示例：
实现代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>鱼儿游动态背景特效</title>
<style type="text/css">
html,
body {
width: 100%;
height: 100%;
margin: 0;
padding: 0
}
body {
background: -webkit-linear-gradient(left, rgba(89, 114, 192, 0.8), rgba(89, 114, 192, 0.2));
background: -o-linear-gradient(right, rgba(89, 114, 192, 0.8), rgba(89, 114, 192, 0.2));
background: -moz-linear-gradient(right, rgba(89, 114, 192, 0.8), rgba(89, 114, 192, 0.2));
background: linear-gradient(to right, rgba(89, 114, 192, 0.8), rgba(89, 114, 192, 0.2));
background-size: 400% 400%;
animation: gradientBG 5s ease infinite
}
@keyframes gradientBG {
0% {
background-position: 0 50%
}
50% {
background-position: 100% 50%
}
100% {
background-position: 0 50%
}
}
</style>
<style type="text/css">
.container {
margin: 0;
padding: 0;
background-color: transparent;
width: 100%;
height: 200px;
z-index: -1;
position: fixed;
bottom: 0;
left: 0
}
</style>
</head>
<body>
<div id="jsi-flying-fish-container" class="container">
</div>
<script>
var RENDERER = {
POINT_INTERVAL: 5,
FISH_COUNT: 3,
MAX_INTERVAL_COUNT: 50,
INIT_HEIGHT_RATE: 0.5,
THRESHOLD: 50,
init: function () {
this.setParameters();
this.reconstructMethods();
this.setup();
this.bindEvent();
this.render()
},
setParameters: function () {
this.window = window;
this.container = document.querySelector("#jsi-flying-fish-container");
this.canvas = document.createElement("canvas");
this.context = this.canvas.getContext("2d");
this.container.appendChild(this.canvas);
this.points = [];
this.fishes = [];
this.watchIds = []
},
createSurfacePoints: function () {
var a = Math.round(this.width / this.POINT_INTERVAL);
this.pointInterval = this.width / (a - 1);
this.points.push(new SURFACE_POINT(this, 0));
for (var b = 1; b < a; b++) {
var c = new SURFACE_POINT(this, b * this.pointInterval)
, d = this.points[b - 1];
c.setPreviousPoint(d);
d.setNextPoint(c);
this.points.push(c)
}
},
reconstructMethods: function () {
this.watchWindowSize = this.watchWindowSize.bind(this);
this.jdugeToStopResize = this.jdugeToStopResize.bind(this);
this.startEpicenter = this.startEpicenter.bind(this);
this.moveEpicenter = this.moveEpicenter.bind(this);
this.reverseVertical = this.reverseVertical.bind(this);
this.render = this.render.bind(this)
},
setup: function () {
this.points.length = 0;
this.fishes.length = 0;
this.watchIds.length = 0;
this.intervalCount = this.MAX_INTERVAL_COUNT;
this.width = this.container.clientWidth;
this.height = this.container.clientHeight;
this.fishCount = this.FISH_COUNT * this.width / 500 * this.height / 500;
this.canvas.setAttribute("width", this.width);
this.canvas.setAttribute("height", this.height);
this.reverse = false;
this.fishes.push(new FISH(this));
this.createSurfacePoints()
},
watchWindowSize: function () {
this.clearTimer();
this.tmpWidth = this.window.innerWidth;
this.tmpHeight = this.window.innerHeight;
this.watchIds.push(setTimeout(this.jdugeToStopResize, this.WATCH_INTERVAL))
},
clearTimer: function () {
while (this.watchIds.length > 0) {
clearTimeout(this.watchIds.pop())
}
},
jdugeToStopResize: function () {
var c = this.window.innerWidth
, a = this.window.innerHeight
, b = (c == this.tmpWidth && a == this.tmpHeight);
this.tmpWidth = c;
