Houdini 18.5 Nodes Object nodes

Common object parameters object node

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Transform tab

Keep Position When Parenting

When the object is re-parented, maintain its current world position by changing the object’s transform parameters.

Child Compensation

When the object is being transformed, maintain the current world transforms of its children by changing their transform parameters.

Pre-transform menu

This menu contains options for manipulating the pre-transform values.

Transform Order

The left menu chooses the order in which transforms are applied (for example, scale, then rotate, then move. 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.

Translate/Rotation/Scale

Uniform Scale

This slider changes the size of an object uniformly along all three axes.

Look At

Constrains an object so it always points at another object’s origin (see pivot point vs. origin ). This is useful if, for example, you want a camera to follow another object.

Look At Up Vector

When specifying a "look at", it is possible to specify an up vector for the look at. Without using an up vector, it is possible to get poor animation when the look at object passes through the Y axis of the target object.

Don’t Use Up Vector

Use this option if the look at object does not pass through the Y axis of the target object.

Use Up Vector

This precisely defines the rotates on the object doing the looking. The up vector specified should not be parallel to the look at direction. See Orient Up Vector below.

Use Quaternions

Quaternions are a mathematical representation of a 3D rotation. This method finds the most efficient means of moving from one point to another on a sphere.

Path Object

Names the object that functions as the path you want this object to move along. For example, you can name an object that provides a spline path for the camera to follow.

Having an object follow an animation path is simple. However, when using a NURBS curve as your path, you might notice that the object speeds up and slows down unexpectedly as it travels along the path. This is usually because the CVs are spaced unevenly. In such a case, use the Resample SOP to redistribute the CVs so that they are evenly spaced along the curve. A caution however - using a Resample sop can be slow if you have an animating path curve.

An alternative method is to append a Basis sop to the path curve and change it to a Uniform Curve. This way, your object will move uniformly down the curve, and there is no need for the Resample sop and the unnecessary points it generates.

Roll

Using the angle control or the editing filed, you can specify an object’s rotation as it animates along the path.

Position

This parameter lets you specify the position of the object along the path. The values you can enter for this parameter range from zero to one, where zero equals the starting point and one equals the end point of the path. The value slider allows for values as high as ten for multiple "passes" along the path.

Orient Along Path

If this option is selected, the object will be oriented along the path. The positive Z axis of the object will be pointing down the path.

Orient Up Vector

When orienting an object, the up vector is used to determine where the positive Y axis points.

Auto-Bank Factor

The Auto-Bank factor rolls the object based on the curvature of the path at its current position. To turn off auto-banking, set the bank scale to 0.

Misc tab

Use Display Color

When this parameter is enabled, and the object is being displayed in wireframe mode in the Viewport, the object will be displayed using the color specified below.

Display color

Set the desired display color by specifying an RGB value here, or by using the HSV sliders. Clicking the Plus button displays a color dialog that allows you to select from a range of predefined colors. Click on the desired color’s name, or on the color swatch, to select that color. The name of the selected color appears highlight to indicate that it is active.

Viewport Selecting Enabled

Enabling this button changes the object’s status to selectable, meaning that the object is capable of being selected for specific commands and of being singled-out as an editable object in the Viewport.

Selection Script

Clicking the button to the right of the edit field displays an open file dialog that lets you search for a script to execute when you click on the selected object in the Viewport using the Select Operation.

Object nodes

  • Agent Cam

    Create and attach camera to a crowd agent.

  • Alembic Archive

    Loads the objects from an Alembic scene archive (.abc) file into the object level.

  • Alembic Xform

    Loads only the transform from an object or objects in an Alembic scene archive (.abc).

  • Ambient Light

    Adds a constant level of light to every surface in the scene (or in the light’s mask), coming from no specific direction.

  • Auto Bone Chain Interface

    The Auto Bone Chain Interface is created by the IK from Objects and IK from Bones tools on the Rigging shelf.

  • Blend

    Switches or blends between the transformations of several input objects.

  • Blend Sticky

    Computes its transform by blending between the transforms of two or more sticky objects, allowing you to blend a position across a polygonal surface.

  • Bone

    The Bone Object is used to create hierarchies of limb-like objects that form part of a hierarchy …

  • Camera

    You can view your scene through a camera, and render from its point of view.

