最近有个需求是需要将场景中的actor进行截图,并且将截图保存成png,png中需要将场景背景忽略掉,只显示特定的actor。
这里是通过SceneCapture2d组件捕捉场景后,将背景的alpha通道设置为0,实现背景透明的功能。
(一)截图成png
(1)在.h文件
UFUNCTION(BlueprintCallable)
UTexture2D* SaveCaptureScene(bool IsSave, class USceneCaptureComponent2D* SceneCapture, const FString& SavePath, int32 NewWidth = 0, int32 NewHeight = 0, int32 CompressionQuality = 100);
//保存为png
bool SaveRenderTargetToDisk(UTextureRenderTarget2D* RenderTarget, const FString& FilePath, int32 NewWidth, int32 NewHeight, int32 CompressionQuality);
//设置png的size
void ResizeImage(const TArray<FColor>& SourceBitmap, int32 SourceWidth, int32 SourceHeight, int32 TargetWidth, int32 TargetHeight, TArray<FColor>& OutBitmap);
//将png转为texture2d
UTexture2D* LoadTextureFromFile(const FString& FilePath);
(2)在.cpp文件
#include "Engine/TextureRenderTarget2D.h"
#include "Components/SceneCaptureComponent2D.h"
#include "IImageWrapperModule.h"
#include "IImageWrapper.h"
#include "FileHelper.h"
#include "Paths.h"
#include "Engine/Texture2D.h"
#include "Misc/FileHelper.h"
#include "ImageUtils.h"
UTexture2D* YourClass::SaveCaptureScene(const UObject* WorldContextObject, bool IsSave, USceneCaptureComponent2D* SceneCapture, const FString& SavePath, int32 NewWidth, int32 NewHeight, int32 CompressionQuality )
{
if (!IsSave)
{
SceneCapture->SetVisibility(false);
return nullptr;
}
if (SceneCapture && SceneCapture->TextureTarget)
{
SceneCapture->SetVisibility(true);
// 捕捉场景
SceneCapture->CaptureScene();
// 将 RenderTarget 保存为 PNG 文件
if (SaveRenderTargetToDisk(SceneCapture->TextureTarget, *SavePath,NewWidth,NewHeight,CompressionQuality))
{
// 导入 PNG 为 UTexture2D
UTexture2D* CapturedTexture = LoadTextureFromFile(*SavePath);
if (CapturedTexture)
{
// 在此处处理导入的纹理,例如将其应用到材质中
UE_LOG(LogTemp, Log, TEXT("LYM_Texture imported successfully."));
return CapturedTexture;
}
else
{
UE_LOG(LogTemp, Error, TEXT("LYM_Failed to import texture."));
return nullptr;
}
}
else
{
UE_LOG(LogTemp, Error, TEXT("LYM_Failed to SavePNG"));
return nullptr;
}
}
UE_LOG(LogTemp, Error, TEXT("LYM_SceneCapture or TextureTarget is invalid."));
return nullptr;
}
bool YourClass::SaveRenderTargetToDisk(UTextureRenderTarget2D* RenderTarget, const FString& FilePath, int32 NewWidth, int32 NewHeight, int32 CompressionQuality)
{
FTextureRenderTargetResource* RenderTargetResource = RenderTarget->GameThread_GetRenderTargetResource();
if (!RenderTargetResource)
{
return false;
}
// 创建位图
TArray<FColor> Bitmap;
if (!RenderTargetResource->ReadPixels(Bitmap))
{
return false;
}
int32 Width = RenderTarget->SizeX;
int32 Height = RenderTarget->SizeY;
// 调整图像大小(如果指定了新的宽度和高度)
if (NewWidth > 0 && NewHeight > 0)
{
TArray<FColor> ResizedBitmap;
