Houdini 20.0 Basics

HUD handles

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Overview

While the parameter editor lets you edit the selected node’s parameters, the HUD (Heads Up Display) handles display in the view and control a parameter on a node. You can group handles together, move them around the view, and adjust their visibility. You can also create persistent HUD handles, which are indicated by a red dot. When you delete a node, any associated HUD handles are automatically deleted.

Use a HUD handle when you want easy access to certain parameters. For example, when you don’t want to switch back and forth between the view and the parameter editor. This means you don’t have to constantly navigate the parameter editor to find the parameter you want to update.

The HUD handle that displays depends on the original parameter type. The following are the available HUD handles:

  • slider

  • checkbox

  • dropdown menu

  • button

  • trackpad

You can bind HUDs to Python states as static (mapped to parameters) or dynamic (mapped to state callbacks) handles (see the hou.ViewerHandleTemplate class).

Note

The following information doesn’t apply to persistent HUD handles.

HUD handles are for each node type and display only when the parameter’s node is selected. When you create a HUD handle for a parameter on a node, a HUD handle is created for the same parameter type on other nodes. For example, if you create a HUD handle for a Transform node’s Translate parameter, other Transform nodes automatically get a HUD handle for their Translate parameter.

Persistent HUDs

Use a persistent HUD handle when you want constant access to certain parameters, such as in the following scenarios:

  • Parameters are on a deeply nested node that’s time consuming to navigate to.

  • You're constantly updating parameters from two different nodes and don’t want to switch back and forth between them.

  • You want to put useful parameters from a character in the view so you can access them even with the view maximized and the parameter editor hidden.

Unlike HUD handles, persistent HUD handles are for each node instance. They stay visible in the view if they are compatible with the current tool. For example, a persistent HUD handle on a sphere stays visible when a Tube node is selected. Persistent HUD handles are greyed out when using incompatible tools, such as the View tool. If your persistent HUD handles appear dimmed, switch to another tool to re-enable the HUD handles.

How to

To...Do this

Create a HUD handle

Drag a parameter from the parameter editor into the view.

The HUD handle is either automatically created or a dropdown menu with the following options displays:

  • HUD Handle adds a slider handle

  • Track Pad Handle adds a trackpad

  • Pivot Handle adds a 3D pivot handle

Create a persistent HUD handle

Use one of the following methods. The only difference is that when you turn off Persistent on a HUD handle created by dragging a parameter, the handle is removed.

  • To set an existing HUD handle as persistent, RMB the handle and turn on Persistent. This keeps the handle in the view when you switch between nodes.

  • To create a persistent HUD handle by dragging a parameter, do the following:

    1. Click and hold a parameter from the parameter editor.

    2. While clicking and holding, also press and hold ⇧ Shift while you drag the parameter into the view.

      The HUD handle is either automatically created or a dropdown menu with the following options displays:

      • HUD Handle

      • Track Pad Handle

      • Pivot Handle

Remove a HUD handle

RMB the handle and click Delete.

Show/hide HUD handles

  • To hide a handle, RMB the handle and turn off Visible.

  • To show or hide a handle, RMB the Handles tool in the toolbox to the left of the view. Use this menu to turn any handles on (show) or off (hide).

Edit a slider HUD handle’s range

You can edit the range only for a slider HUD handle.

  1. RMB the handle and click Settings.

  2. Turn off Use Parm Range, which sets the handle with the default HUD settings. When Use Parm Range is on, you can’t edit the range and the handle uses the node’s parameter settings.

  3. Enter the values for the minimum and maximum limits of the slider.

  4. If you want to prevent the value from being dragged out of limits, turn on Locking for the minimum and/or maximum values.

  5. Click OK.

Edit a HUD handle’s title or label

  • To edit a title, double-click the title. If no title is visible, RMB the handle and turn on Title Visible.

  • To edit the label of a slider, dropdown menu, or trackpad, double-click the label. You can’t edit the label of a checkbox or button.

Position and resize a HUD handle

Make sure Lock Placement is off.

  • To move the handle, drag the top of the handle.

  • To resize the handle, drag the bottom right of the handle.

Lock the HUD handle’s position and size

RMB the handle and turn on Lock Placement.

Lock the HUD handle’s current setting

RMB the handle and turn on Lock Parameters.

Dock HUD handles together to move/resize them as a group

  • To dock specific handles, press and hold ⇧ Shift while you drag the handle above or below another handle. Release the handle when a green line appears.

  • To dock all handles, RMB a handle and choose Dock from the All HUD Handles menu.

Ungroup docked HUD handles

  • To ungroup a specific handle, RMB the handle you want to ungroup and click Undock.

    Tip

    You can also press and hold ⌃ Ctrl while you drag the top of the handle off the stack. A red line appears when the handles are ungrouped.

  • To ungroup a stack of handles, RMB the handle stack and click Undock Stack.

  • To ungroup all handles, RMB a handle and choose Undock from the All HUD Handles menu.

For more options, RMB the handle to open the menu.

Tips

Note

The ⇧ Shift hotkeys won’t work if you have a handle selected. Click in an empty part of the view to deselect the handle.

  • To show or hide all HUD handles, press ⇧ Shift + F2.

  • To lock or unlock the position for all HUD handles, press ⇧ Shift + F3.

  • To move all HUD handles to the bottom-left of the view, press ⇧ Shift + F4.

  • To dock all HUD handles, press ⇧ Shift + F5.

  • To undock all HUD handles, press ⇧ Shift + F6.

  • To update HUD handles during playback, turn on Live Parameter Display during Playback in the Edit menu.

Keyframes

  • To add a keyframe on a slider HUD handle, Alt + LMB on the label or parameter value.

  • To remove a keyframe on a slider HUD handle, select the keyframe in the timeline and then ⌃ Ctrl + LMB on the slider’s label or parameter value.

  • To add a keyframe on a checkbox or dropdown menu HUD handle, Alt + LMB on the widget.

  • To remove a keyframe on a checkbox or dropdown menu HUD handle, ⌃ Ctrl + LMB on the widget.

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