Trouble with SAT style vector projection in C#/XNA
- by ssb
Simply put I'm having a hard time working out how to work with XNA's Vector2 types while maintaining spatial considerations. I'm working with separating axis theorem and trying to project vectors onto an arbitrary axis to check if those projections overlap, but the severe lack of XNA-specific help online combined with pseudo code everywhere that omits key parts of the algorithm, googling has left me little help.
I'm aware of HOW to project a vector, but the way that I know of doing it involves the two vectors starting from the same point. Particularly here:
http://www.metanetsoftware.com/technique/tutorialA.html
So let's say I have a simple rectangle, and I store each of its corners in a list of Vector2s. How would I go about projecting that onto an arbitrary axis? The crux of my problem is that taking the dot product of say, a vector2 of (1, 0) and a vector2 of (50, 50) won't get me the dot product I'm looking for.. or will it? Because that (50, 50) won't be the vector of the polygon's vertex but from whatever XNA calculates. It's getting the calculation from the right starting point that's throwing me off.
I'm sorry if this is unclear, but my brain is fried from trying to think about this. I need a better understanding of how XNA calculates Vector2s as actual vectors and not just as random points.
