Houdini 20.5 Animation

Animation basics

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Overview

Keyframes define the start and end points of an animation sequence. You can add keyframes to specific parameters of an object to control the behavior of an animation. You can also specify the functions for Houdini to use to determine the behavior between keyframes.

How to set keyframes

At the object level, select and transform objects and characters to position them for keyframing.

When you select an object, Houdini automatically adds commonly animated parameters to the channel list. When you set a keyframe, Houdini sets the keyframe on parameters in the channel list.

Note

Before you perform the below operations, at the object level, select the object you want to set keyframes on by clicking the Object Select Mode and Select tool buttons on the left toolbar, and then clicking the object in the viewport. You can also select the object by clicking on the object node in the network editor pane.

Make sure your mouse is hovering over the viewport or playbar when performing the below keyframe operations.

To...Do this

Set keyframes on the parameters in the channel list

Use any of the following:

  • Press the keyframe button on the playbar

  • Press K

  • Choose Edit ▸ Set Keyframe

Note

The Global Set Key animation preference (Edit ▸ Preferences ▸ Animation) determines which parameters in the channel list the keyframes are added to. You can also set the Global Set Key preference on the playbar.

Set keyframes on the parameters of the selected object’s handles

  1. Select the Handles tool on the left toolbar.

  2. Use any of the following:

    • ⌃ Ctrl + K

    • Press on the handle in the viewport and choose Channels and Keyframes ▸ Set Keyframe.

Set keyframes on the selected object’s position

  1. Select the Handles tool on the left toolbar.

  2. ⇧ Shift + T

Set keyframes on the selected object’s rotation

  1. Select the Handles tool on the left toolbar.

  2. ⇧ Shift + R

Set keyframes on the selected object’s scale

  1. Select the Handles tool on the left toolbar.

  2. ⇧ Shift + E

Key everything

  1. Hover over the viewport or network editor.

  2. Press ⌃ Ctrl + A to select all.

  3. Press K.

Prevent certain parameters from being keyframed

In the parameter editor pane, click on the parameter and choose Lock Parameters.

Automatically create keyframes whenever you change parameters (auto-key)

Turn on auto-key by using the down arrow menu to the right of the keyframe button on the playbar. When auto-key is enabled, the keyframe button is rendered with the label AUTO . See keyframing controls for more information.

See the playbar help for more information on how to edit keyframes on the playbar.

How to set and manage keyframes in the parameter editor

To...Do this

Set a keyframe on a parameter

In the parameter editor pane, click on a parameter and choose Keyframes ▸ Set Keyframe.

As a shortcut, you can click the parameter with Alt + to set a keyframe.

Remove a keyframe

  1. On the playbar, move to the keyframe.

  2. In the parameter editor pane, click on a parameter and choose Keyframes ▸ Remove Keyframe. As a shortcut, you can click the parameter with ⌃ Ctrl + to remove a keyframe.

Remove a keyframe on all parameters in the channel list

  1. On the playbar, move to the keyframe.

  2. Press Delete with the mouse hovering over the playbar.

Move to the previous/next keyframe on the playbar

click on a parameter and choose Keyframes ▸ Step to Previous Key or Keyframes ▸ Step to Next Key.

Tip

For parameters with multiple components (for example, a position parameter with X, Y, and Z values), you can click the individual component text boxes to add keyframes for that particular component, or click the parameter label to add keyframes for all of the parameter components at once.

Color coding for keyframes and parameters

Houdini color codes the background of parameter text boxes in the parameter editor and channel list according to the current channel and keyframe status.

Parameter background

State

Black

No channel

This parameter is not animated. It has no channels associated with it.

Green

Keyed

This parameter is animated (controlled by an expression) and you are on a keyframe.

Yellow

Pending changes

This keyed parameter has been changed, but hasn’t been explicitly keyed. You need to explicitly key a changed parameter if auto-commit is turned off.

You can set Houdini to automatically commit changes on keyframes.

Blue

'Tween

This parameter is animated (either with keyframes or an expression), but you are not on a keyframe.

(Click the name of a parameter to switch between showing the current value and the expression.)

Orange

Overridden by CHOPs

This parameter is currently controlled by a channel operator (CHOP).

Light blue

Muted channel

This parameter is animated (either with keyframes or an expression), but the channel is muted in the dopesheet.

Light yellow

Empty channel

This parameter has an empty channel (a channel that doesn’t hold any keyframes). If you delete all the keyframes on the graph, you end up with a parameter with an empty channel.

You can delete the channel on the parameter ( click the parameter and choose Delete Channels) to change the parameter to a black background, or add a single key to turn the parameter into a single keyframe channel (green background).

Purple

Non-default expression language

This parameter uses a different expression language from the current default. Note that this does not indicate which expression language the parameter is set to, only that it is not the current default. Since the default is usually HScript, this often indicates that the parameter has a Python expression.

See python parameter expressions for more information.

The playbar’s keyframe markers and keyframe button also use some of the same color codes to give a quick status of all the keys at the current frame.

View the animation curves for keyframed parameters

See animation editor and channel list.

Animation

Getting started

Next steps

Guru-level