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General User Interface

Draw Lines Smoothly

Enables the OpenGL option of anti-aliasing all vectors in Houdini including the UI and the 3d viewports. You can see this immediately on the wires that connect tiles, the tile profiles, etc.

See also, the Smooth Lines option on the Wireframe subtab of the Optimization tab in the Display Options window.

Color Pane Headers with Network Contexts

The Pane header contains the pane tab and the path gadget, which has a gray background by default. If this is option is turned on, the background color of the pane headers will be changed to their representative network type color.

Show Images for Image Files in File Browsers

The default value for Show Images in image-based file browsers (in the menu over the files).

Left-hand Menus

Build menus to the left, rather than the right of the mouse cursor. This is useful for right handed people using on-screen styli.

Play Audio with Popup Notifications for

Enables or disables the sounds that play with message, warning, or error dialog windows.

File Choosers

Allows you to select a file chooser style.


This option is only available for Macs.

Houdini Chooser Only

Houdini will use own chooser for all file browsing

Mix of Houdini and Native Choosers

Houdini will use native OS’s file chooser for File ▸ Open, and own chooser for all other file browsing.

Native Chooser Only

Houdini will use file chooser native to the OS for all file browsing.

Startup in Desktop

Which desktop appears when Houdini starts up. By default it is Build.

Global UI Size

Allows you to change the Size of the UI. Changes to this parameter will take effect in your next Houdini session.


A very compact size designed to maximize viewer area.


Slightly more compact size than the Normal size, reducing margins and icon sizes.


The default Houdini UI size.


Slightly larger UI size for small, high-res screens. Icon buttons and fonts are about 10% larger.

High DPI

Very large UI size for use with high DPI screens (>200dpi), such as the Macbook Pro’s Retina display.

Network Editor, Nodes, and Trees

Animate network changes

Animates certain changes and transitions in the network editor for clarity (for example, moving nodes out the way when a new node is placed). Turn this off to disable animations.

Use simplified shape when node shapes off

In the network editor’s View menu, you can turn off display of custom node shapes. If that option and this option are both on, Houdini uses an even simpler default node shape (a simple rectangle instead of a rounded rectangle). This may speed up the display of extremely complex networks.

Display full comments and descriptive parameters

By default the network editor cuts off long node comments and descriptive parameter values (displayed below the node name) after a certain number of lines. Turn this on to always display the full text of comments and descriptive parameters no matter how long.

Display VOP input and output descriptive labels

On VOP nodes, label inputs and outputs with the human-readable label instead of the internal name.

Stacked look for nodes with interesting contents

By default, nodes that users might want to dive into (such as unlocked assets, Geometry objects, subnets, and so on) are drawn with a stacked look to make it clear to new users they can dive into them. Turn this option off to never draw the stacked look for any nodes.

Node info windows close when losing focus

When this option is on, if you open an info window with the info button on the node ring, the window stays open until it loses focus, so you don’t have to manually close it. If you turn this option off, the window always stays open until you close it.


On Mac and Windows, this option is on by default. On Linux, this option is off by default, since some users have the window manager set up so "focus follows mouse", which always makes info window close immediately.

Flag hotkeys work on existing node selections

When this option is off (the default), flag hotkeys work by holding the key and clicking a node to set the flag. When this option is on, pressing a flag hotkey sets the flag on the selected node(s).

Allow diving into locked assets

If you turn this off, you cannot dive into locked assets, unless they have a dive target node specified. A studio may want to specify that this option be turned off to prevent artists from accidentally diving into assets and getting lost.

Snap radius

The radius for snapping moved/placed nodes to align with other nodes. Increase this distance to make nodes more likely to move to align with other nodes when dropped.

Connection snap radius

The radius for snapping wires to connectors. Increase this radius to have wires jump onto connectors from farther away. Decrease it to have wires not jump to connectors until you get closer.

Shake distance

Shaking nodes disconnects them from their wires. This slider controls how far you have to move the mouse back and forth for Houdini to recognize a shake. If you are getting accidental disconnects because Houdini thinks you are shaking, you might want to decrease this. Turn the slider all the way down to disable shaking to disconnect.

Show previews on new COP nodes

You can show or hide the preview thumbnail on each individual compositing node. This checkbox controls whether newly created compositing nodes show or hide the preview.

Initial VOP detail level

You can set the compactness level on each individual VOP node. This menu controls what the initial level for newly created VOP nodes.

