= Create, edit, and use Null objects =

Null objects are basically object nodes with transforms, but no rendered geometry.

Null objects are very useful in [keyframe animation|anim] and [character rigging|/char] . By [parenting|/model/objects] objects to the Null, you can transform them using the Null instead of directly.

The default representation of a Null in the viewer is a small green jack, however you can change it to use arbitrary geometry. This is very useful with character rigging as you can make the "user interface" Nulls into shapes corresponding to what they do.

tasks>>
    Create a Null object:
        * At the [Scene level|/basics/objects], click the [Icon:OBJ/null] [Null tool|/shelf/null] on the *Create* shelf tab.

    Change the geometry representation of a Null:
        - Select the Null object. In the parameter editor, click the __Misc__ tab and set the __Control type__ parameter.
        
        _or_
        
        - Double-click the Null object's node in the [network editor|/ref/panes/network] to go inside. The Null object contains surface nodes just like a regular [Geometry container object|/basics/objects]. The surface nodes inside define the look of the Null object in the viewer.
        
            TIP:
                Use the [Font surface node|Node:sop/font] to display text in the Null's geometry. You can use this, for example, to display a character's name in the character's root Null's geometry.

    Change the color of a Null in the viewer:
        * In the Null object's parameter editor, click the __Misc__ tab. Turn on __Set wireframe color__, then edit the __Wireframe color__ parameter.

== Make Null geometry always appear in wireframe ==

Often when you change the geometry of Nulls you want them to stay as wireframe even if you are in a shaded view. By making Null's the curves/surfaces open instead of closed, you can prevent them from being shaded.

To open any curve (except a primitive circle), add an [Ends surface node|Node:sop/ends] and set the __Close U__ parameter to "Unroll".

(You can also make a circle open from the beginning by setting its __Arc type__ parameter to "Open arc".)

To open a surface, add a [Carve surface node|Node:sop/carve]. In the Carve node's parameter editor:

* Turn on __First U__ and set it to 0.
* Turn on __Second U__ and set it to 1.
* Turn on __First V__ and set it to 0.
* Turn on __Second V__ and set it to 1.
* Click __Breakpoints__.
* Click __Extract__.

This extracts the breakpoint curves from the input surface. Then, you can use an [Ends operator|Node:sop/ends] with the "Unroll" setting as above to open the resulting curves.