UnrealEngineUWP/Engine/Source/Developer/TextureFormat/Public/Interfaces/ITextureFormat.h

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "PixelFormat.h"
#include "Serialization/CompactBinary.h"

struct FTextureBuildSettings;
class FChildTextureFormat;

/**
 * Structure for texture format compressor capabilities.
 * This struct is deprecated - FEncodedTextureExtendedData is used instead.
 */
struct FTextureFormatCompressorCaps
{
	FTextureFormatCompressorCaps()
		: MaxTextureDimension_DEPRECATED(TNumericLimits<uint32>::Max())
		, NumMipsInTail_DEPRECATED(0)
		, ExtData_DEPRECATED(0)
	{ }

	// MaxTextureDimension is never set, remove it
	uint32 MaxTextureDimension_DEPRECATED;
	uint32 NumMipsInTail_DEPRECATED;
	uint32 ExtData_DEPRECATED;
};

/**
* Holds various engine configuration parameters that can affect the output of a build but
* should generally be constant across all texture builds. These are sourced from CVars
* and enums/defines that aren't necessarily visible in all modules.
* 
* This structure serializes to compact binary only writing if the values are not default,
* so changing the default initialization without changing the texture build version/guid
* can result in build mismatch.
* 
* Created via GenerateTextureEngineParameters() in TextureDerivedDataTask.cpp.
*/
struct FTextureEngineParameters
{
	bool bEngineSupportsVolumeTextureStreaming = true;			// GEngineSupportsVolumeTextureStreaming
	bool bEngineSupportsTexture2DArrayStreaming = true;			// GEngineSupportsTexture2DArrayStreaming
	int32 NumInlineDerivedMips = 7;								// NUM_INLINE_DERIVED_MIPS
};

static bool GetStreamingDisabledForNonVirtualTextureProperties(bool bInCubeMap, bool bInVolumeTexture, bool bInTextureArray, const FTextureEngineParameters& InEngineParameters)
{
	if (bInCubeMap)
	{
		return true;
	}
	if (bInVolumeTexture && InEngineParameters.bEngineSupportsVolumeTextureStreaming == false)
	{
		return true;
	}
	if (bInTextureArray && InEngineParameters.bEngineSupportsTexture2DArrayStreaming == false)
	{
		return true;
	}
	return false;
}



// Extra data for an encoded texture. For "normal" textures (i.e. linear, without a packed mip tail), this must be
// all zeroes.
struct FEncodedTextureExtendedData
{
	int32 NumMipsInTail = 0;
	uint32 ExtData = 0;
	
	// If true, this texture might change layouts if top mips are striped (i.e. LODBias is not zero).
	bool bSensitiveToLODBias = false;
	
	// If bSensitiveToLODBias is set, this is the LODBias for this layout.
	int8 LODBiasIfSensitive = 0;

	// With packing/tiling, mip sizes are not trivially computable. Not that these sizes must NOT be
	// used for mips prior to tiling. For those, FEncodedTextureDescription::GetMipSizeInBytes().
	TArray<uint64, TInlineAllocator<15 /*MAX_TEXTURE_MIP_COUNT*/>> MipSizesInBytes;
};


/**
* Calculate the number of streaming mips for the given set of texture properties. This must work off
* of properties that can (eventually) be calculated without running a full texture build.
* 
* Texture mips are split in to two large groups: streaming and non-streaming (aka "inline"). Note
* that "inline" is sometimes used as a verb to mean "load off of disk and place in our bulk data".
* "Inline" textures are loaded with the texture asset, and streaming textures are loaded on demand.
* Generally, 7 of the smallest mips are inlined, however some platforms pack a lot of mips in to a single
* allocation ("packed mip tail" = NumMipsInTail). Those mips must all be inlined.
* 
* InNumMips			    The total mips that the texture contains.
* InExtendedData	    If the texture is being built for a platform that provides extended data, pass it
*					    here. For platforms that don't need it (i.e. PC), this should be nullptr.
* InEngineParameters    Holds a vairety of engine configuration constants, create with GenerateEngineParameters()
*
*/
static int32 GetNumStreamingMipsDirect(int32 InNumMips, bool bInCubeMap, bool bInVolumeTexture, bool bInTextureArray, const FEncodedTextureExtendedData* InExtendedData, const FTextureEngineParameters& InEngineParameters)
{
	bool bAllowStreaming = true;
	{
		const bool bDisableStreaming = GetStreamingDisabledForNonVirtualTextureProperties(bInCubeMap, bInVolumeTexture, bInTextureArray, InEngineParameters);
		if (bDisableStreaming)
			bAllowStreaming = false;
	}

