ue-blueprint-fundamentals

Explains Unreal Engine Blueprint architecture, graph types, and the C++ base plus Blueprint subclass workflow.

55|5|Updated Mar 26, 2026
One-click install
npx skills add https://github.com/kevinpbuckley/unreal-engine-skills --skill ue-blueprint-fundamentals-kevinpbuckley
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: ue-blueprint-fundamentals
Source: https://github.com/kevinpbuckley/unreal-engine-skills/tree/main/skills/core/ue-blueprint-fundamentals
Command: npx skills add https://github.com/kevinpbuckley/unreal-engine-skills --skill ue-blueprint-fundamentals-kevinpbuckley

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve? Unreal Engine agents often misunderstand how Blueprints actually work under the hood — the difference between the UBlueprint editor asset and the UBlueprintGeneratedClass runtime class, how graphs compile, and how Blueprint logic maps onto the UObject/reflection model. This Skill provides the correct mental model and exact engine-source references so an agent can reason about Blueprint vs C++ responsibilities, design class hierarchies spanning both, and debug compilation or reparenting issues. ## Core Features & Use Cases - Two-object architecture: Explains UBlueprint (editor asset) vs UBlueprintGeneratedClass (runtime UClass), the skeleton class, and the compilation pipeline with UE 5.8 source citations. - Graph and variable model: Covers Event Graphs, Functions, Construction Scripts, Macros, Interfaces, variable flag mappings to UPROPERTY specifiers, and the SCS component tree. - C++ + Blueprint boundary: Documents UCLASS/UPROPERTY/UFUNCTION specifiers, BlueprintNativeEvent/BlueprintImplementableEvent dispatch, and the idiomatic C++ base + Blueprint subclass pattern with TSubclassOf spawning. - Use Case: When asked to design a weapon system, the agent writes a Blueprintable C++ AWeaponBase with exposed properties and events, then creates BP_Rifle as a thin Blueprint subclass that sets defaults and implements visual responses — avoiding logic-heavy Blueprint pitfalls. ## Quick Start Explain how a Blueprint class relates to its C++ parent and help me design a C++ base class with a Blueprint subclass for a weapon actor.

Frequently Asked Questions about ue-blueprint-fundamentals

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
What is the difference between UBlueprint and UBlueprintGeneratedClass?

UBlueprint is the editor-only asset holding graphs, variable metadata, and component templates, while UBlueprintGeneratedClass is the runtime UClass containing compiled FProperties, UFunctions, and timelines. At runtime only the generated class exists, named <BlueprintName>_C.

How do I expose a C++ class to Blueprints in Unreal Engine?

Mark the class UCLASS(Blueprintable, BlueprintType), expose properties with UPROPERTY(EditAnywhere, BlueprintReadWrite), and functions with UFUNCTION(BlueprintCallable). Use BlueprintImplementableEvent or BlueprintNativeEvent when Blueprint should provide or override behavior.

When should I use C++ versus Blueprint in Unreal Engine?

Use C++ for performance-critical paths, replication internals, large branching systems, and stable base class APIs. Use Blueprint for per-asset configuration, designer tuning, simple event responses, and content references like meshes and sounds.

Why does the Construction Script run multiple times in Unreal Engine?

The Construction Script maps to AActor::OnConstruction and runs on every actor spawn, every property edit on a placed instance, and editor drags when bRunConstructionScriptOnDrag is set. It must be idempotent and never accumulate state across runs.

What is the difference between Blueprint functions and macros?

Functions compile to separate UFunctions with their own call frame and support overriding in child Blueprints. Macros are inlined at the call site at compile time, allow multiple exec pins and latent nodes, but cannot be overridden.

Why do Cast nodes cause memory problems in Blueprints?

A Cast To BP_Foo node creates a hard reference, loading BP_Foo into memory whenever the casting Blueprint loads. Prefer Blueprint interfaces or C++ base types for loose coupling, and soft references for asset management.