Unreal Engine 4 笔记

//*1 调试输出*//
/*case a、快速使用 不设置log类别 默认为LogTemp*/
UE_LOG(LogTemp,Log,TEXT("Your message"));
UE_Log(LogTemp,Warning,TEXT("You Number type of float value is %f"),YourFloatTypeValue);
UE_Log(LogTemp,Error,TEXT("Your Number type of FString value is %s"),YourFStringTypeValue);
//Log:输出日志字体颜色为灰色 Warning:输出字体颜色为黄色 Error：输出字体颜色为红色

/*case b、设置自定义Log类别*/
//在YourCode.h文件中声明自定义Log类别@parm YourLog
DECLARE_LOG_CATEGORY_EXTERN(YourLog, Log, All);
//在YourCode.cpp文件中定义
DEFINE_LOG_CATEGORY(YourLog);
UE_LOG(YourLog, Log, TEXT("This is a message to yourself during runtime!"));

/*case c、触发严重中断 程序执行到此时会触发程序中断*/
UE_LOG(YourLog, Fatal, TEXT("This fringe case was reached! Debug this!"));
//log输出在output log面板中显示

/*case d、 向屏幕打印消息 显示在屏幕上*/
if(GEngine)
{
    GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, TEXT("This is an on screen message!"));
    GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Some variable values: x: %f, y: %f"), x, y));
}
//我们可以在.cpp文件下进行如下宏定义以快速使用该方法
#define print(text) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 1.5, FColor::White,text)

#include "EngineUtils.h"
/*case a、Actor 迭代*/
for (TActorIterator<AStaticMeshActor> ActorItr(GetWorld()); ActorItr; ++ActorItr)
{
    AStaticMeshActor *Mesh = *ActorItr；
}
/*case b、Object迭代*/
for (TObjectIterator<AActor> Itr; Itr; ++Itr)
{
    AActor *Component = *Itr;
}
//Object 迭代可以迭代的内容包括Actor可迭代的内容

//GetHitResultAtScreenPosition函数为引擎框架下APlayerController的方法  
//顾名思义是以屏幕为起点向鼠标所在坐标发出射线，进行碰撞检测
//可查看APlayerController下此函数的定义  
FVector2D cursorPosition(0,0);  
this->GetMousePosition(cursorPosition.X, cursorPosition.Y);  
FHitResult hitInfo(ForceInit);  
FCollisionQueryParams collisionParms(false);  
this->GetHitResultAtScreenPosition(cursorPosition,ECC_PhysicsBody,collisionParms,hitInfo);
//在此处理hitInfo;
/*GetWorld()->LineTraceSingleByObjectType等一系列函数用于处理更多的射线类功能，但APlayerController下已经封装好很多常用的方法。*/

/*此处实现将SceneCapture2D看到的视角复制到Texture中 */ 
/*方式一、 */
/*sceneCapture为SceneCapture2D组件的引用 */ 
/*renderTexture为上图所示textureTarget的引用*/ 
UTexture2D *Texture = UTexture2D::CreateTransient(TextureRenderTarget->SizeX,TextureRenderTarget->SizeY, PF_B8G8R8A8);  
sceneCapture->GetCaptureComponent2D()->UpdateContent();  
TArray<FColor> SurfData;
FRenderTarget *RenderTarget = renderTexture->GameThread_GetRenderTargetResource();
RenderTarget->ReadPixels(SurfData);
void* TextureData = Texture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);
const int32 TextureDataSize = SurfData.Num() * 4;
FMemory::Memcpy(TextureData, SurfData.GetData(), TextureDataSize);
Texture->PlatformData->Mips[0].BulkData.Unlock();
Texture->UpdateResource();

/*方式二、*/
/*使用ConstructTexture2D函数，该函数每次返回的是同一块内存地址*/
sceneCapture->GetCaptureComponent2D()->UpdateContent();  
Texture = renderTexture->ConstructTexture2D(this,"AlphaTex",EObjectFlags::RF_NoFlags,CTF_DeferCompression);  
Texture->CompressionSettings = TextureCompressionSettings::TC_VectorDisplacementmap;  
Texture->UpdateResource();

<?xml version="1.0" encoding="UTF-8"?>  
<Value>  
    <ChildrenSex>Girl</ChildrenSex>  
    <SceneIndex>0</SceneIndex>  
</Value>

#include "XmlParser.h" 
/*写数据*/
    FXmlFile InitVariable(L"X:\\initgameValue.xml");  
    FXmlNode* root = InitVariable.GetRootNode();  
    TArray<FXmlNode*> VarArray = root->GetChildrenNodes();  
    VarArray[0]->SetContent("Your content");  
    VarArray[1]->SetContent("Your content");  
    InitVariable.Save(L"X:\\initgameValue.xml");  
    InitVariable.Clear();  
/*读数据*/
    FXmlFile InitVariable(L"X:\\initgameValue.xml");  
    FXmlNode* root = InitVariable.GetRootNode();  
    TArray<FXmlNode*> VarArray = root->GetChildrenNodes();  
    FString tempContent=VarArray[0]->GetContent();
//一般情况下 文件加载路径不应该是绝对路径 我们可以使用FPaths::GameUserDir()得到项目路径根路径，从而便可以使用相对路径来进行配置文件的加载

/** Covert a string buffer to intrinsic types */
    inline void FromString(int8& OutValue,      const TCHAR* Buffer)    {   OutValue = FCString::Atoi(Buffer);      }
    inline void FromString(int16& OutValue,     const TCHAR* Buffer)    {   OutValue = FCString::Atoi(Buffer);      }
    inline void FromString(int32& OutValue,     const TCHAR* Buffer)    {   OutValue = FCString::Atoi(Buffer);      }
    inline void FromString(int64& OutValue,     const TCHAR* Buffer)    {   OutValue = FCString::Atoi64(Buffer);    }
    inline void FromString(uint8& OutValue,     const TCHAR* Buffer)    {   OutValue = FCString::Atoi(Buffer);      }
    inline void FromString(uint16& OutValue,    const TCHAR* Buffer)    {   OutValue = FCString::Atoi(Buffer);      }
    inline void FromString(uint32& OutValue,    const TCHAR* Buffer)    {   OutValue = FCString::Atoi64(Buffer);    }   //64 because this unsigned and so Atoi might overflow
    inline void FromString(uint64& OutValue,    const TCHAR* Buffer)    {   OutValue = FCString::Strtoui64(Buffer, nullptr, 0); }
    inline void FromString(float& OutValue,     const TCHAR* Buffer)    {   OutValue = FCString::Atof(Buffer);      }
    inline void FromString(double& OutValue,    const TCHAR* Buffer)    {   OutValue = FCString::Atod(Buffer);      }
    inline void FromString(bool& OutValue,      const TCHAR* Buffer)    {   OutValue = FCString::ToBool(Buffer);    }

#include "UnrealString.h"
using namespace LexicalConversion;

FString temp = "3.1415926":
float outFloat; FromString(outFloat, *temp);