Serves as a place-holder in the scene, usually for parenting. this object does not render.
The Null Object serves as a place-holder in a scene, and does not render. It can be used to designate a place in the space of your scene, or as a “look at” object to help coordinate a camera’s movement and field of view.
The Null Object is also used as an End Affector for constructing chains of bones. Its parameters are similar to those of the Geometry Object’s Transform and Miscellaneous tabs.
To change the null’s display geometry, go inside the node (Alt-click the icon in the network editor or select it and press I) and edit the SOPs defining its shape.
You can use the Null Object’s transform to define coordinate systems in either RIB or IFD renderings using the controls on the Render tab.
Placing a Null in the viewer
|Place the null anywhere in the scene|
|Place the null at the origin|
You can change the display, control type, and shading of the null on the Misc tab of the parameter editor.
|Keep Position When Parenting|
When the object is re-parented, maintain its current world position by changing the object’s transform parameters.
This menu contains options for manipulating the pre-transform values. The pre-transform is an internal transform that is applied prior to the regular transform parameters. This allows you to change the frame of reference for the translate, rotate, scale parameter values below without changing the overall transform.
The left menu chooses the order in which transforms are applied (for example, scale, then rotate, then translate). This can change the position and orientation of the object, in the same way that going a block and turning east takes you to a different place than turning east and then going a block.
The right menu chooses the order in which to rotate around the X, Y, and Z axes. Certain orders can make character joint transforms easier to use, depending on the character.
Translation along XYZ axes.
Degrees rotation about XYZ axes.
Non-uniform scaling about XYZ axes.
Local origin of the object. See also setting the pivot point .
Scale the object uniformly along all three axes.
Object to point to. Constrains an object so its
|Look At Up Vector|
When specifying a look at, it is possible to specify an up vector for the look at. This controls the roll of this object when looking at the look at object.
A reference to the curve node or object you want this object to follow.
The orientation of the object around the path.
The position of the object along the path.
If the primitive number does not exist, then it is wrapped back to the beginning. So for numbers greater than
Keyframe this value to animate the object moving along the path.
The Follow Path tool on the shelf automatically sets keyframes on this parameter that you may want to edit or replace.
The Parameterization option controls how position values between 0 and 1 correspond to knots on the path curve.
Controls how the Position parameter is translated into a point on the path curve. Use Arc-length (the default) to interpolate the position values evenly along the physical length of the curve.
Use Uniform to distribute the position values between the knots of the curve. This lets you slow down the object at certain points by bunching up knots in the path curve. However, it is much more convenient to simply edit the animation curve to control the speed of the object along the path.
|Orient Along Path|
Orient the object according to the path’s curvature.
|Orient Up Vector|
The direction vector of the object’s Y axis to orient with.
Controls automatic banking of the object as it turns corners. Set this to
Whether or not this object is displayed. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object, or 1 to show the object. If the checkbox is off, Houdini ignores the value.
|Output transform as render space (RIB/IFD)|
If this parameter is turned on, then the transform of the null will be output to render scripts as a named transform space. As well, the pre-include and post-include will be enabled for inclusion into the render stream. Note that the display of the object must be turned on and the null must match the visible objects of the output driver.
|Set Wireframe Color|
Use the specified wireframe color
The display color of the object
|Viewport Selecting Enabled|
Object is capable of being picked in viewport.
Script to run when the object is picked in the viewport. See select scripts .
|Cache Object Transform|
Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects.
See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache.
Uniform scaling about the xyz axes.
Whether to display only the icon, only the axis, or both.
Switches between the type of geometry to display.
Used in conjunction with circle or plane primitives. Determines which circles or planes to display.
Determines whether to display the primitives as shaded objects or as wireframe objects.
Examples that use this node
|Example for||Example name|
|Fetch||Fetch||Load | Launch|
|IKSolver||SimpleIKSolver||Load | Launch|
|InverseKin||SimpleInverseKin||Load | Launch|
|TransformChain||SimpleTransformChain||Load | Launch|
|Blend Solver||SimpleBlend||Load | Launch|
|Light||TransparentShadows||Load | Launch|
|Muscle||HandleExample||Load | Launch|
|Muscle||JiggleMuscle||Load | Launch|
|RampReference||Load | Launch|
|Follow||FlockOnPath||Load | Launch|
|Follow||NewGroupiesRavage||Load | Launch|
|Lookat||Lookat||Load | Launch|
|Orbit||OrbitAlternate||Load | Launch|
|Add||Add||Load | Launch|
|Fur||FurBallWorkflow||Load | Launch|
|L-system||LSystemMaster||Load | Launch|