UKismetSystemLibrary::LineTraceSingle

function Engine Blueprint Since 4.0

#include "Kismet/KismetSystemLibrary.h"

Access: public Specifiers: staticUFUNCTIONBlueprintCallable

Description

Performs a line trace between Start and End against the given Trace Channel and returns the first blocking hit encountered. Exposed to Blueprint as 'Line Trace By Channel'.

Caveats & Gotchas

• TraceChannel is a Trace Channel (Project Settings > Collision > Trace Channels), not an Object Type like the Overlap family in this same class — a component set to Overlap (not Block) for that channel never registers as a hit here.
• DrawDebugType only draws anything in builds where ENABLE_DRAW_DEBUG is defined (editor/development); the debug visualization is compiled out entirely in shipping builds.
• bIgnoreSelf only has an effect if WorldContextObject resolves to an actor or component with an owning actor — it does nothing if WorldContextObject is an unrelated UObject.

Signature

static ENGINE_API bool LineTraceSingle(const UObject* WorldContextObject, const FVector Start, const FVector End, ETraceTypeQuery TraceChannel, bool bTraceComplex, const TArray<AActor*>& ActorsToIgnore, EDrawDebugTrace::Type DrawDebugType, FHitResult& OutHit, bool bIgnoreSelf, FLinearColor TraceColor = FLinearColor::Red, FLinearColor TraceHitColor = FLinearColor::Green, float DrawTime = 5.0f)

Parameters

Name	Type	Description	Default
WorldContextObject	const UObject*	Object used to resolve which UWorld to run the trace in.	—
Start	const FVector	Start point of the trace in world space.	—
End	const FVector	End point of the trace in world space.	—
TraceChannel	ETraceTypeQuery	Trace Channel to test against (Project Settings > Collision > Trace Channels).	—
bTraceComplex	bool	True to test against per-poly complex collision, false to test against simplified collision.	—
ActorsToIgnore	const TArray<AActor*>&	Actors excluded from the trace.	—
DrawDebugType	EDrawDebugTrace::Type	Debug draw mode for visualizing the trace.	—
OutHit	FHitResult&	Detailed information about the first blocking hit, if any.	—
bIgnoreSelf	bool	If true, ignores the actor owning WorldContextObject.	—
TraceColor	FLinearColor	Color used to draw the non-hit portion of the trace when debug drawing is enabled.	FLinearColor::Red
TraceHitColor	FLinearColor	Color used to draw from the hit point onward when debug drawing is enabled.	FLinearColor::Green
DrawTime	float	How long the debug draw persists, in seconds.	5.0f

Return Type

bool

Example

Trace forward from an actor and read the hit result C++

FHitResult Hit;
TArray<AActor*> ActorsToIgnore;
ActorsToIgnore.Add(this);

const FVector Start = GetActorLocation();
const FVector End = Start + GetActorForwardVector() * 1000.f;

bool bHit = UKismetSystemLibrary::LineTraceSingle(this, Start, End, UEngineTypes::ConvertToTraceType(ECC_Visibility), false, ActorsToIgnore, EDrawDebugTrace::ForDuration, Hit, true);

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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