Unreal裏，比對CodeProject，由空工程用Blueprint搭建自己的ThirdPersonGame

記錄本文只是想說明，Blueprint和代碼實現保持一致，幾乎看着代碼，就能完成Blueprint裏的參數設定。另外，指出說明Unreal Editor工程配置的基本操作。

打開Unreal Editor --> New Project，我們可以看到Unreal給我們提供了ThirdPersonGame的基礎模板，Code版本和Blueprint版本。

下面，我們嘗試看着CodeThirdPerson，由一個EmptyProject（當然，需要Include starter content），自己動手從零開始搭建起BlueprintThirdPerson。

事實上，官方已經有了這個教程，分爲22個視頻講解，挺值得一看並跟着做一遍的： https://www.youtube.com/watch?v=WiHuJcnOuVs

Blueprint裏如何設置MyCharacter的相關參數，只需要看ThirdPersonCodeGame裏Character的Declaration和構造函數。

UCLASS(config=Game)
class AThirdPersonCodeGameCharacter : public ACharacter
{
	GENERATED_UCLASS_BODY()

	/** Camera boom positioning the camera behind the character */
	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
	TSubobjectPtr<class USpringArmComponent> CameraBoom;

	/** Follow camera */
	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
	TSubobjectPtr<class UCameraComponent> FollowCamera;

	/** Base turn rate, in deg/sec. Other scaling may affect final turn rate. */
	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
	float BaseTurnRate;

	/** Base look up/down rate, in deg/sec. Other scaling may affect final rate. */
	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
	float BaseLookUpRate;

AThirdPersonCodeGameCharacter::AThirdPersonCodeGameCharacter(const class FPostConstructInitializeProperties& PCIP)
	: Super(PCIP)
{
	// Set size for collision capsule
	CapsuleComponent->InitCapsuleSize(42.f, 96.0f);

	// set our turn rates for input
	BaseTurnRate = 45.f;
	BaseLookUpRate = 45.f;

	// Don't rotate when the controller rotates. Let that just affect the camera.
	bUseControllerRotationPitch = false;
	bUseControllerRotationYaw = false;
	bUseControllerRotationRoll = false;

	// Configure character movement
	CharacterMovement->bOrientRotationToMovement = true; // Character moves in the direction of input...	
	CharacterMovement->RotationRate = FRotator(0.0f, 540.0f, 0.0f); // ...at this rotation rate
	CharacterMovement->JumpZVelocity = 600.f;
	CharacterMovement->AirControl = 0.2f;

	// Create a camera boom (pulls in towards the player if there is a collision)
	CameraBoom = PCIP.CreateDefaultSubobject<USpringArmComponent>(this, TEXT("CameraBoom"));
	CameraBoom->AttachTo(RootComponent);
	CameraBoom->TargetArmLength = 300.0f; // The camera follows at this distance behind the character	
	CameraBoom->bUseControllerViewRotation = true; // Rotate the arm based on the controller

	// Create a follow camera
	FollowCamera = PCIP.CreateDefaultSubobject<UCameraComponent>(this, TEXT("FollowCamera"));
	FollowCamera->AttachTo(CameraBoom, USpringArmComponent::SocketName); // Attach the camera to the end of the boom and let the boom adjust to match the controller orientation
	FollowCamera->bUseControllerViewRotation = false; // Camera does not rotate relative to arm

	// Note: The skeletal mesh and anim blueprint references on the Mesh component (inherited from Character) 
	// are set in the derived blueprint asset named MyCharacter (to avoid direct content references in C++)
}

我們看到，AThirdPersonCodeGameCharacter 是基於ACharacter，於是，我們創建一個基於Character的Blueprint：MyCharacter。

接下來，跟着構造函數，設置我們的MyCharacter。

<pre name="code" class="cpp">CameraBoom = PCIP.CreateDefaultSubobject<USpringArmComponent>(this, TEXT("CameraBoom"));
CameraBoom->AttachTo(RootComponent);

FollowCamera = PCIP.CreateDefaultSubobject<UCameraComponent>(this, TEXT("FollowCamera"));
FollowCamera->AttachTo(CameraBoom, USpringArmComponent::SocketName);

由此我們知道，需要在Components頁面裏，添加上SpringArm和Camera，Camera作爲SpringArm的子節點。

<img src="https://img-blog.csdn.net/20140725161955161?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvdTAxMDE1MzcwMw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />

</pre><pre name="code" class="cpp">// Don't rotate when the controller rotates. Let that just affect the camera.
	bUseControllerRotationPitch = false;
	bUseControllerRotationYaw = false;
	bUseControllerRotationRoll = false;

由此，我們在Defaults頁面裏，確保這三個參數設置爲false。

（這三個參數來源於ACharacter繼承的APawn class，所以在Pawn類別裏。）

CameraBoom->bUseControllerViewRotation = true; // Rotate the arm based on the controller

FollowCamera->bUseControllerViewRotation = false; // Camera does not rotate relative to arm

設置這兩個參數，我們需要回到Components頁面。

選中前面添加的SpringArm，將參數Use Controller View Rotation勾選上。

選中前面添加的Camera，將參數Use Controller View Rotation的勾選去掉。

這幾個關鍵參數設置好之後，其他的就好說了。當然，你需要在Components頁面裏，指定Mesh，調整Mesh位置和Capsule大小。甚至可能還需要調整SpringArm和Camera的位置。

接下來，主要的工作是在Graph中實現一些MovementInput功能。不詳述了。

要點是：先在Edit==>Project Settings==>Input裏填入相關AxisMappings和ActionMappings。然後，在MyCharacter的Graph的EventGraph裏面，對照着CodeProject裏那些MoveForward和MoveRight等函數的實現，動手搭建這些功能啦。

接下是工程配置了。

需要自己創建一個基於GameMode的Blueprint：MyGame。在Defaults頁面裏，將Default Pawn Class改爲上面自己製作的MyCharacter。