Generating Procedural Textures

In this post I’m going to show you how to create procedural textures inside the editor. While in the following example we will generate a 1024 x 1024 texture using random RGB values, the same approach can be used with different generation algorithms to achieve your goals. This post was written using 4.22 version of the engine so you may have to modify the following code in case you’re using a newer version.

The whole process takes place in a single c++ method (named GenerateTexture) that:

1. Generates the asset file inside the editor
2. Creates the pixel data
3. Copies the pixel data to the file
4. Saves the asset when the above steps are completed

In order to test the following code, I created a C++ class that inherits the actor class and then inside the BeginPlay function I called the GenerateTexture method:

void AProceduralTextureTest::GenerateTexture()
{
	//Create a string containing the texture's path
	FString PackageName = TEXT("/Game/ProceduralTextures/");
	FString BaseTextureName = FString("ProcTexture");
	PackageName += BaseTextureName;

	//Create the package that will store our texture
	UPackage* Package = CreatePackage(NULL, *PackageName);
	GLog->Log("project dir:" + FPaths::ProjectDir());

	//Create a unique name for our asset. For example, if a texture named ProcTexture already exists the editor
	//will name the new texture as "ProcTexture_1"
	FName TextureName = MakeUniqueObjectName(Package, UTexture2D::StaticClass(), FName(*BaseTextureName));
	Package->FullyLoad();

	UTexture2D* NewTexture = NewObject<UTexture2D>(Package, TextureName, RF_Public | RF_Standalone | RF_MarkAsRootSet);

	if (NewTexture)
	{
		int32 TextureWidth = 1024;
		int32 TextureHeight = 1024;

		//Prevent the object and all its descedants from being deleted during garbage collecion
		NewTexture->AddToRoot();

		//Initialize the platform data to store necessary information regarding our texture asset
		NewTexture->PlatformData = new FTexturePlatformData();
		NewTexture->PlatformData->SizeX = TextureWidth;
		NewTexture->PlatformData->SizeY = TextureHeight;
		NewTexture->PlatformData->NumSlices = 1;
		NewTexture->PlatformData->PixelFormat = EPixelFormat::PF_B8G8R8A8;

		
		//uint8* Pixels = GeneratePixels(TextureHeight, TextureWidth);
		//Each element of the array contains a single color so in order to represent information in
		//RGBA we need to have an array of length TextureWidth * TextureHeight * 4
		uint8* Pixels = new uint8[TextureWidth * TextureHeight * 4];
		for (int32 y = 0; y < TextureHeight; y++)
		{
			for (int32 x = 0; x < TextureWidth; x++)
			{
				//Get the current pixel
				int32 CurrentPixelIndex = ((y * TextureWidth) + x);
				//Get a random vector that will represent the RGB values for the current pixel
				FColor RandomColor = FColor::MakeRandomColor();
				
				Pixels[4 * CurrentPixelIndex] = RandomColor.B; //b
				Pixels[4 * CurrentPixelIndex + 1] = RandomColor.G; //g
				Pixels[4 * CurrentPixelIndex + 2] = RandomColor.R; //r
				Pixels[4 * CurrentPixelIndex + 3] = 255; //set A channel always to maximum
			}
		}

		//Allocate first mipmap.
		FTexture2DMipMap* Mip = new FTexture2DMipMap();
		NewTexture->PlatformData->Mips.Add(Mip);
		Mip->SizeX = TextureWidth;
		Mip->SizeY = TextureHeight;

		//Lock the mipmap data so it can be modified
		Mip->BulkData.Lock(LOCK_READ_WRITE);
		uint8* TextureData = (uint8*)Mip->BulkData.Realloc(TextureWidth * TextureHeight * 4);
		//Copy the pixel data into the Texture data
		FMemory::Memcpy(TextureData, Pixels, sizeof(uint8) * TextureHeight * TextureWidth * 4);
		Mip->BulkData.Unlock();


		//Initialize a new texture
		NewTexture->Source.Init(TextureWidth, TextureHeight, 1, 1, ETextureSourceFormat::TSF_BGRA8, Pixels);
		NewTexture->UpdateResource();

		//Mark the package as dirty so the editor will prompt you to save the file if you haven't
		Package->MarkPackageDirty();

		//Notify the editor that we created a new asset
		FAssetRegistryModule::AssetCreated(NewTexture);

		//Auto-save the new  asset
		FString PackageFileName = FPackageName::LongPackageNameToFilename(PackageName, FPackageName::GetAssetPackageExtension());
		bool bSaved = UPackage::SavePackage(Package, NewTexture, EObjectFlags::RF_Public | EObjectFlags::RF_Standalone, *PackageFileName, GError, nullptr, true, true, SAVE_NoError);

		//Since we don't need access to the pixel data anymore free the memory
		delete[] Pixels;
	}
	
}

Here are a couple of textures that were generated by the previous algorithm: