[Interest] best qt class to use to detect line/polygon/region collision

[maitai]

Hello all,

I have a list of lines (QLineF) in 2D space. Some might represent a 
closed polygon, some others are just a line or represent a non closed 
polygon. Classical problem: I need to detect if another given line is 
crossing one of the lines in the list. I don't need the crossing point, 
just to know if it crosses or not.

For the time being, I just iterate on the list and use 
QLineF::intersects(). This is of course badly slow.

I read that post (and many others): 
http://stackoverflow.com/questions/9393672/intersection-point-of-qpainterpath-and-line-find-qpainterpath-y-by-x

Using a QPainterPath seems the right idea, but as it seems it does not 
work with a single line, so maybe I should convert the line in a tiny 
rectangle to be able to use QPainterPath::intersects(). Will that be 
faster?

Before I try that, I was wondering if someone has a better idea as of 
what class to use in qt to solve this? Calculation speed is the most 
important thing in my case.

Thanks for pointing me in the right direction
Philippe Lelong