[英]Javascript snake game bugs
有两个问题,我无法控制蛇,现在它不断地重置而没有给蛇移动的机会。 我认为,如果我继续编码,问题将会消失,但可悲的是,这并不是一个完美的世界。
我尝试了不同的按键代码来控制蛇,但没有用。
window.onload = function() {
var cvs = document.getElementById("canvas");
var ctx = cvs.getContext("2d");
var cvsW = cvs.width;
var cvsH = cvs.height;
var snekW = 10;
var snekH = 10;
//score
var score = 0;
//default direction
var direction = "right";
//read users directions
document.addEventListener("keydown",getDirection);
//To my knowledge this function should control the snake with the
keyboard
function getDirection(e)
{
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 drawSnek(x,y)
{
ctx.fillStyle = "Lime";
ctx.fillRect(x*snekW,y*snekH,snekW,snekH);
ctx.fillStyle = "#000";
ctx.strokeRect(x*snekW,y*snekH,snekW,snekH);
}
var len = 4; //default length of the snake
var snek = []; //the snake is an array
for(var i = len-1; i>=0; i--)
{
snek.push({x:i,y:0});
}
//exceptions for direction of snake
if(direction == "left") snekx--;
else if( direction == "up") sneky--;
else if( direction == "right") snekx++;
else if( direction == "down") sneky++;
//Functions for creating snake food have been removed.
var newHead = { x: snekx, y: sneky};
snek.unshift(newHead);
drawScore(score);
}
setInterval(draw, 10); //I do not fully understand this function
}
您的代码有几个问题:
您需要可以在间隔中调用的绘制函数。 在此绘制功能中,您可以绘制蛇的各个部分。
您无法正确控制蛇,因为在回调函数的下部出现错字。
您必须为蛇的头引入x / y变量,或者使用数组的第一个元素来检索它。
使用snek.unshift
取消移动新位置将导致蛇无限地增长。 使用删除数组元素
snek.splice(len,snek.length - len);
解决了这个问题。
如果仅在屏幕上绘制新元素,则绘制的旧零件仍将存在于新框架中。 一个好主意是使用
ctx.clearRect(0, 0, cvsW, cvsH);
window.onload = function () {
var cvs = document.getElementById("canvas");
var ctx = cvs.getContext("2d");
var cvsW = cvs.width;
var cvsH = cvs.height;
var snekW = 10;
var snekH = 10;
//score
var score = 0;
//default direction
var direction = "right";
//read users directions
document.addEventListener("keydown", getDirection);
//To my knowledge this function should control the snake with the keyboard
function getDirection(e) {
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 drawSnek(x, y) {
ctx.fillStyle = "Lime";
ctx.fillRect(x * snekW, y * snekH, snekW, snekH);
ctx.fillStyle = "#000";
ctx.strokeRect(x * snekW, y * snekH, snekW, snekH);
}
let snekx = 0;
let sneky = 0;
var len = 4; //default length of the snake
var snek = []; //the snake is an array
for (var i = len - 1; i >= 0; i--) {
snek.push({ x: i, y: 0 });
}
function draw() {
ctx.clearRect(0, 0, cvsW, cvsH);
//exceptions for direction of snake
if (direction == "left") snekx--;
else if (direction == "up") sneky--;
else if (direction == "right") snekx++;
else if (direction == "down") sneky++;
//Functions for creating snake food have been removed.
var newHead = { x: snekx, y: sneky };
snek.unshift(newHead);
for(let i = 0; i < snek.length; i++) {
drawSnek(snek[i].x, snek[i].y)
}
snek.splice(len,snek.length - len);
//drawScore(score);
}
setInterval(draw, 50); //I do not fully understand this function
}
固定代码的CodePen: https ://codepen.io/lukasmoeller/pen/PvVzqq?editors = 1111(边界未选中-蛇会离开画布)
setInterval(fn, interval)
setInterval interval
ms interval
使用fn调用一次指定的函数,直到将其清除为止。 可以使用clearInterval
清除间隔,并向其传递setInterval
的返回值。 如果要在开始时延迟函数执行,可以添加setTimeout
,添加一个设置时间间隔的回调:
setTimeout(function(){
setInterval(draw, 50);
}, 1000)
经过1000毫秒后,每隔50毫秒才开始绘制游戏。
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