Display icons in operator tree views by default

Various interfaces in Houdini show hierarchical lists of nodes (for example, the node picker or the tree view pane). Turn this off to not display icons next to node names in these tree views.

Display Embedded Visualizer Editor

When one or more visualizers are attached to a node, display the visualizer settings in a separate tab in the parameter editor.

3D Viewports


Y Up

The standard Houdini orientation with the positive Y axis pointing up.

Z Up

An alternate right-handed orientation with the positive Z axis pointing up.

Tumbling Method

Standard Houdini Tumbling

The normal Houdini method of tumbling the display (using ). It is such that the tumbled is attached to the mouse, and moving the mouse back to the same location on the screen results in the tumble returning the same result for that location. This is intuitive for most users.

Classic Houdini Tumbling

With the classic method of tumbling, you move the mouse in small circular motions counter to the direction you want to turn. You will get a tumble-orientation that moves continuously counter to the direction in which you are moving the mouse. This actually provides more control over the tumble once you have got the knack of it.

80's Style Euler Tumbling

Provides the option for 80's Style Euler tumbling - for those who prefer it.

90's Style Euler Tumbling

When tumbling vertically, do not lock at the y-axis, but tumble right over, now viewing your model upside down. This allows more fluid control while still maintaining a fixed up direction.

Use Alt Key for View Controls

Allows you to tumble, dolly, track, tilt, zoom, and box zoom using the Alt key. See View the scene for more information.

Panning Method

Move Pivot when Panning

The pivot about which the Viewport swivels will always be the center of the Viewport - even if you've panned the geometry off to the side.

Maintain Viewport Pivot when Panning

The pivot about which the view swivels will be maintained around the geometry in question - even when it has been panned away from the center of the Viewport.

Default Tumble Pivot

Determines the default tumbling behavior for new viewers.

Keep Pivot on Tumble

Tumbling will use the current view pivot.

Set Pivot on Tumble

Tumbling will set the view pivot to be on the geometry lying under the mouse at the start of the tumble operation, if any, and otherwise leave the view pivot unchanged.

Default Dolly Direction

Determines the default dolly behavior for new viewers.

Dolly along View Direction

Move the camera in the view direction.

Dolly along Projected Direction

Move the camera along a direction projected from the mouse position at the start of the dolly operation.

Default Zoom Center

Determines the default zoom behavior for new viewers.

Zoom about View Center

Zoom the view about its center.

Zoom about Mouse Position

Zoom the view about the mouse position at the start of the zoom operation.

Default Homing Method

Controls what happens when you hit the home hotkey. The default is Oblique, which has a value of 45 degrees.

Wire Toggle Mode

Allows you to change the shading mode. You can also do this by pressing the W hotkey in the viewport.

Delay Inactive Viewport Redraws

If this option is turned on, Houdini will delay inactive viewport redraws in the quad view. In the quad view, one section is active and the other three are inactive. When an action is done in the active viewport, it will be updated aggressively and the inactive viewports will lag behind. The inactive viewports will be redrawn once the active viewport is completely updated. Turning this option on improves performance.

Highlight component under mouse when selecting

Allows you to turn off the display of highlighting the component under the mouse in the viewport.

Shelf Tools and Tab Menu

Tool History Length

The number of least recently used menu items that are kept as history in the Tab menu.

Tab Menu Operator Namespace Filtering

Determines which variants of the same operator are displayed in the Tab menu. The operator variants share the same base operator name but differ in scope, namespace, and/or version.

Show All Operators

Displays all available operator variants.

Show Only Operators with Preferred Versions

Displays several operator variants, one from each namespace defined for a given operator. For each namespace, an operator variant with the preferred (usually highest) version is displayed.

Show Single Operator from the Preferred Namespace

Displays only one variant of the operator. The displayed variant is from the namespace with the highest precedence order, as configured by the user with HOUDINI_OPNAMESPACE_HIERARCHY environment variable. If there are a few variant candidates in the same namespace, the preferred version is used.


Allow Auto Take Mode for Locked Assets

Allows you to edit contents of locked assets in the auto take mode, overriding the interior parameters inside the current take.


This parameter affects the auto take mode, not takes in general.



Auto-Key: Add Keyframes on Parameter Change

When enabled, parameters changes are immediately processed (i.e. "cooked"), and the changes reflected in the geometry displayed in the Viewport.

