Reference Main Preferences

General User Interface

Enable Double Buffering

Double buffering improves the quality of moving images on a 24 bit monitor. If Double Buffering is not being used, then your work is drawn directly to the screen without any synchronization with the monitor’s refresh rate. This causes areas of the screen which are being frequently redrawn to be displayed while being only partially redrawn. This produces a “flickering” effect. Double-buffering eliminates this flicker.

When Double Buffering is on, the new image is drawn in an offscreen buffer in video ram and then swapped into the display almost instantaneously, thereby eliminating the display of half-drawn images, and the flicker.

Why not have it on all the time? Because some machines do not have sufficient video ram to perform double buffering in full color. The color resolution must be halved and then still-frame image quality is reduced due to dithering.

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.

Play Audio with Popup Notifications

Enables or disables the sound that plays when a message, warning or error dialog pops up.

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.

Global UI Size

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

Network Editor, Nodes, and Trees

Center Zoom on Mouse

Scrolls the Layout Area in the Network Editor so that the tile is right beneath the mouse cursor after placement.

Connect Tiles with Thick Lines

Draws the lines connecting OP tiles with thicker lines.

Connect Tiles with Selectable Links

It allows you to click an existing link between two nodes and reconnect it by clicking on a new node. This option is turned on by default.

Place New tiles immediately

Places tiles immediately upon selecting an OP, instead of waiting for a second click to give the placement location of that new OP.

If the Scroll to the New Tile option is enabled, Houdini will adjust the display of the Network View so the newly placed tile is within view.

Scroll to New Tile

Pans the Layout Area to display newly placed tiles.

Automatically pan when holding down Alt and dragging outside the network editor

If this option is turned on, you can hold Alt when dragging to pan the network editor around instead of dragging and dropping the node. This is useful if you want to put a node somewhere that currently isn’t visible.

Scale Operator Names

Enables or disables the scaling of operator names in the network editor when you zoom in and out.

Minimum Op Name Size

Controls the minimum size that the operator names will zoom to. This can prevent the names from disappearing into illegibility.

Op Name Size

The size of the operator names when no scaling has occured. Use this as an overall scale to affect how readable the operator names are at your preferred working zoom level.

Maximum Op Name Size

Controls the maximum size that operator names will scale to. With the default font, values above 45 will fail.

Highlight the Currently Cooking Node

If enabled, then the tile that is being processed gets lit-up during when its is cooked.

Include Performance Statistics in Node Info

Includes performance info in the pop-up info for the tile.

Change SOP Render and Display Flags Separately

When enabled, when you click on a sop’s render or display flags, both of them will be set at the same time. When disabled, they will change together.

Display Icons in Operator Tree Views by Default

Will display OP tiles in a Tree View.

3D Viewports

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.

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 Homing

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.

Light Pass Color Buffer Type

Allows you to change the type of the auxiliary light buffer used for high quality rendering when Projected Textures or Shadows are enabled in a viewport. Generally you won’t need to change this unless you're experiencing problems with these particular viewport options on your video card. Note that you’ll need to restart Houdini before any changes take effect.

Takes

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.

Note

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

Animation

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-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 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.

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.

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.

Enable Channel Cache

Turning on this checkbox improves display performance in the channel editor by caching channel evaluations. However, this my prevent the channel editor from updating properly when the channel is changed.

Handles

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.

Object

Align to the local space.

World

Align to world space.

View

Align to view.

Parent Object

Align to the object’s first input.

Allow interior picking of Rotate Handles

If this option is turned on, you will be able to select the interior of rotation handles in the 3D viewer when no translation handles are available.

Selecting the interior of the rotation handles performs rotation in all 3 axes simultaneously.

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 Channel Editor If Closed When Scoping From Handles

When scoping from handles, it will open up a new Channel 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.

Objects and Geometry

Preferences

Highlight Object Selections in Viewport

Provides visual feedback when objects are elected in the Viewport.

Scope Channels

When objects are picked in the Viewport, its channels will be scoped.

Open Channel Editor if Closed

Opens a Channel Editor if necessary.

View Overridden Parameters in CHOP Viewer

The channels which are overridden by CHOP control are displayed instead.

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 enabled, it prevents you from losing your selection with a stray click.

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

Never

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.

Always

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.

Kinematic Override

None

If none is selected, there is no kinematic override.

Rest

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

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

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.

Unloading

Never

Never unload SOPs.

Flag

Only unload SOPs if the unload flag is set.

Always

Always unload SOPs.

Memory

Never

Ignore the memory limit.

Always

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.
Tip

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

Tip

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

Particles

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.

Compositing

Cache

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 and Houdini Escape, 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.

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.

Clear Cache

Clears all the compositing caches.

Cooking

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.

Multi-threaded Cooking

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

Number of Threads

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.

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:

None

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.

Image Update Style

Allows you to specify if images should be updated in Strips or in a Spiral fashion.

Selectors

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.

Names

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.

Colors

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.

Generators

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.

Timing

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.

VEX

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.

Cineon

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.

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.

Scripting

Expression Language

hscript

Changes the default expression of new nodes to hscript.

python

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.

Textport

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.

Save Toolbars Automatically

Changes to toolbars 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 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.
Note

You must turn on the Auto Save checkbox in the Edit menu to enable auto saving.

Miscellaneous

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.

Reserve Kb for the Undo System

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

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.
Note

Unit time is always one second.

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.