Signed distance fields are like vtables. You can invert the cross product and you can introspect information that is otherwise not observable. That is you call

Signed distance fields are like vtables. You can invert the cross product and you can introspect information that is otherwise not observable. That is you call a method in user space and it is dispatched to the origin. It is a monad or more specifically an applicative over the geometric inversion. Instead of selecting the segment with the mouse you perform a bind over the generative original data. Thus the projection in the limit provides the functor towards the flat space in which exists the segment that requires selection. You are right. Vtables are not enough but with the borrow checking rust provides you no longer need to track the ownership of the space vectors of the transitive solution. It's pretty complex stuff as a library writer to formulate but once encoded it is not much harder to use than a CSS selector. If you spend a few minutes thinking about it anybody could code it up I'm sure.