AActor::OnConstruction

function Engine Since 4.0

#include "GameFramework/Actor.h"

Access: public Specifiers: virtual

Description

Called when an instance of this class is placed in the editor or spawned at runtime, after native components are created but before BeginPlay. Use for editor-time procedural setup driven by actor properties.

Caveats & Gotchas

• OnConstruction can be called multiple times in the editor whenever actor properties are changed — your implementation must be idempotent and handle repeated calls without leaking components or resources.
• Do not spawn other actors or perform world-modifying operations in OnConstruction during editor-time calls; the world may not be fully loaded and undo/redo can leave orphaned objects.
• Unlike BeginPlay, OnConstruction runs in the editor. Code inside it should not assume gameplay systems (game mode, timers, etc.) are available.

Signature

virtual void OnConstruction(const FTransform& Transform) {}

Parameters

Name	Type	Description	Default
Transform	const FTransform&	The transform the actor was constructed at.	—

Return Type

void

Example

Procedural mesh generation in editor C++

void AMyProceduralActor::OnConstruction(const FTransform& Transform)
{
	Super::OnConstruction(Transform);
	// Regenerate procedural mesh based on current property values
	ProceduralMesh->ClearAllMeshSections();
	GenerateMesh();
}

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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