   3D Math beginner & oliii's collision tutorials
  I'm really a beginner in terms of 3D mathematics but today I started reading oliii's collision tutorials. I'm stuck right at the begining at the axis separation algorithm. I understand the basic idea but I don't seem to understand how do you project a polygon onto the a normal and how the intervals are calculated. As far as I know projecting vectors onto other vectors returns quantities and has nothing to do with intervals. How are the intervals calculated?   
  What you refer to as a 'quantity' from projecting a vector onto another is actually a length. Perhaps your textbook refers to it as a 'scalar quantity'? That would be accurate, but not complete; it's also a length along the vector you're projecting onto. (That is, 'go length x along vector y'). So, without having read oliii's tutorial, it seems to me likely that your quantities and intervals are the same thing.   