Struct Random 

pub struct Random { /* private fields */ }

A reproducible local random stream derived entirely from a hashed key.

Key bytes use FNV-1a, followed by SplitMix64 for each sample. Integer hashing uses little-endian bytes and widens usize/isize to 64 bits. Custom Hash implementations must themselves be deterministic. Rust’s Hash encodings are not a serialization format; cross-version key encoding stability is not promised. This generator is not cryptographic and has no shared mutable state.

use motion_core::Random;
let mut first = Random::from_key(("spark", 42_u64));
let mut second = Random::from_key(("spark", 42_u64));
assert_eq!(first.next_float(), second.next_float());
assert!((10.0..20.0).contains(&first.range(10.0..20.0)));
assert_eq!(first.choose(&[7]), Some(&7));

Implementations

impl Random

pub fn from_key(key: impl Hash) -> Self

Starts a fresh stream; equal keys reproduce the same sequence.

pub fn for_particle(seed: u64, index: u64, step: u64) -> Self

Starts a counter-keyed particle stream without Hash encoding or shared state. Equal seed/index/step values are independent of traversal and worker count.

pub fn next_float(&mut self) -> f64

Returns one of 2^53 equally spaced floating-point values in [0, 1).

pub fn range(&mut self, range: Range<f64>) -> f64

Samples a finite half-open interval, including adjacent float endpoints.

Rounding is clamped below the upper endpoint; no overflowing endpoint subtraction is performed.

Panics

Panics for an empty, reversed or nonfinite range; see Self::try_range.

pub fn try_range(&mut self, range: Range<f64>) -> Result<f64, ValidationError>

Samples like Self::range, reporting an invalid range without advancing the stream.

pub fn unit_vector(&mut self) -> Vector2

Samples a uniform angle using deterministic libm trigonometry.

pub fn choose<'a, Value>(&mut self, values: &'a [Value]) -> Option<&'a Value>

Selects an element without modulo bias; an empty slice returns None.

Trait Implementations

impl Clone for Random

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Random

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

Formats the value using the given formatter.