how do i know if two lines intersect?

[Vincenzo]

I checked member functions of QLine, but there is no function/solution to this problem. I have two lines and if this two lines intersect than i want for return bool value - is it possible some easy way?!

[wysota]

You'll have to do proper math calculations using the y=ax+b formula.

[jacek]

You could use QPainterPath::intersects(), but that's probably an overkill.

[Ginsengelf]

Hi, if you use 2D, two lines will intersect somewhere, if the "a" in wysota's formula is different for both lines, otherwise they are parallel. In 3D it's a different thing...

Ginsengelf

[Vincenzo]

...I thought there is some function in Qt...
But I did it with math calculation like you told me, and now it works... :)