For simplification, it’s sufficient to read my 3rd post which explains everything in one sentence. Sorry for that.
I thought the location of an object is always relative to it’s parent, or to the world if the object has no parent. Why does this not apply to the location of a group instance? IMO, the location of a group instance should also be relative to it’s parent or to the world.
I appended a little example .blend file. The two cubes in front are one group. The small sphere indicates an empty which is the parent of the two cubes. In the background, I added an instance of the group. If you select the group instance, it’s X position is 0. That’s ok.
Now move the empty (by selecting the empty only) +1 on the X axis. This also moves the group instance in the background. IMO, it shouldn’t move.
If you select the group instance again, the location is still 0. As the group instance has no parent, the location should be relative to the world. Please note that the relative position of the cubes to their parent did not change. However, looking at the group instance, it looks as if.
EDIT: In other words, it seems the world coordinates of the original objects are used for group instances instead of their local coordinates, which is an exception to the rule.
Using Blender 2.61, Win7/64
Sample: Demo.zip (60.8 KB)
I mean, the problem with this is that I would have to put the grouped objects always around the origin. Otherwise, there’s always an offset of the objects of the group instance.
The solution is using the empty as the parent, because moving the empty doesn’t change the local coordinates of the grouped objects. Consequently I should be able to move the empty around because it doesn’t influence the coordinates of the grouped objects, consequently it doesn’t influence the location of the objects in the group instance.
Even if I move all my “templates” (= the grouped objects) to a different layer, it’s getting confusing if all templates must be placed at the origin. I guess ther are more ways to do it, but just putting them at their own location would have been the simplest solution.
EDIT: I should rephrase the title: It’s not the group instance location, which is correct. It’s the location of the objects within the group instance, i.e. their local coordinates are equal to the world coordinates of the grouped objects, not equal to the local coordinates of the grouped objects. I didn’t find a setting or option to change this.
Long story short:
I expect the local coordinates of the objects in a group instance to be the same as the local coordinates of the objects in the group.
(Sorry for expressing myself too complicated. I thought I figured it out before posting…)