JavaScript

语言：

JaveScriptBabelCoffeeScript

确定

'use strict';

// Initial Setup

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

var c = canvas.getContext('2d');

canvas.width = innerWidth;

canvas.height = innerHeight;

// Variables

var mouse = {

x: innerWidth / 2,

y: innerHeight / 2

};

var ballCount = 750;

var balls = [];

var gravityPos = [];

var friction = .995;

var explosionDistance = 2;

var shouldExplode = false;

var colors = ['#81C3D7', '#D9DCD6', '#3A7CA5', '#2F6690'];

var bgColor = '#16425B';

// Event Listeners

addEventListener("mousemove", function(event) {

mouse.x = event.clientX;

mouse.y = event.clientY;

gravityPos = [mouse.x, mouse.y];

});

addEventListener("mouseout", function(event) {

gravityPos = [canvas.width / 2, canvas.height / 2];

});

addEventListener("resize", function() {

canvas.width = innerWidth;

canvas.height = innerHeight;

init();

});

addEventListener("click", function() {

init();

});

// Utility Functions

function randomIntFromRange(min, max) {

return Math.floor(Math.random() * (max - min + 1) + min);

}

function randomeFloatFromRange(min, max) {

return Math.random() * (max - min) + min;

}

function randomColor(colors) {

return colors[Math.floor(Math.random() * colors.length)];

}

// Objects

function Ball(px, py, vx, vy, f, radius, color) {

this.p = [px, py];

this.v = [vx, vy];

this.gv = [0, 0];

this.gp = 0;

this.radius = radius;

this.color = color;

this.f = f;

this.update = function() {

// calculate gravity vector

this.gv = [gravityPos[0] - this.p[0], gravityPos[1] - this.p[1]];

// Calculate gravity intensity

var a = gravityPos[0] - this.p[0];

var b = gravityPos[1] - this.p[1];

this.gp = 1 / Math.sqrt(a * a + b * b);

// Explode if needed

if (shouldExplode) {

this.v[0] *= randomeFloatFromRange(-10, 10);;

this.v[1] *= randomeFloatFromRange(-10, 10);;

}

// Reduce ball's own velocity with friction

this.v[0] *= this.f;

this.v[1] *= this.f;

// Calculate new velocity, add gravity

this.v[0] += this.gv[0] * this.gp * this.f;

this.v[1] += this.gv[1] * this.gp * this.f;

// Move

this.p[0] += this.v[0];

this.p[1] += this.v[1];

this.draw();

};

this.draw = function() {

c.save();

c.beginPath();

c.arc(this.p[0], this.p[1], this.radius, 0, Math.PI * 2, false);

c.fillStyle = this.color;

c.fill();

c.closePath();

c.restore();

};

}

// Implementation

function init() {

gravityPos = [canvas.width / 2, canvas.height / 2];

balls = [];

for (var i = 0; i < ballCount; i++) {

var rd = randomeFloatFromRange(1, 7);

var px = randomeFloatFromRange(0, canvas.width / 3) + canvas.width / 3;

var py = randomeFloatFromRange(0, canvas.height / 3) + canvas.height / 3;

var vx = randomeFloatFromRange(-10, 10);

var vy = randomeFloatFromRange(-10, 10);

var f = friction;

balls.push(new Ball(px, py, vx, vy, f, rd, randomColor(colors)));

}

}

// Animation Loop

function animate() {

requestAnimationFrame(animate);

resetCanvas(bgColor);

updateShouldExplode();

for (var i = 0; i < balls.length; i++) {

balls[i].update();

}

}

init();

animate();

function resetCanvas(color) {

if (color) {

c.save();

c.fillStyle = color;

c.fillRect(0, 0, canvas.width, canvas.height);

c.restore();

} else {

c.clearRect(0, 0, canvas.width, canvas.height);

}

}

function updateShouldExplode() {

var x = 0;

var y = 0;

for (var i = 0; i < balls.length; i++) {

x += balls[i].v[0] < 0 ? balls[i].v[0] * -1 : balls[i].v[0];

y += balls[i].v[1] < 0 ? balls[i].v[1] * -1 : balls[i].v[1];

}

shouldExplode = x / balls.length < explosionDistance && y / balls.length < explosionDistance;

}