	int32 NumStreamingMips = 0;
	if (bAllowStreaming)
	{
		// Some platforms pack several mips in to a single entry. If this is the case,
		// those must be non-streaming.
		int32 NumMipsInTail = 0;
		if (InExtendedData)
		{
			NumMipsInTail = InExtendedData->NumMipsInTail;
		}

		int32 NumInlineMips = FMath::Max(NumMipsInTail, InEngineParameters.NumInlineDerivedMips);
		NumStreamingMips = FMath::Max(0, InNumMips - NumInlineMips);
	}
	return NumStreamingMips;
}

// Everything necessary to know the memory layout for an encoded untiled unpacked texture (i.e. enough information
// to describe the texture entirely to a PC hardware API).
// Once a texture gets tiled or gets a packed mip tail, FEncodedTextureEncodedData is additionally
// required to know the memory layout.
struct FEncodedTextureDescription
{	
	int32 TopMipSizeX;
	int32 TopMipSizeY;
	int32 TopMipVolumeSizeZ; // This is 1 if bVolumeTexture == false
	int32 ArraySlices; // This is 1 if bTextureArray == false (including cubemaps)
	EPixelFormat PixelFormat;
	uint8 NumMips;
	bool bCubeMap;
	bool bTextureArray;
	bool bVolumeTexture;
	

	bool operator==(const FEncodedTextureDescription& OtherTextureDescription) const
	{
		return TopMipSizeX == OtherTextureDescription.TopMipSizeX &&
			TopMipSizeY == OtherTextureDescription.TopMipSizeY &&
			TopMipVolumeSizeZ == OtherTextureDescription.TopMipVolumeSizeZ &&
			ArraySlices == OtherTextureDescription.ArraySlices &&
			PixelFormat == OtherTextureDescription.PixelFormat &&
			NumMips == OtherTextureDescription.NumMips &&
			bCubeMap == OtherTextureDescription.bCubeMap &&
			bTextureArray == OtherTextureDescription.bTextureArray &&
			bVolumeTexture == OtherTextureDescription.bVolumeTexture;
	}

	// Returns the slice count for usage cases/platform that expect slice count to include
	// volume texture depth. InMipIndex only affects volume textures.
	int32 GetNumSlices_WithDepth(int32 InMipIndex) const
	{
		if (bVolumeTexture)
		{
			check(bTextureArray == false && bCubeMap == false);
			check(InMipIndex < NumMips);
			return FMath::Max(TopMipVolumeSizeZ >> InMipIndex, 1);
		}

		check ((bTextureArray && ArraySlices >= 1) || (!bTextureArray && ArraySlices == 1));
		int32 Slices = ArraySlices;
		if (bCubeMap)
		{
			Slices *= 6;
		}
		return Slices;
	}

