Unreal Engine Basics
What is the difference between Static, Stationary, and Movable lights?
In the Content Browser, right-click an empty area, choose Blueprint Class, pick a parent class (Actor, Pawn, Character, etc.), name it, and double-click to open the Blueprint editor.
A Decal Actor projects a material onto surfaces in the level within a defined volume, used for bullet holes, blood splatters, dirt, signage, and stylized overlays. It automatically conforms to the geometry it intersects without altering the underlying mesh.
Static lights are baked into lightmaps and cannot change at runtime. Stationary lights can change color and intensity but only cast static shadows. Movable lights are fully dynamic, casting real-time shadows and movable specular highlights, but are the most expensive.
Sample a normal map texture with a Texture Sample node and plug it into the Normal input of the material. Optionally route it through a Normalize node and use a vector parameter to control intensity for tweakable bump strength.
Unreal Engine Basics
What is the CharacterMovementComponent responsible for?
It provides walking, running, jumping, falling, swimming, and flying with capsule collision. It handles slope limits, step height, gravity scaling, network prediction, and smoothing automatically.
A Lightmass Importance Volume marks the region of the level where lightmap baking should be prioritized and at higher quality. Place it around the playable area so the stationary lighting build focuses detail and reduces baking time.
A Post Process Volume applies screen-space effects like bloom, tone mapping, ambient occlusion, color grading, and vignette. Place a volume and configure its settings in the Details panel.
Open Project Settings → Rendering, and under Lighting, set Global Illumination Method to Lumen. Also ensure your level uses compatible materials, dynamic lighting, and that Mesh Distance Fields are enabled for Lumen to function correctly.
Unreal Engine Basics
What is an Exponential Height Fog actor used for?
Event BeginPlay executes once when the actor first enters the world during gameplay. It is commonly used to initialize variables, spawn actors, set up UI, or play startup effects.
A Post Process Volume applies screen-space effects like bloom, tone mapping, ambient occlusion, color grading, and vignette. Place a volume and configure its settings in the Details panel.
Metallic controls whether the surface behaves like a metal. At 1, Base Color becomes the reflection tint with no diffuse; at 0, the material is dielectric with diffuse and small specular reflections. Most non-metals should keep Metallic at 0.
It adds atmospheric distance fading, sky blending, and an optional inscattering color. Height Fog gives a sense of scale and depth to outdoor or large indoor scenes.
Unreal Engine Basics
What is the difference between the Details panel and the World Outliner?
Open the Place Actors panel (Window > Place Actors), search or browse the desired actor class, then drag it into the viewport or right-click in the viewport and choose the actor from the context menu to spawn it at the cursor location.
World Position Offset moves vertices in world space at runtime, enabling procedural effects like flowing water, swaying foliage, dissolve effects, and vertex animation without changing mesh geometry.
The Outliner lists actors present in the level for selection. The Details panel shows editable properties of whatever actor or asset is currently selected, including components, transforms, and exposed variables.
Add a Trigger Box actor to the level. In its Blueprint, add OnActorBeginOverlap, drag from the red pin, and connect nodes like Print String or a custom event for the desired reaction.
Unreal Engine Basics
What is the Pawn class used for in Unreal?
In the Content Browser, right-click an empty area and choose Blueprint Class. Select a parent class (e.g., Actor, Pawn, Character), name the asset, and double-click it to open the Blueprint Editor where you can add components, variables, and graphs.
DefaultEngine.ini is a config file in the Config folder that stores project-level engine settings such as default rendering settings, default classes, physics settings, and packaging options. It persists changes made in Project Settings.
A function is a compiled graph with local variables and outputs, called like a C++ function. A macro is inlined at every call site, sharing nodes with the caller and supporting multiple execution pins.
Pawn is a base actor that can be possessed and controlled by a player or AI. It provides basic movement capability but lacks Character-specific features like crouching.
Unreal Engine Basics
What does the Delay node do?
Press Shift+F1 (Unpossess) to detach from the pawn, or use the Stop button in the Level Editor toolbar to end PIE and return focus to the editor camera at the original viewport position before the play session was launched.
Project Settings stores project-wide configuration including maps and modes, input mappings, packaging settings, rendering features, physics settings, platform-specific options, and project description. Changes here apply to the entire game and update DefaultEngine.ini and DefaultGame.ini.
