title: expand a testPoint area in cocos2d when detecting a touch
body: <p>i have many sprites in my game,which all have bodies in a b2world. and in order to detect a touch i do the next:</p>
  
  <pre><code>currentPosition = [[CCDirector sharedDirector] convertToGL: currentPosition];    
      b2Vec2 locationWorld = b2Vec2(currentPosition.x/PTM_RATIO, currentPosition.y/PTM_RATIO);
  
      for (b2Body* b = world-&gt;GetBodyList(); b; b = b-&gt;GetNext()) 
      {
          b2Fixture *bf1 = b-&gt;GetFixtureList();
          if (bf1-&gt;TestPoint(locationWorld) )
          {
              CCSprite *tempSprite = (CCSprite *) b-&gt;GetUserData();
              if (tempSprite.tag==2    ) 
              {
  </code></pre>
  
  <p>now , because my sprite's body is too small,and he is moving, it is very hard to touch it while it moves, so i need to change this code, in order to detect a <strong>wide area</strong> around this sprite also.
  how do i expand the testpoint to be +- more 50pixels ??</p>
  
  <p>thanks a lot.</p>