	// Returns the slice count for usage cases/platforms that expect slice count to only include
	// cubemap/array slices.
	int32 GetNumSlices_NoDepth() const
	{
		if (bVolumeTexture)
		{
			check(bTextureArray == false && bCubeMap == false);
			return 1; // no such thing as a cube volume, or a volume array.
		}

		check((bTextureArray && ArraySlices >= 1) || (!bTextureArray && ArraySlices == 1));
		int32 Slices = ArraySlices;
		if (bCubeMap)
		{
			Slices *= 6;
		}
		return Slices;
	}

	int32 GetMipWidth(int32 InMipIndex) const
	{
		return FMath::Max(TopMipSizeX >> InMipIndex, 1);
	}
	int32 GetMipHeight(int32 InMipIndex) const
	{
		return FMath::Max(TopMipSizeY >> InMipIndex, 1);
	}
	// Always 1 unless volume texture.
	int32 GetMipDepth(int32 InMipIndex) const
	{
		return bVolumeTexture ? FMath::Max(TopMipVolumeSizeZ >> InMipIndex, 1) : 1;
	}
	static int32 GetMipWidth(int32 InTextureWidth, int32 InMipIndex)
	{
		return FMath::Max(InTextureWidth >> InMipIndex, 1);
	}
	static int32 GetMipHeight(int32 InTextureHeight, int32 InMipIndex)
	{
		return FMath::Max(InTextureHeight >> InMipIndex, 1);
	}
	static int32 GetMipDepth(int32 InTextureDepth, int32 InMipIndex, bool bInVolumeTexture)
	{
		return bInVolumeTexture ? FMath::Max(InTextureDepth >> InMipIndex, 1) : 1;
	}


	// Returns the size of the mip at the given index. Z is 1 unless it's a volume texture.
	FIntVector3 GetMipDimensions(int32 InMipIndex) const
	{
		FIntVector3 Results;
		Results.X = GetMipWidth(InMipIndex);
		Results.Y = GetMipHeight(InMipIndex);
		Results.Z = GetMipDepth(InMipIndex);
		return Results;
	}

	// Returns the byte size of the unpacked/tiled mip. For mip chains that are packed or tiled, use FEncodedTextureExtendedData::MipSizesInBytes.
	uint64 GetMipSizeInBytes(int32 InMipIndex) const
	{
		FIntVector3 MipDims = GetMipDimensions(InMipIndex);
		uint64 SliceByteCount = GPixelFormats[PixelFormat].Get2DImageSizeInBytes(MipDims.X, MipDims.Y);
		return SliceByteCount * GetNumSlices_WithDepth(InMipIndex);
	}

	int32 GetNumStreamingMips(const FEncodedTextureExtendedData* InExtendedData, const FTextureEngineParameters& InEngineParameters) const
	{
		return GetNumStreamingMipsDirect(NumMips, bCubeMap, bVolumeTexture, bTextureArray, InExtendedData, InEngineParameters);
	}

	// Convenience function for iterating over the encoded mips when you need to know how many mips are represented. Use as:
	//
	//	for (int32 EncodedMipIndex = 0; EncodedMipIndex < OutMipTailIndex + 1; EncodedMipIndex++)
	//	{
	//		int32 MipsRepresentedThisIndex = EncodedMipIndex == OutMipTailIndex ? OutMipsInTail : 1;
	//	}
	//
	// This handles mip chains whether or not they have packed mip tails.
	// Note GetNumEncodedMips() == OutMipTailIndex + 1
	//
	void GetEncodedMipIterators(const FEncodedTextureExtendedData* InExtendedData, int32& OutMipTailIndex, int32& OutMipsInTail) const
	{
		OutMipTailIndex = NumMips - 1;
		OutMipsInTail = 1;
		if (InExtendedData && InExtendedData->NumMipsInTail > 1)
		{
			OutMipsInTail = InExtendedData->NumMipsInTail;
			OutMipTailIndex = NumMips - OutMipsInTail;
		}
	}

	// Returns the number of mips that actually carry bulk data for this texture. Nominally the number of total mips,
	// however some platforms have packed mip tails, which means they still have the total number of mips, but the last
	// several are all bundled together for memory savings.
	int32 GetNumEncodedMips(const FEncodedTextureExtendedData* InExtendedData) const
	{
		if (InExtendedData &&
			InExtendedData->NumMipsInTail > 1)
		{
			return NumMips - InExtendedData->NumMipsInTail + 1;
		}
		return NumMips;
	}

