Linear interpolation and iteration, automatically implemented over most float-compatible types.
Just need to know what's halfway between three and five?
```rust use lerp::Lerp;
assert_eq!(3.0.lerp(5.0, 0.5), 4.0); ```
Want to iterate across some points in that range?
```rust // bring the trait into scope use lerp::LerpIter;
// iterate and produce four items evenly spaced between 3.0 and 5.0 // note that the default, open iterator does not include both endpoints // this makes chaining lerping iterators simpler let items: Vec<_> = 3.0f64.lerpiter(5.0, 4).collect(); assert_eq!(vec![3.0, 3.5, 4.0, 4.5], items);
// closed iterators return both ends
asserteq!(vec![3.0, 5.0], 3.0.lerpiter_closed(5.0, 2).collect::
Of course, the real benefit is that it's derivation is broad enough that it also
covers types such as num::Complex<T>. If you have an array-processing library,
and the arrays are T: Add<Output = T> + Mul<F: Float, Output = T>, it'll just
work for them as well.
LerpAs well as working for individual float values, the crate also provides a derive
macro, available with the derive feature, which will be able to generate an
implementation automatically.
This derive implementation will lerp each field of the struct independently
and assumes a generic implementation of Lerp over Float types. If any
of the fields is generic only over one of the float values (f32, f64) that
can be specified by the #[lerp(f32)] or #[lerp(f64)] attributes respectively.
If you would like for the lerp implementation to ignore a field (or if it does
not derive lerp) you can use the #[lerp(skip)] or #[lerp(ignore)] attributes
which will produce the value, untouched from the left value.
Not all types are supported in this derive macro. See [the github issue] for discussion and more information.
toml
[dependencies]
lerp = { version = "0.4", features = ["derive"] }
```rust use lerp::Lerp;
struct Data { a: f64, b: f64 }
assert_eq!( Data { a: 0.0, b: 1.0 }.lerp(Data { a: 1.0, b: 0.0 }, 0.5), Data { a: 0.5, b: 0.5 } ); ```
More derive examples can be seen in the [tests]
toml
[dependencies]
lerp = "0.4"
Auto-built from Travis: https://coriolinus.github.io/lerp-rs/