4

我的游戏基于月球着陆器演示,虽然经过大量修改,我可以达到 40-50fps 左右,但问题是它在 40-50fps 之间波动太大,导致运动图形抖动!这很烦人,让我的游戏看起来很糟糕,而实际上它以良好的帧速率运行。

我尝试将线程优先级设置得更高,但这只会让情况变得更糟……现在它将在 40-60fps 之间波动……

我正在考虑将 FPS 限制在 30 左右,以便它保持不变。这是一个好主意吗?其他人有经验或不同的解决方案吗?

谢谢!

这是我的运行循环

@Override
    public void run() {
        while (mRun) {
            Canvas c = null;
            try {
                c = mSurfaceHolder.lockCanvas(null);
                synchronized (mSurfaceHolder) {
                    if(mMode == STATE_RUNNING){

                        updatePhysics();
                    }
                    doDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    mSurfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
        }

private void updatePhysics() {

        now = android.os.SystemClock.uptimeMillis();

        elapsed = (now - mLastTime) / 1000.0;

        posistionY += elapsed * speed;
        mLastTime = now;
}
4

5 回答 5

22

不要将游戏的逻辑(对象移动等)更新速率建立在帧速率上。换句话说,将您的绘图和逻辑更新代码放在两个单独的组件/线程中。这样你的游戏逻辑就完全独立于你的帧率。

逻辑更新应该基于自上次更新以来已经过去了多少时间(我们称之为delta)。因此,如果您有一个对象以 1px/毫秒的速度移动,那么在每次更新期间,您的对象应该执行以下操作:

public void update(int delta) {
    this.x += this.speed * delta;
}

所以现在即使你的 FPS 滞后,它也不会影响你的对象的移动速度,因为增量会更大,使对象移动得更远以进行补偿(在某些情况下会出现并发症,但这就是要点)。

这是在逻辑更新对象中计算增量的一种方法(在某个线程循环中运行):

private long lastUpdateTime;
private long currentTime;

public void update() {
    currentTime = System.currentTimeMillis();
    int delta = (int) (currentTime - lastUpdateTime);
    lastUpdateTime = currentTime;
    myGameObject.update(delta); // This would call something like the update method above.
}

希望有帮助!请询问您是否有任何其他问题;我一直在自己制作安卓游戏。:)


示例代码:

复制这两个片段(1 个活动和 1 个视图)并运行代码。无论您的 FPS 是什么,结果都应该是一个白点从屏幕上顺利落下。代码看起来有点复杂和冗长,但实际上非常简单;评论应该解释一切。

这个活动课不是很重要。您可以忽略其中的大部分代码。

public class TestActivity extends Activity {

    private TestView view;

    public void onCreate(Bundle savedInstanceState) {
        // These lines just add the view we're using.
        super.onCreate(savedInstanceState);
        setContentView(R.layout.randomimage);
        RelativeLayout rl = (RelativeLayout) findViewById(R.id.relative_layout);
        view = new TestView(this);
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
                10000, 10000);
        rl.addView(view, params);

        // This starts our view's logic thread
        view.startMyLogicThread();
    }

    public void onPause() {
        super.onPause();
        // When our activity pauses, we want our view to stop updating its logic.
        // This prevents your application from running in the background, which eats up the battery.
        view.setActive(false);
    }
}

这堂课是令人兴奋的地方!

public class TestView extends View {

    // Of course, this stuff should be in its own object, but just for this example..
    private float position; // Where our dot is
    private float velocity; // How fast the dot's moving

    private Paint p; // Used during onDraw()
    private boolean active; // If our logic is still active

    public TestView(Context context) {
        super(context);
        // Set some initial arbitrary values
        position = 10f;
        velocity = .05f;
        p = new Paint();
        p.setColor(Color.WHITE);
        active = true;
    }

    // We draw everything here. This is by default in its own thread (the UI thread).
    // Let's just call this thread THREAD_A.
    public void onDraw(Canvas c) {
        c.drawCircle(150, position, 1, p);
    }

    // This just updates our position based on a delta that's given.
    public void update(int delta) {
        position += delta * velocity;
        postInvalidate(); // Tells our view to redraw itself, since our position changed.
    }

