JavaScript

语言：

JaveScriptBabelCoffeeScript

确定

function Ball(x, y, radius) {

this.x = x;

this.y = y;

this.radius = radius;

this.vx = 20;

this.vy = 10;

}

Ball.prototype.draw = function(ctx) {

ctx.save();

ctx.translate(this.x, this.y);

ctx.fillStyle = 'rgba(255, 255, 255, 0.2)';

ctx.beginPath();

ctx.arc(0, 0, this.radius, 0, Math.PI * 2, true);

ctx.fill();

ctx.restore();

}

function Curve(points) {

this.points = points;

this.ballRadius = 5;

this.speed = 0.12;

this.vy = 2 + Math.random() * 2;

}

Curve.prototype.draw = function() {

var length = this.points.length - 2,

ctrlPoint = {},

i;

ctx.save();

ctx.beginPath();

ctx.moveTo(this.points[0].x, this.points[0].y);

for (i = 1; i < length; i++) {

ctrlPoint.x = (this.points[i].x + this.points[i + 1].x) / 2;

ctrlPoint.y = (this.points[i].y + this.points[i + 1].y) / 2;

ctx.quadraticCurveTo(this.points[i].x, this.points[i].y, ctrlPoint.x, ctrlPoint.y);

}

ctx.quadraticCurveTo(this.points[i].x, this.points[i].y, this.points[i + 1].x, this.points[i + 1].y);

ctx.lineWidth = 2;

ctx.lineCap = 'round';

ctx.strokeStyle = '#fff';

ctx.stroke();

ctx.restore();

}

var canvas = document.querySelector('canvas'),

ctx = canvas.getContext('2d'),

W = canvas.width = window.innerWidth,

H = canvas.height = window.innerHeight,

limit = W / 2.2,

horizontalBall = new Ball(100, H / 2, 100),

curves = [];

for (var y = H / 2 - 150; y <= H / 2 + 150; y += 50) {

makeCurve(y)

}

function makeCurve(y) {

var curve, points = [];

for (var x = W / 2 - limit; x <= W / 2 + limit; x += 100) {

points.push({

x: x,

y: y,

oldY: y,

targetY: y - 300 + Math.random() * 600,

speed: 0.1,

vy: 5 + Math.random() * 5,

gravity: 0.85,

vyy: 3 + Math.random() * 4

});

}

curve = new Curve(points);

curves.push(curve)

}

function moveBalls(ball) {

if (ball == horizontalBall) {

if (ball.x + ball.radius > W) {

ball.x = W - ball.radius - 50;

ball.vx *= -1;

} else if (ball.x - ball.radius < 0) {

ball.x = 50 + ball.radius;

ball.vx *= -1;

}

ball.x += ball.vx;

}

}

(function drawFrame() {

requestAnimationFrame(drawFrame, canvas);

ctx.fillStyle = '#17293a';

ctx.fillRect(0, 0, W, H);

curves.forEach(function(curve) {

curve.points.forEach(function(point) {

var dx, dy, dist,

dx2, dy2, dist2,

n = curve.points.indexOf(point);

dx = (horizontalBall.x - point.x);

dy = (horizontalBall.y - point.y);

dist = Math.sqrt(dx * dx + dy * dy);

if (dist < 200) {

if (n % 2 === 0) {

point.y -= point.vyy;

} else if (n % 2 !== 0) {

point.y += point.vyy;

}

} else {

point.vy += (point.oldY - point.y) * point.speed;

point.vy *= point.gravity;

point.y += point.vy;

}

});

curve.draw(ctx);

});

moveBalls(horizontalBall);

}());