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Regrouping Objects

There can be many objects in a scene: A typical stage scene consists of furniture, props, lights, and backdrops. Blender helps you keep everything organized by allowing you to group like objects together.

When modeling a complex object, such as a watch, you may choose to model the different parts as separate objects. However, all of the parts may be attached to each other. In these cases, you want to designate one object as the parent of all the children. Movement and rotation of the parent also affects the children.

Parenting objects

Mode: Object mode

Hotkey: CtrlP

Menu: Object » Parent » Make Parent

Exclamation mark.png
This page uses the old, rather deprecated parenting method – nowadays you should use the Child Of constraint.


Exclamation mark.png
This page mainly talks about object parenting, but you can also parent to a bone or an entire armature, see the Rigging chapter.

Description

Make Parent.

To parent objects, select at least two objects, and press CtrlP. A confirmation dialog will pop up asking Make Parent. Selecting Make Parent confirms and the child/children to parent relationship is created, see image (Make Parent). The last object selected will be the active object (outlined in pink), and will also be the parent object. If you selected multiple objects before selecting the parent, they will all be children of the parent and will be at the same level of the hierarchy (they are “siblings”).

Moving and rotating the parent will also usually move/rotate the child/children. However moving/rotating the child/children of the parent, will not result in the parent moving/rotating. In other words, influence is usually descendant (parent → child/children), and not ascendant (child/children → parent).

Mode: Edit mode (meshes and curves/surfaces)

Hotkey: CtrlP

Menu: Mesh/Curve » Vertices/Control Points » Make Vertex Parent

You can parent an object to a single vertex, a group of vertices or a control point as well; that way the child/children will move when the parent mesh is deformed, like a mosquito on a pulsing artery. In Object mode, select the child/children and then the parent object. ⇆ Tab into Edit mode and on the parent object select either one vertex or control point that defines a single point, or select three vertices that define an area (the three vertices do not have to form a complete face they can be any three vertices of the parent object), and then hit CtrlP and confirm.

At this point if a single vertex was selected a relationship/parenting line will be drawn from the vertex/control point to the child/children. If three vertices were selected then a relationship/parenting line is drawn from the averaged center of the three points (of the parent object) to the child/children. Now, as the parent mesh/curve/surface deforms and the chosen parent vertex/vertices/control points move, the child/children will move as well.

Note
It is in fact a sort of “reversed” hook


Options

Move child

Move child.

You can move a child object to its parent by clearing its origin. The relationship between the parent and child isn’t affected. Select the child object and press AltO. By confirming the dialog the child object will snap to the parent’s location. Use the Outliner view to verify that the child object is still parented.

Remove relationship/Clear Parent

You can remove a parent-child relationship via AltP; see image (Remove relationship).

Remove relationship.

The menu contains:

Clear Parent
If the parent in the group is selected nothing is done. If a child or children are selected they are disassociated with the parent, or freed, and they return to their original location, rotation, and size.
Clear and Keep Transformation (Clear Track)
Frees the children from the parent, and keeps the location, rotation, and size given to them by the parent.
Clear Parent Inverse
Places the children with respect to the parent as if they were placed in the Global reference. This effectively clears the parent’s transformation from the children. For example, if the parent is moved 10 units along the X axis and Clear Parent Inverse is invoked, any selected children are freed and moved -10 units back along the X axis. The “Inverse” only uses the last transformation; if the parent moved twice, 10 units each time for a total of 20 units, then the “Inverse” will only move the child back 10 units, not 20.


Parenting Example

Parenting Example.

The active object, in light pink (cube A), will be made the parent of all the other object(s) in the group (darker pink/purple cube B). The center(s) of all children object(s) are now linked to the center of the parent by a dashed line; see image (Parenting Example). The parent object is cube “A” and the child object is cube “B”. The link is labeled “L”.

At this point, grabbing, rotating, and scaling transformations to the parent will do the same to the children. Parenting is a very important tool with many advanced applications, as we’ll see in later chapters; it is used extensively with advanced animations.

Hints

Outliner view.

There is another way to see the parent-child relationship in groups and that is to use the Outliner view of the Outliner window. Image (Outliner view) is an example of what the Outliner view looks like for the (Parenting Example). Cube “A”’s object name is “Cube_Parent” and cube “B” is “Cube_Child”.

You can also select objects based on their parent relationships, see the selection page.

Separating Objects

Mode: Edit mode (meshes and curves/surfaces only)

Hotkey: P

Menu: Mesh/Curve » Vertices/Control Points » Separate

Description

At some point, you’ll come to a time when you need to cut parts away from a mesh or curve to be separate, but you might wonder how to do that. Well, the operation is easy.

To separate an object, the vertices (or faces, or control points…) must be selected and then separated, though there are several different ways to do this.

Options

Note that for curves/surfaces, you have only one option, corresponding to the first one below.

Selected
This option separates the selection to a new object.
All Loose Parts
Separates the mesh in its unconnected parts.
Suzanne decapitated neatly.
By Material
Creates separate mesh objects for each material.


Grouping objects

Mode: Object mode

Panel: Object » Object and Links

Hotkey: CtrlG

Menu: Object » Parent » Add to New Group

Description

Grouped objects.

Group objects together without any kind of transformation relationship. Use groups to just logically organize your scene, or to facilitate one-step appending or linking between files or across scenes. Objects that are part of a group always shows as light green when selected; see image (Grouped objects). You can mix any kind of objects in a same group.

You can also select all objects in a given group, see the selection page.

Options

Groups pop-up menu.
Adding to, or Creating, a Group
CtrlG pops up a dialog for adding to existing groups or creating a new group; see image (Groups pop-up menu). This same menu is also available via the 3D view header: Object » Group.
Alternatively, with the object selected or in Edit mode, click the Add to Group button shown below in image (Naming a Group). The popup list allows you to click on an existing group, or create a new one.
You can also ostracize, or banish, the selected object from all groups by selecting the Remove from All Groups option.


Naming a Group.
Naming a Group
To name a group, you can use the Buttons window, Object context (F7), Object and Links panel: just click ⇧ ShiftLMB Template-LMB.png in the GR: field and type a meaningful name.
To name groups in the Outliner window, select

Groups as the outliner display from the header combo box, and CtrlLMB Template-LMB.png click on the group name. The name will change to an editable field; make your changes and press ↵ Enter.

Restricting Group Contents via Layers
That cluster of layer buttons below a group designation determines from which layers the group objects will be included when duplicated. If your group contains objects on layers 10, 11 and 12, but you disable the layer 12 button in the group controls, duplicates of that group (using the Dupligroup feature) will only show the portions of the group that reside in layers 10 and 11.
Appending or Linking Groups
To append a group from another .blend file, consult this page. In summary, File » Append or Link » filename » Group » groupname.


Example

Grouped objects.

(Grouped objects) shows two cubes grouped together where A is the last selected object indicated by being drawn in a lighter color.

PassIndex

Mode: Object mode

Panel: Object » Object and Links

Hotkey: Any?

Menu: Any?

The Object and Links panel.

There is one more way for “regrouping” objects: the PassIndex. This is a simple number, and all object this property, by default set to 0. You can change this value in the PassIndex field of the Object and Links panel (Object context and sub-context).

The main purpose of this property is to regroup objects during/after rendering (compositing…), as described in the ID Mask node page. However, you can also use it to select groups of objects.