Hi There!!
In this lecture, we attach the physics handle to the valid actors to pick them up and release them.
The code starts a bit messy but It’ll tidy up as you go through the lecture.
VS Code-
C File-
// Copyright Ateeb Ahmed 2021
#pragma once
#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "PhysicsEngine/PhysicsHandleComponent.h"
#include "Grabber.generated.h"
UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class BUILDING_ESCAPE_API UGrabber : public UActorComponent
{
GENERATED_BODY()
public:
// Sets default values for this component's properties
UGrabber();
// Called every frame
virtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;
protected:
// Called when the game starts
virtual void BeginPlay() override;
private:
UPROPERTY(EditAnywhere)
float Reach = 140.f;
UPhysicsHandleComponent* PhysicsHandle = nullptr;
UInputComponent* InputComponent = nullptr;
void Grab();
void Release();
void FindPhysicsHandle();
void SetupInputComponent();
// Return the first Actor within reach with physics body.
FHitResult GetFirstPhysicsBodyInReach() const;
};
C++ file-
// Copyright Ateeb Ahmed 2021
#include "DrawDebugHelpers.h"
#include "Engine/World.h"
#include "GameFramework/PlayerController.h"
#include "Grabber.h"
#define OUT
// Sets default values for this component's properties
UGrabber::UGrabber()
{
// Set this component to be initialized when the game starts, and to be ticked every frame. You can turn these features
// off to improve performance if you don't need them.
PrimaryComponentTick.bCanEverTick = true;
}
// Called when the game starts
void UGrabber::BeginPlay()
{
Super::BeginPlay();
FindPhysicsHandle();
SetupInputComponent();
}
void UGrabber::SetupInputComponent()
{
InputComponent = GetOwner()->FindComponentByClass<UInputComponent>();
if(InputComponent)
{
UE_LOG(LogTemp, Warning, TEXT("Input component found on %s"), *GetOwner()->GetName());
InputComponent->BindAction("Grab", IE_Pressed, this, &UGrabber::Grab);
InputComponent->BindAction("Grab", IE_Released, this, &UGrabber::Release);
}
}
// Checking for Physics Handle Component
void UGrabber::FindPhysicsHandle()
{
PhysicsHandle = GetOwner()->FindComponentByClass<UPhysicsHandleComponent>();
if (PhysicsHandle)
{
// Physics is found.
}
else
{
UE_LOG(LogTemp, Error, TEXT("NO PHYSICS HANDLE COMPONENT FOUND ON %s!!!"), *GetOwner()->GetName());
}
}
void UGrabber::Grab()
{
UE_LOG(LogTemp, Warning, TEXT("Grabber Pressed!"));
FVector PlayerViewPointLocation;
FRotator PlayerViewPointRotation;
GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(
OUT PlayerViewPointLocation,
OUT PlayerViewPointRotation
);
FVector LineTraceEnd = PlayerViewPointLocation + PlayerViewPointRotation.Vector() * Reach;
FHitResult HitResult = GetFirstPhysicsBodyInReach();
UPrimitiveComponent* ComponentToGrab = HitResult.GetComponent();
// If we hit something then attach the physics handle.
if(HitResult.GetActor())
{
PhysicsHandle->GrabComponentAtLocation
(ComponentToGrab,
NAME_None,
LineTraceEnd
);
}
}
void UGrabber::Release()
{
UE_LOG(LogTemp, Warning, TEXT("Grabbed Released!"));
PhysicsHandle->ReleaseComponent();
}
// Called every frame
void UGrabber::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
Super::TickComponent(DeltaTime, TickType, ThisTickFunction);
// Get player's viewpoint
FVector PlayerViewPointLocation;
FRotator PlayerViewPointRotation;
GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(
OUT PlayerViewPointLocation,
OUT PlayerViewPointRotation
);
FVector LineTraceEnd = PlayerViewPointLocation + PlayerViewPointRotation.Vector() * Reach;
// If the physics handle is attached.
if(PhysicsHandle->GrabbedComponent)
{
PhysicsHandle->SetTargetLocation(LineTraceEnd);
}
// Move the object we are holding.
}
FHitResult UGrabber::GetFirstPhysicsBodyInReach() const
{
// Get player's viewpoint
FVector PlayerViewPointLocation;
FRotator PlayerViewPointRotation;
GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(
OUT PlayerViewPointLocation,
OUT PlayerViewPointRotation
);
FVector LineTraceEnd = PlayerViewPointLocation + PlayerViewPointRotation.Vector() * Reach;
FHitResult Hit;
// Ray-cast out to a certain distance (Reach)
FCollisionQueryParams TraceParams(FName(TEXT("")), false, GetOwner());
GetWorld()->LineTraceSingleByObjectType(
OUT Hit,
PlayerViewPointLocation,
LineTraceEnd,
FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody),
TraceParams
);
//See what it hits
AActor* ActorHit = Hit.GetActor();
if (ActorHit)
{
UE_LOG(LogTemp, Warning, TEXT("LineTrace has hit: %s"), *ActorHit->GetName());
}
return Hit;
}
UE Editor-
I’ve grabbed this cube here-
I’ve released the cube here-
Now I’m able to grab and release this cube or the cone(basically, anything with a physics body).
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I want to ask what NAME_None, .GetActor(), and .GetComponent() does. I’ve read the documentation but didn’t get any satisfactory answers.
Thanks for reading,
BYE!!