Edit an asset’s user interface

Overview

Once you create a digital asset, you can use the Type properties window to edit the new node’s parameter interface. You can promote parameters from the node inside the asset up to the asset’s user interface. You can also add render properties to object assets for control over how they're rendered.

Right click an instance of the asset and choose Type properties, the click the Parameters tab.

As you edit the asset’s interface, remember that you need to click Apply or Accept in the type properties window to see the changes on the node.

Create and promote parameters

To...	Do this
Promote a parameter	In the network editor, dive inside the asset and select the node with the parameter you want to promote. Find the parameter in the parameter editor pane. Then do one of the following: Drag the parameter from a parameter editor into the parameter list of the type properties window. For parameters with multiple components (such as an X,Y,Z position parameter or an R,G,B color parameter), you can promote all components by dragging the parameter label, or a single component by dragging the component’s text box. Or Right-click parameter and choose Export Parameter to Type Properties.
Promote all parameters of a node	In the network editor, dive inside the asset and select the node with the parameter you want to promote. Then drag the node into the parameter list of the type properties window. If you drag a nested digital asset into the list, Houdini will promote the parameters from the nested asset with their organization intact.
Promote hidden or un-draggable parameters	In the type properties window, on the Parameters tab, click the From nodes subtab under Create parameters. This shows a tree view of every parameter on every node in the entire scene. Use it to find the node and parameter you want and drag it into the parameter list under Existing parameters.
Create a new parameter from scratch	In the type properties window, on the Parameters tab, click the By type subtab under Create parameters. Drag the type of parameter you want to create into the parameter list under Existing parameters. You can channel reference the value of the parameter on nodes inside the asset, or use it in scripts.
Make a menu parameter	Create/promote an integer, string, file, or node path parameter. Select the parameter under Existing parameters. Under Parameter description, click the Menu sub-tab. Turn on Use menu, then choose a menu type from the popup menu next to it. Click Menu items to set up a static list of value/label pairs, or click Menu script to write a script to generate the pairs dynamically. See the help for the menu tab for more information. You can channel reference the value of the parameter on nodes inside the asset, or use it in scripts.

Organize parameters

To...	Do this
Organize parameters into groups	In the type properties window, on the Parameters tab, click the By type subtab under Create parameters. Drag a Folder into the parameter list under Existing parameters. With the folder selected, the controls under Parameter description let you edit its type, label, and so on. The Type lets you present folders as tabs, collapsible headings, boxed groupings, and other looks. Drag existing parameters into the new folder. You can also drag a Separator into the parameter list to create a separator line between groups of parameters.
Put consecutive parameters side-by-side to save space	Select the first parameter and turn on Horizontally join to next parameter. If you want to hide the label on a "side" parameter, turn off the checkbox next to the Label option for that parameter.

To...

Do this

Organize parameters into groups

In the type properties window, on the Parameters tab, click the By type subtab under Create parameters.
Drag a Folder into the parameter list under Existing parameters.
With the folder selected, the controls under Parameter description let you edit its type, label, and so on. The Type lets you present folders as tabs, collapsible headings, boxed groupings, and other looks.
Drag existing parameters into the new folder.

You can also drag a Separator into the parameter list to create a separator line between groups of parameters.

Put consecutive parameters side-by-side to save space

Select the first parameter and turn on Horizontally join to next parameter.
If you want to hide the label on a "side" parameter, turn off the checkbox next to the Label option for that parameter.

Set up the asset for animation

To...	Do this
Make a parameter auto-scope in the channel editor	Select the parameter under Existing parameters. In the options under Parameter description, click the Channels sub-tab. Turn on the Autoscope icon next to the channel(s).

Add scripted controls and behavior

To...	Do this
Run a script whenever a parameter changes	In the type properties window, select the parameter under Existing parameters, then under Parameter description, on the Parameter sub-tab, enter a script in the Callback script field. The pop-up menu to the right of the Callback script field lets you choose whether the script is HScript or Python. See the help for the Parameters sub-tab for more information. See the HOM documentation for information on Python parameter callback scripts.
Run a script when an instance is created or destroyed	See the HOM documentation for Python event handlers.

To...

Do this

Run a script whenever a parameter changes

In the type properties window, select the parameter under Existing parameters, then under Parameter description, on the Parameter sub-tab, enter a script in the Callback script field.

The pop-up menu to the right of the Callback script field lets you choose whether the script is HScript or Python.

See the help for the Parameters sub-tab for more information. See the HOM documentation for information on Python parameter callback scripts.

Run a script when an instance is created or destroyed

See the HOM documentation for Python event handlers.

Handles and HUD sliders

You can also promote handles and HUD sliders from nodes inside the asset, so they appear in the viewport when the asset is selected. The type properties window must be open.

If you want a handle to drive parameters on nodes inside the asset, you must first promote the parameters onto the asset, then you can bind them to a handle.

Note

Handles and HUD sliders only appear when you are using the Handles tool, unless you right-click them and turn on "Persistent".

To...	Do this
Promote handles or HUD sliders from inside the asset	Dive inside the asset and select the node with the handle/slider you want to promote. Make the handle visible in the viewport. For HUD sliders, make sure their position and settings are what you want for the asset before promoting them. Right-click the handle or slider and choose Export handle to digital asset. Click Apply or Accept in the type properties window. You may need to deselect and reselect the node for the handle/slider to show up.
Create a handle for parameters on your asset	In the type properties window, click the Handles tab. Click Create handle and choose the type of handle. On the right under Bindings, you can choose which parameters will be modified when the user drags different parts of the handle. Click the drop down menu next to a binding field to choose from all the parameters on the asset.

To...

Do this

Promote handles or HUD sliders from inside the asset

Dive inside the asset and select the node with the handle/slider you want to promote. Make the handle visible in the viewport.

For HUD sliders, make sure their position and settings are what you want for the asset before promoting them.
Right-click the handle or slider and choose Export handle to digital asset.
Click Apply or Accept in the type properties window.

You may need to deselect and reselect the node for the handle/slider to show up.

Create a handle for parameters on your asset

In the type properties window, click the Handles tab.
Click Create handle and choose the type of handle.
On the right under Bindings, you can choose which parameters will be modified when the user drags different parts of the handle. Click the drop down menu next to a binding field to choose from all the parameters on the asset.

HUD slider default field

When you promote a HUD slider, Houdini puts information about the slider in the slider’s Default field on the Handles tab.

As long as you set up the slider the way you want before you promote it, you don’t need to mess with this field. But if you need to edit it for some reason, it uses the following format:

`hudx(105) hudy(130)`	Position in the viewer pane.
`hudw(120) hudh(16)`	Width and height.
`hudnameside(3) hudvalueside(2)`	Where the labels are positioned.
`hudharbourname('name') hudharbourx(105) hudharboury(130)`	Assigns the slider to a group. Sliders in the same group will dock together.
`hudlocklow(1) hudlockhigh(1)`	High and low value limits.
`hudrangehigh(10) hudrangelow(1)`	Slider range.
`ownerop('geo/tube1')`	The original owner of the parameter being controlled.

Edit an asset’s user interface

Overview

Create and promote parameters

Organize parameters

Set up the asset for animation

Add scripted controls and behavior

Handles and HUD sliders

HUD slider default field

Digital assets

Getting started

Creating assets

Next steps