this.tmpHeight = a;
if (b) {
this.setup()
}
},
bindEvent: function () {
this.window.addEventListener("resize", this.watchWindowSize);
this.container.addEventListener("mouseenter", this.startEpicenter);
this.container.addEventListener("mousemove", this.moveEpicenter);
this.container.addEventListener("click", this.reverseVertical)
},
getAxis: function (a) {
var b = this.container.getBoundingClientRect();
return {
x: a.clientX - b.left + this.window.scrollLeft,
y: a.clientY - b.top + this.window.scrollTop
}
},
startEpicenter: function (a) {
this.axis = this.getAxis(a)
},
moveEpicenter: function (b) {
var a = this.getAxis(b);
if (!this.axis) {
this.axis = a
}
this.generateEpicenter(a.x, a.y, a.y - this.axis.y);
this.axis = a
},
generateEpicenter: function (c, d, b) {
if (d < this.height / 2 - this.THRESHOLD || d > this.height / 2 + this.THRESHOLD) {
return
}
var a = Math.round(c / this.pointInterval);
if (a < 0 || a >= this.points.length) {
return
}
this.points[a].interfere(d, b)
},
reverseVertical: function () {
this.reverse = !this.reverse;
for (var b = 0, a = this.fishes.length; b < a; b++) {
this.fishes[b].reverseVertical()
}
},
controlStatus: function () {
for (var b = 0, a = this.points.length; b < a; b++) {
this.points[b].updateSelf()
}
for (var b = 0, a = this.points.length; b < a; b++) {
this.points[b].updateNeighbors()
}
if (this.fishes.length < this.fishCount) {
if (--this.intervalCount == 0) {
this.intervalCount = this.MAX_INTERVAL_COUNT;
this.fishes.push(new FISH(this))
}
}
},
render: function () {
requestAnimationFrame(this.render);
this.controlStatus();
this.context.clearRect(0, 0, this.width, this.height);
this.context.fillStyle = "hsl(0, 0%, 95%)";
for (var b = 0, a = this.fishes.length; b < a; b++) {
this.fishes[b].render(this.context)
}
this.context.save();
this.context.globalCompositeOperation = "xor";
this.context.beginPath();
this.context.moveTo(0, this.reverse ? 0 : this.height);
for (var b = 0, a = this.points.length; b < a; b++) {
this.points[b].render(this.context)
}
this.context.lineTo(this.width, this.reverse ? 0 : this.height);
this.context.closePath();
this.context.fill();
this.context.restore()
}
};
var SURFACE_POINT = function (a, b) {
this.renderer = a;
this.x = b;
this.init()
};
SURFACE_POINT.prototype = {
SPRING_CONSTANT: 0.03,
SPRING_FRICTION: 0.9,
WAVE_SPREAD: 0.3,
ACCELARATION_RATE: 0.01,
init: function () {
this.initHeight = this.renderer.height * this.renderer.INIT_HEIGHT_RATE;
this.height = this.initHeight;
this.fy = 0;
this.force = {
previous: 0,
next: 0
}
},
setPreviousPoint: function (a) {
this.previous = a
},
setNextPoint: function (a) {
this.next = a
},
interfere: function (b, a) {
this.fy = this.renderer.height * this.ACCELARATION_RATE * ((this.renderer.height - this.height - b) >= 0 ? -1 : 1) * Math.abs(a)
},
updateSelf: function () {
this.fy += this.SPRING_CONSTANT * (this.initHeight - this.height);
this.fy *= this.SPRING_FRICTION;
this.height += this.fy
},
updateNeighbors: function () {
if (this.previous) {
this.force.previous = this.WAVE_SPREAD * (this.height - this.previous.height)
}
if (this.next) {
this.force.next = this.WAVE_SPREAD * (this.height - this.next.height)
}
},
render: function (a) {
if (this.previous) {
