Javascript I';我想用箭头键让一个蓝色方块在画布上移动?
DX和DY是蓝色正方形的位置。我试图实现的是,当使用箭头键时,我移动蓝色正方形的位置Javascript I';我想用箭头键让一个蓝色方块在画布上移动?,javascript,html,canvas,project,arrow-keys,Javascript,Html,Canvas,Project,Arrow Keys,DX和DY是蓝色正方形的位置。我试图实现的是,当使用箭头键时,我移动蓝色正方形的位置 const WIDTH = 640; const HEIGHT = 480; const PLAYER_SIZE = 20; const REPAINT_DELAY = 50; const EASY_DELAY = 1750; const MODERATE_DELAY = 1000; const HARD_DELAY = 750; const MAX_BLOCKS = 100; var context; v
const WIDTH = 640;
const HEIGHT = 480;
const PLAYER_SIZE = 20;
const REPAINT_DELAY = 50;
const EASY_DELAY = 1750;
const MODERATE_DELAY = 1000;
const HARD_DELAY = 750;
const MAX_BLOCKS = 100;
var context;
var DX;
var DY;
var rightKey=false;
var leftKey=false;
var-upKey=false;
var downKey=false;
window.onload=init;
函数init()
{
canvas=document.getElementById(“myCanvas”);
context=canvas.getContext(“2d”);
context.fillStyle=“#0000FF”;
DX=宽度/2-播放器大小/2;
DY=高度/2-球员尺寸/2;
setInterval('draw()',25)
}
函数clearCanvas()
{
clearRect(0,0,宽度,高度);
}
函数绘图()
{
clearCanvas();
如果(右键)DX+=5;
如果(左键)DX-=5,则为else;
如果(向上键)DY-=5;
否则,如果(向下键)DY+=5;
如果(DX=宽度)DX=宽度-DY;
如果(DY=高度)DY=高度-DX;
fillRect(DX,DY,PLAYER\u SIZE,PLAYER\u SIZE);
}
函数onKeyDown(evt){
如果(evt.keyCode==39)rightKey=true;
如果(evt.keyCode==37)leftKey=true,则为else;
如果(evt.keyCode==38)upKey=true;
如果(evt.keyCode==40)downKey=true,则为else;
}
功能onKeyUp(evt){
如果(evt.keyCode==39)rightKey=false;
如果(evt.keyCode==37)leftKey=false,则为else;
如果(evt.keyCode==38)upKey=false;
如果(evt.keyCode==40)downKey=false,则为else;
}
我想最后我缺少了两行调用前面两个函数的代码?这就是我感到困惑的地方
这就是我目前所拥有的,目前还不适合我。任何帮助都将不胜感激 代码中的错误如下:
var rightKey = false;
var leftKey = false;
var upKey = false;
var downKey = false;
window.onload = init;
function init()
{
canvas = document.getElementById("myCanvas");
context = canvas.getContext("2d");
context.fillStyle = "#0000FF";
DX = WIDTH / 2 - PLAYER_SIZE / 2;
DY = HEIGHT / 2 - PLAYER_SIZE / 2;
setInterval('draw()', 25)
}
function clearCanvas()
{
context.clearRect(0,0,WIDTH,HEIGHT);
}
function draw()
{
clearCanvas();
if (rightKey) DX += 5;
else if (leftKey) DX -= 5;
if (upKey) DY -= 5;
else if (downKey) DY += 5;
if (DX <= 0) DX = 0;
if ((DX + DY) >= WIDTH) DX = WIDTH - DY;
if (DY <= 0) DY = 0;
if ((DY + DX) >= HEIGHT) DY = HEIGHT - DX;
context.fillRect(DX, DY, PLAYER_SIZE, PLAYER_SIZE);
}
function onKeyDown(evt) {
if (evt.keyCode == 39) rightKey = true;
else if (evt.keyCode == 37) leftKey = true;
if (evt.keyCode == 38) upKey = true;
else if (evt.keyCode == 40) downKey = true;
}
function onKeyUp(evt) {
if (evt.keyCode == 39) rightKey = false;
else if (evt.keyCode == 37) leftKey = false;
if (evt.keyCode == 38) upKey = false;
else if (evt.keyCode == 40) downKey = false;
}
应该是什么时候
setInterval('draw()', 25)
setInterval的第一个参数应该是function,现在它是一个字符串
这是我的简单建议
更新了基于类的移动对象演示:
另外,请参见为什么requestAnimationFrame()比setTimeout()或setInterval()更好:
对于按键操作,我建议您创建一个对象,该对象保存所有键的布尔值,然后在不同对象(例如player)的更新函数上,您只需检查是否按下了所需的键
您不需要再使用keyCode,请参见此处:
我希望这对你有帮助
下面是我在画布上移动播放器对象的完整代码。它可以帮助您思考代码的结构:
setInterval(draw, 25)
世界上最好的游戏
2人移动
基于类的播放器对象和键盘控件
使用箭头键和WASD键移动球
const c=document.getElementById(“画布”);
const ctx=c.getContext(“2d”);
让设置={
宽度:100,
身高:100,
速度:1
};
c、 宽度=设置。宽度;
c、 高度=设置。高度;
/*
为每个按键保留布尔值的对象
*/
让按键={};
函数listenKeyboard(){
文件。添加的文件列表(“键控”,键控);
文件。添加的文件列表(“键控”,键控);
};
常数keyUp=e=>{
按键[e.键]=假;
};
const keyDown=e=>{
//console.log(e.key)
按键[e.键]=真;
};
职业选手{
构造函数(x、y、颜色、左、右、上、下、半径){
这个.x=x;
