For a 2D Unity Project, I needed a really efficient way to get the intersection points between a line segment (as defined by two Vector2) and an axis-aligned Rect in 2D space, where the intersection points are returned as a parametric fraction of the length of the original line segment:
Note how when the line intersects the rect, the green line represents the portion inside the rect, and the parametric representation of the point of intersection along the line is displayed
In my use case the vast majority of lines are either completely inside or completely outside the rect, and so I needed an approach that was very efficient in cases where there is guaranteed no intersection and avoids unecessary raycasts when possible.