- <!doctype html>
- <html>
- <body>
- <canvas id="1" width="400" height="400" ></canvas>
- <script>
- ????let ctx = document.getElementById("1").getContext("2d");
- ????let SpecialLen = 20, snakeDir = 2, snakeDirNow , food = [2,0], snakeBody = [ [0, 0], [1, 0] ]; //2 for right direction
- ????let Map = {}; //map对象存放 location:val ,例‘1,2‘:1 ,1表示蛇身,2表示食物
- ????for(let snakeNode of snakeBody) Map[snakeNode] = 1;
- ????let dirMat = [[-1, 0], [0, -1], [1, 0], [0, 1]]; //0 1 2 3 <- ↑ -> ↓
- ????let pairEqual = ((pair1, pair2) => pair1[0] == pair2[0] && pair1[1] == pair2[1]); //碰撞检测
- ????document.onkeydown = function (env) {
- ????????arrowKeyCode = env.keyCode - 37; //37是"leftArrow"
- ????????if (0 <= arrowKeyCode == arrowKeyCode < 4)
- ????????????if (snakeDirNow !== (arrowKeyCode + 2) % 4) //周期过后才改变方向&&不能走相反方向
- ????????????????snakeDir = arrowKeyCode;
- ????};
- ????!function () {
- ????????let snakeHeadNext = snakeBody[snakeBody.length-1].map((x, i) => x + dirMat[snakeDirNow=snakeDir][i]); //得到蛇头的下一步位置
- ????????if (!pairEqual(snakeHeadNext, food)) { //没吃到食物
- ????????????Map[snakeBody.shift()] = 0; //先去除蛇尾
- ????????????if (snakeBody.some(x=>pairEqual(x,snakeHeadNext)) || !snakeHeadNext.every(x => 0<=x == x < SpecialLen)) //蛇头不对
- ????????????????return document.write("Game Over"); //overwrite all
- ????????}
- ????????snakeBody.push(snakeHeadNext);
- ????????Map[snakeHeadNext] = 1; //蛇头合适,加入蛇身
- ????????while (snakeBody.some(x => pairEqual(x, food)))
- ????????????food = [Math.floor(Math.random() * SpecialLen), Math.floor(Math.random() * SpecialLen)];
- ????????Map[food] = 2;
- ????????for(let i =0;i<SpecialLen ;i++)
- ????????????for(let j =0;j<SpecialLen ;j++){
- ????????????switch (Map[[i,j]]) {
- ????????????????case 1:ctx.fillStyle= ‘purple‘;break;
- ????????????????case 2:ctx.fillStyle= ‘green‘;break;
- ????????????????default:ctx.fillStyle= ‘grey‘;break;
- ????????????}
- ????????????ctx.fillRect(i*SpecialLen,j*SpecialLen, SpecialLen, SpecialLen)
- ????????}
- ????????setTimeout(arguments.callee, 100); //130ms后执行 此function 一次
- ????}()
- </script>
- </body>
- </html>
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