Unreal Engine Technical Notes

Not sure what to build first in UE5? Learn an order to study in, how to set goals, and finish a first mechanic that toggles a room light with the F key.

The five core UE5 concepts, Actor, Component, Blueprint, Level, and GameMode, explained with diagrams and applied to the Third Person template.

What UE5's Viewport, Outliner, Details panel, and Content Browser do, plus the W, E, R, and F shortcuts, practiced in one short lap.

Five UE5 project settings to check first: history saving, startup map, input, editor language, and editor performance, plus restoring a level with Git.

Organize UE5 assets with clear folders and naming rules, read reference relationships, and verify nothing breaks after moving an asset.

Find free props on Fab and add them to UE5: check price, format, and license, inspect them in a test project, and move them with Migrate.

Debug UE5 with Print String and the Output Log to check flow and variable values, plus Key-based overwriting and C++ UE_LOG.

Draw ranges and facing on screen with Draw Debug Sphere and Cone in UE5, and revisit recorded moments with the Visual Logger.

Greybox a level with UE5's Modeling Mode, size boxes and stairs against the player capsule, and walk them to check space and collision.

Where rules and scores belong in UE5: GameMode for rules, GameState for match status, and PlayerState for each player's results.

Link title, stage, and results screens with Open Level in UE5, carry the score in GameInstance, and fade out before transitioning.

Version a UE project with Git: ignore generated files, set up Git LFS, lock assets for collaboration, and understand One File Per Actor.

Package a UE5 game for Windows: startup and included maps, Development versus Shipping, sharing the whole folder, and reading logs when it fails.

Upgrade a work-in-progress UE project safely: back up, use Open a Copy, compare logs and behavior, and know how to roll back.

Turn a manual check into a repeatable UE5 Functional Test in Blueprint that verifies 20 damage takes HP from 100 to 80.

Build a UE5 Editor Utility Widget in Blueprint that rotates and scales selected Actors in bulk with a button, with one-step Undo.

A UE5 capstone: build a 60-second coin-collecting game in Blueprint with score, timer, HUD, results, retry, and high-score saving.

When to use Class Variables versus Local Variables in Blueprint, by scope and persistence, with a fix for a total that doubles from 300 to 600.

Choose between Array, Set, and Map in UE5 Blueprint, learn their main nodes, and count inventory items by ID with a Map.

Choose between Blueprint Functions and Macros by return values, exec pins, and Delay, with a skill check and a 3-second cooldown.

When to use a Level Blueprint versus a Blueprint Class in UE5, shown with a trigger that raises a door 300 cm over 1.5 seconds with a Timeline.

Reuse one health Component on an enemy and a crate in UE5, and learn ActorComponent versus SceneComponent, Owner, and Event Dispatchers.

Three ways Blueprints talk in UE5: Direct Reference, Blueprint Interface, and Event Dispatcher, shown by raising a bridge with the E key.

Create, Bind, Call, and Unbind an Event Dispatcher in UE5 so picking up an item updates the count and the display separately.

Send the same damage message to an enemy and a crate with a Blueprint Interface in UE5, and know when to use Cast instead.

Choose between Event Tick, Timers, and events in UE5 Blueprint, with a watchtower that rotates every 0.5 seconds only while you're near.

Tidy messy Blueprint graphs by splitting, aligning, naming, and extracting functions, without changing what the graph does.

Use the UE5 Blueprint Debugger with breakpoints, Step Into and Step Over, Watch, and Debug Object to fix a zero-damage bug.

Ten common Blueprint mistakes grouped by symptom, slow, buggy, or unreadable, covering Tick, Cast, Pure nodes, references, physics, and Dispatchers.

Deal damage with Apply Damage and handle it with Event AnyDamage in UE5, destroy at 0 HP, and add one second of invincibility.

Manage a chest's four states with an Enum and Switch in UE5 Blueprint so mashing doesn't restart it and resetting mid-way stops cleanly.

Rotate a turret toward the player with a slight lag in UE5 using Rotator, Find Look at Rotation, RInterp To, and Lerp.

Build an automatic door with a UE5 Timeline that closes from its current height if you leave, using keys, curves, Update, Play, and Reverse.

