Why Understanding UE5 Fundamentals Matters
Have you ever started learning Unreal Engine 5 (UE5) only to find yourself overwhelmed by terminology like "Actor? Component? Blueprint?" and stopped in your tracks?
UE5 is an incredibly powerful tool, but to unlock its full potential, you must properly understand the foundational concepts. These concepts are like the "language" and "rules" of the UE5 world—without understanding them, you may encounter unexpected behaviors, inefficient designs, and ultimately, frustration that could lead to giving up.
This article explains the five fundamental concepts you should know first when learning UE5, complete with practical examples and common mistakes.
Actor
Definition and Role
Actor is the base class for all objects that can be placed in a UE5 "Level" (game world). Cameras, player characters, lights, enemies, destructible objects—any entity that exists in the game world is an Actor.
Actors have basic Transform information (position, rotation, scale) and can be spawned (created) or destroyed during gameplay.
Common Mistakes and Best Practices
| Mistake | Best Practice |
|---|---|
| Cramming all functionality into the Actor itself | Think of Actors as "containers" and put functionality in Components. |
| Using Actors for data objects without transforms | Use UObject or Data Assets (e.g., DataTable) for data management, not Actors. |
Blueprint Example: Spawning an Actor
Actors are often dynamically spawned in response to specific events (e.g., game start, player button press).
// Blueprint Event Graph
// When Input Action "IA_Spawn" is triggered, spawn an explosion effect Actor at a specified location
Enhanced Input Action IA_Spawn Triggered
-> Spawn Actor from Class (Class: BP_ExplosionEffect)
-> Set Spawn Transform (Location: Get Player Character Location + Offset)
Component
Definition and Role
Component is a "part" that adds specific functionality or visual representation to an Actor. An Actor alone cannot do anything, but by combining Components, its role is determined.
Here are some typical Components:
- Static Mesh Component: Gives an Actor a static appearance (walls, floors, etc.).
- Skeletal Mesh Component: Gives an Actor an animated appearance (characters, etc.).
- Camera Component: Adds camera (viewpoint) functionality.
- Movement Component: Adds movement logic (e.g., flying, walking).
Relationship Between Actors and Components
The Actor is like a "body" and Components are like "organs and limbs." An Actor can have multiple Components, and through this combination, you can create objects with entirely different behaviors from the same Actor class.
Blueprint Example: Manipulating Components
Components attached to an Actor can be easily accessed and configured from Blueprint.
// Blueprint Event Graph
// Toggle visibility of a Static Mesh Component
Event BeginPlay
-> Get Static Mesh Component
-> Set Visibility (New Visibility: False)
Blueprint
Definition and Role
Blueprint is a visual scripting system built into UE5. By connecting blocks called nodes with wires, you can build game logic without writing C++ code.
It's the most powerful tool for beginners, and most gameplay features can be achieved with Blueprint alone. This makes it easier for artists and designers with limited programming knowledge to participate in game development.
Choosing Between Blueprint and C++ (Best Practices)
| Item | Blueprint | C++ |
|---|---|---|
| Development Speed | Fast (visual, easy iteration) | Slow (requires compilation) |
| Performance | Lower (has overhead) | High (native code) |
| Use Cases | Game logic, event handling, prototyping | Complex calculations, foundational systems, performance-critical parts |
Best Practice: Generally, prototype in Blueprint first, then implement only performance-critical parts or highly reusable foundational features in C++.
Blueprint Code Example (Simple Timer)
// Blueprint Event Graph
// Display a message 3 seconds after game start
Event BeginPlay
-> Delay (Duration: 3.0)
-> Print String (String: "3 seconds have passed!")
Level
Definition and Role
Level refers to the specific map or scene that players experience. A Level contains Actors (terrain, buildings, lights, characters, etc.) and stores their initial states and placement information.
The "world" we work in within the UE5 editor is itself a Level.
Note: UE5 uses terms "World" and "Level"—World is the overall container holding multiple Levels, while Level refers to individual map files within it.
Persistent Level and Sub-Levels
In large-scale games, Levels are divided into multiple smaller Levels for management.
- Persistent Level: The main Level that is always loaded. Used for overall game settings and Actors that always exist (e.g., Sky Light).
- Sub-Level: Smaller Levels that stream (load/unload) into the Persistent Level. This enables efficient management while reducing memory load, even in vast worlds.
Common Mistakes
- Cramming all Actors into a single Level: In large Levels, this not only slows down the editor but causes conflicts during team development.
- Best Practice: Divide into Sub-Levels appropriately and utilize Level Streaming. For larger worlds, UE5's World Partition system is also available. World Partition automatically divides the world into grids and loads only necessary parts.
GameMode
Definition and Role
GameMode is the class that defines game rules and behaviors. It manages not only multiplayer game rules (e.g., Team Deathmatch, Capture the Flag) but also basic settings for single-player games (e.g., player spawn points, player character class).
Important: GameMode only exists on the server side. In single-player games, the PC running the game acts as the server, so GameMode works normally. In multiplayer, GameMode only exists on the host/server and not on each client (joining player's) PC.
Main Elements Managed by GameMode
| Element | Description |
|---|---|
| Default Pawn Class | The default character (Pawn) class that the player controls. |
| Player Controller Class | The controller class that mediates between player input and game rules. |
| HUD Class | The UI class displayed on screen (health bar, score, etc.). |
| Game State Class | The class managing overall game state (score, remaining time, etc.). |
Common Mistakes
- Writing player-specific logic in GameMode: Player movement, attacks, and other player-dependent logic should be written in the Pawn or Player Controller.
- Best Practice: GameMode should focus on "overall game" rules and settings, not individual Actor behaviors.
Relationships Among the Five Concepts
This article explained the five essential concepts for starting Unreal Engine 5.
| Concept | Role |
|---|---|
| Actor | Entities that can be placed in the world (containers) |
| Component | Parts that add functionality to Actors |
| Blueprint | Visual programming language (logic) |
| Level | The game world, map, scene |
| GameMode | The rulebook for the entire game (server-side) |
These concepts appear frequently in UE5 documentation and tutorials. With this foundation, try working with the UE5 editor to experience how these concepts work together.
Good luck on your UE5 learning journey!