title: XNA 2D vector angles - what's the correct way to calculate?
body: <p>what is in XNA in 2D the standard way vector angles work ?</p>
  
  <p>0 degrees points right, 90 points up, 180 left, 270 down ?</p>
  
  <p>What are the 'standard' implementations of </p>
  
  <pre><code>float VectortoAngle(Vector2 vec)
  </code></pre>
  
  <p>and</p>
  
  <pre><code>Vector2 AngleToVector(float angle)
  </code></pre>
  
  <p>so that VectortoAngle(AngleToVector(PI)) == PI ?</p>