In Blender a group is just a collection of objects unrelated to the object relationship. Apparently Group instances are made of an empty plus instances of the group objects. This blend file contains a group made of 3 simple objects and one group instance:
The Suzanne group in this file is made of 3 objects: "Suzanne", "Pole" and "Base"
When exporting this we can make use of Collada library nodes as follows:
<node id="Group-Suzanne" type="NODE"> <node id="Suzanne" type="NODE"> <instance_geometry url="#Suzanne-mesh"/> </node> <node id="Pole" type="NODE"> <instance_geometry url="#Pole-mesh"/> </node> <node id="Stand" type="NODE"> <instance_geometry url="#Stand-mesh"/> </node> </node>
<visual_scene id="Scene"> <node id="Suzanne-Instance" type="NODE"> <instance_node url="#Suzanne-instance"/> <!-- placed at the location of the instance --> </node> </visual_scene>
When importing this, then basically the blend file is reconstructed like the original with one group made of the library nodes and one group instance referring to the group.
- What to do when the user has selected the group instance and the objects in the group.
- How to handle the situation where objects are in multiple groups.
- Should we also take care of the layers where each object is placed? I think that is doable as well.
Is there anything else to consider? Opinions and suggestions are welcome :)