//FImageUtils::ImageResize(Width, Height, Bitmap, NewWidth, NewHeight, ResizedBitmap);
ResizeImage(Bitmap, Width, Height, NewWidth, NewHeight, ResizedBitmap);
Bitmap = MoveTemp(ResizedBitmap); // 使用调整后的图像
Width = NewWidth;
Height = NewHeight;
}
// 处理位图,设置背景透明
for (FColor& Pixel : Bitmap)
{
if (Pixel == FColor::Black) // 假设背景是黑色,或者你可以用特定的颜色进行判断
{
Pixel.A = 0; // 设置 Alpha 通道为 0,透明
UE_LOG(LogTemp, Display, TEXT("LYM_ SetColor = 0"));
}
}
// 压缩为 PNG
IImageWrapperModule& ImageWrapperModule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(FName("ImageWrapper"));
TSharedPtr<IImageWrapper> ImageWrapper = ImageWrapperModule.CreateImageWrapper(EImageFormat::PNG);
if (ImageWrapper.IsValid() && ImageWrapper->SetRaw(Bitmap.GetData(), Bitmap.Num() * sizeof(FColor), Width, Height, ERGBFormat::BGRA, 8))
{
// 设置压缩质量
const TArray<uint8, FDefaultAllocator64> PngData = ImageWrapper->GetCompressed(CompressionQuality);
if (FFileHelper::SaveArrayToFile(PngData, *FilePath))
{
return true;
}
}
return false;
}
void YourClass::ResizeImage(const TArray<FColor>& SourceBitmap, int32 SourceWidth, int32 SourceHeight, int32 TargetWidth, int32 TargetHeight, TArray<FColor>& OutBitmap)
{
//(1)如果需要填充整个png使用这个
//OutBitmap.SetNumUninitialized(TargetWidth * TargetHeight);
//float XRatio = static_cast<float>(SourceWidth) / TargetWidth;
//float YRatio = static_cast<float>(SourceHeight) / TargetHeight;
//for (int32 y = 0; y < TargetHeight; ++y)
//{
// for (int32 x = 0; x < TargetWidth; ++x)
// {
// int32 SrcX = FMath::Clamp(static_cast<int32>(x * XRatio), 0, SourceWidth - 1);
// int32 SrcY = FMath::Clamp(static_cast<int32>(y * YRatio), 0, SourceHeight - 1);
// OutBitmap[y * TargetWidth + x] = SourceBitmap[SrcY * SourceWidth + SrcX];
// }
//}
//(2)如果截图需要居中对齐,用这个
// 清空目标位图并初始化为透明
OutBitmap.SetNumZeroed(TargetWidth * TargetHeight);
// 计算宽高比
float SourceAspect = static_cast<float>(SourceWidth) / SourceHeight;
float TargetAspect = static_cast<float>(TargetWidth) / TargetHeight;
int32 NewWidth, NewHeight;
if (SourceAspect > TargetAspect)
{
// 宽度受限
NewWidth = TargetWidth;
NewHeight = static_cast<int32>(TargetWidth / SourceAspect);
}
else
{
// 高度受限
NewHeight = TargetHeight;
NewWidth = static_cast<int32>(TargetHeight * SourceAspect);
}
// 调整后的图像居中对齐的偏移量
int32 OffsetX = (TargetWidth - NewWidth) / 2;
int32 OffsetY = (TargetHeight - NewHeight) / 2;
// 转换 TArray<FColor> 为 TArray<FLinearColor>
TArray<FLinearColor> SourceData;
SourceData.SetNum(SourceWidth * SourceHeight);
for (int32 i = 0; i < SourceWidth * SourceHeight; ++i)
{
FColor Color = SourceBitmap[i];
SourceData[i] = Color.ReinterpretAsLinear();
}
// 缩放图像
TArray<FLinearColor> ResizedData;
