importing models from CAD

[jgriessen]

I am making cabinet products and want to create SH3D furniture models without extra steps from my manufacturing CAD models. I've looked into using CAD based on Open Cascade libraries such as Freecad and python-occ to do my manufacturing output and serve as reusable models for variations on products. Talking with developers and users of CAD, they say .obj format is a mesh format -- not good for CAD.

How do you use .obj format to get parameterized windows for instance?
I saw a special code name for glass embedded in a .obj file. Is that the extent of special changes to .obj format?


Is there more added to the .obj text file that helps you stretch a window, shelf, counter, etc? Is there a tutorial for window/door creation?

The models I have looked at for cabinets, (not parameterized -- not stretchable) have non-closed-solid problems such that they cannot be operated on with booleans to chop off parts, etc. inside Blender 3D.

Is there a way to reuse such models with Blender? Other 3D editors?

What do you usually use to create furniture models? Are any of the usual ones
in BREP form good for CAD?

What is used to make all those .3ds models listed at http://archive3d.net/ ?

thanks,

John

[hansmex]

create SH3D furniture models without extra steps from my manufacturing CAD models

Whether or not this is possible depends (probably) on which formats you can save or export from your CAD program. When restricting your choices to open source software, I guess Blender offers the most possibilities through its large number of import and export formats.

How do you use .obj format to get parameterized windows for instance?

I even don't understand the question.

Is there more added to the .obj text file that helps you stretch a window, shelf, counter, etc?

I even don't understand the question.

Is there a tutorial for window/door creation?

Check the menu at the top right of this screen. Click on Documentation, User's Guide and Video Tutorial.

Is there a way to reuse such models with Blender? Other 3D editors?

I guess this question should better be asked at the Blender forum.

What do you usually use to create furniture models?

Depending on your needs you can use SH3d itself, Blender, Misfit Model 3D, Art of Illusion or several other programs.

Are any of the usual ones in BREP form good for CAD?

I wouldn't know. I even don't understand the question. What is BREP?

What is used to make all those .3ds models listed at http://archive3d.net/ ?

Seems a good idea to ask that question to the authors of the models.

GENERAL REMARK
SweetHome 3D is primarily meant to make interior designs in 2D, that can be viewed in 3D. Recently a few rather powerful features have been added that make it possible to have excellent visualizations of the interior of your room or house. SH3D has never been intended as a (part of) CAD or CAM or CAE solution, and doesn't offer muchin the form of interfacing with such programs. OBJ and 3DS files (NOT 3ds-max) can be imported, but that's it.

I have the feeling you need a tailormade solution in AutoCad or a similar high specs program.

Hans

[Puybaret]

How do you use .obj format to get parameterized windows for instance?

If you mean window information used to draw their arcs in the 2D plan, this additional information is stored in the properties file that describe each object in the catalog. See here for the list of available properties and download SH3F files for real world examples.

I saw a special code name for glass embedded in a .obj file. Is that the extent of special changes to .obj format?

I wouldn't call that an extent but a special usage in shape names that helped me to define mirrors from sweethome3d_window_mirror prefix and transparent panes from sweethome3d_window_pane prefix. Transparency can also be defined in MTL files, but MTL files weren't supported in the first version of Sweet Home 3D.
Recently, I used sweethome3d_window_pane again in Advanced rendering plug-in to ignore window panes during SunFlow rendering, because this rendering engine can't let light go through transparent objets, unless you use caustics which are very heavy to compute.

Is there more added to the .obj text file that helps you stretch a window, shelf, counter, etc?

Sweet Home 3D uses standard OBJ + MTL files (everything in OBJ format isn't probably supported, but what is supported is enough).

Is there a tutorial for window/door creation?

No but it's not complicated.

Is there a way to reuse such models with Blender? Other 3D editors?

You can export the 3D view to OBJ format to reuse your design in Blender.

What do you usually use to create furniture models?

I use Art of Illusion or Blender.

Are any of the usual ones in BREP form good for CAD?

I have no idea, I don't know what is the goal of your use of CAD.

What is used to make all those .3ds models listed at http://archive3d.net/ ?

Probably 3D Studio Max, but some other tools are able to export at 3DS format.

[jgriessen]

Is there more added to the .obj text file that helps you stretch a window, shelf, counter, etc?

Sweet Home 3D uses standard OBJ + MTL files (everything in OBJ format isn't probably supported, but what is supported is enough).

Thanks for the link to .OBJ file specification info. I will probably
make a script to translate from a STEP file to OBJ.

Does MTL files refer to "Specifies the material library file for the material definitions
set with the usemtl statement. You can specify multiple filenames
with mtllib. " from OBJ format?


Is IGES easier to convert (by a python script I write) to OBJ so it can be used in SweetHome3D?

In other words, which of STEP or IGES is more like a .OBJ file used for a stretchable object in SweetHome3D?

STEP or IGES boundary representations can be output by pythonOCC, a free-open 3D creation tool good for CAM, so those are what I am thinking of. It is possible to create a new exporter in pythonOCC that starts with open cascade model primitives if STEP or IGES lack some detail needed, but that sounds like more work.

What do you usually use to create furniture models?

I use Art of Illusion or Blender.

So far in Blender, my .obj exports always are given more triangles
so they become meshes rather than boundary-reps. Can you stretch a .obj model with many triangles in it in SweetHome3D? I was thinking it would have to be an edge defined, ( b-rep), model to stretch it.

My goal for pythonOCC CAD is to output CAM data and cut shapes, as well as convert or generate data that SweetHome3D can use for stretchable furniture objects. Blender might also be used for marketing illustrations derived from the other data. Blender can't be used as a starting point for me, since it is so easy to accidentally make models with face edges that are close, but not touching, and so not useful for CAM.

John

[Puybaret]

Just a little remark before answering to your questions:
From the version 2.4, Sweet Home 3D supports also the Collada file format.

[jgriessen]

https://collada.org has a title line about interactive media, so probably no STEP, IGES, or CAM going on there...

John

[Puybaret]

Does MTL files refer to "Specifies the material library file for the material definitions
set with the usemtl statement.

Yes

You can specify multiple filenames
with mtllib. " from OBJ format?

I never tried it but I programmed it that way. You can also cite more than one mtllib line.

Is IGES easier to convert (by a python script I write) to OBJ so it can be used in SweetHome3D?
In other words, which of STEP or IGES is more like a .OBJ file used for a stretchable object in SweetHome3D?

I have no knowledge of STEP or IGES format. Please provide some links to documents that describe these formats for a CAD novice like me.

So far in Blender, my .obj exports always are given more triangles
so they become meshes rather than boundary-reps. Can you stretch a .obj model with many triangles in it in SweetHome3D?

I'm not sure if it's what you're talking about, but programmers generally implements exportation to OBJ format with triangles, even if nothing prevents from describing polygons in OBJ format (and Sweet Home 3D supports polygons joining more than 3 vertices).
In all cases, that doesn't prevent an OBJ shape to be stretched in Sweet Home 3D or any other software.