Animation basics

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	Select the Handles tool on the left toolbar. 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	Select the Handles tool on the left toolbar. `⇧ Shift` + `T`
Set keyframes on the selected object’s rotation	Select the Handles tool on the left toolbar. `⇧ Shift` + `R`
Set keyframes on the selected object’s scale	Select the Handles tool on the left toolbar. `⇧ Shift` + `E`
Key everything	Hover over the viewport or network editor. Press `⌃ Ctrl` + `A` to select all. 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	On the playbar, move to the keyframe. 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	On the playbar, move to the keyframe. 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.

Houdini tints parameter backgrounds to indicate various types of animation-related information.

The following shows the default full tint colors. You can change the colors, or change the level of tinting, in the main preferences. In the main menus choose Edit ▸ Preferences, then click Parameters on the left. However, you may want to avoid changing the colors since it will make it harder for other people to understand your parameter editor if it doesn’t use the standard colors.

Parameter background	State
No tint	The parameter is not animated. It has no channels associated with it.
Green	Keyed The parameter is animated (controlled by an expression) and the current frame has a keyframe.
Yellow	Pending changes The keyed parameter has 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	Between keyframes The parameter is animated (either with keyframes or an expression), but the current frame does not have a keyframe. (Click the name of a parameter to switch between showing the current value and the expression.)
Purple	Python expression language The parameter expression language is set to Python. See python parameter expressions for more information.
Gray blue	Muted from dopesheet The parameter is animated (either with keyframes or an expression), but the channel is muted in the dopesheet.
Orange	Overridden by CHOPs The parameter is currently controlled by a CHOP node.
Dark Green	Empty channel The 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. (This can also happen if you enter use a `raw()` or `constant()` parameter expression.) To delete the empty channel, right-click the parameter and choose Delete Channels.

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 basics

Overview ¶

How to set keyframes ¶

How to set and manage keyframes in the parameter editor ¶

Color coding for keyframes and parameters ¶

View the animation curves for keyframed parameters ¶

Animation

Getting started ¶

Next steps ¶

Guru-level ¶