unreal-blueprint-codegen

Unreal Engine Blueprint Code Generation (UE 5.4–5.7)

Generate complete .uasset files (Blueprints, Widget Blueprints, domain assets) from C++ in an editor module. Validated against UE 5.7. Most patterns work back to 5.4.

When this skill applies

User wants to author asset content programmatically — variables, function graphs, event-graph wiring, widget hierarchies, UMG animations, custom asset graphs — instead of clicking through the editor. Typical use case: generating Marketplace sample content (Quick-Start, walkthrough, demo conversations) so it can be regenerated reproducibly instead of hand-pruning binary .uasset files.

If the user only wants runtime widget instantiation (CreateWidget / WidgetTree->ConstructWidget at game time), this skill is overkill — that's just normal UMG.

Hard prerequisites

• C++ editor module with Type=Editor (or UncookedOnly). Python cannot author event graphs — UEdGraph/UK2Node_* are not exposed. Set up a UBlueprintFunctionLibrary in C++ and call its UFUNCTIONs from Python if a Python entry point is needed.
• Module must depend on at least: UnrealEd, BlueprintGraph, Kismet, KismetCompiler, AssetTools, AssetRegistry. Add UMG, UMGEditor, MovieScene, MovieSceneTracks for Widget Blueprints. See assets/experiment-module-template/ for a working .Build.cs.
• IWYU: include each engine header explicitly. Forward-declare UPackage/UObject etc. in your own headers; pull full headers in .cpp only.

The 30-second mental model

Asset = UPackage  +  UObject (e.g. UBlueprint / UWidgetBlueprint / UMyAsset)
                     |
                     +-- source UEdGraph (editor-only, what designers see)
                     |     +-- UK2Node_* / UEdGraphNode_* (the boxes)
                     |           +-- UEdGraphPin (the wires)
                     |
                     +-- generated UClass  <- produced by CompileBlueprint
                           +-- FProperty / UFunction (what code uses at runtime)