游戏中流畅的动画

Question

如何创建"平滑"动画？我正在开发一款关于android的游戏.我知道做平滑动画的默认方式不是最好的:

perFrame() {
    time = highrestime();
    frameTime = time - lastTime;
    lastTime = time;

    // now you could use frameTime as delta. this will lead to not real
    // smooth animations
}

我读了一些关于这个主题的文件.特别是如果你使用物理模拟.着名文章似乎是这样的:http://gafferongames.com/game-physics/fix-your-timestep/ 我创建了一个基本类,如下所示:

public class TimeSystem {
private long mCurrentTime;
private long mAccumulator;
private Simulation mSimulation; 
private Renderer mRenderer;

private static float mSimulationDelta = 1000f / 60f;

public TimeSystem(Simulation simulation, Renderer renderer) {
    mCurrentTime = System.currentTimeMillis();
    mAccumulator = 0;

    mSimulation = simulation;
    mRenderer = renderer;
}

public void notifyNextFrame() {
    long newTime;
    long frameTime;

    newTime =  System.currentTimeMillis();
    frameTime = newTime - mCurrentTime;
    mCurrentTime = newTime;

    if(frameTime > 250)
        frameTime = 250;

    mAccumulator += frameTime;

    // while full steps of simulation steps can be simulated
    while(mAccumulator >= mSimulationDelta) {
        mSimulation.simulate(mSimulationDelta);
        mAccumulator -= mSimulationDelta;
    }

    // render
    mRenderer.render(frameTime / 1000.0f); // frameTime in seconds
}

public interface Simulation
{
    void simulate(float delta);
}

public interface Renderer
{
    void render(float delta);
}
}

我真的不是游戏开发方面的专家,但我希望我理解本文的基础知识..simulate经常被调用以具有固定的时间步长.问题是复杂系统中的动画仍然不顺畅.我的程序中的FPS大约是60FPS.

测试应用程序是用java for android编写的:

    public float x = 40;
public float y = 40;
public float xmove = 0.1f;
public float ymove = 0.05f;

public void simulate(float delta) {
    x += xmove * delta;
    y += ymove * delta;

    if(xmove > 0)
    {
        if(x > 480)
            xmove = -xmove;
    }
    else if(xmove < 0)
    {
        if(x < 0)
            xmove = -xmove;
    }

    if(ymove > 0)
    {
        if(y > 480)
            ymove = -ymove;
    }
    else
    {
        if(y < 0)
            ymove = -ymove;
    }

    RandomSleep(8);
}

Random rnd = new Random();

public void doDraw(Canvas canvas, float delta) {
    Paint paint = new Paint();

    paint.setColor(Color.BLACK);
    paint.setStyle(Paint.Style.FILL);
    paint.setTextSize(30);

    canvas.drawColor(Color.BLUE);
    canvas.drawCircle(x, y, 10, paint);
    canvas.drawText("" + FPSConverter.getFPSFromSeconds(delta), 40, 40, paint);

    RandomSleep(5);
}

public void RandomSleep(int maxMS)
{
    try {
        Thread.sleep((int)(rnd.nextDouble()*maxMS));
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

随机睡眠总和将是最大值.13毫秒.这似乎是极端的,但对于给定的系统,你不应该感觉到差异.(我试图模拟我的游戏系统,找出为什么我的实际游戏引擎中的动画不顺畅;所以我使用的是最糟糕的情况)

编辑:如果没有直接答案,也许有人可以指出我如何找出"错误"的位置.我能做些什么来分析这些事情是否正确？

Answer 1

所以,最后!两周后,我找到了一个简单的解决方案!问题是我使用System.currentTimeMillis(); 看起来这个计时器的分辨率不够高,无法做到流畅的动画.我重写了计时器类,现在它完美无缺.对于任何人如何有类似的问题,并希望使用我的代码:

public class TimeSystem
{
private long mOldTime;
private long mAccumulator;
private long mNewTime;
private long mFrameTime;

private Simulation mSimulation;
private Renderer mRenderer;

private static final long mSimulationDelta = 1000 * 1000 / 10;
private static final float mSimulationDeltaInMilliseconds = mSimulationDelta / 1000;
private static final long mMaxFrameTime = mSimulationDelta;


public TimeSystem(Simulation simulation, Renderer renderer)
{
    mSimulation = simulation;
    mRenderer = renderer;

    mAccumulator = 0;
    mOldTime = System.nanoTime();
}

public void notifyNextFrame()
{
    mNewTime = System.nanoTime();
    mFrameTime = mNewTime - mOldTime;
    mOldTime = mNewTime;

    // if FPS is to slow don't produce even more CPU usage
    if (mFrameTime > mMaxFrameTime)
        mFrameTime = mMaxFrameTime;

    mAccumulator += mFrameTime;

    // while full steps of simulation steps can be simulated
    while (mAccumulator >= mSimulationDelta)
    {
        mSimulation.simulate(mSimulationDeltaInMilliseconds);
        mAccumulator -= mSimulationDelta;
    }

    // render
    mRenderer.render(mFrameTime / 1000f*1000f);
}

public interface Simulation
{
    void simulate(float delta);
}

public interface Renderer
{
    void render(float delta);
}
}

如果你喜欢,我可以随意投票:)谢谢.