spring

Renderer-side physics-based spring descriptor.

Springs animate using a damped harmonic oscillator simulation. Unlike timed transitions, springs have no fixed duration: they settle naturally based on stiffness, damping, and mass. This makes them ideal for interactive animations where the target changes frequently (drag, scroll, hover) because interruption preserves velocity for smooth redirection.

Usage

import plushie/animation/spring

// Custom parameters
spring.new(to: 1.05, stiffness: 200.0, damping: 20.0)

// Named presets
spring.gentle(1.0)
spring.bouncy(1.05) |> spring.from(0.0)

Types

Spring

opaque </>

A physics-based spring descriptor.

pub opaque type Spring

Values

bouncy

</>

pub fn bouncy(to: Float) -> Spring

Bouncy preset: quick with visible overshoot. (stiffness: 300, damping: 10)

encode

</>

pub fn encode(s: Spring) -> node.PropValue

Encode a spring to its wire-format PropValue.

Only non-default fields are included to keep messages compact.

from

</>

pub fn from(s: Spring, from: Float) -> Spring

Set the explicit start value.

gentle

</>

pub fn gentle(to: Float) -> Spring

Gentle preset: slow, smooth, no overshoot. (stiffness: 120, damping: 14)

mass

</>

pub fn mass(s: Spring, mass: Float) -> Spring

Set the mass (higher = slower, heavier).

molasses

</>

pub fn molasses(to: Float) -> Spring

Molasses preset: slow, heavy, deliberate. (stiffness: 60, damping: 12)

new

</>

pub fn new(
  to to: Float,
  stiffness stiffness: Float,
  damping damping: Float,
) -> Spring

Create a new spring with explicit stiffness and damping.

on_complete

</>

pub fn on_complete(s: Spring, tag: String) -> Spring

Set the completion event tag.

snappy

</>

pub fn snappy(to: Float) -> Spring

Snappy preset: quick, minimal overshoot. (stiffness: 200, damping: 20)

stiff

</>

pub fn stiff(to: Float) -> Spring

Stiff preset: very quick, crisp stop. (stiffness: 400, damping: 30)

velocity

</>

pub fn velocity(s: Spring, velocity: Float) -> Spring

Set the initial velocity.