VaSections and Custom Cplanes

It appears that VaSections only orient themselves to World>Top View. Is this correct?

Hi @djhg, yes, that’s correct. Would you like to create sections from not vertical planes? or what would you like to do?

It’s not unusual to need a section perpendicular to a curving plane. In this case it was an arcing metal entrance gate of decorative metal. I imagined I could establish a new cplane oriented to the arch at the desired section point, but the section reverts to World Top.

The work around was to iterate a version of the arch and pivot that instead. That iteration has to be re-edited to update the section to any design changes to the model unless the iteration is a block (which is sometimes undesirable.)

Another work-around is a Rhino clipping plane but their display properties are unreliable for section fills.

Hi @djhg, the option to create not vertical sections is already in our wishlist. And it is also the option to have section attributes on geometry when using clipping planes. So either of these options would help you in this case.

In my experience clipping planes almost never display solid section fills. Clipping Plane Fills! Please

David -

As always, if you provide a simple sample that only uses out-of-the-box functionality for Rhino, I’ll be happy to take a look and check if I see the same here.

Thanks Wim. I’ve spent many an hour experimenting with fills and clipping planes. Sometimes it works, but it never lasts. Because of this inconsistency, posting a simple experiment is problematic, but over the years I’ve provided a few. I don’t think Va interferes. In fact the only reliable method I have found over my past years using Rhino since version 5 is a va Section and Va Hidden display mode. I think the post to which I refer above indicates that others have had a similair experience. I also notice that examples promoting the latest Rhino 7 features - contrary to common technical drawing practice - don’t have a solid fill for clipped objects either but emulate it by using a coloured backface in a cutaway perspective view (coloured backfaces usually aren’t effective for an orthographic technical section). I have taken that as confirmation that clipped fills aren’t a reliable feature. If you’re having consistent success with clipped fills, please let me know and I’ll make it a priority to explore this yet again. It’s one of my biggest bugbears with Rhino.

David -

Thanks. Yes, I’m having consistent success with clipped fills. I have spent a lot of time looking at the samples that you have provided in the past and was always unsuccessful in making them misbehave on my end.

That one is unfortunate. I have asked around for the model but it doesn’t look like we have that hanging around anymore. It’s said to be downloaded from some site on the internet that provides 3D models and I suspect that the object is simply open at some place. As soon as there is even the tiniest gap between surfaces anywhere in the model, the clipping plane won’t created a solid fill.

Mysterious as that seems, it’s good to know. It may not necessarily be inconsistent though. I have found that often a clipped fill from an ordinary Rhino clipping plane would work in a particular detail window in a project for a few sessions, but eventually - sometimes after a day or two - it will simply disappear with no way to get it back. Most of the time nothing has changed with that detail or the objects in the window or with the window itself.

I’m savvy to the ‘watertight’ requirement for proper performance, but that’s not been the issue.

Lately I have had the problem - and this is one for the Va folks I suppose - that even the usually reliable filling of clipped solids in a vaSection won’t show as filled. Though Properties identifies it as Closed, What identifies it as Valid, and ShowEdges identifies no open edges. In such a case I’ve tried exploding and rejoining which has only worked a few times. These uncooperative objects have been panels with moulding profiles swept and BooleanDifferenced out of them. Sometimes those give errors which can be found by one of the aforementioned methods and then corrected by extracting bad surfaces and planarsrfing the resulting holes. But in a few cases I’ve had to draw the fills in layout space.