《Beginning Android(安卓)Games》Chapter3给出的基本框架

一个游戏的基础框架大致分为这几个部分：

1 Window management

2 Input

3 File I/O

4 Graphics

5 Audio

6 Game framework

之后书中给出了具体每一部分接口的定义，如下：

Input接口

public interface Input {public static class KeyEvent{public static final int KEY_DOWN=0;public static final int KEY_UP=1;public int type;public int keyCode;public char keyChar;}public static class TouchEvent{public static final int TOUCH_DOWN=0;public static final int TOUCH_UP=1;public static final int TOUCH_DRAGGED=2;public int type;public int x,y;public int pointer;}public boolean isKeyPressed(int keyCode);public boolean isTouchDown(int pointer);public int getTouchX(int pointer);public int getTouchY(int pointer);public float getAccelX();public float getAccelY();public float getAccelZ();public List<KeyEvent> getKeyEvents();public List<TouchEvent> getTouchEvents();}

FileIO接口

public interface FileIO {public InputStream readAsset(String fileName) throws IOException;public InputStream readFile(String fileName) throws IOException;public OutputStream writeFile(String fileName) throws IOException;}

Audio接口其中还包含了Music和Sound的接口定义

public interface Audio {public Music newMusic(String filename);public Sound newSound(String filename);}

public interface Music {public void play();public void stop();public void pause();public void setLooping(boolean looping);public void setVolume(float volume);public boolean isPlaying();public boolean isStopped();public boolean isLooping();public void dispose();}

public interface Sound {public void play(float volume);public void dispose();}

Graphics接口的定义包括Pixmap

public interface Graphics {public static enum PixmapFormat {ARGB8888, ARGB84444, RGB565}public Pixmap newPixmap(String fileName, PixmapFormat format);public void clear(int color);public void drawPixel(int x, int y, int color);public void drawLine(int x, int y, int x2, int y2, int color);public void drawRect(int x, int y, int width, int height, int color);public void drawPixmap(Pixmap pixmap, int x, int y, int srcX, int srcY,int srcWidth, int srcHeight);public void drawPixmap(Pixmap pixmap,int x,int y);public int getWidth();public int getHeight();}

public interface Pixmap {public int getWidth();public PixmapFormat getFormat();public void dispose();}

最后是Game接口的定义以及抽象类Screen

public interface Game {public Input getInput();public FileIO getFileIO();public Graphics getGraphics();public Audio getAudio();public void setScreen(Screen screen);public Screen getCurrentScreen();public Screen getStartScreen();}

public abstract class Screen {protected final Game game;public Screen(Game game){this.game=game;}//更新状态public abstract void update(float deltaTime);//刷新画面public abstract void present(float deltaTime);public abstract void pause();public abstract void resume();public abstract void dispose();}

以上就基本实现了最简单的框架觉得还是比较清晰的所以照搬记录一下

最后Chapter3还提到了Frame Rate–Independent Movement 也就是固定帧数的问题

例如若每次循环移动1个像素点在60FPS的情况下 1秒就移动了60个像素而30FPS则移动了30个像素这样移动的速度相当于提升了2倍作者给出的解决方案是根据deltaTime 计算应该移动的实际距离也就是从x+=1 改成x+=30*deltaTime 30是希望的每秒移动像素值

————————————题外话——————————

再想到之前看到的一个介绍游戏基本是一个循环：更新状态——重新绘制——休眠——更新状态

而其中的休眠时间并不是一个固定值而是动态计算的休眠长度=理想值-处理用去的时间其实也跟上面的思路类似

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