嗨,我正在用JS做蛇游戏。我正在研究的最初问题是,一旦蛇头接触到画布的边缘,便试图通过使用clearInterval(game);
来停止游戏运行。一旦我弄清楚了,就产生了一个新问题。您不能在画布边缘骑蛇。这是一个问题,因为有时食物会在边缘产生。任何想法,我很困惑。谢谢:)
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
//set canvas dimension equal to css dimension
canvas.width = 768;
canvas.height = 512;
//now put those dimensions into variables
const cvsW = canvas.width;
const cvsH = canvas.height;
//create snake unit
const unit = 16;
//create snake array
let snake = [{x: cvsW/2, y: cvsH/2}];
//delcare global variable to hold users direction
let direction;
//create food object
let food = {
x : Math.floor(Math.random()*((cvsW/unit)-1)+1)*unit,
y : Math.floor(Math.random()*((cvsH/unit)-1)+1)*unit
}
//read user's direction
document.addEventListener('keydown', changeDirection);
function changeDirection(e) {
//set direction
if (e.keyCode == 37 && direction != 'right') direction = 'left';
else if (e.keyCode == 38 && direction != 'down') direction = 'up';
else if (e.keyCode == 39 && direction != 'left') direction = 'right';
else if (e.keyCode == 40 && direction != 'up') direction = 'down';
}
function draw() {
//refresh canvas
ctx.clearRect(0, 0, cvsW, cvsH);
//draw snake
for(let i = 0; i < snake.length; i++) {
ctx.fillStyle = 'limegreen';
ctx.fillRect(snake[i].x, snake[i].y, unit, unit);
}
//grab head position
let headX = snake[0].x;
let headY = snake[0].y;
//check if snake hit wall
if(headX <= 0 || headY <= 0 || headX >= (cvsW-unit) || headY >= (cvsH-unit)) {
clearInterval(runGame);
}
//posistion food on board
ctx.fillStyle = 'red';
ctx.fillRect(food.x, food.y, unit, unit);
//send the snake in chosen direction
if(direction == 'left') headX -= unit;
else if(direction == 'up') headY -= unit;
else if(direction == 'right') headX += unit;
else if(direction == 'down') headY += unit;
//create new head
let newHead = {x: headX, y: headY}
if(headX == food.x && headY == food.y) {
//create new food position
food = {
x : Math.floor(Math.random()*((cvsW/unit)-1)+1)*unit,
y : Math.floor(Math.random()*((cvsH/unit)-1)+1)*unit
}
//add 3 units to the snake
snake.unshift(newHead);
snake.unshift(newHead);
snake.unshift(newHead);
}
else {
//remove tail
snake.pop();
}
//add head to snake
snake.unshift(newHead);
}
//run game engine
let runGame = setInterval(draw, 70);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Snake Game</title>
<style>
body {
background-color: #333;
}
canvas {
background-color: #4d4d4d;
margin: auto;
display: block;
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
width: 750px;
height: 500px;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script src="script.js"></script>
</body>
</html>