Auto-Key Tuples Parameters

When this checkbox is turned on, and when the Auto-Key is active, keyframes are inserted on all tuple parameters. This is very important when animating using the manipulators.

Auto-Commit: Save Parameter Change at Keyframes

When you change keyed parameters on keyframes, the new values are automatically saved as the new keyed values. You do not need to explicitly key the values.

Set Auto-Scope Flag when Creating Channels

Automatically turns on the auto-scope flag when creating a channel. This is for advanced use cases where Scope Parameters with Animation isn’t enough.

Set Additional First Key at Frame

Will set an extra keyframe at the specified frame (typically frame 1) when a keyframe is added. If left blank, no extra keyframes will be added.

If set to '1' - it will approximate the behavior of older (pre H6) versions of Houdini, which would automatically add a key at the first frame.

Global Set Key

Set Keys on Pending Channels

Set keys on channels where changes have been made.

Set Keys on All Scoped Channels

Sets keys on all channels which are scoped.

Initial Segment

Default / Rotation Function

You can set the default segment interpolation function to be of the type you specify here. e.g. cubic. You can also set the default function used for rotations.

Added Segments

Auto Function

Attempt to automatically determine the best function to interpolate between added keyframes. When disabled, adding keyframes inserts segments of the type specified here.

Auto Slope

Attempt to automatically match incoming / outgoing slopes on channels. When disabled, adding keyframes will set the new segment slopes to the specified value.

Hold Last Key

When adding keyframes in the last segment of a channel, the final segment is modified to hold it at the same value between the last keyframe and the end of the animation. Enabling this parameter allows you to insert keyframes repeatedly without changing the interpolation of the last segment.

Animation Editor and Motion FX Viewer

Scope Parameters With Autoscope Enabled

Parameters of the selected node(s) which are marked as autoscope will be displayed in the Animation Editor.

Scope Parameters With Animation

When this checkbox is turned on, the Animation Editor will scope parameters that have animation. It’s an easy way to see the animated parameters on selected nodes without having to set the auto-scope flag or scoping channels manually.

Scope Parameters from Descendants

When this checkbox is turned on, the Animation Editor will expand the selected nodes to include all the child nodes.

Scope Parameters from Constraints

When this checkbox is turned on, the Animation Editor will expand the selected nodes to include all the constraints nodes.

Open Animation Editor if Closed

If enabled, a new Animation Editor window will pop-up if there is none currently visible in the desktop.

Follow Scoped Channel References

If enabled, the autoscope list follows channel references and CHOP exports. When this checkbox is turned off, you will see the result of the expression in the graph editor, but won’t be able to edit any keyframes.

View Overridden Parameters in Motion FX View

Parameters of the selected node(s) that are currently overridden by CHOPs will be displayed in the Motion FX View pane.


Available Render Nodes

Lists the render nodes available in Houdini that you can enable or disable.It is possible to override the preferences with the HOUDINI_DEFAULT_RENDERERS environment variable. Any render nodes thus overridden will be grayed out in the preferences. If a render node, which is not enabled in this list, exists in the scene, its temporary enabled state will be noted in the Enabled By column. Any render node enabled through that mechanism will not affect the session-to-session preferences.

Make All Render Nodes Available in Tool Palette and Tab Menu

If enabled, all render nodes will be shown in the output driver tool palette and tab menu. Otherwise, only the subset of render nodes selected in Available Render Nodes will be shown.


Hide Locked Handle Parts

Keeps locked handle parts from being displayed. You will need to reload the file to take effect for existing handles.

Color Transform Handles By Axis

If this option is turned on, the transform handles in the 3D viewer will display different colors depending on the axis they affect.

Keep handle alignment when reselecting

If this option is turned on, the transform handles in the 3D viewer will maintain the same orientation when different objects are selected.

Default Handle Alignment

Determines the initial orientation for transform handles in the 3D viewer.


Align to the local space.


Align to world space.


Align to view.

Parent Object

Align to the object’s first input.

Handle Scale

Scales fixed-size handles in the viewports.

Pick Distance (Pixels)

Specifies how far away the mouse cursor can be from a handle in order to pick and manipulate that handle.

Show Negative Axes for Translate Handles

Extends the translation handle axes in the negative direction.

Show Planar Dragging Targets for Translate Handles

Shows small draggable translate planes away from the center of the handle.