Set up Input Actions and Mapping Contexts in UE5 Enhanced Input, then build WASD movement, jumping, a hold trigger, and switching control schemes.

Build a key rebinding screen in UE5 with Input Key Selector and Enhanced Input user settings, saving the jump key and showing the current binding.

Add gamepad support in UE5: the left stick, Dead Zone tuning, analog triggers, menu focus, and detecting the input method with Common Input.

Fix invisible walls in UE5 by showing a Static Mesh's collision, choosing between Simple and Complex, and rebuilding it with Auto Convex.

Use collision channels and profiles in UE5 so a shield blocks enemy bullets but lets friendly ones through, and read Block, Overlap, and Ignore.

Tune UE5 Character Movement for speed, acceleration, jump height, air time, and air control, then add a Shift sprint.

Use a Line Trace in UE5 to detect the box in front of you: set start and end, choose trace channels, and read the hit result.

Fire a projectile on left click in UE5 with Spawn Actor and Projectile Movement, damage a box on hit, and clean up with collision and lifespan.

Make a character collapse into a ragdoll on the R key in UE5, with Physics Asset bodies and joints and a push from Add Impulse.

Build an HP bar with a UMG Widget Blueprint in UE5, covering anchors, the Percent value, and updating it through an Event Dispatcher.

Fix menu focus order with UMG Navigation, update displays only when needed, and choose between Invalidation Box and Retainer Box in UE5.

Attach an overhead HP bar with a Widget Component and float damage numbers with UMG animation, including Screen versus World space.

Build a UE5 pause menu that opens and closes with the P key using Set Game Paused, with input routing, the cursor, and resume and restart buttons.

Build a UE5 settings screen for window size, quality, and music volume that applies and saves Game User Settings and survives a relaunch.

Build a villager conversation with UE5 Data Tables and UMG: typewriter text, skipping, branching choices, and returning control afterward.

Turn UE5's Third Person template into two-player split screen with Create Local Player, keyboard and gamepad assignment, and per-player HUDs.

Use a State Machine and Blend Space in a UE5 Animation Blueprint to blend idle, walk, run, and jump from speed and airborne state.

Retarget a Mixamo run onto Manny in UE5 with IK Rig chains and the IK Retargeter, including A-pose and T-pose alignment and export.

Use Animation Montages, Slots, and Notifies in UE5 to open a hitbox only during the downswing, prevent double hits, and clean up on interruption.

Build a short UE5 Sequencer cutscene that pans to a boss and returns control to the player, with Camera Cuts, Blueprint playback, and skipping.

Run the Game Animation Sample to see how Motion Matching picks starts, stops, and turns from Pose and Trajectory, and how to reuse it.

Build a UE5 enemy that patrols, chases the player on sight, and returns to patrol, using Selector, Sequence, the Blackboard, and Observer Aborts.

Find why UE5 AI won't move by showing the NavMesh with the P key, testing AI MoveTo, fitting agent size, and handling moving obstacles.

Set up sight and hearing with UE5 AI Perception, and add an investigate branch to a Behavior Tree so the enemy checks the clue and returns to patrol.

Learn UE5 StateTree with patrol, chase, and search states, Tasks, Transitions, and passing data into conditions, and when to use it over Behavior Trees.

Use UE5's EQS to have a hit enemy pick cover: generate candidates, filter and score them, build a Context, and connect it to a Behavior Tree.

Sound Wave is the audio; Sound Cue is how it plays. Add Random and Modulator variation to footsteps in UE5 and trigger them with an Animation Notify.

Make a campfire fade with distance using Sound Attenuation, and add separate music and effects sliders with Sound Class and Sound Mix in UE5.

Create a looping engine sound with a MetaSound Source in UE5 and change its pitch at runtime through an Input and an Audio Component.

Add drums to calm exploration music when entering a combat area, layering tracks in MetaSounds and fading their volume from Blueprint.

Learn UE5 material basics with Base Color, Metallic, Roughness, and Normal, then create Material Instances and override the parent's values.

Light a dark corridor in UE5 with Point, Spot, and Rect Lights, and learn Lumen bounce lighting, locking exposure, and what to check when light doesn't reach.

Adjust brightness and color with a UE5 Post Process Volume, and change the mood in one area with Unbound, Priority, and Blend Radius.

