RenderStaticMeshWithoutComponentsinUnrealEngine

LightWeightSMActor.cpp

// Fill out your copyright notice in the Description page of Project Settings.


#include "LightWeightSMActor.h"
#include "Engine/StaticMeshActor.h"
#include "StaticMeshSceneProxyDesc.h"
#include "PrimitiveSceneDesc.h"
// Sets default values
ALightWeightSMActor::ALightWeightSMActor()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

}

// Called when the game starts or when spawned
void ALightWeightSMActor::BeginPlay()
{
	Super::BeginPlay();
	UWorld* world = GetWorld();

	if (MeshActorTemplate && world)
	{
		Primitives.Empty();
		for (int32 i = 0; i < 100; i++)
		{
			//Initialize
			TSharedPtr<FStaticMeshSceneProxyDesc> ProxyDesc = MakeShared<FStaticMeshSceneProxyDesc>(MeshActorTemplate->GetStaticMeshComponent());
			FStaticMeshSceneProxyDesc* staticMeshSceneProxyDesc = ProxyDesc.Get();
			FPrimitiveSceneProxyDesc* ProxyDescPtr = staticMeshSceneProxyDesc;

			FPrimitiveSceneDesc* PrimitiveSceneDesc = new FPrimitiveSceneDesc();
			PrimitiveSceneDesc->ProxyDesc = ProxyDescPtr;
			PrimitiveSceneDesc->World = world;
			PrimitiveSceneDesc->PrimitiveUObject = this;
			PrimitiveSceneDesc->AttachmentRootPosition = GetActorLocation() + FVector(i* Interval, 0, 0);
			PrimitiveSceneDesc->PrimitiveSceneData = new FPrimitiveSceneInfoData();
			PrimitiveSceneDesc->PrimitiveSceneData->SceneProxy = new FStaticMeshSceneProxy(*staticMeshSceneProxyDesc, false);
			const FTransform trs = FTransform(FVector(i * Interval, 0, 0));
			PrimitiveSceneDesc->RenderMatrix = trs.ToMatrixWithScale();

			PrimitiveSceneDesc->LocalBounds = MeshActorTemplate->GetStaticMeshComponent()->GetStaticMesh()->GetBounds();
			PrimitiveSceneDesc->Bounds = PrimitiveSceneDesc->LocalBounds.TransformBy(PrimitiveSceneDesc->RenderMatrix);
			Primitives.Add(PrimitiveSceneDesc);
			ProxyDescs.Add(ProxyDesc);
			
		}
		world->Scene->BatchAddPrimitives(Primitives);

	}

}

void ALightWeightSMActor::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
	UWorld* world = GetWorld();
	if (world)
	{
		for (FPrimitiveSceneDesc* PrimitiveSceneDesc : Primitives)
		{
			world->Scene->RemovePrimitive(PrimitiveSceneDesc);
		}
	}
	Super::EndPlay(EndPlayReason);
}

void ALightWeightSMActor::BeginDestroy()
{
	UWorld* world = GetWorld();
	if (world)
	{
		for (FPrimitiveSceneDesc* PrimitiveSceneDesc : Primitives)
		{
			world->Scene->RemovePrimitive(PrimitiveSceneDesc);
		}
	}
	Super::BeginDestroy();
}

// Called every frame
void ALightWeightSMActor::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);
}

LightWeightSMActor.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "LightWeightSMActor.generated.h"

UCLASS(Blueprintable, Abstract)
class ALightWeightSMActor : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	ALightWeightSMActor();

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
	virtual void BeginDestroy() override;
public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;

	UPROPERTY(EditAnywhere)
		float Interval = 500.0f;

	UPROPERTY(EditAnywhere)
		class AStaticMeshActor* MeshActorTemplate;
	TArray<FPrimitiveSceneDesc*> Primitives;
	TArray<TSharedPtr<struct FStaticMeshSceneProxyDesc>> ProxyDescs;
};