title: Cocos2d and iOS: Can't understand use of control points using ccBezierConfig
body: <p>EDIT: If the question is badly written have a look at the video (<a href="http://youtu.be/IQ_Jf0O0KGc" rel="nofollow">3</a>), same link as in the bottom of this page. </p>
  
  <p>I am trying to draw a very simple bezier curve using <strong>ccBezierConfig</strong> and Cocos2D. Reading on Wikipedia I tried to understand a bit controls points and found this image:</p>
  
  <p><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Bezier_2_big.png/240px-Bezier_2_big.png" rel="nofollow">http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Bezier_2_big.png/240px-Bezier_2_big.png</a></p>
  
  <p>If you look on the wikipedia page from which I took the image there is a cool animation. Have a look <a href="http://en.wikipedia.org/wiki/Bezier_curve" rel="nofollow">here</a>.</p>
  
  <p>This is the code I used:</p>
  
  <pre><code>        CCSprite *r = [CCSprite spriteWithFile:@"hi.png"];
          r.anchorPoint = CGPointMake(0.5f, 0.5f);
          r.position = CGPointMake(0.0f, 200.0f);
  
          ccBezierConfig bezier;
          bezier.controlPoint_1 = CGPointMake(0.0f, 200.0f);
          bezier.controlPoint_1 = CGPointMake(180.0f, 330.0f);
          bezier.endPosition = CGPointMake(320.0f,200.0f);
  
          id bezierForward = [CCBezierBy actionWithDuration:1 bezier:bezier];
          [r runAction:bezierForward];
          [self addChild:r z:0 tag:77];
  </code></pre>
  
  <p>The app runs on Portrait mode and my speculation matching the control points of <a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Bezier_2_big.png/240px-Bezier_2_big.png" rel="nofollow">1</a> and the ones in my code was that:</p>
  
  <pre><code>sprite.position should correspond to P0
  bezier.controlPoint_1 should correspond to P0 
  bezier.controlPoint_2 should correspond to P1
  bezier.endPosition  should correspond to P2
  </code></pre>
  
  <p>I did try two approaches. By setting the position of the sprite and by not setting it.</p>
  
  <p>I assumed that position should be the same as controlPoint_1 as in the wikipedia schema <a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Bezier_2_big.png/240px-Bezier_2_big.png" rel="nofollow">1</a> there are only three points.  </p>
  
  <p><strong>I get an output I don't quiet understand.. I made a little video of it, is a private youtube video:</strong></p>
  
  <p><strong><a href="http://youtu.be/IQ_Jf0O0KGc" rel="nofollow">to see the video click here</a></strong></p>