# Extend surface towards a loft

Hi all,

I have a quick and maybe an stupid question, but I’m just stock on this definition.
I’m trying to draw a simple ‘V’ shape support behind a bridge deck. The ‘V’ is an ellipse section than runs through a V shaped polyline formed by three points, two on the underside of the deck and one in the middle, at a lower level. In order to control the section of the support, I’ve oriented the plane of the section with the perpendicular frames of the rail.

I have two problems. One is that it fails to connect the surface in the middle point. Two, and more important, I cannot link it to the deck as the surface does not touch it in some areas. Is there any simple way to do this? If I extrude the support surfface towards the deck until it hits it and then get the intersection curve, I cannot manage to get a soft loft afterwards if I use it with the others.

I’ll appreciate if someone can bring some light to this matter, as it is stopping me to finish the whole task.

VShape.gh (21.3 KB)

It may be a “simple” question for you but in fact, a proper answer is rather complex and requires considerable effort. It is evident from examining your model that there are quite a few possible suggestions for improving it… So many, in fact, that I don’t even know where to begin. Really, answering this isn’t simple at all. This code will have to speak for itself (white group).

VShape_2018Apr8a.gh (23.5 KB)

Please avoid the word “simple” unless it’s simple for you!

Hi @Joseph_Oster, thanks a lot for you time. You are right, ‘simple’ is not the right word, sorry about that. I just meant that is something that would be sorted relatively quick if you are more experienced than myself, as I am at a very beginner level at this moment.

This option looks good to me for the task I am currently doing, but it works just within a certain range. When I increase the span of the bridge, the extended polyline becomes too short that the diagonal supports doesn’t pierce the deck. So the intersection doesn’t happens at 100% unless I manually extend the curve again, which is not very practical.

I’ll keep trying to work it out. I’m always open to new suggestions. I will post it if I manage to complete it

thanks again!

Yeah, that’s what I meant. To make this fully parametric, the algorithm/model needs to be modified more substantially, such that the points used to define the support structure move when the bridge is scaled. That’s the core “trick” of GH and it doesn’t happen automagically, it has to be designed so parts stay connected. Have fun.