Frame independent movement.

[BobbyMcWho]

Hey @zenspider ,

I attended your talk at rubyconf, and asked the question about time based rendering since you had mentioned having to turn on vsync to slow the animations to a point that they didn't just zip off the screen. I don't know much about SDL or the strategies used to implement time based rendering, but I wanted to open the discussion here. Here's a tutorial that I came across in a brief search, that seems to implement frame independent movement.

http://lazyfoo.net/tutorials/SDL/44_frame_independent_movement/index.php