html

star

JS

main.j遇新是直朋能到s

var can;

var ctx;

var w,h;

var girlPic = new Image();

var starPic = new Image();

var num = 60;

var stars = [];

var lastTime,deltaTime;

var switchy;

var life = 0;

function init(){

can = document.getElementById("canvas");

ctx = can.getContext("2d");

w = can.width;

h = can.height;

document.addEventListener("mousemove",mousemove,false);

girlPic.src = "img/girl.jpg";

starPic.src = "img/star.png";

for(var i=0;i

var obj = new starObj();

stars.push(obj);

stars[i].init();

}

lastTime = Date.now();

gameloop();

}

document.body.onload = init;

function gameloop(){

window.requestAnimationFrame(gameloop);

var now = Date.now();

deltaTime = now - lastTime;

lastTime = now;

drawBackground();

drawGril();

drawStars();

aliveUpdate();

}

function drawBackground(){

ctx.fillStyle ="#393550";

ctx.fillRect(0,0,w,h);

}

function drawGril(){

//drawImage(img,x,y,width,height)

ctx.drawImage(girlPic,100,150,600,300);

}

function mousemove(e){

if(e.offsetX||e.layerX){

var px = e.offsetX == undefined?e.layerX:e.offsetX;

var py = e.offsetY == undefined?e.layerY:e.offsetY;

//判断px py在范围内

if(px>100&&px<700&&py>150&&py<450){

switchy =true;

}

else{

switchy =false;

}

//console.log(switchy);

}

}commonFunctions.js

window.requestAnimFrame = (function() {

return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||

function( /* function FrameRequestCallback */ callback, /* DOMElement Element */ element) {

return window.setTimeout(callback, 1000 / 60);

};

})();

stars.js

var starObj = function(){

this.x;

this.y;

this.picNo;

this.timer;

this.xSpd;

this.ySpd;

}

starObj.prototype.init = function(){

this.x = Math.random()*600+100;

this.y = Math.random()*300+150;

this.picNo =Math.floor(Math.random()*7);

this.timer = 0;

this.xSpd = Math.random()*3-1.5;

this.ySpd = Math.random()*3-1.5;

}

starObj.prototype.update = function(){

this.x += this.xSpd*deltaTime*0.01;

this.y += this.ySpd*deltaTime*0.01;

//this.x 超过范围

if(this.x<100||this.x>693){

this.init();

return;

}

//this.y超出范围 重生

if(this.y<150||this.y>443){

this.init();

return;

}

this.timer +=deltaTime;

if(this.timer>60){

this.picNo += 1;

this.picNo %= 7;

this.timer = 0;

}

}

starObj.prototype.draw = function(){

// save()

ctx.save();

//globalAlpha 全局透明度

ctx.globalAlpha = life;

//drawImage(img,sx,sy,swidth,sheight,x,y,width,height);

ctx.drawImage(starPic,this.picNo*7,0,7,7,this.x,this.y,7,7);

//restore()

ctx.restore();

}

function drawStars(){

for(var i = 0;i

stars[i].update();

stars[i].draw();

}

}

function aliveUpdate(){

if(switchy){ //in area

//show stars

life +=0.3*deltaTime*0.05;

if(life>1){

life = 1;

}

}else{ //out area

//hide stars

life -=0.3*deltaTime*0.05;

if(life<0){

life=0;

}效果图

素材图片

本文来源于网络：查看 >https://blog.csdn.net/u014041540/article/details/52194544