Sort+sweep detection: FINALLY

Okay, so I'm super happy that I've gotten the sort/sweep implementation more or less working for my collision detection. It took me a good long while, but it's working now, and the performance increase is noticeable.

My previous collision detection did the following:
Make a list of everything.
Go through each item on the list.
Test it for collisions with everything.

It's very easy to do and very inefficient. The new algorithm does the following:
Make a list of everything.
Make a new list of the beginning and ending positions on the X axis of each item and sort this list by these X positions.
Go through each item on the list.
Test it for collisions with any objects whose X position is between the start and end positions of this object in the second list.

That's a poor way of putting it. Here's a much better explanation. It even has pictures.

So anyway, it turns a really simple but time consuming problem into a somewhat complicated but much faster problem. I still haven't addressed the major issue for XBox, the mid-game creation of objects, and that will be one of my next major goals. Nevertheless, on my laptop it can go up to 1024 sprites (the most I'm supported at the current time) with virtually no hits to the performance. The video posted is a good deal slower due to the screenshot software.

Also, I don't think I've posted a video since I've made a few changes to the interface. I changed the screen size to 720p, so it's a big taller and a lot longer. I've moved things around a little to account for overscan on my HDTV. Finally, I've made the lives and the score displays a good deal bigger. I think it looks pretty.

Video: Extincathon sort sweep collision detection