Allow Planar Dragging of Translate Handles Between Axes

Allows you to select a drag plane between the translation handle axes in the 3D viewer.

Prefer Planar Dragging Between Axes Over Back Facing Axes

Disables the back facing parts of translation arrows, so that when you are dragging on a plane you don’t accidentally select them.

Allow Dragging of Rotate Handles Between Rings

Allows you to click and drag between the rings of rotation handles in the 3D viewer when no translation handles are available. This will allow you to perform rotations in all 3 axes simultaneously.

Allow Indirect Handle Dragging with MMB

Allows you to drag handles with the without starting the drag on the handle itself.

Not all handles support this option. When multiple handles are displayed, the one closest to the mouse cursor that does support it will be chosen.

Translate Handle

Controls how indirect dragging behaves with translate handles.

Map Drag to Axis

Drags along the handle axis best matching the mouse motion.

Map Drag to Construction Plane

Drags across the construction plane, defaulting to the view plane when the construction plane is not displayed.

Map Drag to View Plane

Drags across the view plane, regardless of whether or not the construction plane is displayed.

Spider Handle

Controls how indirect dragging behaves with the spider handle available for joints.

Map Drag to Axis

Drags along the handle axis best matching the mouse motion.

Map Drag to Construction Plane

Drags across the construction plane, defaulting to the view plane when the construction plane is not displayed.

Map Drag to View Plane

Drags across the view plane, regardless of whether or not the construction plane is displayed.

Prefer Indirect Translate Over Indirect Rotate

Controls which operation indirect dragging performs for handles showing both translate and rotate components.

Prefer Indirect Translate Over Indirect Vector Rotate

Controls which operation indirect dragging performs for handles showing both translate and vector rotate components.

Prefer Indirect Translate Over Indirect Scale

Controls which operation indirect dragging performs for handles showing both translate and Scale components.

Hide Rotate Handle Rings Parallel to the View Direction

If this option is turned on, rotate handles will hide any rings edge on to the current view direction. Turning this option off will only affect rotate handles without any translate axes.

Show View Axis Ring for Rotate Handles

If this option is turned on, rotate handles will draw an outer ring for rotating about the current view axis.

Default Transform Handles to Gimbal Mode

If this option is turned on, the initial mode of rotation handles in the 3D viewer will be in Gimbal Mode. In gimbal mode, the rotation circle handles will always be aligned so that manipulating them will only affect the rotation angle of their respective axis.

Default 2D Orientation Handle Transform is Global

This setting affects the orientation handles for manipulating lights and cameras. There are two ways to manipulate the handle: in local space or in global space.

If this option is turned on, the default mode will be in global space. To manipulate in local space, hold down the shift key when manipulating the handle. If this setting is turned off, the default mode will be in local space, and the shift key needs to be held down for global space manipulations.

Open Animation Editor If Closed When Scoping From Handles

When scoping from handles, it will open up a new Animation Editor (if one is not already open).

Scope Channels When Setting Keyframes

Do not Scope

Do not alter what is displayed.

Add to Scope

Add channels to the scope in addition to whatever channels are already being displayed.

Replace Scope

Replace whatever channels are scoped when adding keyframes to handles.

Interactive Tools

Use Cook Selection to Update Geometry Selection Type in SOP States

Specifies whether SOP tools update the component selection type to match the type of component the tool operates on.

This addresses the situation where you've selecting one component type, say edges, but the node takes that edge selection, and generates output of a different type, say faces. In that case, you would see a faces selected in the viewport, but if you started selecting, you would still be selecting edges. When this option is on, if for example the node generates faces, Houdini automatically switches the selection mode to faces.

If you change this preference while a tool is active, you may need to leave and re-enter the tool for this to take effect. Not all tools support this preference.

Automatically Turn Construction Plane On

Toggle which interactive tools automatically turn on the construction plane when started with it off but the reference plane on.

Objects and Geometry


Highlight Object Selections in Viewport

Provides visual feedback when objects are selected in the Viewport.

Automatic Parameter Folder Flipping when Picked in Viewer

Flips parameter pane folders to the folder that contains the first parameter that is referenced by any channel in the selected object if such a reference exists.

Default Geometry Display

Specifies the default geometry display mode of the 3D viewer. This only affects the 3D viewer in Geometry selection mode.

Show Current Operator

Geometry is displayed and selected from the current (ie. the last selected) node.

