Random Access RNG

A fast, deterministic random number generator with hierarchical seeding and random access capabilities.

Features

🚀 Fast: Uses XXH3 hash function for high performance
🎯 Deterministic: Same seed always produces the same sequence
🌳 Hierarchical: Create child RNGs with different seeds
📍 Random Access: Jump to any position without generating intermediate values
🛤️ Path-based: Use paths to create RNG hierarchies
🔧 Standard Compatible: Implements RngCore and SeedableRng traits

Quick Start

Add to your Cargo.toml:

[dependencies]
random_access_rng = "0.1.0"

Basic usage:

use random_access_rng::RandomAccessRNG;

// Create a new RNG with a seed
let mut rng = RandomAccessRNG::new("my_seed");

// Generate random numbers
let value = rng.next_u64();

// Create child RNGs
let child = rng.get("child_key");

// Use path-based seeding
let path_rng = rng.path("level1/level2/level3");

Examples

Procedural Terrain Generation

use random_access_rng::RandomAccessRNG;
use rand::Rng;

fn generate_terrain(world_seed: &str, x: i32, y: i32) -> f64 {
    let world = RandomAccessRNG::new(world_seed);
    let terrain = world.path(&format!("terrain/{}/{}", x, y));
    
    // Generate height value
    let height = terrain.random::<f64>();
    height * 1000.0 // Scale to 0-1000 range
}

// Generate terrain for different coordinates
let height1 = generate_terrain("world_seed", 10, 20);
let height2 = generate_terrain("world_seed", 10, 20); // Same result
let height3 = generate_terrain("world_seed", 15, 25); // Different result

Game Development

use random_access_rng::RandomAccessRNG;

struct GameWorld {
    rng: RandomAccessRNG,
}

impl GameWorld {
    fn new(seed: &str) -> Self {
        Self {
            rng: RandomAccessRNG::new(seed),
        }
    }
    
    fn generate_enemy(&self, enemy_type: &str) -> Enemy {
        let enemy_rng = self.rng.get(enemy_type);
        Enemy::new(enemy_rng)
    }
    
    fn generate_item(&self, location: &str) -> Item {
        let item_rng = self.rng.path(&format!("items/{}", location));
        Item::new(item_rng)
    }
}

let world = GameWorld::new("game_seed");
let enemy = world.generate_enemy("goblin");
let item = world.generate_item("forest/chest");

Key Concepts

Deterministic Randomness

The same seed always produces the same sequence, making it perfect for:

Procedural generation
Reproducible simulations
Testing and debugging

let mut rng1 = RandomAccessRNG::new("test_seed");
let mut rng2 = RandomAccessRNG::new("test_seed");

// Both RNGs produce identical sequences
assert_eq!(rng1.next_u64(), rng2.next_u64());
assert_eq!(rng1.next_u64(), rng2.next_u64());

Hierarchical Seeding

Create independent child RNGs that maintain deterministic properties:

let parent = RandomAccessRNG::new("world_seed");

// Different aspects can have their own RNGs
let terrain_rng = parent.get("terrain");
let enemy_rng = parent.get("enemies");
let item_rng = parent.get("items");

// Each child RNG is independent and deterministic

Random Access

Jump to any position in the sequence instantly:

let mut rng = RandomAccessRNG::new("seed");

// Jump directly to position 1000
let value_at_1000 = rng.seek_u64(1000);

// Jump to position 5000
let value_at_5000 = rng.seek_u64(5000);

// Jump to back position 0
let value_at_5000 = rng.seek_u64(0);

Path-Based Seeding

Use file system-like paths to create RNG hierarchies:

let world = RandomAccessRNG::new("world_seed");

// Create RNGs for specific locations
let forest_rng = world.path("biomes/forest");
let cave_rng = world.path("biomes/cave");
let village_rng = world.path("structures/village");

Performance

This RNG is designed for speed and uses the XXH3 hash function, which is:

Extremely fast
High quality for non-cryptographic purposes
Well-distributed output

Security Notice

This RNG is NOT cryptographically secure. It's designed for:

Procedural generation
Simulation and testing
Game development
Any application requiring deterministic randomness

For security-sensitive applications, use a cryptographically secure RNG marked by the CryptoRng trait.

Installation