> For the complete documentation index, see [llms.txt](https://docs.engagevr.io/developer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.engagevr.io/developer/afx/animation-curves.md). # Animation curves You can use animation curve nodes to create a two-dimensional graph that describes a changing value. The most common use is to describe how a value changes over time. For example, you could graph how an object's velocity should change over time - describing it's acceleration or deceleration behavior. Another example could be to graph the changing rate of particle emissions over time when simulating a firework. ## Using the Animation Curve node Use the animation curve node to define a two-dimensional graph for an animation curve.

* To edit the curve, select the thumbnail rectangle. This is initially a blank gray rectangle, but will show a preview of the graph.

### Choosing a preset curve * To load a preset curve, select a thumbnail at the bottom of the animation curve editor panel. If the preset that you want to use is not visible, select the cog icon to open the presets panel. ### Saving a curve as a preset To save a curve as a preset, complete the following steps: 1. In the animation curve editor, create the curve that you want to save as a preset. 2. In the lower-left corner of the animation curve editor, select the cog icon. 3. In the **Presets** panel, select **New**. ### Adjusting keys on a curve * To move a key, select and drag the key. * To adjust the tangent of the curve at a key, first select the key, and then drag one of the grips that appears. {% hint style="info" %} By default the curve is between 0 and 1.0 on both X and Y axis. You can drag the start and end keys to change the minimum and maximum values for the curve. {% endhint %}

### Adding a key to a curve * To add a key, right-click on the curve, and then select **Add Key**.

### Changing behavior outside of X bounds By default, an animation curve clamps values outside the defined X (time) range. To change the behavior, select the cog icon next to either the first or last keys, and select the desired behavior from the list that appears. {% hint style="info" %} You can choose different behaviors for values before the graph and for values after the graph. {% endhint %}

Options to change behavior outside of set bounds

The following table describes the available options.

Option	Description
Loop	The graph repeats the same shape.
Ping Pong	The graph is mirrored.
Clamp	The graph retains a constant value.

## Accessing values from an animation curve Use an `Animation Curve Evaluate` node to access values from an animation curve. You provide the time (X axis) value, and the node outputs the corresponding Y axis value.