Show Display Operator

Geometry is displayed and selected from the node with the display flag enabled.

Default Context Creation

Specifies the default context creation mode. To change it in the 3D viewer, use the icon menu in the upper-right corner.

Create at Object Level

Creating new geometry (eg. Box tool) from the shelf will create a new object to contain it.

Create in Context

Geometry will be created within the current context (eg. another piece of geometry in the same object).

Use Existing Selection to Complete Actions

If enabled, tools use the existing selection if available to complete their actions when they are invoked.

Secure Selection On by Default

Enables secure selection by default. When secure selection is enabled, it prevents you from losing your selection with a stray click.

Create Full Loop Selections Through Any Topology

When enabled, loop selections performed in the viewport will create full loops even if this means passing through regions of irregular topology. If this option is disabled, loops will terminate at points where there are multiple possible paths. Consider the example of selecting a longitudinal edge on a polygon mesh sphere. If this option is turned on, an edge loop will be created that passes through the poles of the sphere. If this option is turned off, the loop will stop at the poles.

Select Entire Subnets On by Default

When enabled, the default behavior will be to select the subnets when you select the containing node.

Highlight Selected Geometry in Viewport

When an object is selected, Houdini will highlight the corresponding object in the Viewport.

Popup Menu Selection

If this option is turned on, a menu will pop-up when clicking a spot in the 3D viewer for selecting has multiple objects to allow you to choose which one to select.

When clicking on a spot in the 3D viewer for selecting has multiple objects, a menu will pop-up to allow choosing between them.

Keep Position when Parenting


When set to Never, objects will not maintain their world position when you parent objects together, rather, they will assume a space relative to the parent object.


When set to Always, objects will maintain their world position and orientation even if you rewire an object node to set its parent (this is done by changing the object’s Transform/Rotate/Scale parameters).

Use Object Flag

This setting will maintain an object’s world position according to the Keep Position When Parenting parameter of the individual object.

Bone Kinematic Override


If none is selected, there is no kinematic override.

IK Rest Pose

If rest is selected, all bones are cooked at their rest positions. The bone rest positions control how Inverse Kinematics are solved for them.

Capture Pose

If capture is selected, all bones are cooked at their capture positions. The bone capture positions are used when capturing skin geometry using the Capture and Capture Proximity SOPs.

Keep Position When Moving

If this option is turned on, moving an object will not affect the position and orientation of its child objects. This is done by modifying the child object pre-transforms and/or transform parameters.

Read-Only Pre-Transforms

If this option in turned on, you will not be able to manipulate objects' pre-transforms.

=== SOP Caching == (sopcache)

Cull Level

Higher settings tell Houdini to be more aggressive at keeping the cache size down, saving memory at the expense of speed.

Memory Limit

The amount of memory to use to cache geometry transforms.



Never unload SOPs.


Only unload SOPs if the unload flag is set.


Always unload SOPs.



Ignore the memory limit.


Unload SOPs when the memory limit is reached.

OBJ Caching

Houdini can cache object transforms for individual objects once it’s calculated them when you turn on the object’s Cache data option. 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 on by default for Sticky and Bone objects.

Memory limit

The amount of memory to use to cache object transforms.

Enforce Limit

Controls whether Houdini observes the Memory limit or not.

Clear cache

Empties the cache immediately.


To turn off caching on all objects without setting their individual Cache data options, set the memory limit to 0 and click Clear cache.


You can use the objcache command to manage the OBJ cache through HScript.


Skip Particle Info Generation (Faster)

Bypasses the generation of info in the pop tiles' info pop-up (click tile with ). This speeds up the particle simulation, at the expense of generating more informative feedback.

Motion and Audio

Maximum Time Slice Size (Frames)

This option allows you to limit the size of a Time Slice, expressed in frames. The default maximum is 60 frames. This is useful if you only need a few frames of history, and the Playbar is jumping ahead by large intervals. If a Time Slice is larger than this maximum size, it will be clipped from the current frame backwards (causing a gap between this slice and the previous one). The slice will always end on the current frame.

Enable Time Slice Flag when Creating CHOP

Sets the default behavior for when you place a CHOP in the Layout Area.

All chops with Time Slice capability created while this option is on will have their Time Slice flags enabled by default. Otherwise, all chops are created with the Time Slice flag turned off. This is a convenient option to leave on when creating and working with large Time Sliced networks. This option is off by default.