Handle high-detail Static Meshes with Nanite in UE5: enable and visualize it, compare cost on a rock field, and see where it doesn't apply.

Build a third-person camera with a Spring Arm that avoids walls, add an over-the-shoulder view, and switch smoothly on right-click in UE5.

Learn how particles, Emitters, and Systems relate in UE5 Niagara, turn a template into a one-shot spark burst, and play it from Blueprint.

Flash only the hit box red for 0.2 seconds with a Dynamic Material Instance and a Timeline connected to your damage logic in UE5.

Build a 252 m Landscape in UE5, sculpt hills, paint a path with Layer Blend and Layer Info, and scatter plants with Foliage, no extra assets needed.

Scatter trees with UE5's PCG framework, filter out steep slopes, and clear space around a path with a Spline and Difference.

Add hitstop, screen shake, and knockback to attacks in UE5 Blueprint, and tune them so they never overwhelm.

Show another camera's view as a minimap or in-game monitor with a UE5 Render Target, including capture range, UI display, and timed updates.

Bundle item data into a Blueprint Struct with Make and Break, and learn why editing a copy doesn't change the array until you use Set Array Elem.

Tune enemy stats in a CSV and load them into a UE5 Data Table, with Structs, Row Names, and Get Data Table Row's found and not-found paths.

Store an enemy's name, HP, and mesh in a Data Asset and swap the data on the same Blueprint Actor to add enemy types in UE5.

Save gold to a file with UE5's Save Game in Blueprint and load it back after restarting Play, covering slots, Cast, and save failures.

Add fields to a UE5 Save Game without breaking old saves, using a SaveVersion, defaults, and a one-time migration that carries gold over.

Respawn the player at the last checkpoint after a fall in UE5, resetting fall speed, fading the screen, and preventing double execution.

Carry score and clear records across levels with UE5's GameInstance, using Get Game Instance and Cast, and reset cleanly for a new run.

Build a UE5 Blueprint inventory for picking up and using herbs, with Data Asset definitions, Map quantities, stack limits, and total capacity.

Build a UE5 Blueprint quest from accepting to reporting and a one-time reward, separating quest definitions from progress across four states.

Switch a menu between Japanese and English with UE5's Localization Dashboard, from Text versus String to gathering, compiling, and saving the language.

Create your first UE5 C++ class as a Blueprint user, using UCLASS, UPROPERTY, and UFUNCTION to spin a prop you tune and call from Blueprint.

Split work between Blueprint and C++ in UE5: shared HP math in C++, max HP and death effects in child Blueprints, verified with Apply Damage.

Choose between GameInstance, World, and LocalPlayer Subsystems by lifetime, and build a C++ score Subsystem that carries over to the next level.

Learn Gameplay Tag hierarchies and Containers in UE5 by making holy water that hurts only undead, with Has Tag and Exact Match.

What UE5's Gameplay Ability System handles, shown with a 20 MP spell: Abilities, Effects, Attributes, tags, and when to adopt GAS.

Read UE5's stat unit Frame, Game, Draw, and GPU times, tell FPS from milliseconds, and compare under identical conditions to find what's slow.

Record a trace with Unreal Insights, read the Timing Insights timeline, Inclusive and Exclusive times, and compare after removing per-frame searches.

Reduce rendering cost in UE5 with LODs, frustum and occlusion culling, and Cull Distance Volumes, and check the results with FreezeRendering.

Draw many identical rocks and pillars cheaply with ISM in UE5, place them with Add Instance, and choose between ISM, HISM, and Foliage.

Load only the parts of a large UE5 map you need with World Partition and Level Streaming, using Level Streaming Volumes and Blueprint.

Reuse three bullets instead of destroying them with a Blueprint object pool, covering in-use checks, timers, Projectile Movement, and empty pools.

Hard versus soft references in UE5, and loading a mesh only when needed with Async Load Asset, including failure, retry, and checking memory.

Build a door both players see open in UE5, splitting RPCs and Replication into request, decision, and shared state, with RepNotify and ownership pitfalls.

Build a join menu with UE5's Create, Find, and Join Session for two PCs on one LAN, and handle empty results and failures.