	// Returns the description _for the single mip level_ (i.e. no further mips)
	FEncodedTextureDescription GetDescriptionForMipLevel(const FEncodedTextureExtendedData* InExtendedData, int32 InMipIndex) const
	{
		check(InMipIndex < NumMips);

		FEncodedTextureDescription MipTextureDescription = *this;
		FIntVector3 TailFirstMipDims = GetMipDimensions(InMipIndex);
		MipTextureDescription.TopMipSizeX = TailFirstMipDims.X;
		MipTextureDescription.TopMipSizeY = TailFirstMipDims.Y;
		MipTextureDescription.TopMipVolumeSizeZ = TailFirstMipDims.Z;
		MipTextureDescription.NumMips = 1;
		if (InExtendedData && InExtendedData->NumMipsInTail && InMipIndex >= NumMips - InExtendedData->NumMipsInTail)
		{
			// we must only ever get the first mip tail index!
			check(InMipIndex == NumMips - InExtendedData->NumMipsInTail);

			// We want the layout for the entire tail.
			MipTextureDescription.NumMips = IntCastChecked<uint8>(InExtendedData->NumMipsInTail);
		}		
		return MipTextureDescription;
	}

	FEncodedTextureDescription RemoveTopMips(const FEncodedTextureExtendedData* InExtendedData, int32 InRemoveCount) const
	{
		check(InRemoveCount < NumMips);

		FEncodedTextureDescription MipTextureDescription = *this;
		FIntVector3 TailFirstMipDims = GetMipDimensions(InRemoveCount);
		MipTextureDescription.TopMipSizeX = TailFirstMipDims.X;
		MipTextureDescription.TopMipSizeY = TailFirstMipDims.Y;
		MipTextureDescription.TopMipVolumeSizeZ = TailFirstMipDims.Z;
		MipTextureDescription.NumMips = NumMips - InRemoveCount;
		if (InExtendedData && InExtendedData->NumMipsInTail && InRemoveCount >= NumMips - InExtendedData->NumMipsInTail)
		{
			// we must only ever get the first mip tail index!
			check(InRemoveCount == NumMips - InExtendedData->NumMipsInTail);

			// We want the layout for the entire tail.
			MipTextureDescription.NumMips = IntCastChecked<uint8>(InExtendedData->NumMipsInTail);
		}
		return MipTextureDescription;
	}
};

/**
*	Interface for platform formats that consume a linear, unpacked texture that an be built on
*	a host platform (e.g. windows) and then tile/pack it as necessary.
*/
class ITextureTiler
{
public:
	/**
	*	The generic texture tiling build function expects the following functions to exist that
	*	do what they say on the tin.
	* 
	*	static const FUtf8StringView GetBuildFunctionNameStatic()
	*	static FGuid GetBuildFunctionVersionGuid()
	*/
	
	/**
	* Generate and return any out-of-band data that needs to be saved for a given encoded texture description and LODBias.
	*/
	virtual FEncodedTextureExtendedData GetExtendedDataForTexture(const FEncodedTextureDescription& InTextureDescription, int8 InLODBias) const = 0;

	virtual const FUtf8StringView GetBuildFunctionName() const = 0;

	/**
		InLinearSurfaces must have the necessary input mips for the mip level - i.e. for a packed mip tail,
		InMipIndex is the index of the top mip of the tail, and InLinearSurfaces must have all the source mips
		for the entire tail.
	*/
	virtual FSharedBuffer ProcessMipLevel(const FEncodedTextureDescription& InTextureDescription, const FEncodedTextureExtendedData& InExtendedData, TArrayView<FMemoryView> InLinearSurfaces, int32 InMipIndex) const = 0;
};

/**
 * Interface for texture compression modules.
 * 
 * Note that if you add any virtual functions to this, they almost certainly need to be plumbed through
 * ChildTextureFormat! This is why the Format is passed around - ChildTextureFormat needs it to resolve to
 * the base format.
 */
class ITextureFormat
{
public:

	/**
	 * Checks whether this texture format can compress in parallel.
	 *
	 * @return true if parallel compression is supported, false otherwise.
	 */
	virtual bool AllowParallelBuild() const
	{
		return false;
	}