Minimal Time Slice Cooks

Some Time Sliced chops can minimize their cooking, rather than cooking every frame. When cooking is unnecessary, or it produces the same output, these chops will stop cooking until an input changes.

chops that have this feature are:

  • Copy chop

  • Count chop

  • Envelope chop

  • Lag chop

  • Spring chop

  • Trigger chop

Minimal Cooking will not apply to these Time Sliced chops if they have non-constant chop inputs or time dependent chop inputs. This option is off by default. It can speed up puppeteering and chop networks that respond to isolated inputs or events.



Interactive Cache Size

The size of the tile cache, in MB. If you use the compositor constantly, you should set this to a fairly large value (half the available memory for systems with more than 256Mb). This only applies to interactive applications.

Non-interactive Cache Size

The size of the tile cache, in MB, that is used when the compositor is not being used interactively (hbatch, hython).

Reduce Cache Size when Idle

In interactive applications like Houdini, when the compositor goes idle for a short time (5 minutes) it begins slowly pruning the cache down to this size. This can free up memory for use in the rest of the application.

Clear Cache

Clears all the compositing caches.


Multi-threaded Cooking

If enabled, multi-threaded cooking is enabled. Otherwise, only 1 thread is used to cook images (the main Houdini process).


Specifies the number of threads to use when cooking. If set to 1, only the main Houdini thread cooks images (as if Multi-threaded cooking was off). To saturate a multiprocessing computer, use twice as many cooking threads as processors.

Use GPU to Assist Compositing

Allows certain COPs to be accelerated using OpenGL. Changing this preference requires a restart of Houdini. The following is a list of available accelerated operations. Operations that are greatly accelerated are marked with a *.

  • 2D transforms, including motion blur*

  • Fog (noisy fog*)

  • Z-composite

  • Lighting (all, volumetric*)

  • Environment map

  • all basic color corrections (bright, gamma, color curve, HSV, hue curve*, color correct, etc)

  • Expand*

  • Convolve*

  • Deform*

  • Corner Pin & Unpin

  • Noise (perlin, imp. perlin, sparse*, alligator*; no random)

Use Collapsible Pixel Operators

If enabled, collapsible pixel operators in series (blue COPs) will be combined into one operation. If off, they are all processed individually.

Tile Size

The size of the tiles. The image is divided into these tiles and processed in chunks. If you are always working at a specific resolution, you may want to specify a tile size that exactly divides the horizontal and vertical resolution. Changing this value will flush all the caches. A tile must have at least 1024 pixels in it.

Resolution Limit

Allows you to specify the max. size an image in the compositor is allowed to be.


Cook Displayed Operators on Startup or Load

If this option is turned on, COPs that are displayed cook initially when the hip file is loaded. If this option is turned off, they will not cook and the viewport will remain black.

Use Fast Interactive Cooking

If enabled, the resolution of images is automatically down-scaled to a smaller resolution while an interactive edit is in progress (dragging a handle, sliding a slider or XCF slider). This gives much quicker feedback at the expense of quality. If off, the image will be cooked at normal resolution.

Only Use Fast Cooking On Slow Operations

If enabled, fast operations (like Bright, Gamma and Timing COPs) do not cause the interactive down-scaling of images. If off, all operations down-scale the image during user interaction.

Use Fast Cooking on Images Larger Than

Sets a lower resolution limit on the images that will be down-scaled during user interaction. Images smaller than this limit will not be down-scaled. In the case that the image doesn’t match the aspect ratio of this preference, the number of pixels in the images is compared and used as the limit.

Interactive Rendering Fraction

Specifies the down-scale factor. Smaller factors give much faster updates during interaction at the expense of image quality.

Cooking Feedback

Allows you to set the type of feedback which you receive while a single image is cooking:


Nothing updates until the image is finished cooking.

Progress Bar

A progress bar at the top of the image viewer updates periodically while cooking the image.

Image Update

The viewport containing the image being cooked updates periodically, showing the actual progress of the cook. This has a fairly minimal performance hit.


Never Prompt for Optional Inputs

If enabled, once the minimum number of sources are connected, input selection is considered to be complete. If an Always Place option is specified, the COP will be immediately placed in its selected Viewport.

Never Prompt for a Generator’s Input(s)

If enabled, inputs for generators are never prompted.

