看Ue4角色代碼——跳躍與實現二段跳

看了一下終於發現了跳躍的關鍵代碼

bool UCharacterMovementComponent::DoJump(bool bReplayingMoves)
{
    if ( CharacterOwner && CharacterOwner->CanJump() )
    {
        // Don't jump if we can't move up/down.
        if (!bConstrainToPlane || FMath::Abs(PlaneConstraintNormal.Z) != 1.f)
        {
            Velocity.Z = JumpZVelocity;
            SetMovementMode(MOVE_Falling);
            return true;
        }
    }
    
    return false;
}

這里跳躍就和JumpZVelocity聯系在一起了，同時運動狀態改成了Falling（我認為這里設置Falling是不對的，因為在空中有上升還有下落兩個狀態），不過MovementComponent有判斷停止下落的函數，可以在狀態機里直接用。

 

當然判斷是否可以跳躍就是另一回事了，你也可以自己寫一個跳躍函數。

首先是CharactorMovementComponent中的DoJump(),里面檢測一下能不能跳躍,（即是否允許角色Z方向的移動，因為要兼容別的類型的游戲。
），之后在ACharacter中DoJump()中與CanJump()進行與運算，CanJump返回CanJumpInternal(),CanJumpInternal()是個事件，所以我們需要
去看CanJumpInternal_Implementation()，果然CanJumpInternal_Implementation是個虛函數，所以修改跳躍邏輯就修改這個函數就好了。

看一下CanJumpInternal_Implementation的邏輯

bool ACharacter::CanJumpInternal_Implementation() const
{
    const bool bCanHoldToJumpHigher = (GetJumpMaxHoldTime() > 0.0f) && IsJumpProvidingForce();

    return !bIsCrouched && CharacterMovement && (CharacterMovement->IsMovingOnGround() || bCanHoldToJumpHigher) && CharacterMovement->IsJumpAllowed() && !CharacterMovement->bWantsToCrouch;
}

 

!bIsCrouched角色的運行模式不能為蹲

CharacterMovement->IsMovingOnGround() 確定角色是否還處於走路狀態

bCanHoldToJumpHigher的是判斷當按下跳躍鍵的時候，是否還能到達最高點

CharacterMovement->IsJumpAllowed() 角色運動組件是否可以跳

!CharacterMovement->bWantsToCrouch不能正在做下蹲動作

 

另外補充一下相關代碼

float UCharacterMovementComponent::GetMaxJumpHeight() const
{
    const float Gravity = GetGravityZ();
    if (FMath::Abs(Gravity) > KINDA_SMALL_NUMBER)
    {
        return FMath::Square(JumpZVelocity) / (-2.f * Gravity);
    }
    else
    {
        return 0.f;
    }
}

一個重力下落公式

void UCharacterMovementComponent::JumpOff(AActor* MovementBaseActor)
{
    if ( !bPerformingJumpOff )
    {
        bPerformingJumpOff = true;
        if ( CharacterOwner )
        {
            const float MaxSpeed = GetMaxSpeed() * 0.85f;
            Velocity += MaxSpeed * GetBestDirectionOffActor(MovementBaseActor);
            if ( Velocity.Size2D() > MaxSpeed )
            {
                Velocity = MaxSpeed * Velocity.GetSafeNormal();
            }
            Velocity.Z = JumpOffJumpZFactor * JumpZVelocity;
            SetMovementMode(MOVE_Falling);
        }
        bPerformingJumpOff = false;
    }
}

 ----------------------------------------------------------------------------------------------

如何實現:

首先在你的角色類的頭文件中加入

virtual bool CanJumpInternal_Implementation() const override;

覆蓋CanJumpInternal事件。

之后在Cpp文件中加入

bool AThirdPersonCharacter::CanJumpInternal_Implementation() const
{
    const bool bCanHoldToJumpHigher = (GetJumpMaxHoldTime() > 0.0f) && IsJumpProvidingForce();

    //return !bIsCrouched && CharacterMovement && (CharacterMovement->IsMovingOnGround() || bCanHoldToJumpHigher) && CharacterMovement->IsJumpAllowed() && !CharacterMovement->bWantsToCrouch;
　　
    return !bIsCrouched && CharacterMovement  && CharacterMovement->IsJumpAllowed() && !CharacterMovement->bWantsToCrouch;
}

我把(CharacterMovement->IsMovingOnGround() || bCanHoldToJumpHigher)刪掉了，這里就替換上你的二段跳邏輯即可

 

在頭文件中加入2個用於判斷二段跳的變量

//最大跳躍次數
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Jump")
int32 MaxJumpNum = 2;

//當前跳躍次數
int32 JumpNum=2;

當然把JumNum在構造函數中賦值才是正確選擇 

 

覆蓋事件

    //virtual void OnMovementModeChanged(EMovementMode PrevMovementMode, uint8 PreviousCustomMode = 0) override;

    virtual void Landed(const FHitResult& Hit) override;

2個都可以用，第一個功能更加強大

 

然后在Cpp文件里：

void AThirdPersonCharacter::Jump()
{
    if (JumpNum>0)
    {
        bPressedJump = true;
        JumpKeyHoldTime = 0.0f;
        JumpNum = JumpNum - 1;
    }
}

void AThirdPersonCharacter::Landed(const FHitResult& Hit)
{
    Super::Landed(Hit);
    JumpNum = MaxJumpNum;
}

當然之前的按鍵事件綁定也需要修改一下

void AThirdPersonCharacter::SetupPlayerInputComponent(class UInputComponent* InputComponent)
{
    // Set up gameplay key bindings
    check(InputComponent);
　　//把這個Jump改為你自己剛才定義的Jump
    InputComponent->BindAction("Jump", IE_Pressed, this, &AThirdPersonCharacter::Jump);
    InputComponent->BindAction("Jump", IE_Released, this, &ACharacter::StopJumping);

    InputComponent->BindAxis("MoveForward", this, &AThirdPersonCharacter::MoveForward);
    InputComponent->BindAxis("MoveRight", this, &AThirdPersonCharacter::MoveRight);

    // We have 2 versions of the rotation bindings to handle different kinds of devices differently
    // "turn" handles devices that provide an absolute delta, such as a mouse.
    // "turnrate" is for devices that we choose to treat as a rate of change, such as an analog joystick
    InputComponent->BindAxis("Turn", this, &APawn::AddControllerYawInput);
    InputComponent->BindAxis("TurnRate", this, &AThirdPersonCharacter::TurnAtRate);
    InputComponent->BindAxis("LookUp", this, &APawn::AddControllerPitchInput);
    InputComponent->BindAxis("LookUpRate", this, &AThirdPersonCharacter::LookUpAtRate);

    // handle touch devices
    InputComponent->BindTouch(IE_Pressed, this, &AThirdPersonCharacter::TouchStarted);
    InputComponent->BindTouch(IE_Released, this, &AThirdPersonCharacter::TouchStopped);
}