this.previous.height += this.force.previous;
this.previous.fy += this.force.previous
}
if (this.next) {
this.next.height += this.force.next;
this.next.fy += this.force.next
}
a.lineTo(this.x, this.renderer.height - this.height)
}
};
var FISH = function (a) {
this.renderer = a;
this.init()
};
FISH.prototype = {
GRAVITY: 0.4,
init: function () {
this.direction = Math.random() < 0.5;
this.x = this.direction
? this.renderer.width + this.renderer.THRESHOLD
: -this.renderer.THRESHOLD;
this.previousY = this.y;
this.vx = this.getRandomValue(4, 10) * (this.direction ? -1 : 1);
if (this.renderer.reverse) {
this.y = this.getRandomValue(
this.renderer.height * 1 / 10,
this.renderer.height * 4 / 10
);
this.vy = this.getRandomValue(2, 5);
this.ay = this.getRandomValue(0.05, 0.2);
} else {
this.y = this.getRandomValue(
this.renderer.height * 6 / 10,
this.renderer.height * 9 / 10
);
this.vy = this.getRandomValue(-5, -2);
this.ay = this.getRandomValue(-0.2, -0.05);
}
this.isOut = false;
this.theta = 0;
this.phi = 0;
},
getRandomValue: function (b, a) {
return b + (a - b) * Math.random();
},
reverseVertical: function () {
this.isOut = !this.isOut;
this.ay *= -1;
},
controlStatus: function (a) {
this.previousY = this.y;
this.x += this.vx;
this.y += this.vy;
this.vy += this.ay;
if (this.renderer.reverse) {
if (this.y > this.renderer.height * this.renderer.INIT_HEIGHT_RATE) {
this.vy -= this.GRAVITY;
this.isOut = true;
} else {
if (this.isOut) {
this.ay = this.getRandomValue(0.05, 0.2);
}
this.isOut = false;
}
} else {
if (this.y < this.renderer.height * this.renderer.INIT_HEIGHT_RATE) {
this.vy += this.GRAVITY;
this.isOut = true;
} else {
if (this.isOut) {
this.ay = this.getRandomValue(-0.2, -0.05);
}
this.isOut = false;
}
}
if (!this.isOut) {
this.theta += Math.PI / 20;
this.theta %= Math.PI * 2;
this.phi += Math.PI / 30;
this.phi %= Math.PI * 2;
}
this.renderer.generateEpicenter(
this.x + (this.direction ? -1 : 1) * this.renderer.THRESHOLD,
this.y,
this.y - this.previousY
);
if (
(this.vx > 0 && this.x > this.renderer.width + this.renderer.THRESHOLD) ||
(this.vx < 0 && this.x < -this.renderer.THRESHOLD)
) {
this.init();
}
},
render: function (a) {
a.save();
a.translate(this.x, this.y);
a.rotate(Math.PI + Math.atan2(this.vy, this.vx));
a.scale(1, this.direction ? 1 : -1);
a.beginPath();
a.moveTo(-30, 0);
a.bezierCurveTo(-20, 15, 15, 10, 40, 0);
a.bezierCurveTo(15, -10, -20, -15, -30, 0);
a.fill();
a.save();
a.translate(40, 0);
a.scale(0.9 + 0.2 * Math.sin(this.theta), 1);
a.beginPath();
a.moveTo(0, 0);
a.quadraticCurveTo(5, 10, 20, 8);
a.quadraticCurveTo(12, 5, 10, 0);
a.quadraticCurveTo(12, -5, 20, -8);
a.quadraticCurveTo(5, -10, 0, 0);
a.fill();
a.restore();
a.save();
a.translate(-3, 0);
a.rotate(
(Math.PI / 3 + Math.PI / 10 * Math.sin(this.phi)) *
(this.renderer.reverse ? -1 : 1)
);
a.beginPath();
if (this.renderer.reverse) {
a.moveTo(5, 0);
a.bezierCurveTo(10, 10, 10, 30, 0, 40);
a.bezierCurveTo(-12, 25, -8, 10, 0, 0);
} else {
a.moveTo(-5, 0);
a.bezierCurveTo(-10, -10, -10, -30, 0, -40);
a.bezierCurveTo(12, -25, 8, -10, 0, 0);
}
a.closePath();
a.fill();
a.restore();
a.restore();
this.controlStatus(a);
},
};
RENDERER.init();
</script>
</body>
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