	/**
	*	Return the name of the encoder used for the given format.
	* 
	*	Used for debugging and UI.
	* */
	virtual FName GetEncoderName(FName Format) const = 0;

	/** 
		Exposes whether the format supports the fast/final encode speed switching in project settings. 
		Needs the Format so that we can thunk through the child texture formats correctly.
	*/
	virtual bool SupportsEncodeSpeed(FName Format) const
	{
		return false;
	}

	/**
	 * @returns true in case Compress can handle other than RGBA32F image formats
	 */
	virtual bool CanAcceptNonF32Source(FName Format) const
	{
		return false;
	}

	/**
	 * Gets the current version of the specified texture format.
	 *
	 * @param Format The format to get the version for.
	 * @return Version number.
	 */
	virtual uint16 GetVersion(
		FName Format,
		const FTextureBuildSettings* BuildSettings = nullptr
	) const = 0;

	/**
	 * Gets an optional derived data key string, so that the compressor can
	 * rely upon the number of mips, size of texture, etc, when compressing the image
	 *
	 * @param InBuildSettings Reference to the build settings we are compressing with.
	 * @param InMipCount Mip count of the physical texture that will be built - 0 for virtual textures.
 	 * @param InMip0Dimensions Mip width/height/slices of the physical texture that will be built - 0s for virtual textures.
	 * @return A string that will be used with the DDC, the string should be in the format "<DATA>_"
	 */
	virtual FString GetDerivedDataKeyString(const FTextureBuildSettings& InBuildSettings, int32 InMipCount, const FIntVector3& InMip0Dimensions) const
	{
		return TEXT("");
	}

	/**
	 * Gets the list of supported formats.
	 *
	 * @param OutFormats Will hold the list of formats.
	 */
	virtual void GetSupportedFormats( TArray<FName>& OutFormats ) const = 0;

	/**
	* Gets the capabilities of the texture compressor.
	*
	* @param OutCaps Filled with capability properties of texture format compressor.
	*/
	UE_DEPRECATED(5.1, "Hasn't been used in a while.")
	virtual FTextureFormatCompressorCaps GetFormatCapabilities() const { return FTextureFormatCompressorCaps(); }

	/**
	* Gets the capabilities of the texture compressor.
	*
	* @param OutCaps Filled with capability properties of texture format compressor.
	*/
	UE_DEPRECATED(5.1, "Use GetExtendedDataForTexture instead to get the same information without the actual image bits.")
	virtual FTextureFormatCompressorCaps GetFormatCapabilitiesEx(const FTextureBuildSettings& BuildSettings, uint32 NumMips, const struct FImage& ExampleImage, bool bImageHasAlphaChannel) const
	{
		return FTextureFormatCompressorCaps();
	}

	/**
	 * Calculate the final/runtime pixel format for this image on this platform
	 */
	UE_DEPRECATED(5.1, "Use GetEncodedPixelFormat(BuildSettings, bImageHasAlphaChannel) instead")
	virtual EPixelFormat GetPixelFormatForImage(const FTextureBuildSettings& BuildSettings, const struct FImage& Image, bool bImageHasAlphaChannel) const
	{
		return GetEncodedPixelFormat(BuildSettings, bImageHasAlphaChannel);
	}
	

	/**
	* Returns what the compressed pixel format will be for a given format and the given settings.
	* 
	* bInImageHasAlphaChannel is whether or not to treat the source image format as having an alpha channel,
	* independent of whether or not it actually has one.
	*/
	virtual EPixelFormat GetEncodedPixelFormat(const FTextureBuildSettings& InBuildSettings, bool bInImageHasAlphaChannel) const
	{
		return PF_Unknown;
	}

	/**
	* Generate and return any out-of-band data that needs to be saved for a given encoded texture description. This is
	* for textures that have been transformed in some way for a platform. LODBias is needed because in some cases the tiling
	* changes based on the top mip actually given to the hardware.
	*/
	virtual FEncodedTextureExtendedData GetExtendedDataForTexture(const FEncodedTextureDescription& InTextureDescription, int8 InLODBias) const
	{
		return FEncodedTextureExtendedData();
	}

