Question

我正在研究基本的太空射击游戏，目前玩家只是一个圈子。

在Opera，Firefox和IE9中玩游戏时，我的游戏都是滞后的。

我尝试过研究这个问题，但我不确定是什么问题。

我做错了吗？

有什么想法吗？

以下是代码：

<!doctype html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>Space Game Demo</title>
    </head>
    <body>
        <section>
            <div>
                <canvas id="canvas" width="640" height="480">
                    Your browser does not support HTML5.
                </canvas>
            </div>
            <script type="text/javascript">
//Start of script
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

var x = 200;
var y = 200;
var thrust = 0.25;
var decay = 0.99;
var maxSpeed = 2;
var turnSpeed = 2;
var tempSpeed = 0;
var direction = 0;
var xSpeed = 0;
var ySpeed = 0;

function move() {
if (38 in keysDown) { // Player holding up
    xSpeed += thrust * Math.sin(direction * (Math.PI / 180));
    ySpeed += thrust * Math.cos(direction * (Math.PI / 180));
}
else {
    xSpeed *= decay;
    ySpeed *= decay;
}
if (37 in keysDown) { // Player holding left
    direction += turnSpeed;
}
if (39 in keysDown) { // Player holding right
    direction -= turnSpeed;
}
if (40 in keysDown) { // Player holding down
}

tempSpeed = Math.sqrt((xSpeed * xSpeed) + (ySpeed * ySpeed));
if(tempSpeed > maxSpeed) {
    xSpeed *= maxSpeed / tempSpeed;
    ySpeed *= maxSpeed / tempSpeed;
}

x += xSpeed;
y += ySpeed;
}

function degtorad(angle) {
return angle * (Math.PI/180);
}

function loop() {
ctx.clearRect(0, 0, canvas.width, canvas.height);

ctx.fillStyle = "grey";
ctx.strokeStyle = "black";
ctx.beginPath();
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.stroke();

move();
ctx.strokeStyle = "red";
ctx.beginPath();
ctx.arc(x,y,10,0,2*Math.PI);
ctx.stroke();
}

setInterval(loop, 2);
var keysDown = {};

addEventListener("keydown", function (e) {
keysDown[e.keyCode] = true;
}, false);

addEventListener("keyup", function (e) {
    delete keysDown[e.keyCode];
}, false);

            </script>
        </section>
    </body>
</html>

Answer 1

使用 window.requestAnimationFrame ，这就是它的意思。现在你正试图以每两毫秒一步的速度运行游戏 - 大约是500 FPS。

// target the user's browser.
(function() {
  var requestAnimationFrame = window.requestAnimationFrame || 
                              window.mozRequestAnimationFrame || 
                              window.webkitRequestAnimationFrame ||
                              window.msRequestAnimationFrame;

  window.requestAnimationFrame = requestAnimationFrame;
})();

function loop() {
    // game loop logic here...
}

requestAnimationFrame(loop);

Answer 2

delete keysDown[e.keyCode];

也不好。不断创建和删除数组元素要比将其值设置为true / false慢得多。

keysDown[e.keyCode] = false;    //  faster & better

FPS应与显示器刷新率相同。如果你看不到，高FPS对你来说没什么意义。除了说CPU将更难以计算无法在屏幕上呈现的帧。甚至在理论上都没有。

Html5 / Javascript游戏滞后

2 个答案: