easing

Convert normalized animation progress into an interpolation weight. Each function takes t and returns a float.

import easing

start = 10.0
end = 30.0
progress = 0.5
weight = easing.InOutQuad(progress)
position = start + (end - start) * weight
assert position == 20.0

Use Linear(t) for constant speed. Each family below provides In<Name>(t), Out<Name>(t), and InOut<Name>(t):

Family	Curve
`Sine`	Sinusoidal easing.
`Quad`, `Cubic`, `Quart`, `Quint`	Polynomial easing of increasing degree.
`Expo`	Exponential change.
`Circ`	Circular curve.
`Back`	Overshoot before settling.
`Elastic`	Spring-like oscillation.
`Bounce`	Bouncing transition.

For example, OutCubic(t) slows toward the endpoint. Clamp elapsed-time progress to [0, 1] in your application. Back and Elastic curves can deliberately overshoot that output range, so the result is not always suitable as an opacity value without further clamping.

API declarations: easing.pyi.