- dot_product = (l1.endPointData().x() - l1.startPointData().x()) * \
- (l2.endPointData().x() - l2.startPointData().x()) + \
- (l1.endPointData().y() - l1.startPointData().y()) * \
- (l2.endPointData().y() - l2.startPointData().y())
+ dot_product = (l1.endPoint().x() - l1.startPoint().x()) * \
+ (l2.endPoint().x() - l2.startPoint().x()) + \
+ (l1.endPoint().y() - l1.startPoint().y()) * \
+ (l2.endPoint().y() - l2.startPoint().y())