    // The important part!
    // This starts another thread (let's call this THREAD_B). THREAD_B will run completely
    // independent from THREAD_A (above); therefore, FPS changes will not affect how
    // our velocity increases our position.
    public void startMyLogicThread() {
        new Thread() {
            public void run() {
                // Store the current time values.
                long time1 = System.currentTimeMillis();
                long time2;

                // Once active is false, this loop (and thread) terminates.
                while (active) {
                    try {
                        // This is your target delta. 25ms = 40fps
                        Thread.sleep(25);
                    } catch (InterruptedException e1) {
                        e1.printStackTrace();
                    }

                    time2 = System.currentTimeMillis(); // Get current time
                    int delta = (int) (time2 - time1); // Calculate how long it's been since last update
                    update(delta); // Call update with our delta
                    time1 = time2; // Update our time variables.
                }
            }
        }.start(); // Start THREAD_B
    }

    // Method that's called by the activity
    public void setActive(boolean active) {
        this.active = active;
    }
}
于 2010-07-22T21:11:57.450 回答
3

我在想上面的某些代码可能并不是真的有什么问题,而是效率低下。我说的是这段代码...

   // The important part!
// This starts another thread (let's call this THREAD_B). THREAD_B will run completely
// independent from THREAD_A (above); therefore, FPS changes will not affect how
// our velocity increases our position.
public void startMyLogicThread() {
    new Thread() {
        public void run() {
            // Store the current time values.
            long time1 = System.currentTimeMillis();
            long time2;

            // Once active is false, this loop (and thread) terminates.
            while (active) {
                try {
                    // This is your target delta. 25ms = 40fps
                    Thread.sleep(25);
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }

                time2 = System.currentTimeMillis(); // Get current time
                int delta = (int) (time2 - time1); // Calculate how long it's been since last update
                update(delta); // Call update with our delta
                time1 = time2; // Update our time variables.
            }
        }
    }.start(); // Start THREAD_B
}

具体来说,我正在考虑以下几行......

// This is your target delta. 25ms = 40fps
Thread.sleep(25);

在我看来,只是让线程闲置无所事事是浪费宝贵的处理时间,而实际上你想要做的是执行更新,那么,如果更新花费的时间少于 25 毫秒,那么睡眠线程以获得更新期间使用的内容和 25 毫秒(或任何您选择的帧速率)的差异。这样,更新将在当前帧被渲染时发生,并将完成,以便下一帧更新使用更新后的值。

我能想到的唯一问题是需要进行某种同步,以便当前帧渲染不使用部分更新的值。也许更新为您的一组值的新实例,然后在渲染之前使新实例成为当前实例。

我想我记得在一本图形书中读过一些关于目标是在保持所需帧速率的同时执行尽可能多的更新,然后并且只有它们执行屏幕更新。

这当然需要一个线程来驱动更新 - 如果您使用 SurfaceView,当您锁定画布时,渲染由该线程控制(理论上,无论如何根据我的理解)。

所以,在代码中,它更像是......

// Calculate next render time
nextRender = System.currentTimeInMillis() + 25;

while (System.currentTimeInMillis() < nextRender)
{
    // All objects must be updated here
    update();

    // I could see maintaining a pointer to the next object to be updated,
    // such that you update as many objects as you can before the next render, and 
    // then continue the update from where you left off in the next render...
}

// Perform a render (if using a surface view)
c = lockCanvas() blah, blah...
// Paint and unlock

// If using a standard view
postInvalidate();

祝你好运,任何使用它的人的任何反馈肯定会帮助我们所有人学到一些东西......

巴巴蒂

于 2011-11-12T03:38:08.077 回答
0

我认为这是关于垃圾收集器

于 2010-10-21T06:07:59.577 回答
0

如果您的游戏动作繁重,我会使用 SurfaceView 而不是 View。如果您不需要快速更新 GUI,那么 View 很好,但对于 2D 游戏,使用 SurfaceView 总是更好。

于 2010-12-05T07:01:19.853 回答
0

我有一个类似的问题,抖动使大物体的移动看起来不均匀。即使“速度”相同,但不同长度的步数使动作看起来很跳跃。Broody - 你说 SurfaceView 更好,但是,在 Android 3.0 之后情况并非如此,因为 View 是硬件加速的,但 .lockCanvas 返回的画布不是。史蒂文 - 是的,这可能会导致漏洞,但很容易检测到。/雅各布

于 2013-06-11T19:43:13.467 回答