Android游戏开发：物理游戏之重力系统开发--圆形自由落体Demo

    本节为大家提供有关物理游戏的知识，讲解了一个简单的圆形自由落体Demo的编写。。

Java代码

package com.himi;   

import java.util.Random;   

import java.util.Vector;   

import android.content.Context;   

import android.graphics.Canvas;   

import android.graphics.Color;   

import android.graphics.Paint;   

import android.util.Log;   

import android.view.KeyEvent;   

import android.view.SurfaceHolder;   

import android.view.SurfaceView;   

import android.view.SurfaceHolder.Callback;   

public class MySurfaceViee extends SurfaceView implements Callback, Runnable {   

    private Thread th;   

    private SurfaceHolder sfh;   

    private Canvas canvas;   

    private Paint paint;   

    private boolean flag;   

    public static int screenW, screenH;   

    private Vector<MyArc> vc;//这里定义装我们自定义圆形的容器   

    private Random ran;//随即库   

    public MySurfaceViee(Context context) {   

        super(context);   

        this.setKeepScreenOn(true);   

        vc = new Vector<MyArc>();   

        ran = new Random();//备注1   

        sfh = this.getHolder();   

        sfh.addCallback(this);   

        paint = new Paint();   

        paint.setAntiAlias(true);   

        setFocusable(true);   

    }   

    public void surfaceCreated(SurfaceHolder holder) {   

        flag = true;//这里都是上一篇刚讲过的。。。   

        th = new Thread(this);   

        screenW = this.getWidth();   

        screenH = this.getHeight();   

        th.start();   

    }   

    public void draw() {   

        try {   

            canvas = sfh.lockCanvas();   

            canvas.drawColor(Color.BLACK);   

            if (vc != null) {//当容器不为空，遍历容器中所有圆形画方法   

                for (int i = 0; i < vc.size(); i++) {   

                    vc.elementAt(i).drawMyArc(canvas, paint);   

                }   

            }   

        } catch (Exception e) {   

            // TODO: handle exception   

        } finally {   

            try {   

                if (canvas != null)   

                    sfh.unlockCanvasAndPost(canvas);   

            } catch (Exception e2) {   

            }   

        }   

    }   

    private void logic() {//主逻辑   

        if (vc != null) {//当容器不为空，遍历容器中所有圆形逻辑   

            for (int i = 0; i < vc.size(); i++) {   

                vc.elementAt(i).logic();   

            }   

        }   

    }   

    @Override  

    public boolean onKeyDown(int keyCode, KeyEvent event) {   

        //当按键事件响应，我们往容器中仍个我们的圆形实例   

        vc.addElement(new MyArc(ran.nextInt(this.getWidth()), ran.nextInt(100), ran.nextInt(50)));   

        return true;   

    }   

    public void run() {   

        // TODO Auto-generated method stub   

        while (flag) {   

            logic();   

            draw();   

            try {   

                Thread.sleep(100);   

            } catch (Exception ex) {   

            }   

        }   

    }   

    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {   

        Log.v("Himi", "surfaceChanged");   

    }   

    public void surfaceDestroyed(SurfaceHolder holder) {   

        flag = false;   

    }   

}  

       OK，代码都很简单，也很清晰！ 稍微说一句：像MyArc里面也有类似MysurfaceView中一样的方法 logic() 以及draw()，这样能更好的管理我们的代码结构，思路清晰，各尽其责，避免混乱。