Unreal Engine 4：学习笔记（十一）Plugins
如何使代码模块化，使用Plugins可能是一种比较好的方式，下面通过一个例子，讲一讲如何创建和使用Plugins。
一、创建C++工程TestPlugins:
从菜单中选择"Edit"->"Plugins"，会弹出如下窗口：
点出“New Plgin”，在弹出的窗口中选中“Blank”，然后输入“Shape”，点出“Create Plugin”后，会创建一个名为“Shape”的plugin：
工程的目录结构如下：
从上图可以看到，Shape Plugin的代码目录和TestPlugin工程的基本上是一样的，都有Source文件夹和.uproject文件，Source文件夹下都有.Build.cs文件。打开“Shape.Build.cs”文件，可以看到内容如下：
// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved.
using UnrealBuildTool;
public class Shape : ModuleRules
{
public Shape(ReadOnlyTargetRules Target) : base(Target)
{
PCHUsage = ModuleRules.PCHUsageMode.UseExplicitOrSharedPCHs;
PublicIncludePaths.AddRange(
new string[] {
"Shape/Public"
// ... add public include paths required here ...
}
);
PrivateIncludePaths.AddRange(
new string[] {
"Shape/Private",
// ... add other private include paths required here ...
}
);
PublicDependencyModuleNames.AddRange(
new string[]
{
"Core",
// ... add other public dependencies that you statically link with here ...
}
);
PrivateDependencyModuleNames.AddRange(
new string[]
{
"CoreUObject",
"Engine",
"Slate",
"SlateCore",
// ... add private dependencies that you statically link with here ...
}
);
DynamicallyLoadedModuleNames.AddRange(
new string[]
{
// ... add any modules that your module loads dynamically here ...
}
);
}
}内容和TestPlugin.Build.cs大致相同，主要是多了对“Public”和“Private”这两个目录的包含，实际上TestPlugin也可以创建这两个目录来存放代码，只要在TestPlugin.Build.cs中中加入如下代码即可：
PublicIncludePaths.AddRange(
new string[] {
"TestPlugin/Public"
// ... add public include paths required here ...
}
);
PrivateIncludePaths.AddRange(
new string[] {
"TestPlugin/Private",
// ... add other private include paths required here ...
}
);二、在Shape中添加代码：
代码目录结构：
Shape--+
|-Public--+
| |-circle.h
|
|-Private-+
|-circle_impl.h
|-circle_impl.cpp
|-circle.cpp// circle.h
// 圆的接口类
class SHAPE_API Circle {
public:
virtual ~Circle() {};
// 接口方法：面积
virtual double area() = 0;
static Circle* create(double radius); // 创建circle实例
static void destroy(Circle* circlePtr); // 销毁circle实例
};// circle.cpp
#include "circle.h"
#include "circle_impl.h"
Circle* Circle::create(double radius) {
Circle* circlePtr = new CircleImpl(radius);
return circlePtr;
};
void Circle::destroy(Circle* circlePtr) {
delete circlePtr;
};// circle_impl.h
#include "circle.h"
// 圆的具体实现类
class CircleImpl : public Circle {
private:
double radius;
public:
CircleImpl(double radius);
double area() override;
};// circle_impl.cpp
#include "circle_impl.h"
#include
inline double pi() {
return std::atan(1) * 4;
};
CircleImpl::CircleImpl(double _radius) : radius(_radius) {
};
double CircleImpl::area() {
return pi() * radius * radius;
}; 中宏SHAPE_API会自动被识别，用于把Plugin导出成dll，可能的名字为UE4Editor-Shape.dll。
三、 修改TestPlugin工程
在“TestPlugin.Build.cs”中添加“Shape”Plugin，否则编译时会找不到。
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "Shape" });修改ATestPluginGameModeBase：
// TestPluginGameModeBase.h
#pragma once
#include "CoreMinimal.h"
#include "GameFramework/GameModeBase.h"
#include "circle.h"
#include "TestPluginGameModeBase.generated.h"
/**
*
*/
UCLASS()
class TESTPLUGIN_API ATestPluginGameModeBase : public AGameModeBase
{
GENERATED_BODY()
private:
Circle* circle;
public:
ATestPluginGameModeBase();
~ATestPluginGameModeBase();
void BeginPlay();
};// TestPluginGameModeBase.cpp
#include "TestPluginGameModeBase.h"
ATestPluginGameModeBase::ATestPluginGameModeBase() {
circle = Circle::create(10);
UE_LOG(LogTemp, Log, TEXT("circle.area=%f"), circle->area());
};
ATestPluginGameModeBase::~ATestPluginGameModeBase() {
};
void ATestPluginGameModeBase::BeginPlay() {
Circle::destroy(circle);
UE_LOG(LogTemp, Log, TEXT("destroy circle"));
};同时在UEEditor将当前Level的GameMode设置成TestPluginGameModeBase：
编译后，点Play，就可以在Output Log中看到打印的日志了。
参考文档：
https://docs.unrealengine.com/en-us/Programming/Plugins
https://wiki.unrealengine.com/An_Introduction_to_UE4_Plugins