[游戏开发]UE4 C++之实现二阶贝塞尔曲线

任务：实现物体沿着二阶贝塞尔曲线运动

原理介绍参考链接：贝塞尔曲线 总结_PlayBoy's 部落格-CSDN博客_贝塞尔曲线

关键代码如下：

BezierCurve.h

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

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "BezierCurve.generated.h"

UCLASS()
class DATALEARN_API ABezierCurve : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	ABezierCurve();

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;

private:
	void SetMeshToBezierCurve(double curTime);

public:
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	class UStaticMeshComponent* Mesh;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	class UStaticMeshComponent* StartMesh;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	class UStaticMeshComponent* FirstMesh;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	class UStaticMeshComponent* FinalMesh;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	FVector FirstPos;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	FVector FinalPos;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "NPC|BezierCurve")
	float DurationTime;

private:
	double StartTime;
};

BezierCurve.cpp

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


#include "BezierCurve.h"
#include "Components/StaticMeshComponent.h"
#include "DrawDebugHelpers.h"
#include "Kismet/GameplayStatics.h"

// Sets default values
ABezierCurve::ABezierCurve()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

	StartMesh = CreateDefaultSubobject<UStaticMeshComponent>("StartMesh");
	RootComponent = StartMesh;
	FirstMesh = CreateDefaultSubobject<UStaticMeshComponent>("FirstMesh");
	FinalMesh = CreateDefaultSubobject<UStaticMeshComponent>("FinalMesh");
	Mesh = CreateDefaultSubobject<UStaticMeshComponent>("Mesh");

	DurationTime = 2000;
}

// Called when the game starts or when spawned
void ABezierCurve::BeginPlay()
{
	Super::BeginPlay();
	FirstPos = FirstMesh->GetRelativeLocation();
	FinalPos = FinalMesh->GetRelativeLocation();
	StartTime = FPlatformTime::ToMilliseconds64(FPlatformTime::Cycles64());

	FVector actorLocation = GetActorLocation();
	UWorld* myWorld = GetWorld();
	DrawDebugLine(myWorld, actorLocation, actorLocation + FirstPos, FColor::Red, true);
	DrawDebugLine(myWorld, actorLocation + FirstPos, actorLocation + FinalPos, FColor::Red, true);
}

// Called every frame
void ABezierCurve::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);
	double curTime = FPlatformTime::ToMilliseconds64(FPlatformTime::Cycles64());
	SetMeshToBezierCurve(curTime);
}

void ABezierCurve::SetMeshToBezierCurve(double curTime)
{
	float tmpT = fmod(curTime - StartTime, DurationTime) / DurationTime;
	FVector resLocation;
	resLocation.X = 2 * tmpT * (1 - tmpT) * FirstPos.X + tmpT * tmpT * FinalPos.X;
	resLocation.Y = 2 * tmpT * (1 - tmpT) * FirstPos.Y + tmpT * tmpT * FinalPos.Y;
	resLocation.Z = 2 * tmpT * (1 - tmpT) * FirstPos.Z + tmpT * tmpT * FinalPos.Z;

	Mesh->SetRelativeLocation(resLocation);

	FVector drawCenter =  Mesh->GetRelativeLocation() + GetActorLocation();
	UWorld* myWorld = GetWorld();
	DrawDebugSphere(myWorld, drawCenter, 0.5, 10,FColor::Blue, false, 2);
}

效果如下图：

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