Game Development Unity Engine Flashcards

24 sample cards from the Unity 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 Unity's Avatar system and what is retargeting in humanoid animation?

   An Avatar maps a model's bone hierarchy onto Unity's standardized Humanoid rig. Retargeting uses this mapping to apply the same humanoid animation clip to different characters regardless of their exact proportions or skeletons.

2. In Unity UI, what is the Canvas and what are its three main Render Modes?

   The Canvas is the root area on which all UI elements are drawn. Its three Render Modes are Screen Space - Overlay (drawn on top of everything, independent of camera), Screen Space - Camera (rendered by a specific camera at a distance), and World Space (UI exists as a 3D object in the scene).

3. What is the RectTransform and how does it differ from a regular Transform?

   RectTransform is a specialized Transform for UI elements that adds a rectangle (width/height), anchors, pivot, and offsets for layout. Unlike a plain Transform (point-based), it defines a 2D area and supports responsive positioning relative to its parent rect.

4. In Unity UI, what do anchors and the pivot control on a RectTransform?

   Anchors define how a UI element attaches to and scales relative to its parent's rectangle (enabling responsive resizing). The pivot is the local point around which the element rotates, scales, and is positioned within its own rect.

5. What is the purpose of a Layout Group (e.g., Horizontal/Vertical/Grid) and the Content Size Fitter in Unity UI?

   Layout Groups automatically arrange child UI elements in rows, columns, or grids with spacing/padding. A Content Size Fitter resizes an element to fit its content. Together they build dynamic, self-adjusting UI without manual positioning.

6. How does Unity's UI event system detect which UI element the user clicks, and what component is required?

   An EventSystem GameObject with an Input Module processes input and dispatches events. Raycasting is performed by a Graphic Raycaster on the Canvas to determine which UI element (with a raycast-target graphic) is under the pointer, then routes events to it.

7. In Unity UI, what is the difference between UGUI (Unity UI) and UI Toolkit?

   UGUI is the traditional GameObject/Canvas-based UI system using RectTransforms and components in the scene. UI Toolkit is a newer retained-mode system using UXML (structure) and USS (style sheets), inspired by web/CSS, offering better scalability and editor tooling.

8. In Unity audio, what is the difference between an AudioSource and an AudioListener?

   An AudioSource plays audio clips in the scene (the emitter). An AudioListener receives/hears audio and is usually attached to the main Camera. There should typically be only one active AudioListener; spatialized sound is computed relative to it.

9. What is the difference between 2D and 3D (Spatial Blend) sound on an AudioSource in Unity?

   Spatial Blend controls positioning: 2D (blend = 0) plays at constant volume regardless of position (UI/music). 3D (blend = 1) attenuates with distance and pans based on the source's location relative to the AudioListener, creating positional audio.

10. What is the human range of audible frequencies, and how does sample rate relate to it via the Nyquist theorem? Answer in LaTeX.

    Humans hear roughly $20\ \text{Hz}$ to $20{,}000\ \text{Hz}$. The Nyquist theorem requires the sample rate to be at least twice the highest frequency: $f_s \geq 2 f_{max}$, which is why $44{,}100\ \text{Hz}$ (over $2 \times 20\,\text{kHz}$) is a standard audio sample rate.

11. What is an Audio Mixer in Unity and what are Snapshots used for?

    An Audio Mixer routes and processes audio through groups/channels, applying volume, effects (reverb, EQ, compression), and ducking. Snapshots store a configuration of mixer settings that can be smoothly transitioned at runtime (e.g., muffling audio when paused).

12. What is audio ducking and how is it commonly implemented in Unity's Audio Mixer?

    Ducking automatically lowers the volume of one audio group (e.g., music) when another (e.g., dialogue) plays. In Unity it is implemented with a Duck Volume effect on the target group linked via a Send from the triggering group's signal.

13. In Unity networking, what is the difference between authoritative server and client-side prediction?

    An authoritative server holds the definitive game state and validates all actions to prevent cheating. Client-side prediction lets the client immediately simulate its own input locally for responsiveness, then reconciles with the server's authoritative state when it arrives.

14. In Unity networking (Netcode), what is a NetworkObject and what does a NetworkBehaviour add over a normal MonoBehaviour?

    A NetworkObject gives a GameObject a network identity so it can be spawned and synchronized across clients (with an owner and a network ID). A NetworkBehaviour extends MonoBehaviour to support networked features like NetworkVariables and Remote Procedure Calls (RPCs).

15. What is the difference between a ServerRpc and a ClientRpc in Unity Netcode?

    A ServerRpc is called by a client and executed on the server (client-to-server request/command). A ClientRpc is called by the server and executed on connected clients (server-to-clients broadcast/notification).

16. Why is UDP typically preferred over TCP for real-time game networking, and what tradeoff does it involve?

    UDP is connectionless and does not guarantee delivery or ordering, giving lower latency with no head-of-line blocking retransmission delays. The tradeoff is that packets may be lost or arrive out of order, so games add their own reliability/ordering only where needed.

17. In multiplayer bandwidth optimization, what are interest management and delta compression?

    Interest management sends each client only the state relevant to it (e.g., nearby objects) instead of the whole world, reducing traffic. Delta compression transmits only the changes since the last update rather than full state snapshots, further cutting bandwidth.

18. How is a game's frame rate related to frame time, and what frame time corresponds to 60 FPS? Answer in LaTeX.

    Frame rate and frame time are reciprocals: $$\text{FPS} = \frac{1}{\Delta t}$$ where $\Delta t$ is seconds per frame. For $60$ FPS, $\Delta t = \frac{1}{60} \approx 16.67\ \text{ms}$ per frame.

19. In Unity performance, what is a draw call and why does reducing draw calls improve performance?

    A draw call is a command to the GPU to render a set of geometry (typically per material/mesh batch). Each call has CPU overhead; too many draw calls make the CPU the bottleneck. Reducing them (via batching/atlasing) lowers overhead and increases frame rate.

20. What is the difference between static batching and dynamic batching in Unity?

    Static batching combines non-moving objects that share a material into one mesh at build/load time to reduce draw calls (costs more memory). Dynamic batching automatically batches small moving meshes sharing a material at runtime, saving draw calls but adding CPU cost per object.

21. In Unity, what is object pooling and why does it improve performance over Instantiate/Destroy?

    Object pooling pre-creates and reuses a pool of objects (activating/deactivating them) instead of repeatedly calling Instantiate and Destroy. This avoids runtime allocation and garbage-collection spikes, giving smoother performance for frequently spawned objects like bullets.

22. What causes garbage collection (GC) spikes in Unity, and how can they be minimized?

    GC spikes come from frequent heap allocations of managed objects (e.g., 'new' in Update, boxing, string concatenation, LINQ) that the garbage collector must later reclaim, causing frame hitches. Minimize by caching references, reusing buffers, avoiding per-frame allocations, and using structs/pools.

23. What is Level of Detail (LOD) in Unity and how does it optimize rendering?

    LOD swaps a mesh for progressively simpler versions as an object moves farther from the camera (managed by an LOD Group). This reduces the vertex/triangle count rendered for distant objects, saving GPU/CPU work while preserving apparent visual quality.

24. What is occlusion culling versus frustum culling in Unity?

    Frustum culling skips rendering objects outside the camera's view frustum. Occlusion culling additionally skips objects that are inside the frustum but hidden behind other opaque objects (occluders), preventing wasted rendering of things the camera cannot actually see.

What this deck covers

Unity Engine flashcards FAQ