UE4 Pixel Perfect GameViewportClient

DataGameViewportClient.cpp

#include "DataGameViewportClient.h"
#include "Engine.h"
#include "Engine/LocalPlayer.h"
#include "SceneView.h"

constexpr int RENDER_WIDTH = 320;
constexpr int RENDER_HEIGHT = 180;

UDataGameViewportClient::UDataGameViewportClient(FVTableHelper& Helper)
	: Super(Helper)
{
}

void UDataGameViewportClient::LayoutPlayers()
{
	ULocalPlayer* LocalPlayer = GetMainPlayer();	
	if (LocalPlayer && Viewport)
	{
		FIntPoint ViewportSize = Viewport->GetSizeXY();
		
		int RenderScale = FMath::Min(ViewportSize.X / RENDER_WIDTH, ViewportSize.Y / RENDER_HEIGHT);
		FIntPoint RenderSize = FIntPoint(RENDER_WIDTH * RenderScale, RENDER_HEIGHT * RenderScale);

		LocalPlayer->Size.X = float(RenderSize.X) / float(ViewportSize.X);
		LocalPlayer->Size.Y = float(RenderSize.Y) / float(ViewportSize.Y);
		LocalPlayer->Origin = (FVector2D(1.0f, 1.0f) - LocalPlayer->Size) * 0.5f;
	}
}

void UDataGameViewportClient::FinalizeViews(class FSceneViewFamily* ViewFamily, const TMap<ULocalPlayer*, FSceneView*>& PlayerViewMap)
{
	Super::FinalizeViews(ViewFamily, PlayerViewMap);

	ULocalPlayer* LocalPlayer = GetMainPlayer();
	if (FSceneView* SceneView = PlayerViewMap[LocalPlayer])
	{
		if (Viewport)
		{
			FIntPoint ViewportSize = Viewport->GetSizeXY();

			int RenderScale = FMath::Min(ViewportSize.X / RENDER_WIDTH, ViewportSize.Y / RENDER_HEIGHT);
			SceneView->FinalPostProcessSettings.ScreenPercentage = 100.0f / RenderScale;
		}
	}
}

ULocalPlayer* UDataGameViewportClient::GetMainPlayer()
{
	const TArray<ULocalPlayer*>& PlayerList = GetOuterUEngine()->GetGamePlayers(this);
	if (PlayerList.Num() > 0)
	{
		return PlayerList[0];
	}
	return nullptr;
}

DataGameViewportClient.h

#pragma once

#include "Engine/GameViewportClient.h"
#include "DataGameViewportClient.generated.h"

UCLASS()
class UDataGameViewportClient : public UGameViewportClient
{
	GENERATED_BODY()

public:
	UDataGameViewportClient(FVTableHelper& Helper);

	virtual void LayoutPlayers() override;
	virtual void FinalizeViews(class FSceneViewFamily* ViewFamily, const TMap<ULocalPlayer*, FSceneView*>& PlayerViewMap) override;

private:
	ULocalPlayer* GetMainPlayer();
};

DefaultScalability.ini

[PostProcessQuality@0]
r.Upscale.Quality=0

[PostProcessQuality@1]
r.Upscale.Quality=0

[PostProcessQuality@2]
r.Upscale.Quality=0

[PostProcessQuality@3]
r.Upscale.Quality=0

[PostProcessQuality@Cine]
r.Upscale.Quality=0