Javascript使图像在屏幕上反弹
我已经为反弹球编写了代码(在画布上使用arc()方法)。我想知道如何使图像在屏幕上反弹。这是我以前的代码(注意launchBall()函数将是运行反弹图像的函数):Javascript使图像在屏幕上反弹,javascript,Javascript,我已经为反弹球编写了代码(在画布上使用arc()方法)。我想知道如何使图像在屏幕上反弹。这是我以前的代码(注意launchBall()函数将是运行反弹图像的函数): 分数:0 var-dx=3; var-dy=3; var x=100; 变量y=100; var半径=20; var区间; 函数startBall(){ 间隔=设定间隔(发射球,20); } 函数launchBall(){ var c=document.getElementById(“画布”); var ctx=c.getCon
分数:0
var-dx=3;
var-dy=3;
var x=100;
变量y=100;
var半径=20;
var区间;
函数startBall(){
间隔=设定间隔(发射球,20);
}
函数launchBall(){
var c=document.getElementById(“画布”);
var ctx=c.getContext(“2d”);
ctx.clearRect(0,01275695);
ctx.beginPath();
弧(x,y,半径,0,2*Math.PI);
ctx.fillStyle=“红色”;
ctx.fill();
document.getElementById
如果(x1255)dx=-dx;
如果(y675)dy=-dy;
x=x+dx;
y=y+dy;
}
document.getElementById(“div”).onmousemove=函数(e){
document.getElementById(“image”).style.top=e.pageY-25+“px”;
document.getElementById(“image”).style.left=e.pageX-25+“px”;
}
var c=document.getElementById(“canvas”)代码>什么画布?那只是我懒得删除的早期代码:)
<!DOCTYPE HTML>
<html>
<body onload="startBall()" oncontextmenu="return false;" style="cursor: none; overflow: hidden;">
<center>
<div id="div" style="width: 1600px; height: 700px; border: 2px solid #000000; background-color: grey;">
<br>
<img draggable="false"id="image" style="position: absolute;" width="50" height="50"src="http://www.clker.com/cliparts/b/a/b/0/1207156679935151925noxin_crosshairs.svg.hi.png"/>
</div>
<center>
<p>Score: <a>0</a></p>
</center>
<script>
var dx = 3;
var dy = 3;
var x = 100;
var y = 100;
var radius = 20;
var interval;
function startBall(){
interval = setInterval(launchBall, 20);
}
function launchBall(){
var c = document.getElementById("canvas");
var ctx = c.getContext("2d");
ctx.clearRect(0, 0, 1275, 695);
ctx.beginPath();
ctx.arc(x, y, radius, 0, 2 * Math.PI);
ctx.fillStyle = "red";
ctx.fill();
document.getElementById
if(x<20 || x>1255) dx=-dx;
if(y<20 || y>675) dy=-dy;
x = x + dx;
y = y + dy;
}
document.getElementById("div").onmousemove = function(e) {
document.getElementById("image").style.top = e.pageY -25 + "px";
document.getElementById("image").style.left = e.pageX -25 +"px";
}
</script>
</body>
</html>