unity-ecs-patterns

Unity ECS Patterns

Production patterns for Unity's Data-Oriented Technology Stack (DOTS) including Entity Component System, Job System, and Burst Compiler.

When to Use This Skill

• Building high-performance Unity games
• Managing thousands of entities efficiently
• Implementing data-oriented game systems
• Optimizing CPU-bound game logic
• Converting OOP game code to ECS
• Using Jobs and Burst for parallelization

Core Concepts

1. ECS vs OOP

Aspect	Traditional OOP	ECS/DOTS
Data layout	Object-oriented	Data-oriented
Memory	Scattered	Contiguous
Processing	Per-object	Batched
Scaling	Poor with count	Linear scaling
Best for	Complex behaviors	Mass simulation

2. DOTS Components

Entity: Lightweight ID (no data)
Component: Pure data (no behavior)
System: Logic that processes components
World: Container for entities
Archetype: Unique combination of components
Chunk: Memory block for same-archetype entities

Patterns

Pattern 1: Basic ECS Setup

using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;
using Unity.Burst;
using Unity.Collections;

// Component: Pure data, no methods
public struct Speed : IComponentData
{
    public float Value;
}

public struct Health : IComponentData
{
    public float Current;
    public float Max;
}

public struct Target : IComponentData
{
    public Entity Value;
}

// Tag component (zero-size marker)
public struct EnemyTag : IComponentData { }
public struct PlayerTag : IComponentData { }

// Buffer component (variable-size array)
[InternalBufferCapacity(8)]
public struct InventoryItem : IBufferElementData
{
    public int ItemId;
    public int Quantity;
}

// Shared component (grouped entities)
public struct TeamId : ISharedComponentData
{
    public int Value;
}

Pattern 2: Systems with ISystem (Recommended)