Houdini 20.0 Animation

Animating string parameters

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In Houdini, you can keyframe the value of string parameters.


You can embed global and local variables (such as $F, the current frame number) and expressions inside backticks in most string parameters. For example:

Frame: $F
You are `fit($F, 0, 240, 0, 100)`% done.

In some cases this is easier than keyframing individual values for a string parameter.


  1. On the Create tab, click Font.

  2. Double-click the font_object node to dive inside.

  3. Click the font surface node.

  4. In the parameter editor, set the Text parameter to Hello.

  5. Right click the Text label and choose Keyframes ▸ Set keyframe.

    You can also Alt-click the label to set a keyframe on the parameter.

  6. Use the playbar to move the current time.

  7. Change the Text parameter to There.

  8. The parameter background is yellow, indicating an uncommitted change to an animated parameter. Alt-click the label to commit the change.

    (If the auto-commit preference is on, you will not need to commit the change.)


The keyframes appear in the graph editor and are editable, but the different string values are not apparent (the graph line is always flat).

Once you've keyed a string parameter (that is, created an animation channel on the parameter), you will need to be aware of whether you are editing the parameter in “expression mode” or “value mode”.

  • Clicking a parameter label switches between “value mode” (normal label background), showing the current value of the parameter, and “expression mode” (filled label background), showing the expression driving the parameter.

  • In value mode, an animated string parameter shows the current string value, for example Hello. In expression mode, an animated string parameter shows an expression that evaluates to the string value, for example "Hello".


Getting started

Next steps