How to use keyboard events to realize character walking in js-JS Tutorial-php.cn

How to use keyboard events to realize character walking in js

王林

Release： 2020-03-11 11:07:51

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How to use keyboard events to realize character walking in js

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How to use keyboard events to realize character walking in js

Rendering pictures:

How to use keyboard events to realize character walking in js

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Example code:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    html
    {
      background-color: deepskyblue;
    }
    div
    {
      width: 32px;
      height: 32px;
      background-image: url("img/Actor01-Braver03.png");
      position: absolute;
    }
  </style>
</head>
<body>
  <div></div>
  <script>
    var key=0;
    var bool=false;
    var speed=2;//每次行走的距离
    var actor;//人物div
    const HEIGHT=33;//人物的高
    const WIDTH=32;//人物的宽
    var arr=[1,3,2,0];//4排图像 代表 下 左 右 上
    var num=0;
    var jumpBool=false;
    var actorSkinSpeed=8;
    var jumpSpeed=-15;
    init();
    function init() {
      window.addEventListener("keydown",keyHandler);
      window.addEventListener("keyup",keyHandler);
      actor=document.querySelector("div");
      setInterval(animation,16);
      //按键驱动不能实现 实现的是通过按键触发相应动画 实现我们的人物的帧动画 跳转
    }
     
    function keyHandler(e) {
      bool=e.type==="keydown";
      key=e.keyCode;
      if(!bool){
        num=0;
        actor.style.backgroundPositionX=-num*WIDTH+"px";
      }
      if(key===32 && !jumpBool){//跳跃 空格驱动
        jumpBool=true;
      }
    }
     
    function animation() {
      jump();
      if(!bool)return;
      walk();//单方向行走 实现
      changeDirection();//方向确定时 内部行走的实现
    }
     
    function jump() {
      if(!jumpBool)return;
      jumpSpeed+=1;
      if(jumpSpeed===15){
        jumpBool=false;
        jumpSpeed=-15;
        return;
      }
      actor.style.top=actor.offsetTop+jumpSpeed+"px";
    }
     
    function changeDirection() {
      actorSkinSpeed--;
      if(actorSkinSpeed>0) return;
      actorSkinSpeed=8;
      num++;
      if(num>3) num=0;
      actor.style.backgroundPositionX=-num*WIDTH+"px";
    }
  
    function walk() {
      switch (key){
        case 37://左 ×1 第二排
          actor.style.left=actor.offsetLeft-speed+"px";
          actor.style.backgroundPositionY=-arr[0]*HEIGHT+"px";
          break;
        case 38://上 ×3 第四排
          actor.style.top=actor.offsetTop-speed+"px";
          actor.style.backgroundPositionY=-arr[1]*HEIGHT+"px";
          break;
        case 39://右 ×2 第三排
          actor.style.left=actor.offsetLeft+speed+"px";
          actor.style.backgroundPositionY=-arr[2]*HEIGHT+"px";
          break;
        case 40://下 ×0 第一排
          actor.style.top=actor.offsetTop+speed+"px";
          actor.style.backgroundPositionY=-arr[3]*HEIGHT+"px";
          break;
  
      }
    }
  </script>
</body>
</html>

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