	/**
	 * Compresses a single image.
	 *
	 * @param Image The input image.  Image.RawData may be freed or modified by CompressImage; do not use after calling this.
	 * @param BuildSettings Build settings.
 	 * @param InMip0Dimensions X/Y = Width/Height; Z = 1 unless volume texture, then its depth
	 * @param InMip0NumSlicesNoDepth see FEncodedTextureDescription::NumSlices_NoDepth()
	 * @param InMipIndex Mip index of current image in the overall texture.
	 * @param InMipCount Total mips this texture will be created with.
	 * @param DebugTexturePathName The path name of the texture we are building, for debug logging/filtering/dumping.
	 * @param bImageHasAlphaChannel true if the image has a non-white alpha channel.
	 * @param OutCompressedMip The compressed image.
	 * @returns true on success, false otherwise.
	 */
	virtual bool CompressImage(
		FImage& Image,
		const FTextureBuildSettings& BuildSettings,
		const FIntVector3& InMip0Dimensions,
		int32 InMip0NumSlicesNoDepth,
		int32 InMipIndex,
		int32 InMipCount,
		FStringView DebugTexturePathName,
		bool bImageHasAlphaChannel,
		struct FCompressedImage2D& OutCompressedImage
	) const = 0;

	/**
	 * Compress an image (or images for a miptail) into a single mip blob.
	 *
	 * @param Images The input image(s).  Image.RawData may be freed or modified by CompressImage; do not use after calling this.
	 * @param NumImages The number of images (for a miptail, this number should match what was returned in GetExtendedDataForTexture, mostly used for verification)
	 * @param BuildSettings Build settings.
	 * @param InMip0Dimensions X/Y = Width/Height; Z = 1 unless volume texture, then its depth
	 * @param InMip0NumSlicesNoDepth see FEncodedTextureDescription::NumSlices_NoDepth()
	 * @param InMipIndex Mip index of current image in the overall texture.
	 * @param InMipCount Total mips this texture will be created with.
	 * @param DebugTexturePathName The path name of the texture we are building, for debug logging/filtering/dumping.
	 * @param bImageHasAlphaChannel true if the image has a non-white alpha channel.
	 * @param ExtData Extra data that the format may want to have passed back in to each compress call (makes the format class be stateless)
	 * @param OutCompressedMip The compressed image.
	 * @returns true on success, false otherwise.
	 */
	virtual bool CompressImageEx(
		FImage* Images,
		const uint32 NumImages,
		const FTextureBuildSettings& BuildSettings,
		const FIntVector3& InMip0Dimensions,
		int32 InMip0NumSlicesNoDepth,
		int32 InMipIndex,
		int32 InMipCount,
		FStringView DebugTexturePathName,
		bool bImageHasAlphaChannel,
		uint32 ExtData,
		FCompressedImage2D& OutCompressedImage) const
	{
		// general case can't handle mip tails
		if (Images == nullptr || NumImages > 1)
		{
			return false;
		}
		
		return CompressImage(*Images, BuildSettings, InMip0Dimensions, InMip0NumSlicesNoDepth, InMipIndex, InMipCount, DebugTexturePathName, bImageHasAlphaChannel, OutCompressedImage);
	}

	/**
	 * An object produced by PrepareTiling and used by SetTiling and CompressImageTiled.
	 * This is used as an inheritance base for tiling formats to add their own information.
	 */
	struct FTilerSettings
	{
	};

