.length / settings.particles.duration, // particles/sec
time;
function pointOnHeart(t) {
return new Point(
160 * Math.pow(Math.sin(t), 3),
130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25
);
}
var image = (function() {
var canvas = document.createElement('canvas'),
context = canvas.getContext('2d');
canvas.width = settings.particles.size;
canvas.height = settings.particles.size;
function to(t) {
var point = pointOnHeart(t);
point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;
point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;
return point;
}
context.beginPath();
var t = -Math.PI;
var point = to(t);
context.moveTo(point.x, point.y);
while (t < Math.PI) {
t += 0.01; // baby steps!
point = to(t);
context.lineTo(point.x, point.y);
}
context.closePath();
context.fillStyle = 'red';
context.fill();
var image = new Image();
image.src = canvas.toDataURL();
return image;
})();
function render() {
requestAnimationFrame(render);
var newTime = new Date().getTime() / 1000,
deltaTime = newTime - (time || newTime);
time = newTime;
context.clearRect(0, 0, canvas.width, canvas.height);
var amount = particleRate * deltaTime;
for (var i = 0; i < amount; i++) {
var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
var dir = pos.clone().length(settings.particles.velocity);
particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
}
particles.update(deltaTime);
particles.draw(context, image);
}
function onResize() {
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
}
window.onresize = onResize;
setTimeout(function() {
onResize();
render();
}, 10);
})(document.getElementById('pinkBoard'));
</script>
</body>
</html>
