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Problem importing DXF files

Posted: Sun Jan 12, 2014 3:35 pm
by Pauly1060
Hi everyone, I'm really enjoying using great stella and have made many interesting models, however I've come up against a problem, I'm making and importing new models into great stella and I get lots of errors, the main one is a 'model has no faces create convex core instead' type error but then nothing loads. I have exported from my 3d package but it's very unreliable, often with no enough decimal precision.

What I would like to know is, what is the best way to import models and which format. I've not tried off format yet.

The type of polyhedra I want to make are like the subdivided ones for example: a cube subdivided by two looks like 4 squares on each face of the cube, I want to be able to make my own subdivisions and then load the polyhedra back into great stella. I know that I get a co planar warning message when I load this type of polygon but up until now I haven't produced a model that will load back into great stella.

Any help would be greatly appreciated

Posted: Mon Jan 13, 2014 4:18 pm
by Peter Kane
This is really a case of the blind leading the blind, because I haven't eny experience of importing models, but the Stella Help file says this:
"If all else fails, and you can't find a way to create your favourite model in Stella4D, fear not! You can always import it from an external file. Currently the only format supported for import is OFF. It's a simple format and you should be able to figure it out from the example below. Please be sure to use as much precision in the vertex positions as possible, or you may run into problems. I recommend using 17 decimal places if you are creating files in this format. The OFF models must also be properly closed surfaces (with an even number of faces meeting at each edge). If not, it can't be opened, but you will be offered the choice to create the convex hull of the model in the OFF file, which allows you to get at least some of the vertices in. You may then wish to use Faceting Mode to connect these vertices together in other ways. You could even create OFF files with only vertices (no faces) and let Stella4D figure out how to connect them together for you. "

Posted: Mon Jan 13, 2014 9:01 pm
by Pauly1060
Thanks Peter, that does help quite a lot, I'll try some files in OFF format and let you know how I get on.

Posted: Thu Jan 16, 2014 4:05 am
by robertw
Actually, Stella can import DXF files now, as of version 4.0, but I guess I forgot to update that help file. From the version history:

"3D DXF files can now be imported, but I fear they generally lack the accuracy required, but it may be useful in some cases."

So yeah, most other programs won't put them out in a usable format. You also need to make sure the surface is closed (exactly 2 faces meet at each edge). Send me a DXF file if you can and I'll check it to see what's wrong. Unfortunately DXF varies a lot so it's hard to account for everything.

OFF is the simplest and best format if you can manage to write to it.

If you just want subdivided cubes, you can do this easily in Stella anyway.

"Poly->Create X x Y x Z Block" creates a block made of smaller cubes, and leaves the faces subdivided as you wanted.

Or subdivide any polyhedron using "Poly->Subdivide Faces".