do you even loft bro?

Entree

Lofting is really an evolution of older massing routines that used to be commonplace within Revit before the advent of exclusive massing and massing (adaptive, curtain panel etc) component files – namely sweep, blend, and swept blend. Now however, these functions are relegated to the component section of Revit project files, and are not strictly massing tools, but more family creators in-project. There, history lesson done.

So let’s talk about lofting as a more specific act of creating a mass. The principle is simple: draw two or more profiles at a relative distance, and then connect them via an extruded mass that ‘blends’ one profile to the next. Simple enough? Good.

So what happens when you want more complex profiles? Well, in short, your hurdles and sensitivity to failure increase exponentially, exacerbated by any large variables in your lofting profiles. Let’s discuss.

 

The Meat

I’m going to really give two examples here;

The first is creating a loft along a reference line, to which you can ‘host’ profiles and then create your mass along that path. It can be thought of as a complex ‘swept-blend’ – except that you’re using more than two profiles, and the opportunity for a more complicated path is exploited. Very simply like this:

The second seems more simple at first, but actually is quite difficult to get a firm handle on. In principle, it is a series of profiles that are hosted to reference planes and/or levels. These profiles can be created within the mass file ad-lib, or nested as external files that contain model lines.

In this example, I’ve used ‘spline by points’, which are great because they’re controllable through the points placed. They are a series of nested profiles, so that I can control the complexity of the mass in a more indirect way, and can keep the ‘collector’ mass file a little bit tidier. If I want to adjust a profile, I simply open that profiles *.rfa, adjust the underlying reference lines (I’ll do a post later about how to best do this), and then re-load into the collector. The mass will adjust itself and voila, job done. You’ll find that sometimes the mass will break when you re-load the profile, and this is more commonly because you’ve deleted a line and redrawn it (the specific line ID can no longer be seen by the mass), or the line complexity has changed so much that the mass can’t ‘flex’ itself adequately. 4 times out of 5, you can just select the lines again and recreate the mass. But that 1 time out of 5 you’ve done something it can’t reconcile, and that means you have to put your investigation hat on. And it’s an ugly, ugly piece of headwear. If you’re going to commit to a life of conceptual massing in Revit and Vasari, get used to this:

Dessert - But sir, it is only wafer thin

The reasons why they fail are many and varied. I’m going to use a project I’ve been working on for a while as a case study for going through these over a number of posts – it’s important that you understand it’s a collection of things, and that using Revit / Vasari is a frustrating and imperfect experience. In this blog, the word ‘hack’ is going to feature quite often, and I will be offering less than ideal solutions that are, to put it simply, necessary.

 

I realise that I’ve covered some basic fundamentals here, but this blog is really for exploring the more advanced aspects of creating parametric models in Revit / Vasari. It’s necessary to set this up in order to cover some more complicated issues. It's also important that the views of this blog are chiefly concerned with the implementation of these programs as tools - in no way should the act of creating parametrics replace the role of design.

In the immortal words of Cyberdyne Systems model 101, I’ll be back.