Android collision detection - Round check

 

round checks ideas: two from the center of the circle is smaller than the radius of the two circles and then collide , and vice versa , no collisions

 

  

    /** 
     * 两个圆的碰撞检测 
     * @param x1 
     * @param y1 
     * @param r1 
     * @param x2 
     * @param y2 
     * @param r2 
     * @return 
     */ 
    public static boolean CheckCollideCircle(int x1, int y1, int r1, int x2, 
            int y2, int r2) { 
        boolean iscollide=false; 
        //两点之间的距离 小于两半径之和就发生了碰撞 
        if(Math.sqrt(Math.pow(x1-x2,2)+Math.pow(y1-y2, 2))<=r1+r2){ 
            iscollide=true; 
        } 
        return iscollide; 
    }

 

 

Liezi below with a full description

 

  

public class CircleSurfaceView extends SurfaceView implements Callback,Runnable { 
    int x1=70,y1=110,r1=40; 
    int x2=220,y2=110,r2=40; 
    boolean isCollide=false;//是否发生碰撞 
    SurfaceHolder surfaceHolder; 
    Paint paint; 
    boolean flag=false; 
    int sleeptime=100; 
    Thread thread; 
    public CircleSurfaceView(Context context) { 
        super(context); 
        surfaceHolder=getHolder(); 
        surfaceHolder.addCallback(this); 
        paint=new Paint(); 
        paint.setTextSize(12); 
        thread=new Thread(this); 
        flag=true; 
    } 
     
    public void draw(Canvas canvas) { 
        canvas.drawColor(Color.BLACK); 
        if(isCollide){ 
            paint.setColor(Color.RED); 
            canvas.drawText("Collide", 0, 30, paint); 
        } 
        else { 
            paint.setColor(Color.WHITE); 
            canvas.drawText("Not Collide", 0, 30, paint); 
        } 
        canvas.drawCircle(x1, y1, r1, paint); 
        canvas.drawCircle(x2, y2, r2,paint); 
    } 
    /** 
     * 触屏点击事件 
     */ 
    @Override 
    public boolean onTouchEvent(MotionEvent event){ 
        x1=(int)event.getX()-r1/2; //圆心坐标 
        if(CheckCollide.CheckCollideCircle(x1, y1, r1, x2, y2, r2)){//检查碰撞的方法 
            isCollide=true; 
        } 
        else { 
            isCollide=false; 
        } 
        return true; 
    } 
 
     
    @Override 
    public void surfaceCreated(SurfaceHolder holder) { 
        // TODO Auto-generated method stub 
        if(!thread.isAlive()){ 
            thread.start(); 
        } 
    } 
 
    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) { 
        // TODO Auto-generated method stub 
        flag=false; 
        thread=null; 
    } 
    @SuppressLint("WrongCall") 
    @Override 
    public void run() { 
        // TODO Auto-generated method stub 
        Canvas canvas=null; 
        while (flag) { 
            try { 
                canvas=surfaceHolder.lockCanvas(); 
                synchronized (canvas) { 
                    draw(canvas);     
                } 
            } catch (Exception e) { 
                Log.e("Collide", e.getMessage()); 
            }finally{ 
                if(canvas!=null){ 
                    surfaceHolder.unlockCanvasAndPost(canvas); 
                } 
            } 
            try { 
                Thread.sleep(sleeptime); 
            } catch (Exception e) { 
                Log.e("Collide", e.getMessage()); 
            } 
        } 
    } 
 
    @Override 
    public void surfaceChanged(SurfaceHolder holder, int format, int width, 
            int height) { 
        // TODO Auto-generated method stub 
         
    } 
 
}