Glossary
This page defines the core terms used in Yarrow.
- Alpha
Normalized progress of a transition — 0 means just started, 1 means complete.
- Delta
Time elapsed between the previous and current frame.
Used to keep updates consistent across frame rates.
- Lerp
Linear interpolation between two values based on alpha.
Used to calculate a value that lies between a start and end point.
For example, if you're moving an object from x = 100 to x = 200,
and the current alpha is 0.5, lerp will return 150.
When alpha is 0, it returns the start value; when 1, it returns the end.
Lerp ensures smooth, gradual transitions over time.
- Transition
A smooth change of a single property over time — e.g., position from A to B.
- Animation
A sequence of one or more transitions, possibly with delays, easing, and looping.
- Delay
Amount of time before a transition or animation starts running.
- Duration
Total time it takes for a transition or animation to complete (including delay, repeats, etc...)
- Easing
A function that maps linear alpha to a non-linear curve, changing how the transition progresses over time.
Instead of moving at a constant speed, easing controls acceleration and deceleration — this gives motion a more natural or stylized feel.
For example
- linear keeps a constant speed (no easing)
- ease-in starts slow, then speeds up
- ease-out starts fast, then slows down
- ease-in-out starts slow, speeds up in the middle, then slows down again
Easing functions are essential for making animations feel smooth and responsive rather than robotic or mechanical.
- Loop
Specifies if and how many times an animation should repeat. Can be finite or infinite.
- Speed
Multiplier for animation timing. 2.0 plays it twice as fast, 0.5 half as fast.