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js实现贪吃蛇小游戏教程

来源:互联网搜集 作者:秩名 人气: 发布时间:2019-10-29
本篇文章主要介绍了js实现贪吃蛇小游戏教程,对大家的学习或者工作具有一定的参考学习价值,感兴趣的小伙伴们可以参考一下,也感谢大家对酷站(ku0.com)的支持。
方法如下:

index.html


<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>贪吃蛇</title>
  <link rel="stylesheet" href="style.css" >
</head>
<body>
  <div id="game">
    <div id="explain">
      <div>操作WASD 空格开始/暂停 R重新开始</div>
      <div>当前分数:<span id="grade">0</span>分</div>
    </div>
    <canvas id="snakegame" width="500" height="500">
    </canvas>
  </div>
  <script type="text/javascript" src="main.js" charset="UTF-8"></script>
</body>
</html>

style.css

*{
  padding: 0;
  margin: 0;
}
#game {
  width: 500px;
  margin: auto;
}
#explain {
  width: 500px;
}
#explain div{
  width: 500px;
  height: 30px;
}
#snakegame {
  background: green;
}
 

main.js

/**
 * el 挂载的元素
 * attribute 贪吃蛇的属性
 */
class Game {
  constructor (el, attribute) {
    this.el = document.getElementById(el);
    // 获取画布的宽高
    this.el.elW = parseInt(window.getComputedStyle(this.el).width);
    this.el.elH = parseInt(window.getComputedStyle(this.el).height);
    this.init(attribute);
    this.keyListening();
  }
  // 初始化
  init(attribute) {
    this.attribute = {
      color: "red", // 颜色
      direction: "rigth", // 移动方向
      state: "pause", // 状态 run pause end
      grade: 0, // 分数
      body: [{x: 20, y: 0}, {x: 0, y: 0}], // 贪吃蛇身体
      wh: 20, // 矩形的宽高
      speed: 200 // 速度
    };
    if (attribute) {
      this.newAttribute = attribute;
      Object.keys(attribute).forEach(key => {
        this.attribute[key] = attribute[key];
      });
    }
    this.food ={
      x: 0,
      y: 0,
      color: 'red'
    }
    this.draw();
    this.foodDraw();
  }
  // 绘制贪吃蛇
  draw() {
    let el = this.el;
    let { body, wh, color } = this.attribute;
    // 确定浏览器是否支持canvans元素
    if (el.getContext) {
      let context = snakegame.getContext("2d");
      context.fillStyle = color;
      body.forEach( key => {
        context.fillRect(key.x, key.y, wh, wh);
      });
    }
  }
  // 随机生成食物
  foodDraw() {
    let el = this.el, wh = this.attribute.wh;
    this.food.x = Math.floor(Math.random()*(el.elW - wh)),
    this.food.y = Math.floor(Math.random()*(el.elH - wh));
    while (this.isOverlap()) {
      this.food.x = Math.floor(Math.random()*(el.elW - wh)),
      this.food.y = Math.floor(Math.random()*(el.elH - wh));
    }
    if (el.getContext) {
      let context = snakegame.getContext("2d");
      context.fillStyle = this.food.color;
      context.fillRect(this.food.x, this.food.y, wh, wh);
    }
  }
  // 判断食物是否与贪吃蛇的身体重叠
  isOverlap() {
    let { wh } = this.attribute;
    let food = this.food;
    let flag = false;
    function isIn(key, x, y) {
      if (key.x <= x && key.x + wh >= x && key.y <= y && key.y + wh >= y) {
        return true;
      } else {
        return false;
      }
    }
    this.attribute.body.forEach(key => {
      // 食物的上下左右四个点一个点在贪吃蛇的身体内就判断为重叠
      if (isIn(key, food.x, food.y) || isIn(key, food.x, food.y + wh) || isIn(key, food.x + wh, food.y) || isIn(key, food.x + wh, food.y + wh)) {
        flag = true;
      }
    });
    return flag;
  }
  // 清除图形
  clear(x, y, width, height) {
    // 确定浏览器是否支持canvans元素
    if (this.el.getContext) {
      let context = snakegame.getContext("2d");
      context.clearRect(x, y, width, height);
    }
  }
  // 游戏状态更新
  updateState(state) {
    this.attribute.state = state;
    if (state === "run") {
      this.run();
    } 
  }
  // 游戏线程
  run() {
    let { body, wh, speed} = this.attribute;
    let time = setInterval(() => {
      // 判断游戏线程是否在运行
      if (this.attribute.state !== 'run') {
        clearInterval(time);
      }
      let obj = {};
      switch(this.attribute.direction) {
        case 'left':
          obj['x'] = body[0].x - wh;
          obj['y'] = body[0].y;
          break;
        case 'rigth':
          obj['x'] = body[0].x + wh;
          obj['y'] = body[0].y;
          break;
        case 'up':
          obj['x'] = body[0].x;
          obj['y'] = body[0].y - wh;
          break;
        case 'down':
          obj['x'] = body[0].x;
          obj['y'] = body[0].y + wh;
          break;
      }
      body.unshift(obj);
      // 判断是否吃到食物 
      if (this.isOverlap()) {
        this.clear(this.food.x, this.food.y, wh, wh);
        this.attribute.grade++; 
        this.foodDraw();
        this.draw();
      } else {
        if (this.end()) {
          alert("游戏结束");
          this.updateState('end');
          clearInterval(time);
        } else {
          let item = body.pop();
          this.clear(item.x, item.y, wh, wh);
          this.draw();
        }
      }
    }, speed);
  }
  // 键盘事件监听
  keyListening() {
    document.onkeydown = (event) => {
      let e = event || window.event || arguments.callee.caller.arguments[0];
      if (e && e.keyCode === 87 && this.attribute.direction !== 'down') { // 按下W
        this.attribute.direction = 'up';
      }
      if (e && e.keyCode === 65 && this.attribute.direction !== 'rigth') { // 按下A
        this.attribute.direction = 'left';
      }
      if (e && e.keyCode === 68 && this.attribute.direction !== 'left') { // 按下D
        this.attribute.direction = 'rigth';
      }
      if (e && e.keyCode === 83 && this.attribute.direction !== 'up') { // 按下W
        this.attribute.direction = 'down';
      }
      if (e && e.keyCode === 32) { // 按下空格 
        let state;
        if (this.attribute.state === 'pause') {
          state = 'run';
        } 
        if (this.attribute.state === 'run') {
          state = 'pause';
        }
        this.updateState(state);
      }
      if (e && e.keyCode === 82) { // 按下R键
        this.reStart();
      }
    } 
  }
  // 是否死亡
  end() {
    let body = [...this.attribute.body];
    let obj = body.shift();
    let flag = false;
    if (obj.x < 0 || obj.x >= this.el.elW || obj.y < 0 || obj.y >= this.el.elH) {
      flag = true;
    }
    body.forEach(key => {
      if (key.x === obj.x && key.y === obj.y) {
        flag = true;
      }
    });
    return flag;
  }
  // 重新开始
  reStart() {
    // 清除整个画布
    this.clear(0, 0, this.el.elW, this.el.elH);
    // 重新开始
    this.init(this.newAttribute);
  }
}
let game = new Game("snakegame", {color: "yellow"});
let grade = document.getElementById("grade");
let oldGrade = game.attribute.grade;
setInterval(() => {
  if (oldGrade !== game.attribute.grade) {
    oldGrade = game.attribute.grade;
    grade.innerText = game.attribute.grade;
  }
})

效果如下:


原文链接:https://blog.csdn.net/qq_37473645/article/details/102758190

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