Как сделать, чтобы мяч отскакивал от границ "холста"?
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Keyboard input</title>
</head>
<body>
<canvas id="canvas" width="200" height="200"></canvas>
<script src="https://code.jquery.com/jquery-2.1.0.js"></script>
<script type="text/javascript">
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var width = canvas.width;
var height = canvas.height;
var circle = function (x, y, radius, fillCircle) {
ctx.beginPath();
ctx.arc(x, y, radius, 0, Math.PI * 2, false);
if (fillCircle) {
ctx.fill();
} else {
ctx.stroke();
}
};
var Ball = function () {
this.x = width / 2;
this.y = height / 2;
this.xSpeed = 5;
this.ySpeed = 0;
};
Ball.prototype.move = function() {
this.x += this.xSpeed;
this.y += this.ySpeed;
if (this.x < 0) {
this.x = width;
} else if (this.x > width) {
this.x = 0;
} else if (this.y < 0) {
this.y = height;
} else if (this.y > height) {
this.y = 0;
}
};
Ball.prototype.draw = function () {
circle(this.x, this.y, 10, true);
};
Ball.prototype.setDirection = function(direction) {
if (direction === "up") {
this.xSpeed = 0;
this.ySpeed = -5;
} else if (direction === "down") {
this.xSpeed = 0;
this.ySpeed = 5;
} else if (direction === "left") {
this.xSpeed = -5;
this.ySpeed = 0;
} else if (direction === "right") {
this.xSpeed = 5;
this.ySpeed = 0;
} else if (direction === "stop") {
this.xSpeed = 0;
this.ySpeed = 0;
}
};
var ball = new Ball;
var keyActions = {
32: "stop",
37: "left",
38: "up",
39: "right",
40: "down"
};
$("body").keydown(function (event) {
var direction = keyActions[event.keyCode];
ball.setDirection(direction);
});
setInterval(function () {
ctx.clearRect(0, 0, width, height);
ball.draw();
ball.move();
ctx.strokeRect(0, 0, width, height)
}, 30);
</script>
</body>
</html>
