Referencing objects

Hi everyone! It’s my first post here, I hope I’m in the right section to ask this question.

I have started using Blender like five times. This time I got a bit more involved in the whole animation thing, which makes me think I’ll stick to it longer. Though I know the basics of both 3D modelling AND Blender, I have still a lot to learn.

I am trying to make an animation, and I’m trying my hand at something a bit more complex than the usual bouncing ball. Since I come from a programming background, I’d like to have a reference object that will be used multiple times in my project. For example, if I model a streetlamp, I’d like to be able to have the original model as if it was an OOP class, and then in my project create multiple “istances” of the streetlamp. So that, if I make changes to the original, the instances are changed too (I am aware of the troubles that heavy changes may produce on the animation sequence; those would be small changes, for example texture-related ones).

I’ve read about linking to models from an external .blend file. Now I’m wondering, since I’ve created a new scene in my project file, and I’m modeling the objects in that scene (which, I know, may not be the best way to do this), I’m wondering if it’s possible to re-use in a scene an object from another scene. I think I understand it’s possible, but I couldn’t find anywhere how to do it.

I’d also appreciate a lot if someone experienced could give me hints about this - i.e., not much about the modeling/rendering techniques (which I’m learning from a lot of interesting tutorials), but about the “project workflow” so to say, i.e. how to mantain an animation with a large number of objects and such.

Thanks in advance!

Take your street lamp and add it to a group.
Press F7 and click add to group.
the default name is “group”, so make sure you give it a unique name, like streetlamp.
Save this file.

Open a new file and delete the default cube.
Choose File/Append-Link from the file menu.
It is important that you click the “Link” button. “Append” is the default.
Browse to your streetlamp scene and choose “Group” and you should see the streelamp group that you just created.
Click the Load Library button and what, nothing happens?

That is not really true, your group did load, but nothing does appear in the blender scene.
At this point use the Space Bar and add an Empty to the scene.
Press F7, once again, to bring up the object properties for the empty.
In the GR: field type the name of your group. (i.e. streetlamp)
Then click the DupliGroup button and your streetlamp will appear.

Now you have an externally linked object in your scene. There are pros/ and cons to this. The main disadvantage is now you can not edit the object or it’s materials. So you will have to open the external scene and make the edit then come back to the “host” scene that contains the externally linked reference.

I tried to use your method to reference the file itself… but I can’t. Three questions:

  1. I’ve seen I can also link to objects. Are there pros/cons to linking to Groups rather than Objects?

  2. Isn’t there any method to link from within the file?

  3. If I create an empty and make a few objects its children, can I safely assume that any change made to the empty is made to the children too? I mean, if I cut or copy the parent, are all the children cut or copied too?

Sorry to double post, but I found it myself.

Without the need to create any Empty object, just hit space and Add > Group. You’ll get a list of all groups in your file AND the linked ones. As far as what my experiments show, it does in fact reference the original object - without the need to work on two files at a time.

Am I doing wrong? Hs this feature in v.2.46 (the one I’m using) now changed?

Alt-D will create a linked duplicate. If you make a change to the original mesh the copy will change too.

you can also use dupliverts, or an array.

I’d really like some clarification about how “Add…Group” is the same or different than using DupliGroups.

I see, in the Outliner view, how this appears to create a DupliGroup “object” … which (unlike an Empty that is designated in this way) shows all of the animation that may be associated with the grouped object.

It is also not-at-all clear to me what difference "ALT+"DKEY has, if any. A duplicate made with SHIFT+DKEY appears identical to me.

This is a really interesting discussion, and I’m afraid I don’t know most of the answers. I’d like to know some of this stuff too.

About duplicates, though:

Shift+DKey makes a duplicate. When you create a duplicate this way, it is identical to the original. However, when you change one, nothing happens to the other.

Alt+DKey makes a linked duplicate. When you change one, the other changes too.

None of this has anything to do with groups, and I’m not sure how to get an object from one scene into another within the same .blend file. I know it can be done, I’m just not sure what the steps are.

I would type something new, but the above instructions should work.