UE4 ShooterGame Demo的開火的代碼

之前一直沒搞懂按下鼠標左鍵開火之后，代碼的邏輯是怎么走的，今天看懂了之前沒看懂的部分，進了一步

ShooterCharacter.cpp

void AShooterCharacter::OnStartFire()
{AShooterPlayerController* MyPC = Cast<AShooterPlayerController>(Controller);if (MyPC && MyPC->IsGameInputAllowed()){if (IsRunning()){SetRunning(false, false);}StartWeaponFire();}
}

void AShooterCharacter::StartWeaponFire()
{if (!bWantsToFire){bWantsToFire = true;if (CurrentWeapon){CurrentWeapon->StartFire();}}
}

ShooterWeapon.cpp，其中Role==ROLE_Authority表示該程序運行在服務器。如果是客戶端，則將調用ServerStartFire來調用服務端的StartFire方法。這是多人游戲中的機制

void AShooterWeapon::StartFire()
{if (Role < ROLE_Authority){ServerStartFire();}if (!bWantsToFire){bWantsToFire = true;DetermineWeaponState();}
}

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void AShooterWeapon::DetermineWeaponState()
{EWeaponState::Type NewState = EWeaponState::Idle;if (bIsEquipped){if( bPendingReload  ){if( CanReload() == false ){NewState = CurrentState;}else{NewState = EWeaponState::Reloading;}}        else if ( (bPendingReload == false ) && ( bWantsToFire == true ) && ( CanFire() == true )){NewState = EWeaponState::Firing;}}else if (bPendingEquip){NewState = EWeaponState::Equipping;}SetWeaponState(NewState);
}

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void AShooterWeapon::SetWeaponState(EWeaponState::Type NewState)
{const EWeaponState::Type PrevState = CurrentState;if (PrevState == EWeaponState::Firing && NewState != EWeaponState::Firing){OnBurstFinished();}CurrentState = NewState;if (PrevState != EWeaponState::Firing && NewState == EWeaponState::Firing){OnBurstStarted();}
}

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void AShooterWeapon::OnBurstStarted()
{// start firing, can be delayed to satisfy TimeBetweenShotsconst float GameTime = GetWorld()->GetTimeSeconds();if (LastFireTime > 0 && WeaponConfig.TimeBetweenShots > 0.0f &&LastFireTime + WeaponConfig.TimeBetweenShots > GameTime){GetWorldTimerManager().SetTimer(TimerHandle_HandleFiring, this, &AShooterWeapon::HandleFiring, LastFireTime + WeaponConfig.TimeBetweenShots - GameTime, false);}else{HandleFiring();}
}

下面標紅的FireWeapon這個函數，實際上在AShooterWeapon中是一個虛函數，并且沒有實現，實現是放在了子類中。它有兩個子類，分別是AShooterWeapon_Instant（彈道類）和AShooterWeapon_Projectile（投擲類）

我覺得肯定真正使用到的類就是這兩個子類，所以包括之前的這個流程，實際上都是子類中的，只不過是從父類中繼承而已，當然我此時此刻沒有去深究那些方法的可見性修飾符，是否會被繼承這些細節問題，我先暫時這么認為吧

void AShooterWeapon::HandleFiring()
{if ((CurrentAmmoInClip > 0 || HasInfiniteClip() || HasInfiniteAmmo()) && CanFire()){if (GetNetMode() != NM_DedicatedServer){SimulateWeaponFire();}if (MyPawn && MyPawn->IsLocallyControlled()){FireWeapon();UseAmmo();// update firing FX on remote clients if function was called on serverBurstCounter++;}}else if (CanReload()){StartReload();}else if (MyPawn && MyPawn->IsLocallyControlled()){if (GetCurrentAmmo() == 0 && !bRefiring){PlayWeaponSound(OutOfAmmoSound);AShooterPlayerController* MyPC = Cast<AShooterPlayerController>(MyPawn->Controller);AShooterHUD* MyHUD = MyPC ? Cast<AShooterHUD>(MyPC->GetHUD()) : NULL;if (MyHUD){MyHUD->NotifyOutOfAmmo();}}// stop weapon fire FX, but stay in Firing stateif (BurstCounter > 0){OnBurstFinished();}}if (MyPawn && MyPawn->IsLocallyControlled()){// local client will notify serverif (Role < ROLE_Authority){ServerHandleFiring();}// reload after firing last roundif (CurrentAmmoInClip <= 0 && CanReload()){StartReload();}// setup refire timerbRefiring = (CurrentState == EWeaponState::Firing && WeaponConfig.TimeBetweenShots > 0.0f);if (bRefiring){GetWorldTimerManager().SetTimer(TimerHandle_HandleFiring, this, &AShooterWeapon::HandleFiring, WeaponConfig.TimeBetweenShots, false);}}LastFireTime = GetWorld()->GetTimeSeconds();
}

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void AShooterWeapon_Instant::FireWeapon()
{const int32 RandomSeed = FMath::Rand();FRandomStream WeaponRandomStream(RandomSeed);const float CurrentSpread = GetCurrentSpread();const float ConeHalfAngle = FMath::DegreesToRadians(CurrentSpread * 0.5f);

　　 //獲取AShooterPlayerController的rotation的單位向量const FVector AimDir = GetAdjustedAim();const FVector StartTrace = GetCameraDamageStartLocation(AimDir);const FVector ShootDir = WeaponRandomStream.VRandCone(AimDir, ConeHalfAngle, ConeHalfAngle);const FVector EndTrace = StartTrace + ShootDir * InstantConfig.WeaponRange;const FHitResult Impact = WeaponTrace(StartTrace, EndTrace);ProcessInstantHit(Impact, StartTrace, ShootDir, RandomSeed, CurrentSpread);CurrentFiringSpread = FMath::Min(InstantConfig.FiringSpreadMax, CurrentFiringSpread + InstantConfig.FiringSpreadIncrement);
}

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