Houdini 19.5 Basics

Configuring Houdini

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Houdini has configuration options in many different places. Some of the most important:

  • Main preferences window:

    Choose Edit ▸ Preferences ▸ category.

  • Display options:

    Click the Display Options button in the 3D view (and some other views) to get options related to the view.

  • Option windows. Click the options button in a window or pane to edit its options.

See also how to change the hotkeys and how to customize the shelf.

Common UI customizations

You can customize the UI for a particular workflow, project, or facility.

To...Do this

Scale the Houdini UI

Choose Edit ▸ Preferences ▸ General user interface and change the Global UI size option.

You can also set the HOUDINI_UISCALE as an environment variable to access a full range of scaling values as a percentage of the normal size (default is 100).

Adjust the UI colors

Choose Edit ▸ Color settings.

Use Houdini 8-style pane coloring to show network type

Choose Edit ▸ Preferences ▸ General user interface and turn on Color pane headers with network contexts.

Add preset colors to the palette in the color picker dialog

  1. Use the color sliders to choose the color you want.

  2. Alt + LMB anywhere in the palette area to add the current color there. The color will be appended as the last entry.

    The color definition is saved in $HOME/houdiniX.Y/.palette (where X.Y is the version number of Houdini) so it persists between Houdini sessions.

Remove preset colors from the palette in the color picker dialog

  1. ⌃ Ctrl + LMB on the color entry in the palette area to be removed.

Common viewer customizations

To...Do this

Change the tumbling behavior

  1. Choose Edit ▸ Preferences ▸ 3D Viewports.

  2. Click a tumbling method. The default is 80s-style Euler tumbling, which doesn’t let you tilt the horizon or go upside-down by tumbling (you can still tilt using special keys, see the section on viewing).

Turn off multicolored handles

With this option off, Houdini will draw handles all-red instead of coloring the axes red, green, and blue.

  1. Choose Edit ▸ Preferences ▸ Handles.

  2. Turn off Color transform handles by axis.

Use a black background in the 3D viewer

  1. Click the viewport options menu and choose Display ▸ Display Options or press D to open the Display Options window.

  2. Click the Background tab.

  3. Set the Color Scheme pop-up menu to Dark.

Change the background color in a compositing viewer

  1. In a compositing viewer pane, open the right side toolbar and click Display Options or press D to open the Display Options window.

  2. Click the Background tab.

  3. Click the color swatch to choose a color.

Common network editor customizations

To...Do this

Choose whether to zoom in and out from the center or based on the mouse position

  1. Choose Edit ▸ Preferences ▸ Network Editor, Nodes and Trees.

  2. Turn Center zoom on mouse on or off.

Change how wires are drawn

  1. In the network editor, press D to open the display options.

  2. On the Network View/Display tab, set the Link style option.

Automatically place new nodes instead of requiring a click

  1. Choose Edit ▸ Preferences ▸ Network Editor, Nodes and Trees.

  2. Turn on Place new tiles immediately.

Paths and locations

Houdini uses two types of environment variables for specifying directories: paths (lists of locations to check for files), and locations (paths of directories).

In a command line shell, run hconfig -ap to show the current path and location assignments, and instructions and shortcuts for setting the variables.


Locations, like $HSITE (directory of site-specific files) and $HIP (the directory containing the current .hip file), specify the directory in which to find files for various purposes.

Unlike a path, a location variable can’t have multiple directories; it’s simply used to avoid hard-coding locations, as in $HFS/geo/model.bgeo instead of /usr/joe/files/show/act1/scene1/geo/model.geo. This makes the .hip file much more portable between machines and operating systems.


You can set the $HSITE variable to a directory containing site-specific files. You can set the $JOB variable to a directory containing project-specific files. The two locations are included in the path, but not defined by default. So, if you define one or both, they will already be included in the path.


The $HSITE directory must contain a houdiniX.Y directory (such as houdini9.0). If no such directory exists, Houdini will not search in $HSITE.


Paths, like $HOUDINI_PATH, can have more than one location, and Houdini searches the locations in the path in the order they appear in the variable.

Houdini uses paths to search for various file types (for example, $HOUDINI_GEOMETRY_PATH for .geo files) when the file’s location is not absolute.

For example, the default $HOUDINI_GEOMETRY_PATH is:


If you add a location to the path:


…then you can just use model.bgeo in a geometry file parameter and Houdini will find it if it exists in $HIP/geo/.

Some important Houdini paths:


Geometry (.geo) files.


Houdini digital asset (.hda) files.


HScript (.cmd) files.


Image files.


Channel and audio files.


Compiled VEX (.vex) files.

This not a full list of search paths. In a command shell, run hconfig -ap to see all available path variables.

Configuration files

Houdini will search certain paths to build up the configuration when it launches. The main path is in the environment variable HOUDINI_PATH. For different options, Houdini may find the first file it finds, or it may aggregate all files found in the path.

  • Execute the first startup scripts it finds (123.cmd and 456.cmd). See event scripts.

  • hopmanager.pref file (for OTL configuration). See Operator type manager.

  • OPmenu file (for customizing RMB menu options of nodes).

  • FBres file (for customizing the list of preset resolutions in pop-up menus on render nodes, lights, and cameras).

  • FBrender file (for customizing the list of preset sequence filename patterns in pop-up menus).

  • Most files under $HFS/houdini ($HH). You can copy these files into $HOME/houdiniX.Y (which is earlier on the HOUDINI_PATH) and modify them to override the files in $HH.


Preference files (.pref) that are outside of $HOME/houdiniX.Y must be suffixed with .nosave in order for them to be recognized, even if they occur earlier in the HOUDINI_PATH (ie, ui.pref.nosave).

Preventing user changes

  • If you are creating/copying .pref and/or .desk files manually instead of using the graphical interface (for example, to enforce uniform layouts/preferences across all machines), you can usually append .nosave to the filename to prevent the files from being overwritten with user changes. The user can still change the settings in a session, but those changes will not be saved between sessions.

  • For desktop (pane layout) files, this is the same as turning on the “no save” option in the desktop editing interface.

  • The downside is that a preference file often contains many different preferences and you may not want to lock them all down. The .nosave feature is most useful to override hopmanager.pref settings to provide a consistent set of OTLs.

  • Make sure the .nosave version of the file is higher in the HOUDINI_PATH than a regular version.

See also


Getting started

Next steps