blaster/Source/Blaster/Components/LagCompensationComponent.cpp

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


#include "LagCompensationComponent.h"

#include "Components/BoxComponent.h"

ULagCompensationComponent::ULagCompensationComponent()
{
	PrimaryComponentTick.bCanEverTick = true;
}

void ULagCompensationComponent::BeginPlay()
{
	Super::BeginPlay();
	
}

void ULagCompensationComponent::SaveFramePackage(FFramePackage& Package)
{
	Character = Character == nullptr ? Cast<ABlasterCharacter>(GetOwner()) : Character;
	if (Character)
	{
		Package.Time = GetWorld()->GetTimeSeconds();
		for (auto& BoxPair : Character->HitCollisionBoxes)
		{
			FBoxInformation BoxInformation;
			BoxInformation.Location = BoxPair.Value->GetComponentLocation();
			BoxInformation.Rotation = BoxPair.Value->GetComponentRotation();
			BoxInformation.BoxExtend = BoxPair.Value->GetScaledBoxExtent();

			Package.HitBoxInfo.Add(BoxPair.Key, BoxInformation);
		}
	}
}

FFramePackage ULagCompensationComponent::InterpBetweenFrames(const FFramePackage& OlderFrame, const FFramePackage& YoungerFrame, float HitTime)
{
	const float Distance = YoungerFrame.Time - OlderFrame.Time;
	const float InterpFraction = FMath::Clamp((HitTime - OlderFrame.Time) / Distance, 0.f, 1.f);

	FFramePackage InterpFramePackage;
	InterpFramePackage.Time = HitTime;

	for (auto& YoungerPair : YoungerFrame.HitBoxInfo)
	{
		const FName& BoxInfoName = YoungerPair.Key;
		const FBoxInformation& OlderBox = OlderFrame.HitBoxInfo[BoxInfoName];
		const FBoxInformation& YoungerBox = YoungerFrame.HitBoxInfo[BoxInfoName];

		FBoxInformation InterpBoxInfo;
		InterpBoxInfo.Location = FMath::VInterpTo(OlderBox.Location, YoungerBox.Location, 1.f, InterpFraction);
		InterpBoxInfo.Rotation = FMath::RInterpTo(OlderBox.Rotation, YoungerBox.Rotation, 1.f, InterpFraction);
		InterpBoxInfo.BoxExtend = OlderBox.BoxExtend;

		InterpFramePackage.HitBoxInfo.Add(BoxInfoName, InterpBoxInfo);
	}
	
	return InterpFramePackage;
}

void ULagCompensationComponent::ShowFramePackage(const FFramePackage& Package, const FColor Color)
{
	for (auto& BoxInfo : Package.HitBoxInfo)
	{
		DrawDebugBox(
			GetWorld(),
			BoxInfo.Value.Location,
			BoxInfo.Value.BoxExtend,
			FQuat(BoxInfo.Value.Rotation),
			Color,
			false,
			4.f
		);
	}
}

void ULagCompensationComponent::ServerSideRewind(ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart, const FVector_NetQuantize& HitLocation,
	float HitTime)
{
	bool bReturn = HitCharacter == nullptr ||
		HitCharacter->GetLagCompensation() == nullptr ||
			HitCharacter->GetLagCompensation()->FrameHistory.GetHead() == nullptr ||
			HitCharacter->GetLagCompensation()->FrameHistory.GetTail() == nullptr;

	if (bReturn) return;

	// Frame package that we check to verify a hit
	FFramePackage FrameToSheck;
	bool bShouldInterpolate = true;
	
	const TDoubleLinkedList<FFramePackage>& History = HitCharacter->GetLagCompensation()->FrameHistory;
	const float OldestHistoryTime = History.GetTail()->GetValue().Time;
	const float NewestHistoryTime = History.GetHead()->GetValue().Time;
	if (OldestHistoryTime > HitTime)
	{
		// Too far back, too laggy to do SSR
		return;
	}
	if (OldestHistoryTime == HitTime)
	{
		FrameToSheck = History.GetTail()->GetValue();
		bShouldInterpolate = false;
	}
	if (NewestHistoryTime <= HitTime)
	{
		FrameToSheck = History.GetHead()->GetValue();
		bShouldInterpolate = false;
	}
	auto Younger = History.GetHead();
	auto Older = History.GetHead();
	while (Older->GetValue().Time > HitTime)
	{
		if (Older->GetNextNode() == nullptr) break;
		Older = Older->GetNextNode();
		if (Older->GetValue().Time > HitTime)
		{
			Younger = Older;
		}
	}
	if (Older->GetValue().Time == HitTime)
	{
		FrameToSheck = Older->GetValue();
		bShouldInterpolate = false;
	}

	if (bShouldInterpolate) // Why not just check if FrameToCheck == nullptr?
	{
		// Interpolate between Younger and Older
	}
}

void ULagCompensationComponent::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

	if (FrameHistory.Num() <= 1)
	{
		FFramePackage ThisFrame;
		SaveFramePackage(ThisFrame);
		FrameHistory.AddHead(ThisFrame);
	}
	else
	{
		float HistoryLength = FrameHistory.GetHead()->GetValue().Time - FrameHistory.GetTail()->GetValue().Time;
		while (HistoryLength > MaxRecordTime)
		{
			FrameHistory.RemoveNode(FrameHistory.GetTail());
			 HistoryLength = FrameHistory.GetHead()->GetValue().Time - FrameHistory.GetTail()->GetValue().Time;
		}
		FFramePackage ThisFrame;
		SaveFramePackage(ThisFrame);
		FrameHistory.AddHead(ThisFrame);
		ShowFramePackage(ThisFrame, FColor::Red);
	}
}