一起來看流星雨

var context;

var arr = new Array();

var starCount = 800;

var rains = new Array();

var rainCount =20;

//初始化畫布及context

function init(){

//獲取canvas

var stars = document.getElementById("stars");

windowWidth = window.innerWidth; //當前的窗口的高度

stars.width=windowWidth;

stars.height=window.innerHeight;

//獲取context

context = stars.getContext("2d");

}

//創建一個星星對象

var Star = function (){

this.x = windowWidth * Math.random();//橫坐標

this.y = 5000 * Math.random();//縱坐標

this.text=".";//文本

this.color = "white";//顏色

//產生隨機顏色

this.getColor=function(){

var _r = Math.random();

if(_r<0.5){

this.color = "#333";

}else{

this.color = "white";

}

}

//初始化

this.init=function(){

this.getColor();

}

//繪制

this.draw=function(){

context.fillStyle=this.color;

context.fillText(this.text,this.x,this.y);

}

}

//畫月亮

function drawMoon(){

var moon = new Image();

moon.src = "./images/moon.jpg"

context.drawImage(moon,-5,-10);

}

//頁面加載的時候

window.onload = function() {

init();

//畫星星

for (var i=0;i

var star = new Star();

star.init();

star.draw();

arr.push(star);

}

//畫流星

for (var i=0;i

var rain = new MeteorRain();

rain.init();

rain.draw();

rains.push(rain);

}

drawMoon();//繪制月亮

playStars();//繪制閃動的星星

playRains();//繪制流星

}

//星星閃起來

function playStars(){

for (var n = 0; n < starCount; n++){

arr[n].getColor();

arr[n].draw();

}

setTimeout("playStars()",100);

}

/*流星雨開始*/

var MeteorRain = function(){

this.x = -1;

this.y = -1;

this.length = -1;//長度

this.angle = 30; //傾斜角度

this.width = -1;//寬度

this.height = -1;//高度

this.speed = 1;//速度

this.offset_x = -1;//橫軸移動偏移量

this.offset_y = -1;//縱軸移動偏移量

this.alpha = 1; //透明度

this.color1 = "";//流星的色彩

this.color2 = ""; //流星的色彩

/****************初始化函數********************/

this.init = function () //初始化

{

this.getPos();

this.alpha = 1;//透明度

this.getRandomColor();

//最小長度，最大長度

var x = Math.random() * 80 + 150;

this.length = Math.ceil(x);

// x = Math.random()*10+30;

this.angle = 30; //流星傾斜角

x = Math.random()+0.5;

this.speed = Math.ceil(x); //流星的速度

var cos = Math.cos(this.angle*3.14/180);

var sin = Math.sin(this.angle*3.14/180) ;

this.width = this.length*cos ; //流星所占寬度

this.height = this.length*sin ;//流星所占高度

this.offset_x = this.speed*cos ;

this.offset_y = this.speed*sin;

}

/**************獲取隨機顏色函數*****************/

this.getRandomColor = function (){

var a = Math.ceil(255-240* Math.random());

//中段顏色

this.color1 = "rgba("+a+","+a+","+a+",1)";

//結束顏色

this.color2 = "black";

}

/***************重新計算流星坐標的函數******************/

this.countPos = function ()//

{

//往左下移動,x減少，y增加

this.x = this.x - this.offset_x;

this.y = this.y + this.offset_y;

}

/*****************獲取隨機坐標的函數*****************/

this.getPos = function () //

{

//橫坐標200--1200

this.x = Math.random() * window.innerWidth; //窗口高度

//縱坐標小于600

this.y = Math.random() * window.innerHeight; //窗口寬度

}

/****繪制流星***************************/

this.draw = function () //繪制一個流星的函數

{

context.save();

context.beginPath();

context.lineWidth = 1; //寬度

context.globalAlpha = this.alpha; //設置透明度

//創建橫向漸變顏色,起點坐標至終點坐標

var line = context.createLinearGradient(this.x, this.y,

this.x + this.width,

this.y - this.height);

//分段設置顏色

line.addColorStop(0, "white");

line.addColorStop(0.3, this.color1);

line.addColorStop(0.6, this.color2);

context.strokeStyle = line;

//起點

context.moveTo(this.x, this.y);

//終點

context.lineTo(this.x + this.width, this.y - this.height);

context.closePath();

context.stroke();

context.restore();

}

this.move = function(){

//清空流星像素

var x = this.x+this.width-this.offset_x;

var y = this.y-this.height;

context.clearRect(x-3,y-3,this.offset_x+5,this.offset_y+5);

// context.strokeStyle="red";

// context.strokeRect(x,y-1,this.offset_x+1,this.offset_y+1);

//重新計算位置，往左下移動

this.countPos();

//透明度增加

this.alpha -= 0.002;

//重繪

this.draw();

}

}

//繪制流星

function playRains(){

for (var n = 0; n < rainCount; n++){

var rain = rains[n];

rain.move();//移動

if(rain.y>window.innerHeight){//超出界限后重來

context.clearRect(rain.x,rain.y-rain.height,rain.width,rain.height);

rains[n] = new MeteorRain();

rains[n].init();

}

}

setTimeout("playRains()",2);

}

/*流星雨結束*/

body{

background-color: black;

}

body,html{width:100%;height:100%;overflow:hidden;}

總結

以上是生活随笔為你收集整理的代码制作数字流星雨_js代码实现流星雨的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。