这个。y=y;
这个颜色=颜色;
this.left=左;
这个。右=右;
this.up=up;
this.down=向下;
这个半径=半径;
}
画(){
ctx.fillStyle=this.color;
ctx.beginPath();
ctx.arc(this.x,this.y,this.radius,0,Math.PI*2,false);
ctx.closePath();
ctx.fill();
}
更新(){
if(按[this.left]键){
此.x-=settings.speed;
}
if(按[this.right]键){
此.x+=settings.speed;
}
if(按[this.up]键){
此.y-=设置.speed;
}
if(按[this.down]键){
此.y+=settings.speed;
}
//屏幕边界
如果(this.x<0+this.radius)this.x=0+this.radius;
如果(this.y<0+this.radius)this.y=0+this.radius;
如果(this.x>settings.width-this.radius)this.x=settings.width-this.radius;
如果(this.y>settings.height-this.radius)this.y=settings.width-this.radius;
}
}
/*
创建播放器对象
*/
让p1=新玩家(25,25,“红色”,“箭头左”,“箭头右”,“箭头向上”,“箭头向下”,10);
让p2=新玩家(75,75,“黑色”,“a”,“d”,“w”,“s”,5);
函数绘图(){
clearRect(0,0,settings.width,settings.height);
p1.draw();
p2.draw();
};
函数更新(){
draw();
listenKeyboard();
p1.update();
p2.update();
requestAnimationFrame(更新);
};
requestAnimationFrame(更新);
嘿,我的答案对你有什么帮助吗?你不确定你是否试图通过使用箭头键在画布上移动一个蓝色方块?在我的答案中添加了新信息,请查看并接受,你满意吗。代码中的错误在setInterval第一个参数中。请接受或评论好吗?@seignix1155您已在此处登录,但没有回复我的评论或回答?如果你不接受答案,你为什么要问?
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>World's BEstest Game</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<h1 style="font-family: Comic Sans MS; color: hotpink; text-shadow: 2px 2px 2px pink">2 Player Movement</h1>
<p>Class based player objects and keyboard controls</p>
<p>Use the arrow and WASD keys to move your balls</p>
<canvas id="canvas" style="border:1px solid black; border-radius: 5px;">
</canvas>
<script>
const c = document.getElementById("canvas");
const ctx = c.getContext("2d");
let settings = {
width: 100,
height: 100,
speed: 1
};
c.width = settings.width;
c.height = settings.height;
/*
Object holding boolean values for every keypress
*/
let keyPresses = {};
function listenKeyboard() {
document.addEventListener("keyup", keyUp);
document.addEventListener("keydown", keyDown);
};
const keyUp = e => {
keyPresses[e.key] = false;
};
const keyDown = e => {
// console.log(e.key)
keyPresses[e.key] = true;
};
class Player {
constructor(x, y, color, left, right, up, down, radius) {
this.x = x;
this.y = y;
this.color = color;
this.left = left;
this.right = right;
this.up = up;
this.down = down;
this.radius = radius;
}
draw() {
ctx.fillStyle = this.color;
ctx.beginPath();
ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
ctx.closePath();
ctx.fill();
}
update() {
if (keyPresses[this.left]) {
this.x -= settings.speed;
}
if (keyPresses[this.right]) {
this.x += settings.speed;
}
if (keyPresses[this.up]) {
this.y -= settings.speed;
}
if (keyPresses[this.down]) {
this.y += settings.speed;
}
// Screen bounds
if (this.x < 0 + this.radius) this.x = 0 + this.radius;
if (this.y < 0 + this.radius) this.y = 0 + this.radius;
if (this.x > settings.width - this.radius) this.x = settings.width - this.radius;
if (this.y > settings.height - this.radius) this.y = settings.width - this.radius;
}
}
/*
Creating the player objects
*/
let p1 = new Player(25, 25, "red", "ArrowLeft", "ArrowRight", "ArrowUp", "ArrowDown", 10);
let p2 = new Player(75, 75, "black", "a", "d", "w", "s", 5);
function draw() {
ctx.clearRect(0, 0, settings.width, settings.height);
p1.draw();
p2.draw();
};
function update() {
draw();
listenKeyboard();
p1.update();
p2.update();
requestAnimationFrame(update);
};
requestAnimationFrame(update);
</script>
</body>
</html>