title: How does DirectX determine winding order?
body: <p>How does DirectX determine polygon winding orders? I'm curious in particular about backface culling. From researching this I have seen it suggested that DX calculates a surface normal and takes the dot product of that and the camera vector, and culls if that is > 0. </p>
  
  <p>Firstly, is this the technique that DirectX actually employs? Secondly, if this is the case, given that there two normals to every surface - one opposed to the other - how does DirectX know which normal to use? </p>