When you set two keys in Rive, the frames in between those keys are automatically calculated. This is called interpolation. The interpolation can be customized to create dramatically different results.
To change the interpolation type, first, select a key on the timeline. The interpolation pane will update to show how the value will change from the specified key to the next key.
The interpolation graph to the right is a visual representation of how the value will change over time from the selected key to the next with the x-axis representing time and the y-axis representing the change in the chosen property.
Linear is the default interpolation type, and it creates a constant rate of change from one key value to the next.
Cubic interpolation uses a curve to interpolate between key values. It gives you two handles that can be dragged to customize the curve.
The default cubic curve creates a gentle curve from the first key to the next, which results in the value changing slowly at the start and end, and changing the most in the middle.
Hold doesn't interpolate values between keys. It simply holds the current value until the next key is reached, where the next value is set instantly.