Always Place the New COP in the Current Viewport

If enabled, once selection of all inputs is complete the COP will be placed in the current viewport without prompting for the destination viewport.

Always Place New Generators in a New Viewport

If enabled, generators will be added to a new viewport, if available (otherwise the current Viewport is used). If off, you will be prompted for a destination viewport.


This page allows you to customize the names of common plane types. The default names are the first letter of the English plane name, capitalized. These are the names that are used in the scope fields, plane lists, VEX scripts and output Houdini .pic files.


COPs can be colored by family type. Any new COP in that family will have its tile colored to the family color for easy identification.

Enable COP Auto Coloring

Enables or disables this feature for all COP types. You can also individually disable family types that are not important to you.


The color for all generators. Because generators can take an input and generate planes 'inline' (in the middle of a network), this helps you spot where in the network planes may be created or masked.

Pixel Functions

The color for all Collapsible pixel operations. Because collapsible pixel operations only work when grouped together in a chain, this helps you optimize your network for these types of operations.


The color for all timing-related operations and non-image related operations (like merge and delete). These operations normally do not cook images or use any cache memory. This helps you track down timing changes in a large network.


The color for all VEX-based operations. VEX COPs have the special characteristic that all plane names matching the VEX script’s parameter names override those parameters on a per-pixel basis, so it is important to recognize these COPs.


This page defines the default values for all Cineon parameters in all new File COPs and Compositor output drivers. It also defines the cineon parameters that are used when a Cineon file is loaded or saved outside these two contexts (like from the Save Image… COP tile menu). Cineon files have an extension of .cin.

Convert from 10 bit Log

If enabled, the Cineon file is converted into linear space. Otherwise it remains in its 10 bit log space (with values from 0 - 1024).

LUT File

The LookUp Table file containing the 10bit cineon conversion (.lut). This file may be created manually or with the standalone icineon or ilut tools.

Black Point

The Cineon value (0-1023) that maps to black when converted to linear colorspace. This and the White Point and Film Gamma is used when loading Cineon files (.cin). This only has an effect if the LUT File field is empty, otherwise the LUT is used for the conversion instead.

White Point

The Cineon white point, which defines the Cineon value (0-1023) which represents 90% image intensity. This parameter is not used if a LUT file is specified.

Film Gamma

The Cineon film gamma, which defines the gamma to use in the conversion from Cineon space to linear image space (the space which the compositor operates in). This parameter is not used if a LUT file is specified.


Expression Language


Changes the default expression of new nodes to hscript.


Changes the default expression of new nodes to python.

Parameter Fields

Entry boxes for parameters, such as those in the parameter editor.

Text Editors

Multiline text editors, such as those located in Edit Comments.


The textport.

Syntax Highlighting

Turns on text colors to help you differentiate between syntax.

Parenthesis and Quote Matching

Highlights the matching parenthesis or quote when your cursor moves over it. This lets you know if things are properly matched up as well as where complicated expressions begin and end.

Context Sensitive Popup Help

Shows the possible completion names when you start typing a valid function name or operator path. It also provides help as to the parameters of that function.

Desktops and Toolbars

Save Desktops Automatically

Changes to Panes within Desktops are saved automatically.

Show Hidden Files

Shows files that are marked as hidden (whose filename starts with a period).

Show All Files

Shows all files, regardless of what type they are.

Path Menu Behavior

Allows you to define the path menu behavior when you open the Desktop Manager window and use the drop-down menus to switch the Location of a desktop, instead of being prompted each time (default behavior).

Save and Load Options

Save Method

Overwrite File

Will overwrite the existing file you opened with the present state of the hip file.

Increment Filename

If enabled, and the name of your file contains a number, then the number will be bumped up by one every time you save the file. This does not happen with Save As, only with Save (also see the -i option on the mwrite command in the Scripting section).

Make Numbered Backup

With this setting, the filename of the .hip file will remain the same, but backup files will be created which are incrementally numbered. The default backup directory is: ./backup and the backed up files will have a __bak{num}_ suffix.

Save View Commands For

This preference is helpful for reducing file bloat.

All Viewers

Save view commands for all existing viewers (whether currently open or not), as well as any stashed view commands for viewers which have not yet been created.

Existing Viewers

Save view commands for all existing viewers (whether currently open or not), skipping any stashed view commands for viewers which have not yet been created.

Open Viewers

Save view commands only for viewers that are currently open.

