2D colision with vector map
I'm *trying* to develop a game (2D top view, - I guess details about the actual game are fairly unimportant at the moment so i'll skip that bit) and I want to have colision detection between my vehicles (for example a hovercraft and a tank) which shouldn't be too hard, depending on how I do it, most probably their colisions would be based on circles around them, based on "pool-table" style collisons.
Ok i'll stop raving and get to the point:
I want to have a vector-based map (ie. either using GDI regions or a more useful polygon library that one of you can suggest?) and I need to be able to find what line I would have crossed by moving from one point *ouside* the region to a point *inside* the region, and thus be able to find its normal and what angle I should be bouncing off at etc... BUT preferably I would like to be able to do even more - i'd like to be able to check it against a circular region around each player (not vital... i'm sure I *could* live without that kind of collision on the terrain)
Can anyone point me on the right track or give me any suggestions? First person to answer my question gets a million bucks.
No money will be receieved as a result of helping me. "Million bucks" is merely a figure of speech, actually referring to a "million bucks" worth of my gratitude ;-)