Delay halts execution for a specified number of seconds, then resumes from its Completed pin. Useful for timed events, cooldowns, or staggered spawn sequences.
Select the actor in the viewport or Outliner, press Ctrl+W (or Cmd+D on macOS), and a copy is placed at the same location, ready to be moved with the transform gizmo.
Unreal Engine Basics
What does the World Position Offset material input do?
It displaces vertex positions at runtime in the vertex shader. Used for wind sway, tessellation, procedural deformation, and dissolving effects without moving geometry on the CPU.
Make Array creates a literal Array at compile time from the values wired into its pins. Useful for passing a fixed list of items into functions or constructing test data inline.
A Physics Constraint is an actor that connects two physical objects with limits on movement, rotation, and force. It is used to create ragdolls, doors, chains, wheels, and any jointed mechanical assembly simulated by the physics engine.
World Position Offset moves vertices in world space at runtime, enabling procedural effects like flowing water, swaying foliage, dissolve effects, and vertex animation without changing mesh geometry.
Unreal Engine Basics
What is a Data Layer in World Partition?
It displaces vertex positions at runtime in the vertex shader. Used for wind sway, tessellation, procedural deformation, and dissolving effects without moving geometry on the CPU.
Data Layers are runtime-loadable actor groups within World Partition, like interior rooms or dynamic structures. They enable precise streaming control beyond distance-based loading.
A Directional Light simulates distant light like the sun, casting parallel rays across the entire level. It drives sun direction, color, intensity, and atmospheric scattering when paired with Sky Atmosphere.
A Material Instance is an asset derived from a parent Material that can override specific parameters (colors, textures, scalar values) without recompiling the full material. It allows many visual variations of one base shader for performance and artist workflow efficiency.
Unreal Engine Basics
What is a Widget Blueprint used for?
Widget Blueprints create UMG-based user interface elements like HUDs, menus, and dialogs. They use a designer canvas combined with a graph for interactive logic.
A Timeline node plays a simple track-based animation over time, such as moving an actor, fading alpha, or rotating a component. You add float, vector, or color tracks and drive outputs with it inside the Event Graph.
A Blend Space blends multiple animations based on input values, typically speed and direction. A 1D Blend Space uses one axis, while a 2D Blend Space uses two axes to interpolate smoothly between animations such as walking and running.
Cook transforms project assets into platform-specific formats. Package bundles the cooked content into a distributable installer or folder, ready for end-user distribution and launch.
Unreal Engine Basics
What is the purpose of the Saved folder in a UE project?
A Timeline plays a curve over time, driving outputs like floats, vectors, or colors. It is used for animations such as doors opening, UI fades, or camera dollies without Tick logic.
The Saved folder contains auto-generated files including logs, screenshots, crash dumps, save games, config overrides, and the AssetRegistry. You should generally exclude it from source control and let Unreal regenerate it as needed.
The AnimGraph is the visual graph that evaluates the final pose each frame, combining state machines, blend spaces, IK, and cached poses before passing the result to the Output Pose node.
The Construction Script runs when an actor is placed or moved in the editor, and again whenever a property changes. It is commonly used for procedural setup such as spawning meshes, adjusting transforms, or generating editor-only logic.
Unreal Engine Basics
What does the Texture Streaming pool size setting affect?
Enable Simulation Generates Hit Events on the component. Implement the On Component Hit or On Component Begin Overlap events exposed on the relevant collision component to receive execution pins and access the Other Actor and Hit information.
Texture Streaming Pool Size, found in Project Settings > Rendering, limits the total video memory allocated for streamed textures. Too small causes blurriness or low-res textures; too large wastes memory. Adjust based on target hardware GPU capability.
The Content Browser is the editor panel that displays your project's folder structure and all imported or created assets such as meshes, textures, materials, Blueprints, and sounds. You can create folders, rename, move, and open assets from here.
World Settings, accessible from the Window menu, exposes level-specific settings like the selected GameMode override, NavMesh settings, lightmass quality, kill Z, and audio volumes. Changes here affect only the currently open level, not the entire project.
Unreal Engine Basics
What does the Stat FPS command display?
A Timeline node plays a simple track-based animation over time, such as moving an actor, fading alpha, or rotating a component. You add float, vector, or color tracks and drive outputs with it inside the Event Graph.
Stat FPS shows the current frames-per-second plus frame time in milliseconds at the top of the viewport. It is a quick way to measure real-time performance and verify whether the game is hitting its target frame budget.