  • Common object parameters

  • Dop Network

    The DOP Network Object contains a dynamic simulation.

  • Environment Light

    Environment Lights provide background illumination from outside the scene.

  • Extract Transform

    The Extract Transform Object gets its transform by comparing the points of two pieces of geometry.

  • Fetch

    The Fetch Object gets its transform by copying the transform of another object.

  • Formation Crowd Example

    Crowd example showing a changing formation setup

  • Franken Muscle

    Creates a custom muscle by combining any number of geometry objects, muscle rigs, and muscle pins.

  • Fuzzy Logic Obstacle Avoidance Example

  • Fuzzy Logic State Transition Example

  • Geometry

    Container for the geometry operators (SOPs) that define a modeled object.

  • Groom Merge

    Merges groom data from multiple objects into one.

  • Guide Deform

    Moves the curves of a groom with animated skin.

  • Guide Groom

    Generates guide curves from a skin geometry and does further processing on these using an editable SOP network contained within the node.

  • Guide Simulate

    Runs a physics simulation on the input guides.

  • Hair Card Generate

    Converts dense hair curves to a polygon card, keeping the style and shape of the groom.

  • Hair Card Texture Example

    An example of how to create a texture for hair cards.

  • Hair Generate

    Generates hair from a skin geometry and guide curves.

  • Handle

    The Handle Object is an IK tool for manipulating bones.

  • Indirect Light

    Indirect lights produce illumination that has reflected from other objects in the scene.

  • Instance

    Instance Objects can instance other geometry, light, or even subnetworks of objects.

  • Light

    Light Objects cast light on other objects in a scene.

  • Light template

    A very limited light object without any built-in render properties. Use this only if you want to build completely custom light with your choice of properties.

  • Microphone

    The Microphone object specifies a listening point for the SpatialAudio CHOP.

  • Mocap Acclaim

    Import Acclaim motion capture.

  • Mocap Biped 1

    A male character with motion captured animations.

  • Mocap Biped 2

    A male character with motion captured animations.

  • Mocap Biped 3

    A male character with motion captured animations.

  • Muscle

    The Muscle object is a versatile tool that can be used when rigging characters and creatures with musculature.

  • Muscle Pin

    Creates a simple rigging component for attaching regions of a Franken Muscle to your character rig.

  • Muscle Rig

    Creates the internal components of a muscle (the rig), by stroking a curve onto a skin object.

  • Null

    Serves as a place-holder in the scene, usually for parenting. this object does not render.

  • Object nodes

    Object nodes represent objects in the scene, such as character parts, geometry objects, lights, cameras, and so on.

  • Path

    The Path object creates an oriented curve (path)

  • PathCV

    The PathCV object creates control vertices used by the Path object.

  • Python Script

    The Python Script object is a container for the geometry operators (SOPs) that define a modeled object.

  • Ragdoll Run Example

    Crowd example showing a simple ragdoll setup.

  • Reference Image

    Container for the Compositing operators (COP2) that define a picture.

  • Rivet

    Creates a rivet on an objects surface, usually for parenting.

  • Simple Biped

    A simple and efficient animation rig with full controls.

  • Simple Female

    A simple and efficient female character animation rig with full controls.

  • Simple Male

    A simple and efficient male character animation rig with full controls.

  • Sound

    The Sound object defines a sound emission point for the Spatial Audio chop.

  • Stadium Crowds Example

    Crowd example showing a stadium setup

  • Stereo Camera Rig

    Provides parameters to manipulate the interaxial lens distance as well as the zero parallax setting plane in the scene.

  • Stereo Camera Template

    Serves as a basis for constructing a more functional stereo camera rig as a digital asset.

  • Sticky

    Creates a sticky object based on the UV’s of a surface, usually for parenting.

  • Street Crowd Example

    Crowd example showing a street setup with two agent groups

  • Subnet

    Container for objects.

  • Switcher

    Acts as a camera but switches between the views from other cameras.

  • Tissue Solver

    Collects muscles, anatomical bone models, and skin objects and places them into a single dynamics simulation.

  • Toon Character

    A ready-to-animate Toon Character.

  • Top Network

    The TOP Network Object contains nodes for running tasks.

  • VR Camera

    Camera supporting VR image rendering.

  • Viewport Isolator

    A Python Script HDA providing per viewport isolation controls from selection.

  • glTF