个回答

• 拼命柯南

  2015-11-18 18:22:02

  function drawBackground()

  {

  ctx2.drawImage(bgPic,0,0,canWidth,canHeight);

  }

  这是background.js

  var can1;

  var can2;

  
  

  var ctx1;

  var ctx2;

  
  

  var canWidth;

  var canHeight;

  
  

  var lastTime;

  var deltaTime;

  
  

  var bgPic =new Image();

  document.body.onload =game;

  function game()

  {

  
  

      init;

  lastTime =Date.now();

  deltaTime =0;

  gameloop();

  }

  function init()

  {

  //获得canvas context

  can1 =document.getElementById("canvas1");//fishes,dust,UI,circle

  ctx1 =can1.getContext('2d');

  can2 =document.getElementById("canvas2");//background,ane,fruits

  ctx2 =can2.getContext('2d');

  
  

  bgPic.src ="./src/background.jpg";

      

  canWidth =can1.width;

  canHeight =can1.height;

  
  

  }

  function gameloop()

  {

  requestAnimFrame(gameloop);//setInterval,setTimeout,frame per second

  var now =Date.now();

  deltaTime =now - lastTime;

  lastTime =now;

  
  

  drawBackground();

  }

  这是main.js

  1

• wslover

  2015-11-18 17:14:22

  调用这个函数的对像不对吧，把你的代码贴上来吧

  0