By Jason van Gumster

Under some circumstances, parenting doesn’t make sense for organizing a set of objects in Blender. A good example is a lighting setup that you want to adjust and reuse. Sure, you can rationalize that perhaps the key light is the most important light and therefore should be the parent, but that logic is a bit of a stretch and doesn’t make much sense in more complex setups.

For these cases, Blender’s grouping feature is ideal. To create a group, select all the objects you want to include in the group and press Ctrl+G or click Object→Group→Create New Group. All the objects in the group share a green selection outline rather than the default orange, to indicate that the object is a member of at least one group.

The notion of an object being a member of at least one group highlights another example of how grouping and parenting differ. Whereas an object can have only one parent, it can be a member of any number of groups. If you go to the Object→Group menu, you have a number of options:

  • Create New Group (Ctrl+G): This option is always available and creates a new group, adding your selected objects to it.

  • Remove from Groups (Ctrl+Alt+G): This option is always available, and choosing it removes the selected objects from any groups they may be a member of. Removing all objects from all groups doesn’t delete those groups while your Blender session is still active.

  • Remove from All Groups (Shift+Ctrl+Alt+G): This is a quick shortcut to remove the selected objects from all of the groups they may be a member of.

  • Add Selected to Active Group (Shift+Ctrl+G): To use this feature, you need the active object to be the member of a group. Then any objects you have selected become members of all the groups your active object is a member of.

  • Remove Selected from Active Group (Shift+Alt+G): Choose this option, and all your selected objects (including the active object) are removed from any groups in the active object.

Furthermore, it’s worth knowing that groups have names. Check out the Object section of the Properties editor. This section contains a panel named Groups, listing the groups to which the selected object belongs. Left-click any group name to change it to something more relevant to that group’s organization. Clicking the X next to the group name removes the selected object from that group.

The set of layer buttons under the group name, labeled Dupli Visibility, have a special application for larger, more complex projects that involve linking groups between .blend files. Basically, if some objects in your group are on a layer that isn’t enabled in these buttons, then those objects aren’t visible when the group is linked to another file.

Many game engines and other 3D applications have a notion of grouping that’s very different from Blender’s grouping. They tend to treat all members of a group as a single unit, regardless of which one gets selected. They also tend to treat groups hierarchically; an object can only belong to one group (in turn, that group can be a member of another group, but the base object is still only a member of one). In fact, this behavior is a lot more like parenting in Blender than grouping. To mimic this behavior more seamlessly, use the following steps:

  1. Create an Empty object near the center of your “grouping” of objects and display it as a cube (Shift+A→Empty→Cube).

  2. Adjust the size of the Empty (Empty Properties→Size) to roughly include all of the objects in your grouping.

  3. Name the Empty something clever to indicate the grouping’s name (Object Properties).

  4. Make all objects you’re grouping a child of the Empty (select each object, select the Empty, Ctrl+P→Object).

With this bit of legwork done, you can select the Empty’s cube outline to transform your whole grouping. Even better, your grouping will be hierarchically organized in the Outliner. Many game engine export scripts properly recognize and translate this structure to their native means of grouping.