android游戏开发二——圆的碰撞

碰撞是个很重要的内容，我这先简单介绍一下。

 

 

CircleActivity代码；

 

package yy.circle;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

public class CircleActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(new Circle(this));
    }

}

 

 

Circle代码；

 

package yy.circle;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;

public class Circle extends SurfaceView implements Callback,Runnable {
        private SurfaceHolder sfh;
        private Paint paint;
        private Thread thread;
        private boolean flag;
        private Canvas canvas;
        private int screenW,screenH;
        //private Bitmap bmp;
        private int x1=20,y1=20,r1=20;
        private int x2=50,y2=50,r2=20;
        private boolean isCollsion;
        private PaintFlagsDrawFilter pfd=new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);
    public Circle(Context context){
         super(context);
         sfh=this.getHolder();
         sfh.addCallback(this);
         paint=new Paint();
         paint.setColor(Color.WHITE);
         paint.setAntiAlias(true);
         //bmp=BitmapFactory.decodeResource(this.getResources(), R.drawable.icon);
         setFocusable(true);
        }
    public void surfaceCreated(SurfaceHolder holder){
     screenW=this.getWidth();
     screenH=this.getHeight();
     flag=true;
     thread=new Thread(this);
     thread.start();
    }
    public void myDraw(){
     try{
      canvas=sfh.lockCanvas();
      if(canvas!=null){
      canvas.setDrawFilter(pfd); 
      canvas.drawColor(Color.BLACK);
      if(isCollsion){
       paint.setColor(Color.RED);
       paint.setTextSize(20);
       canvas.drawText("Collision!",0,30,paint);
      }
      else{paint.setColor(Color.WHITE);}
      
      canvas.drawCircle(x1, y1 , r1, paint);
      canvas.drawCircle(x2, y2, r2, paint);
      //canvas.drawBitmap(bmp, 100, 100, paint);
      }
     }catch(Exception e){}
     finally{
      if(canvas!=null){
       sfh.unlockCanvasAndPost(canvas);
      }
     }
    }
    public boolean onTouchEvent(MotionEvent event){
     x1=(int)event.getX()-r1;
     y1=(int)event.getY()-r1;
     if(isCollsionWithCircle(x1,y1,r1,x2,y2,r2)){
      isCollsion=true;
     }else{
      isCollsion=false;
     }
     return true;
    }
    private boolean isCollsionWithCircle(int x1, int y1, int r1, int x2,
   int y2, int r2) {
  /*if(x1>=x2&&x1>=x2+r2+r1){
   return false;
  }
  else if(x1<=x2&&x1+r1+r2<=x2){
   return false;
  }
  else if(y1>=y2&&y1>=y2+r2+r1){
   return false;
  }
  else if(y1<=y2&&y1+r1+r2<=y2){
   return false;
  }*/
     if((r1+r2)*(r1+r2)<=(x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)){
      return false;
     }
     
  return true;
 }
 public boolean onKeyDown(int keyCode,KeyEvent event){
     return super.onKeyDown(keyCode, event);
    }
    public void logic(){}
    public void run(){
     while(flag){
      long start=System.currentTimeMillis();
      myDraw();
      logic();
      long end=System.currentTimeMillis();
      try{
       if(end-start<50){
        Thread.sleep(50-(end-start));
       }
      }catch (InterruptedException e) {
    e.printStackTrace();
   }
     }
    }
    public void surfaceChanged(SurfaceHolder holder,int format,int width,int height){}
    public void surfaceDestroyed(SurfaceHolder holder){
     flag=false;
    }
}