The Event BeginPlay node fires once on each actor when play starts, after construction and initialization, making it the standard place to set up gameplay logic like spawning actors, starting timers, or initializing variables.
PlayerController is an actor possessed by each local player that handles input mapping, possessing/unpossessing pawns, displaying the HUD, and interfacing with the camera. It receives input events from the player and translates them into game actions via Blueprint.
Unreal Engine Basics
What does the Cook Commandlet do when packaging a project?
The Cook commandlet processes all content for the target platform, converting assets to platform-specific formats, compressing textures, and stripping editor-only data. The cooked output is what is bundled into the final packaged build.
A Directional Light simulates a distant light source like the sun, casting parallel rays across the entire scene. It is typically used for outdoor lighting and is the main contributor of light in outdoor levels with a sky atmosphere.
Widget Blueprints create UMG-based user interface elements like HUDs, menus, and dialogs. They use a designer canvas combined with a graph for interactive logic.
Press Show → Collision or use the Show menu, or press the Collision button in the main toolbar. This reveals collision shapes for actors, useful for debugging blocking volumes, triggers, and physics setup before gameplay testing.
Unreal Engine Basics
What is an Animation Montage in Unreal?
In the Content Browser, right-click an empty area and choose Blueprint Class. Select a parent class (e.g., Actor, Pawn, Character), name the asset, and double-click it to open the Blueprint Editor where you can add components, variables, and graphs.
It is a container Blueprint holding static functions callable from any other Blueprint or C++. It is ideal for reusable utility code that does not depend on a specific actor instance.
An Animation Montage is a reusable sequence that plays a specific animation on a slot, optionally blended with the base state machine. It's commonly used for attacks, reloads, and upper-body actions.
The Stat GPU console command shows real-time GPU rendering performance broken down by category: render thread time, draw calls, triangles, shadow passes, post-processing, and other GPU bottlenecks. It is essential for diagnosing rendering-related performance issues.
Unreal Engine Basics
What does the AnimGraph play in an Animation Blueprint?
The Significance Manager assigns a numeric importance score to actors based on distance, angle, and custom rules, so less important AI, animation, or effects can be throttled at runtime to maintain frame rate on dense scenes.
The AnimGraph is the visual graph that evaluates the final pose each frame, combining state machines, blend spaces, IK, and cached poses before passing the result to the Output Pose node.
A Directional Light simulates distant light like the sun, casting parallel rays across the entire level. It drives sun direction, color, intensity, and atmospheric scattering when paired with Sky Atmosphere.
PlayerController is an actor possessed by each local player that handles input mapping, possessing/unpossessing pawns, displaying the HUD, and interfacing with the camera. It receives input events from the player and translates them into game actions via Blueprint.
Unreal Engine Basics
Why do dynamic shadows from a stationary light not update in real time?
Stationary lights have their indirect lighting baked into lightmaps and only direct shadow casting is dynamic. To get fully dynamic shadows that respond instantly, switch the light to Movable at the cost of no baked contribution.
AnimNotify lets you trigger events at specific frames in an animation, like footsteps, particle spawns, or sound playback. Set them up in the animation sequence's notify track.
Select the light actor, find the Cast Shadows property in the Details panel, and ensure it is checked. You can also adjust the Shadow Bias, Shadow Resolution, and Lighting Channels to tune shadow quality and accuracy.
Flush Persistent Debug Lines removes all previously drawn Draw Debug Line, Draw Debug Sphere, and similar persistent debug visualizations from the world. It is useful for clearing stale debug data between events or when transitioning levels in Blueprints.
Unreal Engine Basics
What is the Content Browser used for in Unreal Engine?
AnimNotify lets you trigger events at specific frames in an animation, like footsteps, particle spawns, or sound playback. Set them up in the animation sequence's notify track.
Unreal Engine 5 emphasizes Lumen, a real-time global illumination and reflections system that uses hardware ray tracing or software fallback to dynamically light scenes, replacing traditional baked lightmaps in many workflows.
The Content Browser is the panel that displays the project's folder structure (under /Content/) and lets you create, import, rename, move, and open assets like Blueprints, textures, meshes, and materials.
The Construction Script runs when an actor is placed or moved in the editor, and again whenever a property changes. It is commonly used for procedural setup such as spawning meshes, adjusting transforms, or generating editor-only logic.
