Random Extensions

RandExtensions provides a comprehensive set of extension methods for the FastRandom class, making common random operations more intuitive and expressive.

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Overview

Feature	Description
Element Selection	Random selection from arrays, lists, and sequences
Direction Generation	4-way and 8-way random directions
Color Generation	Random, pastel, and dark colors
Enum Selection	Random enum values with caching
Sign	Random sign (1 or -1)
Shuffling	Shuffle lists in-place
Dice Rolling	Roll multiple dice and sum results
Point Generation	Random points within a circle
Angles	Random angles in radians or degrees
Probability	Chance checks with any probability

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Element Selection

Choice (Array)

Selects a random element from an array.

var rng = FastRandom.Shared;
var items = new[] { "apple", "banana", "cherry" };

string selected = rng.Choice(items);

Choice (List)

Selects a random element from a read-only list.

var list = new List<string> { "apple", "banana", "cherry" };
string selected = rng.Choice(list);

Choice (Sequence)

Selects a random element from any sequence using reservoir sampling.

IEnumerable<string> items = GetItems();
string selected = rng.Choice(items);

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Direction Generation

RandomDirection

Generates a random 4-way direction (Up, Right, Down, Left).

Vect2 direction = rng.RandomDirection();
// Returns Vect2.Up, .Right, .Down, or .Left

RandomDirection8Way

Generates a random 8-way direction including diagonals.

Vect2 direction = rng.RandomDirection8Way();
// Returns any of the 8 cardinal and intercardinal directions

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Color Generation

RandomColor

Generates a random RGB color with full value range (0-255).

Color color = rng.RandomColor();
// Returns a color with random R, G, B values

RandomPastelColor

Generates a random pastel color with light values (128-255).

Color pastel = rng.RandomPastelColor();
// Returns a color with light, soft values

RandomDarkColor

Generates a random dark color with low values (0-127).

Color dark = rng.RandomDarkColor();
// Returns a color with dark, muted values

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Enum Selection

RandomEnum

Generates a random value from the specified enum type with caching.

public enum EnemyType { Goblin, Orc, Troll, Dragon }

EnemyType type = rng.RandomEnum<EnemyType>();
// Returns a random enum value

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Sign and Shuffling

NextSign

Generates a random sign (1 or -1).

int sign = rng.NextSign();  // 1 or -1

Shuffle

Shuffles a list in-place using the Fisher-Yates algorithm.

var list = new List<int> { 1, 2, 3, 4, 5 };
rng.Shuffle(list);
// list is now in random order

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Dice Rolling

RollDice

Rolls dice and returns the sum.

// Roll 3 six-sided dice
int sum = rng.RollDice(3, 6);  // 3d6, sum between 3 and 18

// Roll 2 ten-sided dice
int sum2 = rng.RollDice(2, 10);  // 2d10

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Point Generation

RandomPointInCircle (Unit Circle)

Generates a random point uniformly within a unit circle.

Vect2 point = rng.RandomPointInCircle();
// Returns a point within a circle of radius 1

RandomPointInCircle (Custom Radius)

Generates a random point uniformly within a circle of the specified radius.

Vect2 point = rng.RandomPointInCircle(5f);
// Returns a point within a circle of radius 5

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Angle Generation

RandomAngle

Generates a random angle in radians (0 to 2π).

float angle = rng.RandomAngle();
// Returns a random angle in radians

RandomAngleDegrees

Generates a random angle in degrees (0 to 360).

float angle = rng.RandomAngleDegrees();
// Returns a random angle in degrees

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Probability

Chance

Returns true with the specified probability.

// 25% chance
if (rng.Chance(0.25f))
{
    Console.WriteLine("Lucky!");
}

// 50% chance
if (rng.Chance(0.5f))
{
    Console.WriteLine("Heads!");
}
else
{
    Console.WriteLine("Tails!");
}

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Examples

Random Enemy Spawning

public Enemy SpawnEnemy(Vect2 position)
{
    var rng = FastRandom.Shared;
    
    // Random enemy type
    EnemyType type = rng.RandomEnum<EnemyType>();
    
    // Random direction to face
    Vect2 direction = rng.RandomDirection();
    
    // Random color variation
    Color color = rng.RandomPastelColor();
    
    // Random position offset within range
    Vect2 offset = rng.RandomPointInCircle(50f);
    
    return EnemyFactory.Create(type, position + offset, direction, color);
}

Random Loot Generation

public List<Item> GenerateLoot()
{
    var rng = FastRandom.Shared;
    var loot = new List<Item>();
    
    // Random amount of items (1-5)
    int count = rng.RollDice(1, 5);
    
    var allItems = _itemDatabase.GetAllItems();
    
    for (int i = 0; i < count; i++)
    {
        var item = rng.Choice(allItems);
        loot.Add(item);
    }
    
    return loot;
}

Random Weather

public void UpdateWeather()
{
    var rng = FastRandom.Shared;
    
    // 30% chance of rain
    if (rng.Chance(0.3f))
    {
        _currentWeather = Weather.Rainy;
    }
    // 20% chance of snow
    else if (rng.Chance(0.2f))
    {
        _currentWeather = Weather.Snowy;
    }
    else
    {
        _currentWeather = Weather.Clear;
    }
}

Random Particle System

public void EmitParticles(Vect2 position, int count)
{
    var rng = FastRandom.Shared;
    
    for (int i = 0; i < count; i++)
    {
        // Random velocity direction
        Vect2 direction = rng.RandomDirection8Way();
        float speed = rng.RangeFloat(50f, 200f);
        Vect2 velocity = direction * speed;
        
        // Random color variation
        Color color = rng.RandomColor();
        
        // Random lifespan
        float lifespan = rng.RangeFloat(0.5f, 2f);
        
        _particleSystem.Emit(position, velocity, color, lifespan);
    }
}

Random Puzzle Generation

public void GeneratePuzzle()
{
    var rng = FastRandom.Shared;
    
    // Random symbols
    var symbols = new[] { 'A', 'B', 'C', 'D', 'E' };
    
    // Shuffle the sequence
    var sequence = symbols.ToList();
    rng.Shuffle(sequence);
    
    // Random starting position
    int startIndex = rng.Next(symbols.Length);
    
    // Random rotation for each symbol
    foreach (var symbol in sequence)
    {
        float rotation = rng.RandomAngleDegrees();
        // Apply rotation
    }
}

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Summary

Method	Description
Choice	Selects a random element
RandomDirection	Returns a random 4-way direction
RandomDirection8Way	Returns a random 8-way direction
RandomColor	Returns a random color
RandomPastelColor	Returns a random pastel color
RandomDarkColor	Returns a random dark color
RandomEnum	Returns a random enum value
NextSign	Returns 1 or -1
Shuffle	Shuffles a list in-place
RollDice	Rolls dice and returns the sum
RandomPointInCircle	Returns a random point within a circle
RandomAngle	Returns a random angle in radians
RandomAngleDegrees	Returns a random angle in degrees
Chance	Returns true with a given probability

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