title: How does coordinate system handedness relate to rotation direction and vertices ordering?
body: <p>While trying to understand different coordinate systems I came across <a href="http://www.evl.uic.edu/ralph/508S98/coordinates.html" rel="noreferrer">this website</a>, which states:
  RenderMan uses <code>left-handed coordinate system</code> and the positive rotation is <code>clockwise</code>, while OpenGL uses <code>right-handed coordinate system</code> and the positive rotation is <code>counter-clockwise</code>.</p>
  
  <p>My question is whether the rotation direction and the coordinate system handedness are just two distinct conventions or this results from maths itself ?</p>
  
  <p>Similarly, I know that the front facing vertices of triangles have to be ordered in <code>counter-clokwise</code> direction in OpenGL. Does this too relate to coordinate system handedness or it's just another unrelated convention ? </p>
  
  <p>And thirdly, when a picture of random coordinate system with axes labeled as <code>x, y, z</code> is thrown before me, how do I tell which one is left handed and which one is right handed ?
  I know there is a rule with right hand and the middle and the index fingers and the thumb, but everyone seems to use it differently. How should I align my fingers with these axes ?</p>
  
  <p>Sorry for probably mixing a lot of unrelated stuff together, but after reading all kinds of internet sources, things start to blend together in my head.</p>