<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>弱智贪吃蛇</title>
<style>
.container{
margin: 50px auto;
}
.row {
display: flex;
justify-content: center;
margin-top: 0.5rem;
margin-bottom: 0.5rem;
}
.game_over {
color: red;
font-size: 1rem;
display: none;
}
#bg{
display: block;
box-shadow: -2px -2px 2px #EFEFEF, 5px 5px 5px #B9B9B9;
cursor: pointer;
}
.restart{
display: none;
}
</style>
</head>
<body>
<div class="container">
<div class="row game_over">
GAME OVER !
</div>
<div class="row">
<div class="col speed">
速度:
<select name="speed" id="">
<option value="1">1x</option>
<option value="2">2x</option>
<option value="3">3x</option>
<option value="4">4x</option>
<option value="5">5x</option>
</select>
</div>
<div class="col start">
<button type="button" onclick="start();">开始</button>
</div>
<div class="col restart">
<button type="button" onclick="location.reload();">重新开始</button>
</div>
<div class="col">
分数:<span class="score">0</span>
</div>
</div>
<div class="row">
<canvas id="bg" width="450px" height="450px"></canvas>
</div>
</div>
<script>
const leftCode = 37,rightCode=39,upCode=38,downCode=40;
window.onload = function() {
initParams();
drawBackgroud();
window.onkeydown = turnAround;
}
//转向
function turnAround() {
if(Snake.gameover) {
return;
}
//不能掉头的情况
if(Snake.direction == leftCode && event.keyCode == rightCode
|| Snake.direction == rightCode && event.keyCode == leftCode
|| Snake.direction == upCode && event.keyCode == downCode
|| Snake.direction == downCode && event.keyCode == upCode
) {
return;
}
Snake.direction = event.keyCode;
run();
}
//初始化数据
function initParams() {
let tag = document.getElementById("bg");
let context = tag.getContext("2d");
let lineSize = localStorage.getItem("lineSize") ? localStorage.getItem("lineSize") : 45;
context.strokeStyle = '#bfbfbf';
//游戏背景的宽度
let width = tag.clientWidth > tag.clientHeight ? tag.clientHeight : tag.clientWidth;
//格子间距
let lineGap = Math.floor(width / lineSize);
//起始x坐标
let startX = (tag.clientWidth - lineGap * lineSize) / 2 + lineGap / 2;
//起始y坐标
let startY = (tag.clientHeight - lineGap * lineSize) / 2 + lineGap / 2;
window.Snake = {tag,context,lineSize,width,lineGap,startX,startY,rewardPoint:{x:null,y:null},points:[], direction : rightCode, runCode : null,gameover:false};
}
//设置数据
function setParams(param) {
if(typeof param !== "object") {
throw "param must object";
}
for (const key in param) {
if (Object.hasOwnProperty.call(param, key)
&& Object.hasOwnProperty.call(window.Snake, key)) {
window.Snake[key] = param[key];
}
}
}
//画背景格子
function drawBackgroud() {
let snake = window.Snake;
for (var i = 0; i < snake.lineSize; i++) {
drawLine(snake.startX + i * snake.lineGap, snake.startY,
snake.startX + i * snake.lineGap, snake.tag.clientHeight - snake.startY
);
drawLine(snake.startX, snake.startY + i * snake.lineGap,
snake.tag.clientWidth - snake.startX, snake.startY + i * snake.lineGap
);
}
}
//画某个点
function drawPoint(x,y,isReward) {
let snake = window.Snake;
snake.context.fillStyle = isReward ? "#FF0000" : "#000";
snake.context.fillRect(snake.startX + x * snake.lineGap + snake.context.lineWidth, snake.startY + y * snake.lineGap + snake.context.lineWidth, snake.lineGap - snake.context.lineWidth * 2, snake.lineGap - snake.context.lineWidth * 2);
}
function clearPoint(x,y) {
if(x == null || y == null) {
return;
}
let snake = window.Snake;
let point = {x: snake.startX + x * snake.lineGap + snake.context.lineWidth, y : snake.startY + y * snake.lineGap + snake.context.lineWidth};
snake.context.clearRect(point.x, point.y, snake.lineGap - snake.context.lineWidth * 2, snake.lineGap - snake.context.lineWidth * 2);
}
function randomReward() {
clearPoint(Snake.rewardPoint.x, Snake.rewardPoint.y);
let points = [];
for(let i = 0; i < Snake.lineSize - 1; ++i) {
for (let j = 0; j < Snake.lineSize - 1; ++j) {
let exists = false;
for (const p of Snake.points) {
if(i == p.x && j == p.y) {
exists = true;
break;
}
}
if(!exists) {
points.push({x:i,y:j});
}
}
}
let snake = window.Snake;
function random () {
return points[Math.floor(Math.random() * points.length)];
}
let point = random();
setParams({ rewardPoint: point});
drawPoint(point.x, point.y, true);
}
function run() {
let headX = Snake.points[0].x, headY = Snake.points[0].y;
if(Snake.direction == rightCode) {
//水平向右
headX++;
}else if (Snake.direction == leftCode) {
//水平向左
headX--;
}else if (Snake.direction == upCode) {
//垂直向上
headY--;
}else if (Snake.direction == downCode) {
//垂直向下
headY++;
}else {
return;
}
if(headX < 0 || headX >= Snake.lineSize - 1 || headY < 0 || headY >= Snake.lineSize - 1) {
gameover();
return;
}
for (const p of Snake.points) {
if (p.x == headX && p.y == headY) {
gameover();
return;
}
}
if(headX != Snake.rewardPoint.x || headY != Snake.rewardPoint.y) {
let lastPoint = Snake.points.pop();
clearPoint(lastPoint.x, lastPoint.y);
}else {
randomReward();
}
drawPoint(headX, headY);
Snake.points.unshift({ x: headX, y: headY });
document.querySelector(".score").innerText = Snake.points.length;
}
function gameover() {
Snake.gameover = true;
if(Snake.runCode) {
window.clearInterval(Snake.runCode);
}
document.querySelector(".game_over").style.display = "flex";
}
function initHead() {
let head = {x:0,y:0};
drawPoint(head.x, head.y, false);
Snake.points.push(head);
}
function restart() {
document.querySelector(".start").style.display = "flex";
document.querySelector(".restart").style.display = "none";
document.querySelector(".speed").style.display = "flex";
}
function start() {
document.querySelector(".start").style.display = "none";
document.querySelector(".restart").style.display = "flex";
document.querySelector(".speed").style.display = "none";
//画蛇头
initHead();
//初始化一个奖励
randomReward();
let code = window.setInterval(run, 500 / document.querySelector(".speed>select").value);
setParams({runCode:code});
}
function drawLine(x1,y1,x2,y2) {
Snake.context.moveTo(x1, y1);
Snake.context.lineTo(x2, y2);
Snake.context.stroke();
}
</script>
</body>
</html>
