physics simulation

[wysota]

You have to calculate everything manually yourself. You can use QLineF and QPointF to calculate intersections but the rest requires pure math skills. That's one of the reasons I'm suggesting GraphicsView.

[john_god]

I did a program like that where points would move inside a rectangle, like balls in a pool table. If I correctly understood, you have user draw lines with different angles than the horizontal and vertical lines of the rectangle. It´s all math like Wysota said, but if you think it can help you, I can try to find my code and show you, but it's old and made in MFC6 with opengl.