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//! # Soy //! Rust interpolation library. //! //! # Usage //! The main trait used for interpolation is [`soy::Lerper`]. It requires a //! single method, `calculate`, which calculates interpolation progression at a //! given time. //! //! Example implementing linear interpolation, taken directly from `soy`'s //! implementation: //! ``` //! struct Linear; //! //! impl soy::Lerper for Linear { //! fn calculate(&self, t: f32) -> { //! t //! } //! } //! ``` //! //! [0]: trait.Lerper.html #![deny(missing_docs)] mod bezier; mod constants; use core::ops::{Add, Mul, Sub}; pub use bezier::{cubic_bezier, Bezier}; pub use constants::*; /// Interpolate between two values given an interpolation method. /// /// # Arguments: /// - `lerper`: Interpolation method to use. /// - `start`: Initial data point. /// - `end`: Final data point. /// - `t`: Amount to interpolate between the values. /// /// # Usage /// ``` /// fn main() { /// let start = 5.0; /// let end = 10.0; /// /// let quarter = soy::lerp(soy::Linear, start, end, 0.25); /// assert_eq!(quarter, 6.25); /// /// let half_way = soy::lerp(soy::Linear, start, end, 0.5); /// assert_eq!(half_way, 7.5); /// } /// ``` pub fn lerp<T, D>(lerper: T, start: D, end: D, t: f32) -> D where T: Lerper, D: Copy, D: Add<Output = D>, D: Sub<Output = D>, D: Mul<f32, Output = D>, { start + (end - start) * lerper.calculate(t) } /// Trait implemented by all interpolating methods. pub trait Lerper { /// Given a timing function _y = f(t)_, this method calculates the _y_ value /// at the given _t_. fn calculate(&self, t: f32) -> f32; } /// Linear interpolator: _f(t) = t_. pub struct Linear; impl Lerper for Linear { fn calculate(&self, t: f32) -> f32 { t } }