如果您只是希望播放器在到达墙壁时停止，您可以应用一些数学运算：
例如：假设你的播放器是一个 10px x 10px 的矩形，右边墙的 X 位置是 200。
矩形右侧的X位置计算如下：
var playerRightSide = player.x + player.width;
您可以像这样测试玩家是否已经到达墙壁：
if( playerRightSide >= 200 )
如果用户试图将他们的播放器推到墙外，您可以使用播放器 X 位置将播放器固定在墙的左侧。
if( playerRightSide >= 200 ) { player.x = 190; }
190 是墙的 X 位置 (200) 减去玩家的宽度 (10)。
如果您有兴趣进行更高级的碰撞测试，请进一步阅读。
许多基本的游戏碰撞可以分为 3 种类型：
下面是如何检测这些常见碰撞的说明。
假设您这样定义一个圆：
var circle1={
x:30,
y:30,
r:10
};
假设你这样定义一个矩形：
var rect1={
x:20,
y:100,
w:20,
h:20
};
您可以像这样检测圆形与圆形碰撞...
...使用此 Circle vs Circle 碰撞测试代码：
// return true if the 2 circles are colliding
// c1 and c2 are circles as defined above
function CirclesColliding(c1,c2){
var dx=c2.x-c1.x;
var dy=c2.y-c1.y;
var rSum=c1.r+c2.r;
return(dx*dx+dy*dy<=rSum*rSum);
}
您可以像这样检测矩形与矩形的碰撞...
...使用这个 Rectangle vs Rectangle 碰撞测试代码：
// return true if the 2 rectangles are colliding
// r1 and r2 are rectangles as defined above
function RectsColliding(r1,r2){
return !(r1.x>r2.x+r2.w || r1.x+r1.w<r2.x || r1.y>r2.y+r2.h || r1.y+r1.h<r2.y);
}
您可以像这样检测矩形与圆形的碰撞...
...使用这个 Rectangle vs Circle 碰撞测试代码：
// return true if the rectangle and circle are colliding
// rect and circle are a rectangle and a circle as defined above
function RectCircleColliding(rect,circle){
var dx=Math.abs(circle.x-(rect.x+rect.w/2));
var dy=Math.abs(circle.y-(rect.y+rect.y/2));
if( dx > circle.r+rect.w2 ){ return(false); }
if( dy > circle.r+rect.h2 ){ return(false); }
if( dx <= rect.w ){ return(true); }
if( dy <= rect.h ){ return(true); }
var dx=dx-rect.w;
var dy=dy-rect.h
return(dx*dx+dy*dy<=circle.r*circle.r);
}
例如，您可以使用这些碰撞测试来响应玩家触摸通电立方体：
// create a circular player object
// that's located at [30,30] and has a radius of 10px
var player={x:30,y:30,r:10};
// create a rectangular power-up at position [200,30]
var powerup={x:200, y:30, w:20, h:20};
// Let's say the user keys the player to coordinate [200,35]
// (touching the power-up)
player.x = 220;
player.y = 35;
// you can test if the circular player is touching the rectangular power-up
if( RectCircleColliding(powerup,player) ) {
// the player has collided with the power-up, give bonus power!
player.power += 100;
}
这是代码和小提琴：http://jsfiddle.net/m1erickson/u6t48/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:20px; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
window.requestAnimFrame = (function(callback) {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
ctx.fillStyle="lightgray";
ctx.strokeStyle="skyblue";
// top collision circle vs circle
var circle1={x:30,y:30,r:10};
var circle2={x:70,y:40,r:10};
var circle3={x:100,y:30,r:10};
var direction1=1;
// middle collision rect vs rect
var rect1={x:20,y:100,w:20,h:20};
var rect2={x:50,y:110,w:20,h:20};
var rect3={x:90,y:100,w:20,h:20};
var direction2=1;
// bottom collision rect vs circle
var circle4={x:30,y:200,r:10};
var rect4={x:50,y:205,w:20,h:20};
var circle5={x:100,y:200,r:10};
var direction3=1;
function drawAll(){
ctx.clearRect(0,0,canvas.width,canvas.height);
drawCircle(circle1);
drawCircle(circle2);
drawCircle(circle3);
drawCircle(circle4);
drawCircle(circle5);
drawRect(rect1);
drawRect(rect2);
drawRect(rect3);
drawRect(rect4);
}
function drawCircle(c){
ctx.beginPath();
ctx.arc(c.x,c.y,c.r,0,Math.PI*2,false);
ctx.closePath();
ctx.fill();
ctx.stroke();
}
function drawRect(r){
ctx.beginPath();
ctx.rect(r.x,r.y,r.w,r.h);
ctx.closePath();
ctx.fill();
ctx.stroke();
}
// return true if the 2 circles are colliding
function CirclesColliding(c1,c2){
var dx=c2.x-c1.x;
var dy=c2.y-c1.y;
var rSum=c1.r+c2.r;
return(dx*dx+dy*dy<=rSum*rSum);
}
// return true if the 2 rectangles are colliding
function RectsColliding(r1,r2){
return !(r1.x>r2.x+r2.w || r1.x+r1.w<r2.x || r1.y>r2.y+r2.h || r1.y+r1.h<r2.y);
}
// return true if the rectangle and circle are colliding
function RectCircleColliding(rect,circle){
var dx=Math.abs(circle.x-(rect.x+rect.w/2));
var dy=Math.abs(circle.y-(rect.y+rect.h/2));
if( dx > circle.r+rect.w/2 ){ return(false); }
if( dy > circle.r+rect.h/2 ){ return(false); }
if( dx <= rect.w ){ return(true); }
if( dy <= rect.h ){ return(true); }
var dx=dx-rect.w;
var dy=dy-rect.h
return(dx*dx+dy*dy<=circle.r*circle.r);
}
var fps = 15;
function animate() {
setTimeout(function() {
requestAnimFrame(animate);
// circle vs circle
circle2.x = circle2.x+direction1;
if( CirclesColliding(circle2,circle1) || CirclesColliding(circle2,circle3) ){
direction1=-direction1;
}
// rect vs rect
rect2.x = rect2.x+direction2;
if( RectsColliding(rect2,rect1) || RectsColliding(rect2,rect3) ){
direction2=-direction2;
}
// rect vs circle
rect4.x = rect4.x+direction3;
if( RectCircleColliding(rect4,circle4) || RectCircleColliding(rect4,circle5) ){
direction3=-direction3;
}
drawAll();
}, 1000 / fps);
}
animate();
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=300 height=300></canvas>
</body>
</html>