Thank you to all who’ve added input to this discussion so far. This is the discussion I’d hoped to generate. Having read through everybody’s replies, I’d like to address some of the aggregate perspectives that have been shared so far.
Intersect Shouldn’t Punt When Encountering Areas of Intersection
Several posts talk about how Booleans are really just shortcut implementations of the Intersect/Trim/Split/Join (ITSJ) design pattern. Agreed. I realized this when trying to understand and resolve my first Boolean related problem. So when I broken down my characterization to the 4 component steps, I found is that it was the Intersect operation that was generating an erroneous (read: incomplete) set of intersection curves. I posted my findings along with a possible solution in an email to McNeel tech support and in this discussion an edited version of which I’ve quoted again below. But the only response I received from McNeel was that I shouldn’t expect any changes in the product that improves Booleans.
The unexpected behavior I’ve been having with Rhino, and by extension Grasshopper, is that the current implementation of the Rhino Intersect command is generating an incomplete network of curves when given 2 surfaces having regions that are (almost) coincident. When Intersect determines that there’s no single curve able to represent the intersection in those areas, but rather an area of intersection, Intersect erroneously doesn’t generate any curve to represent that portion of the intersection — which is mathematically incorrect. This decision to “punt” in these situations renders the generated results to not be useful for subsequent steps of the ITSJ design pattern. Rather than not including these areas of intersection in the network of curves, Intersect should generate any non-kinky, non-looping curve(s) through a region of intersection that connects with all other intersection curves adjacent to the region. Any valid curve is far more useful — and mathematically correct — than no curve through these regions.
Informative and Detailed Error Reporting Will Save Users’ Time
A number of users feel as I do that the error information available when an operation fails is insufficient.
The Rhino Learning Curve Is Fractally Steep
While some responses have suggested that I’m just too new to Rhino, a number of long-time Rhino users have said that they are continually “learning” the product’s idiosyncrasies, and expect that they will never really know what the product will do every time. What they’ve learned from their years of experience is how to hack their designs to work around Rhino’s quirks.
I conclude from these stories that, sure, I’m green, but that I, all of us, are destine to be forever “green” because the current development methodology results in a product that can never really be understood.
Wow.
In his reply to a companion posting in the Grasshopper discussions, Paul N Jeffies said…
One thing that’s important to understand when using Rhino for this kind of thing is that Rhino does not have a particularly meaningful conception of a ‘solid object’ - solids are defined simply as a collection of (infinitely thin) NURBS surfaces joined together with no gaps between. That’s part of the reason for the problems with booleans in Rhino, but it also means that you don’t really need boolean operations since you can do everything by exploding the polysurface and using the Intersect/Trim/Split commands on the individual surfaces to build up the boundary surfaces you want, then rejoin into a solid afterwards.
As a software architect with ~40 years of tech experience, I would again suggest that the root cause of the product’s unknowability is the lack of rigor so far exhibited in defining the layers of abstraction. If proper rigor were applied, then, from a user’s perspective, a solid really would be a solid. The proper way to reduce a solid to a set of adjacent surfaces would be to use a function like ExplodeSolid, and to get a set of curves from a surface we would have to use ExplodeSurface, and so on. So rigor doesn’t prohibit users from pulling back the curtain, but rather empowers the core development team to enforce encapsulation at the current layer of abstraction — whether point, curve, surface, solid, or whatever.
The Solution Begins With Changing The Conversation
With all this said, I don’t believe that Rhino is fatally flawed or impossible to fix. I also don’t believe that the resulting loss of productivity is the users’ fault. I do believe though that the first step is for all, McNeel and users, to name the condition, raise this as a high priority, work collaboratively to define a corrected abstraction stack, and add appropriate rigor to the implementation of the next major release.
About a month ago I spent about 1/2 hour searching through the Rhino discussions for topics related to The Boolean Problem. I found literally 100’s of posting, with many noops like I am now saying they were giving up and going to another tool because Rhino’s learning curve was too steep. Yes, filleting and trimming are two other big Rhino problems that I believe have similar roots. Yet I wonder whether these deep-seated challenges could, in fact, be overcome — by first changing the conversation.
I’d again ask what other, more experienced users think.
- Bob