Hole in model becomes solid in Shapediver

Hi guys,

In rhino my grasshopper model creates a preview like this:

In shapediver, the same model looks like this:

It seems like the hole gets filled up by Shapediver. What can I do about this?

It’s hard to tell from the screenshots but could you post a minimal definition replicating the issue so we can have a closer look.

I’ve sent you a link to the model. I cannot seem to repeat the problem with a minimal definition.

Things can go wrong if you use Deconstruct Brep and similar components as the resulting element list order may vary between computers as explained in this blog post or tutorial below:

This video can also give you some ideas how to build your model in more reliable and efficient way:

Can you elaborate on which components are similar? There’s no deconstruct brep in my file, but perhaps an explode curve component. Correct me if I’m wrong but doesn’t explode curve always keep the order and direction according to the start point? @DavidRutten

I was replying a bit too quick without watching the video, sorry. It seems like Explode curve also doesn’t keep the same order. Quite surprising actually. I’ll try to fix that and see if it solves it.

The slower you go, the faster you get there :wink:

More on the subject below:

Hmm but wait, maybe I was again a bit too quick in replying. :smiley: In the video they only talk about Exploding/Deconstructing breps, which I get that it splits up the model in a different way on a different computer because there’s no “start” to a polysurface, as you have with curves.

Before I spend time trying to fix the order after every explode curve component, I’d need to be sure that the order is indeed not consistent. As far as I know when you split a curve using the explode curve component, it uses the startpoint and direction of the curve to determine the order of the segments it returns. I tested this as well by drawing lines in Rhino and it seems to match what I was assuming.

Is this not true in your experience?

Not always. See this topic I posted a while ago. As it happens, the difference is not only between Rhino 5 and Rhino 6 but depending on other factors as well (service releases, tolerance settings, system configuration…)

I see, interesting, but I don’t think this is the same problem I’m having. A circle is made up off 1 segment. Using explode on the circle returns 1 segment. Using shatter on a circle with 2 values splits the circle in 2 different segments and alters the startpoints.

I have only polylines which get exploded into single line segments.

It might be that explode always returns the same result. and that your hole issue comes from somewhere else in your definition. It strongly looks like it is linked to the issue mentioned by Pavol, but it might also be a tolerance issue or a version issue. You could do further testing by uploading a minimal definition where you only output the curve segments and check if the order and/or number of segments is identical on your system and on ShapeDiver.

I managed to filter the part out from the rest and am getting the same issue. But cannot figure out what’s causing this: https://app.shapediver.com/m/bugtest

It looks like there’s 2 objects on top of each other but as far as I can see in GH there’s only 1 mesh that goes to the display geometry component.

Ok, so I finally found out what it was. The problem is not in the explode component, since explode keeps the original order of the curve. Instead the problem was in the join component which I was overlooking, and which obviously messed up the order. Sorry about bothering you guys with this one. @pavlov @mathieu1