Game Development Unreal Engine Flashcards

24 sample cards from the Unreal Engine deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the difference between an Event Dispatcher and a direct function call in Blueprints?

   An Event Dispatcher implements the observer pattern: one Blueprint broadcasts an event and any number of other Blueprints that bound to it respond, enabling decoupled one-to-many communication instead of a direct reference call.

2. What is a Cast node in Blueprints and when does it fail?

   A Cast node attempts to convert an object reference to a specific class type. It succeeds only if the object actually is (or derives from) that class; otherwise the Cast Failed execution pin fires and the target output is invalid.

3. In Unreal C++, what is the purpose of the UPROPERTY() macro?

   UPROPERTY() exposes a C++ member variable to the Unreal reflection system, enabling editor visibility/editing, Blueprint access, replication, serialization, and garbage-collection tracking, controlled by specifiers like EditAnywhere, BlueprintReadWrite, and Replicated.

4. In Unreal C++, what do the UFUNCTION() and UCLASS() macros do?

   UCLASS() registers a class with Unreal's reflection/GC system so it can be a UObject; UFUNCTION() exposes a function to reflection, enabling Blueprint calls, RPC/replication (e.g., Server, Client, NetMulticast), and editor integration.

5. What is the naming-prefix convention for Unreal C++ classes (U, A, F, T)?

   U prefixes UObject-derived classes (e.g., UActorComponent), A prefixes Actor-derived classes (e.g., ACharacter), F prefixes plain structs/non-UObject types (e.g., FVector), and T prefixes templates (e.g., TArray).

6. What is a Skeleton, Skeletal Mesh, and Skeletal Mesh's relationship to animation in Unreal Engine?

   A Skeleton is a hierarchy of bones. A Skeletal Mesh is geometry bound (skinned) to that skeleton. Animations (sequences) drive bone transforms, deforming the mesh; the Skeleton asset is shared across meshes and animations.

7. What is an Animation Blueprint and what are its two main graphs?

   An Animation Blueprint controls how a Skeletal Mesh is animated. Its two core graphs are the Event Graph (updates variables each frame) and the AnimGraph (blends poses/state machines to output the final pose).

8. What is a Blend Space in Unreal Engine animation?

   A Blend Space is an asset that smoothly interpolates between multiple animations based on one or two input values (e.g., speed and direction), commonly used to blend walk/run animations.

9. In multiplayer Unreal Engine, what is the difference between the Server and Clients in the authority model?

   Unreal uses a server-authoritative model: the server (or listen-server host) has authority over game state, spawns replicated Actors, and validates gameplay; clients receive replicated updates and send input/RPCs to the server.

10. What is variable Replication in Unreal networking and how is it enabled?

    Replication automatically syncs a variable's value from the server to clients. It is enabled by marking the property Replicated (UPROPERTY(Replicated) in C++ or 'Replicated' in Blueprint) and registering it in GetLifetimeReplicatedProps; changes propagate only server to client.

11. What are the three RPC types in Unreal Engine and their direction?

    Server RPC (client calls, runs on server), Client RPC (server calls, runs on the owning client), and NetMulticast RPC (server calls, runs on server and all connected clients).

12. What is a Level of Detail (LOD) and how does it optimize rendering?

    LOD provides multiple lower-polygon versions of a mesh that the engine swaps in as the object moves farther from the camera, reducing triangle count and draw cost for distant objects while preserving near-object quality.

13. What is a draw call, and why does reducing draw calls improve performance?

    A draw call is a command sent to the GPU to render a batch of geometry with a given material/state. Fewer draw calls reduce CPU overhead; techniques like instancing, merging meshes, and shared materials lower the count and improve frame rate.

14. What are common Unreal Engine profiling tools for finding performance bottlenecks?

    Unreal Insights, the 'stat' console commands (e.g., stat FPS, stat Unit, stat GPU), the GPU Visualizer, and Shader Complexity view mode help identify CPU-bound vs GPU-bound bottlenecks.

15. In the 'stat unit' display, what do Game, Draw, and GPU times represent?

    Game is CPU time spent on gameplay/tick logic, Draw is CPU time preparing render commands (render thread), and GPU is time the graphics card spends rendering the frame. The largest of these determines the frame-time bottleneck.

16. What frame time corresponds to a target of 90 FPS, a common VR requirement?

    $\frac{1000\ \text{ms}}{90} \approx 11.1$ ms per frame. VR typically demands 90 FPS (about 11 ms budget) to maintain comfort and avoid motion sickness.

17. What is a VR Pawn setup in Unreal Engine and what components are typically used?

    A VR Pawn typically uses a scene root with a Camera component parented to it representing the headset (HMD), plus MotionController components for tracked hand controllers, enabling roomscale tracking.

18. What VR-specific rendering technique reduces cost by rendering both eyes efficiently in Unreal Engine?

    Instanced Stereo Rendering (and forward shading with MSAA) reduces the overhead of rendering the scene twice (one per eye) by drawing both eye views in a single pass, improving VR performance.

19. What does 'Packaging' a project mean in Unreal Engine?

    Packaging compiles the project and cooks its content into a platform-specific, standalone build (executable plus cooked assets) that can run without the editor on a target platform such as Windows, Android, or consoles.

20. What is 'cooking' content in Unreal Engine?

    Cooking converts editor assets into an optimized, platform-specific binary format that the runtime can load directly, stripping editor-only data and compiling shaders for the target platform.

21. What is the difference between a Development, Shipping, and Debug build configuration when packaging?

    Debug/DebugGame keep full debug symbols and are slowest; Development enables profiling and logging with reasonable performance; Shipping is the fully optimized, stripped configuration for final release with logging/console disabled.

22. What is a Pak file (.pak) in Unreal Engine packaging?

    A .pak file is a packaged archive bundling cooked assets into a single container for distribution and efficient loading; it can also be used for patches and downloadable content (DLC).

23. What are common distribution platforms and requirements for publishing an Unreal Engine game?

    Platforms include Steam, Epic Games Store, mobile app stores (Google Play, Apple App Store), and consoles (which require approved developer programs). Requirements include correct build configuration, platform SDKs, signing/certificates, and store compliance/age ratings.

24. Under the current Unreal Engine license, when do royalties to Epic Games typically apply?

    For games and off-the-shelf products, Epic charges a 5% royalty on gross revenue above a per-product lifetime threshold (1,000,000 USD); revenue below that threshold and non-game/custom uses are generally royalty-free per the EULA terms.

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