MonoGame笔记(九)其他几个时间相关程序设计

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这里介绍其他几个和时间相关的程序设计: 1. 调整单个动画的速度 2.显示帧率(FPS) 3.定时器

调整单个动画的速度

调整游戏本身的帧率可以影响动画的速度, 但这样的影响是全局的. 不同动画之间的速度是不一样的, 所以需要单个调节. 以下是Learn XNA 4.0中的相关代码:

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int timeSinceLastFrame = 0; //自上一帧之后经过了多少时间。
int millisecondsPerFrame = 50 //动画播放的帧率
timeSinceLastFrame += gameTime.ElapsedGameTime.Milliseconds; 
if (timeSinceLastFrame > millisecondsPerFrame) 
{ 
    timeSinceLastFrame-= millisecondsPerFrame; 
    ++currentFrame.X; 
    if (currentFrame.X >= sheetSize.X) //spritesheet
    { 
        currentFrame.X = 0; 
        ++currentFrame.Y; 
        if (currentFrame.Y >= sheetSize.Y) 
            currentFrame.Y = 0; 
    } 
}

显示帧率FPS

来自上一篇笔记中提到作者的文章Displaying the framerate https://blogs.msdn.microsoft.com/shawnhar/2007/06/08/displaying-the-framerate/
技巧和调整单个动画的速度一样, 这里作者使用1秒钟Draw调用的次数来作为帧率

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public class FrameRateCounter : DrawableGameComponent
{
    ContentManager content;
    SpriteBatch spriteBatch;
    SpriteFont spriteFont;

    int frameRate = 0;
    int frameCounter = 0;
    TimeSpan elapsedTime = TimeSpan.Zero;


    public FrameRateCounter(Game game): base(game)
    {
        content = new ContentManager(game.Services);
    }

    protected override void LoadGraphicsContent(bool loadAllContent)
    {
        if (loadAllContent)
        {
            spriteBatch = new SpriteBatch(GraphicsDevice);
            spriteFont = content.Load<SpriteFont>("Font");
        }
    }

    protected override void UnloadGraphicsContent(bool unloadAllContent)
    {
        if (unloadAllContent)
            content.Unload();
    }


    public override void Update(GameTime gameTime)
    {
        elapsedTime += gameTime.ElapsedGameTime;

        if (elapsedTime > TimeSpan.FromSeconds(1))//elapsedTime大于1秒
        {
            elapsedTime -= TimeSpan.FromSeconds(1);
            frameRate = frameCounter;
            frameCounter = 0;
        }
    }

    public override void Draw(GameTime gameTime)
    {
        frameCounter++;

        string fps = string.Format("fps: {0}", frameRate);

        spriteBatch.Begin();

        spriteBatch.DrawString(spriteFont, fps, new Vector2(33, 33), Color.Black);
        spriteBatch.DrawString(spriteFont, fps, new Vector2(32, 32), Color.White);
        
        spriteBatch.End();
    }
}

使用方式:在Game的构造方法中加入下面一行, 关于Component和SpriteFont见以后的笔记
Components.Add(new FrameRateCounter(this));

作者还使用了SpriteFont来显示:

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<?xml version="1.0" encoding="utf-8"?>
<XnaContent xmlns:Graphics="Microsoft.Xna.Framework.Content.Pipeline.Graphics">
  <Asset Type="Graphics:FontDescription">
   <FontName>Arial</FontName>
   <Size>14</Size>
   <Spacing>2</Spacing>
   <Style>Regular</Style>
   <CharacterRegions>
     <CharacterRegion><Start>f</Start><End>f</End></CharacterRegion>
     <CharacterRegion><Start>p</Start><End>p</End></CharacterRegion>
     <CharacterRegion><Start>s</Start><End>s</End></CharacterRegion>
     <CharacterRegion><Start>:</Start><End>:</End></CharacterRegion>
     <CharacterRegion><Start> </Start><End> </End></CharacterRegion>
     <CharacterRegion><Start>0</Start><End>9</End></CharacterRegion>
   </CharacterRegions>
  </Asset>
</XnaContent>

定时器

https://www.gamedev.net/forums/topic/473544-how-to-make-a-timer-using-xna/

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public class TimerComponent : GameComponent
{
    TimeSpan interval = new TimeSpan(0, 0, 1);
    TimeSpan lastTick = new TimeSpan();

    public event EventHandler Tick;

    public TimeSpan Interval
    {
        get { return interval; }
        set { interval = value; }
    }

    public TimerComponent(Game game)
        : base(game)
    {
    }

    public override void Update(GameTime gameTime)
    {
        if (gameTime.TotalGameTime - lastTick >= interval)
        {
            if (Tick != null)
                Tick(this, null);

            lastTick = gameTime.TotalGameTime;
        }
    }
}

或者可以试下.NET自带的Timer