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API REFERENCE / BLUEPRINT HELPERS

Selection helpers

Blueprint classes for resolving screen clicks and traces to Fragment model elements. The task-oriented walkthrough remains in Blueprint examples.

classesRuntimeBlueprint

UFragmentSelectAtScreenPos​

Select At Screen Pos​

Blueprint
Starts an asynchronous screen-to-world trace, promotes merged cells or HLOD proxies when needed, and retries until a concrete element is resolved.

Inputs: WorldContextObject: UObject*, PC: APlayerController*, ScreenPos: FVector2D, TraceLength: float, TraceChannel: ECollisionChannel, MaxRetries: int32
Outputs: Resolved delegate (LocalId: int64, OwningFragment: AFragment*, HitLocation: FVector, CellHandle: FFragmentCellHandle) or Failed delegate (Reason: EFragmentSelectFailReason)

UFragmentSelectionStatics​

Peek At Screen Pos​

Blueprint
Performs a synchronous direct HISMC lookup without promoting LOD1 cells or activating proxies.

Inputs: WorldContextObject: UObject*, PC: APlayerController*, ScreenPos: FVector2D, TraceLength: float, TraceChannel: ECollisionChannel
Outputs: Success: bool, OutLocalId: int64, OutModelGuid: FString, OutOwningFragment: AFragment*, OutHitLocation: FVector, OutCellHandle: FFragmentCellHandle

Trace First Visible Hit​

Blueprint
Walks a world-space ray while skipping ghosted or hidden Fragment instances.

Inputs: WorldContextObject: UObject*, Start: FVector, End: FVector, TraceChannel: ECollisionChannel, bTraceComplex: bool
Outputs: Success: bool, OutHit: FHitResult

Trace First Visible Hit By Object Types​

Blueprint
Object-type variant of Trace First Visible Hit.

Inputs: WorldContextObject: UObject*, Start: FVector, End: FVector, ObjectTypes: TArray<EObjectTypeQuery>, bTraceComplex: bool
Outputs: Success: bool, OutHit: FHitResult

Clear All Overrides​

Blueprint
Clears every hot-promotion override across loaded models.

Inputs: WorldContextObject: UObject*
Outputs: none

Promote All Cells For Model​

Blueprint
Forces every cell of a model into LOD0 and enables trace collision for selection-heavy UI modes.

Inputs: WorldContextObject: UObject*, ModelGuid: FString
Outputs: none

Demote Cell​

Blueprint
Clears the hot-promotion override for one cell.

Inputs: WorldContextObject: UObject*, Handle: FFragmentCellHandle
Outputs: Success: bool

Is Cell Handle Valid​

Blueprint
Checks whether a cell handle contains a resolved cell.

Inputs: Handle: FFragmentCellHandle
Outputs: Valid: bool