Unreal Engine Basics
How do you tag an Actor so it can be found with Get All Actors With Tag?
In the Content Browser, right-click an empty area and choose Blueprint Class. Select a parent class (e.g., Actor, Pawn, Character), name the asset, and double-click it to open the Blueprint Editor where you can add components, variables, and graphs.
Press F while the actor is selected to frame it in the viewport. This centers the camera on the actor regardless of its current position.
Select the actor in the level, open the Details panel, and add a string to the Actor Tags array. Then call Get All Actors With Tag, supplying the same string, to retrieve all actors in the world carrying that tag.
A variable stores data (int, float, bool, vector, object reference, etc.) for use in the Blueprint. In the My Blueprint panel click the + button, give it a name, set its type via the dropdown, and compile.
Unreal Engine Basics
What is the difference between Editor builds and Shipping builds in UE?
An Animation Montage is a reusable sequence that plays a specific animation on a slot, optionally blended with the base state machine. It's commonly used for attacks, reloads, and upper-body actions.
Editor builds include debugging tools and the editor itself; useful during development. Shipping builds strip debug features, console commands, and logging for smaller, optimized retail-ready binaries.
Game Instance persists across level loads for the entire game session, unlike Game Mode/State which reset per level. Use it to store save data, player profiles, and persistent UI state.
FName is interned and case-insensitive, ideal for identifiers looked up frequently. FString is a mutable dynamic string better for user-facing text or constructed messages.
Unreal Engine Basics
What is Lumen in Unreal Engine 5?
Lumen is UE5's dynamic global illumination and reflections system. It updates lighting in real time for moving lights and objects without precomputed lightmaps, supporting reflections and bounced light.
The Content Browser is the editor panel that displays your project's folder structure and all imported or created assets such as meshes, textures, materials, Blueprints, and sounds. You can create folders, rename, move, and open assets from here.
Event BeginPlay fires once on the server and each client when the actor is spawned and ready. It is the standard place to initialize variables, attach components, or kick off gameplay logic.
A NavMesh is automatically generated walkable surface data that AI agents use for pathfinding. It is built from the level's collision geometry during a Navigation Mesh Bounds Volume and allows AI controllers to navigate around obstacles to reach targets.
Unreal Engine Basics
What is the Actor class in Unreal Engine?
An Actor is the base class for any object that can be placed in a level. It supports transform, replication, and spawning. Pawns, Characters, Static Mesh Actors, and Trigger Volumes all inherit from AActor.
Widget Blueprints create UMG-based user interface elements like HUDs, menus, and dialogs. They use a designer canvas combined with a graph for interactive logic.
Select the actor in the level, open the Details panel, and add a string to the Actor Tags array. Then call Get All Actors With Tag, supplying the same string, to retrieve all actors in the world carrying that tag.
Post Process Volumes apply effects like bloom, color grading, exposure, vignette, and lens flares to the rendered scene. They can be global or area-specific.
Unreal Engine Basics
What shortcut toggles the Unreal Editor between perspective and orthographic viewports?
Collision Channels define how actors interact with each other during physics queries and overlap/trace tests. Unreal provides default channels like Visibility, Camera, Pawn, and WorldStatic, plus customizable Object and Trace channels for game-specific logic.
The Output Log displays runtime messages, warnings, errors, and print string outputs from Blueprints. It is essential for debugging gameplay logic and shader compilation issues.
A Material Function is a reusable group of material nodes saved as its own asset. You can call it inside other materials by dragging it from the Palette, allowing shared complex logic like triplanar mapping, noise, or snow blending across many materials.
Press F10 in the editor viewport to cycle between perspective and orthographic camera modes. This helps with level layout and aligning geometry to grid axes.
Unreal Engine Basics
What is a Decal Actor in Unreal used for?
World Position Offset moves vertices in world space at runtime, enabling procedural effects like flowing water, swaying foliage, dissolve effects, and vertex animation without changing mesh geometry.
A Decal Actor projects a material onto surfaces in the level within a defined volume, used for bullet holes, blood splatters, dirt, signage, and stylized overlays. It automatically conforms to the geometry it intersects without altering the underlying mesh.
In the variable's Details panel set Replication to 'Replicated'. Only the server can change it, and updates automatically push to all clients; useful for health, ammo, or team scores.
It directly assigns a linear velocity vector to a simulating physics body. Useful for launching projectiles, knockbacks, or restoring expected motion after physics teleports an actor.