Game Development References

Unreal vs Unity: Key Differences

Understanding the fundamental differences between Unreal Engine and Unity can help developers transition between engines more effectively.

Rendering Pipeline

Unreal Engine

Deferred rendering by default

Unity

Universal Render Pipeline (URP) or High Definition Render Pipeline (HDRP)

Material System

Unreal Engine

Node-based material editor with real-time preview

Unity

Shader Graph (similar to Unreal but needs package installation)

Scripting

Unreal Engine

C++ and Blueprint visual scripting

Unity

C# with Visual Studio or VS Code

Physics

Unreal Engine

PhysX with built-in Chaos physics

Unity

PhysX by default, can switch to Havok

Unreal Engine Gameplay Ability System

The Gameplay Ability System (GAS) is a powerful framework for implementing game mechanics and abilities.

Key Benefits

  • Replicated by Default: Built-in networking support
  • Data-Driven Design: Define abilities via data assets
  • Predictive Gameplay: Client-side prediction support
  • Modular Architecture: Easy to extend and modify

1. Gameplay Abilities

  • Self-contained gameplay mechanics
  • Can be triggered by input or events
  • Handle timing and targeting

2. Gameplay Effects

  • Modify attributes (health, mana)
  • Apply status effects
  • Stack and expire automatically

3. Gameplay Tags

  • Flexible categorization system
  • Control ability activation
  • Define ability relationships

4. Gameplay Attributes

  • Network-replicated stats
  • Support for base values
  • Automatic validation

Game AI Technologies

Modern game AI combines multiple technologies to create engaging and realistic behaviors:

1. Behavior Trees

Purpose

Decision making and action selection

Benefits

  • Visual design of AI logic
  • Easy to debug and modify
  • Reusable behaviors

Use Cases

Combat AI, NPC daily routines, strategic decision making

2. Reinforcement Learning

Purpose

Learning optimal strategies through experience

Benefits

  • NPC strategy optimization
  • Adaptive AI opponents
  • Behavior imitation

3. Hierarchical State Machines

Purpose

Organizing and managing AI states

Benefits

  • Complex behavior organization
  • Nested states for detailed control

4. Utility AI

Purpose

Dynamic decision making

Benefits

  • Score-based action selection
  • Context-aware behavior
  • Emotional simulation
  • Natural-feeling decisions
  • Easy to tune and balance
  • Handles complex scenarios

5. Pathfinding

Algorithms

  • A* (standard approach)
  • Navigation Meshes
  • Hierarchical Pathfinding

Advanced Features

  • Dynamic obstacle avoidance
  • Group movement coordination

6. Perception Systems

Sight

Field of view calculations

Hearing

Sound event detection

Memory

Track known information

Team Communication

Share information between AI agents