Auto Save Every Minutes

Specifies the interval for the auto save feature.

Auto Save Method

Overwrite File

Will overwrite the existing file you opened with the present state of the hip file.

Increment Filename

If enabled, and the name of your file contains a number, then the number will be bumped up by one every time the file saves.

Make Numbered Backup

With this setting, the filename of the .hip file will remain the same, but backup files will be created which are incrementally numbered. The default backup directory is: ./backup and the backed up files will have a auto{num} suffix.


You must turn on the Auto Save checkbox in the Edit menu to enable auto saving. Auto-save is automatically disabled when Houdini starts up, because it can slow down Houdini and take up a lot of disk space if it is left on unintentionally. You must manually enable it for each session.

Warn About Deprecated Operators

If enabled, Houdini will open a warning dialog box with the list of nodes using operators that have been marked as deprecated. Toggle off if you prefer not to see such warnings.


Operators that have been marked deprecated may be subject to removal from future versions of Houdini.

Hip File Options

Unit Length

The length in meters of one Houdini unit. This value is used by some unit-specific DOPs parameters.

Unit Mass

The mass in kilograms of one Houdini unit. This value is used by some unit-specific DOPs parameters.


Unit time is always one second.


Notification Area

Notifications, such as errors, warnings, prompts, and help tips can be displayed directly in the viewport or the status bar. Only messages related to the viewport will be shown in the viewport; cook messages and progress will be still be reported in the status bar.


Notifications will appear at the bottom of the viewport.

Status Bar

Notifications will appear in the main status bar of Houdini.

Help Tip Area

Notifications that act purely as help tips and do not direct actions or reports warnings or errors can be treated differently than other notifications.


Help tips will appear at the bottom of the viewport.

Status Bar

Help tips will appear in the main status bar of Houdini.


Help tips will not be shown.

Echo Hotkey Commands

Commands executed by hotkeys will have their action displayed in the viewport or status bar.

Message Time Limit

Help tips, messages, and hotkeys will be shown for a short time if this option is enabled, otherwise they will be shown until the next message replaces it. The duration of the display can be specified as well.

Warning Dialogs

The options in this window allow you to toggle warnings on and off. By default all of the warning dialogs are turned on.

Performance Options

Percentage Thresholds

This setting controls the color values used to display relative cook times for node when using the performance monitor.

For more information on how to use the ramp, see Ramp parameters.

External Tools

File Compare

External GUI compare (diff) program.

Executable Path

The full path to the executable.

Command Line Arguments

This arguments used when launching the external compare (diff) program. The following variables can be used when constructing the command line:


(Required) Replaced with the path to the 'older' file, also considered the 'left' file.


(Required) Replaced with the path to the 'newer' file, also considered the 'right' file.


Replaced with a title to use for the left side instead of the temp file name.


A title to use for the right side instead of the temp file name.

Folder Compare

External GUI compare program that supports comparing folders. See File Compare for more detailed information.


Restrict Web Browser to Safe Commands

Restricts the HScript commands that can be run from the Houdini embedded web browser. Turning on this option can help prevent malicious scripts from running commands through Houdini.

Use External Help Server

Opens the Houdini help documentation in your system’s default web browser instead of Houdini’s built-in browser.

Reserve n KB for the Undo System

Specifies how much memory should be used for Houdini’s Undo system - the more memory you allocate, the more Houdini can Undo.

Delete Channels When Reverting to Defaults

Causes the Revert to Defaults operation to delete any channels on the parameters changed by this operation.

Revert Invisible Parameters to Defaults

Specifies whether or not invisible parameters should be affected by a Revert to Defaults operation.

Make Spare Parameters for Unknown Channels

If this option is turned on, spare parameters are created to hold the values of extra parameters that are not in your version of Houdini so that you can see what changed and possibly rescue the values, rather than discarding those parameters into the bitbucket. This is useful when your hip file is from an older version or if the otl defining the node is older. However, you can turn this option off if you do not want to clutter your nodes with obsolete parameters.

Spare/HDA Parameter Deletion

When you are in a Type Properties and you delete one of your parameters, there might be parameters inside the asset that point to that parameter.

The default is to Automatically Delete all References that are found. Automatically Delete only Simple Channel References does a more conservative job which could leave some references, but is less likely to destroy complicated expressions. Do Not Automatically Delete any References leaves dangling references, yet eliminates the possibility of expressions being affected.