	/**
	 * Compress an image (or images for a miptail) into a single mip blob with device-specific tiling.
	 *
	 * @param Image The input image.  May be freed!
	 * @param BuildSettings Build settings.
	 * @param bImageHasAlphaChannel true if the image has a non-white alpha channel.
	 * @param DebugTexturePathName The path name of the texture we are building, for debug logging/filtering/dumping.
	 * @param OutCompressedMip The compressed image.
	 * @param Tiler The tiler settings.
	 * @returns true on success, false otherwise.
	 */
	virtual bool CompressImageTiled(
		FImage* Images,
		uint32 NumImages,
		const FTextureBuildSettings& BuildSettings,
		FStringView DebugTexturePathName,
		bool bImageHasAlphaChannel,
		TSharedPtr<FTilerSettings>& TilerSettings,
		struct FCompressedImage2D& OutCompressedImage) const
	{
		unimplemented();
		return false;
	}

	/**
	 * Whether device-specific tiling is supported by the compressor.
	 *
	 * @param BuildSettings Build settings.
	 * @returns true if tiling is supported, false if it must be done by the caller
	 *
	 */
	virtual bool SupportsTiling() const
	{
		return false;
	}

	/**
	 * Prepares to compresses a single image with tiling. The result OutTilerSettings is used by SetTiling and CompressImageTiled.
	 *
	 * @param Image The input image.
	 * @param BuildSettings Build settings.
	 * @param bImageHasAlphaChannel true if the image has a non-white alpha channel.
	 * @param OutTilerSettings The tiler settings that will be used by CompressImageTiled and SetTiling.
	 * @param OutCompressedImage The image to tile.
	 * @returns true on success, false otherwise.
	 */
	virtual bool PrepareTiling(
		const FImage* Images,
		const uint32 NumImages,
		const FTextureBuildSettings& BuildSettings,
		bool bImageHasAlphaChannel,
		TSharedPtr<FTilerSettings>& OutTilerSettings,
		TArray<FCompressedImage2D>& OutCompressedImage
	) const
	{
		unimplemented();
		return false;
	}
	
	/**
	 * Sets the tiling settings after device-specific tiling has been performed.
	 *
	 * @param BuildSettings Build settings.
	 * @param TilerSettings The tiler settings produced by PrepareTiling.
	 * @param ReorderedBlocks The blocks that have been tiled.
	 * @param NumBlocks The number of blocks.
	 * @returns true on success, false otherwise.
	 */
	virtual bool SetTiling(
		const FTextureBuildSettings& BuildSettings,
		TSharedPtr<FTilerSettings>& TilerSettings,
		const TArray64<uint8>& ReorderedBlocks,
		uint32 NumBlocks
	) const
	{
		unimplemented();
		return false;
	}

	/**
	 * Cleans up the FTilerSettings object once it is finished.
	 * 
	 * @param BuildSettings Build settings.
	 * @param TilerSettings The tiler settings object to release.
	 */
	virtual void ReleaseTiling(const FTextureBuildSettings& BuildSettings, TSharedPtr<FTilerSettings>& TilerSettings) const
	{
		unimplemented();
	}

	/**
	 * Obtains the current global format config object for this texture format.
	 * 
	 * This is only ever called during task creation - never in a build worker
	 * (FormatConfigOverride is empty)
	 * 
	 * @param BuildSettings Build settings.
	 * @returns The current format config object or an empty object if no format config is defined for this texture format.
	 */
	virtual FCbObject ExportGlobalFormatConfig(const FTextureBuildSettings& BuildSettings) const
	{
		return FCbObject();
	}

	/**
	 * If this is an Alternate Texture Format, return the prefix to apply 
	 */
	virtual FString GetAlternateTextureFormatPrefix() const
	{
		return FString();
	}

	virtual const FChildTextureFormat* GetChildFormat() const
	{
		return nullptr;
	}
	
	/**
	 * Identify the latest sdk version for this texture encoder
	 *   (note the SdkVersion is different than the TextureFormat Version)
	 */
	virtual FName GetLatestSdkVersion() const
	{
		return FName();
	}
	
	UE_DEPRECATED(5.0, "Legacy API - do not use")
	virtual bool UsesTaskGraph() const
	{
		unimplemented();
		return true;
	}

public:

	/** Virtual destructor. */
	virtual ~ITextureFormat() { }
};