Crate unit_intervals 

unit-interval

Small constrained float types for values in the closed intervals [0, 1] and [-1, 1].

This crate provides UnitInterval and SignedUnitInterval wrappers for normalized floating-point values. They are useful for values such as opacity, progress, blend factors, percentages represented as fractions, centered offsets, joystick axes, and other quantities where the valid range is part of the type.

Constructors reject out-of-range values and NaN; saturating constructors clamp inputs into range. Operations that can leave the interval are available in checked and saturating forms, while operations that are mathematically closed over the interval return constrained values directly.

Examples

use unit_intervals::UnitInterval;

let opacity = UnitInterval::new(0.8).unwrap();
let clamped = UnitInterval::saturating(1.2);

assert_eq!(opacity.get(), 0.8);
assert_eq!(clamped, UnitInterval::ONE);

use unit_intervals::{SignedUnitInterval, UnitInterval};

let axis = SignedUnitInterval::new(-0.5).unwrap();
let scale = UnitInterval::new(0.25).unwrap();

assert_eq!((axis * scale).get(), -0.125);
assert_eq!(axis.saturating_add(scale).get(), -0.25);
assert_eq!(
    axis.checked_add(SignedUnitInterval::<f32>::ONE),
    Some(SignedUnitInterval::<f32>::HALF),
);

Crate features

• assertions: enables internal invariant assertions in non-test builds. Tests always enable these assertions.
• arbitrary: enables arbitrary::Arbitrary support for generating valid fuzz inputs.
• bytemuck: enables bytemuck::Zeroable, bytemuck::NoUninit, and bytemuck::CheckedBitPattern support. These wrappers do not implement bytemuck::Pod because not every backing float bit pattern satisfies their interval invariants.
• num-traits: enables conversion and bounds traits from num_traits.
• std: enables APIs that require the Rust standard library. The crate is otherwise no_std.
• rand_distr: enables rand_distr distribution support for UnitInterval and SignedUnitInterval.
• rkyv: enables zero-copy serialization and checked deserialization through the inner floating-point value.
• serde: enables transparent serialization and checked deserialization through the inner floating-point value.
• unsafe: allows unsafe code and enables unchecked constructors and operations such as UnitInterval::new_unchecked and SignedUnitInterval::new_unchecked. These APIs assume the caller has already proven that the produced value is inside the relevant interval and is not NaN.

Modules

randomrand_distr

Random sampling support through rand_distr.

Structs

SignedUnitInterval

A floating-point value constrained to the closed signed unit interval [-1, 1].

SignedUnitIntervalError

Error returned when converting an out-of-range value into a SignedUnitInterval.

UnitInterval

A floating-point value constrained to the closed unit interval [0, 1].

UnitIntervalError

Error returned when converting an out-of-range value into a UnitInterval.

Traits

UnitIntervalFloat

Floating-point support required by UnitInterval.