Struct Spring 

pub struct Spring { /* private fields */ }

The animation vocabulary: the shell-fed frame clock (FrameTime) plus the pure easing/interpolation/spring math a widget or app advances it through, flat-re-exported from frust-core::anim. Time enters from the shell during paint (PaintCtx::frame_time); nothing here reads a clock. The analytic response of a SpringDesc released from an initial displacement + velocity toward equilibrium at 0.

Positions returned by Spring::position are displacements from equilibrium (the target), so equilibrium is always 0. The closed-form solution branches on the damping regime; all three are exact (no numerical integration), which is what lets a fling be evaluated at an arbitrary frame time without accumulating step error.

Implementations

impl Spring

pub fn new(desc: SpringDesc, x0: f64, v0: f64) -> Spring

Solve the spring released from displacement x0 (relative to equilibrium) with initial velocity v0.

Degenerate parameters (non-positive mass/stiffness) fall back to a critically-damped unit spring so the constructor never produces NaN.

pub fn position(&self, t: f64) -> f64

The displacement from equilibrium at elapsed time t (seconds).

pub fn velocity(&self, t: f64) -> f64

The velocity (d displacement / d t) at elapsed time t (seconds).

pub fn is_at_rest(&self, t: f64, epsilon: f64) -> bool

Whether the spring has effectively settled at equilibrium by time t: both |position| and |velocity| are below epsilon.

Trait Implementations

impl Clone for Spring

fn clone(&self) -> Spring

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Spring

impl Debug for Spring

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.