Can´t open files created in GH 1.0.0004

Creating or just re-saving a file in GH for Rhino 6 WIP makes it impossible to open the file in 0.9.0076 for Rhino 5.

Rhino get´s stuck in not responding and CPU and Memory consumption raises, but nothing happens.

Nevertheless I can copy-past from one instance to another.

When trying to nail down the problem, I couldn´t.

But I think it has something to do with internalised Breps. At least those end up as Null Breps, when opening the file in Gh for Rh5. My assumption is a lot of internalised Breps just cause a lot of problems downstream and this way it takes forever to load the file.

Attachments:

InternalisedBrepsInRH6.gh, 39 KB

Replies to This Discussion

Permalink Reply by David Rutten on March 1, 2017 at 7:53am

It could be a problem with V4 versus V5 versus V6 opennurbs data. When Grasshopper switched from Rhino4 to Rhino5, I think the opennurbs versioning format was initially kept specifically at V4 to ensure compatibility of files, but I can't remember all the changes that were made to this over time.

At the moment geometry is serialized using Opennurbs 5.0, but if that fails Opennurbs 6.0 is used instead. It would fail for types that didn't exist in ON5, such as sub-d objects or n-gon meshes, but it may also fail under other conditions, specifically when bad/corrupt geometry is involved.

Deserialization is the mirror image, first data is read using an ON6 filter, if that fails an ON5 one, and if that fails an ON4 one. But this is obviously code that is new to Grasshopper in Rhino6, as earlier versions would not have been able to try and read ON6 flavour data.

It is surprising that copy-paste and save-open would work differently, they're supposed to use the exact same code throughout. Unfortunately I don't even have Rhino5 any more, but no doubt someone else in McNeel can help me debug this. I may also have to talk to Steve Baer and Dale Lear to see what information (if any) we can harvest from an OpenNurbs byte-array supposedly representing some shape without trying to construct an actual instance (which may fail).

Permalink Reply by phillip on March 1, 2017 at 9:13am