ResizedData.SetNum(NewWidth * NewHeight);
FImageUtils::ImageResize(SourceWidth, SourceHeight, SourceData, NewWidth, NewHeight, ResizedData);
// 转换 TArray<FLinearColor> 回 TArray<FColor>
TArray<FColor> ResizedBitmap;
ResizedBitmap.SetNum(NewWidth * NewHeight);
for (int32 i = 0; i < NewWidth * NewHeight; ++i)
{
ResizedBitmap[i] = ResizedData[i].ToFColor(true);
}
// 将调整后的图像绘制到目标位图中
for (int32 Y = 0; Y < NewHeight; Y++)
{
for (int32 X = 0; X < NewWidth; X++)
{
int32 SourceIndex = Y * NewWidth + X;
int32 TargetIndex = (Y + OffsetY) * TargetWidth + (X + OffsetX);
OutBitmap[TargetIndex] = ResizedBitmap[SourceIndex];
}
}
}
UTexture2D* YourClass::LoadTextureFromFile(const FString& FilePath)
{
TArray<uint8> RawFileData;
if (!FFileHelper::LoadFileToArray(RawFileData, *FilePath))
{
return nullptr; // 文件加载失败
}
IImageWrapperModule& ImageWrapperModule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(FName("ImageWrapper"));
EImageFormat ImageFormat = ImageWrapperModule.DetectImageFormat(RawFileData.GetData(), RawFileData.Num());
if (ImageFormat == EImageFormat::Invalid)
{
return nullptr; // 图像格式无效
}
TSharedPtr<IImageWrapper> ImageWrapper = ImageWrapperModule.CreateImageWrapper(ImageFormat);
if (ImageWrapper.IsValid() && ImageWrapper->SetCompressed(RawFileData.GetData(), RawFileData.Num()))
{
TArray<uint8> RawData;
if (ImageWrapper->GetRaw(ERGBFormat::BGRA, 8, RawData))
{
// 创建 UTexture2D 并填充它的数据
UTexture2D* Texture = UTexture2D::CreateTransient(ImageWrapper->GetWidth(), ImageWrapper->GetHeight(), PF_B8G8R8A8);
if (Texture)
{
void* TextureData = Texture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);
//锁定和解锁纹理数据以写入图像内容
FMemory::Memcpy(TextureData, RawData.GetData(), RawData.Num());
Texture->PlatformData->Mips[0].BulkData.Unlock();
//更新纹理资源以使更改生效
Texture->UpdateResource();
return Texture;
}
}
}
return nullptr; // 导入失败
}
(3)在蓝图中添加SceneCapture2d组件:首先如果你不需要这个组件一直捕捉的话,需要将它隐藏并且将自动激活关了,不然会很耗性能
(4)组建一个RT用于捕捉:
(5)将PrimitiveRenderMode设置为UseShowOnlyList,CaptureSource设置为FinalColor(LDR)inRGB
(60设置为UseShowOnlyList后,就需要将你需要截图的特定actor添加到数组中。因为我这个showactors中有很多别的actor,所以需要拿到所有的子类一起添加进去
(7)截图并保存:GetProjectSaveDirectory是项目的save缓存路径,剩下两个是项目content路径和项目路径。
PS:使用这种方法时场景最好是白天的时候,不然可能会出现一坨黑的情况。
(二)实时显示
(1)创建一个RT
(2)如果是需要在ui上一直实时显示的话,就需要基于RT创建一个材质用于ui。
(3)将节点修改为UserInterface(用于ui)和Translucent(可使用透明)
(4)在ui中创建一张image使用这个材质
(5)scenecapture组件使用默认设置即可
(6)UI中可以实时的看到捕捉到的画面
(7)但是这种会将背景也一起捕捉到,如果不需要背景的话,就需要使用UseShowOnlyList方式。将需要显示的actor添加到数组中
(8)材质用再将opacity节点连上,如果不连的话,背景就是纯黑色的
(9)修改完之后运行即可看到ui中只有需要显示的actor,背景就被剔除掉了。
(三)小地图
如果是需要做小地图那种的,就是显示人物在场景中移动,
(1~5) 前五步和第二种实时显示的情况步骤是一样的,
(6)将ProjectionType改为Orthographic,另外一个orthoWidth就是你需要显示的size大小,根据需要设置
(7)修改完之后就能在ui中看到效果