dds.h

#ifndef DDS_H
#define DDS_H
// Minimal cross-platform DDS texture utility created by Turánszki János for Wicked Engine: https://github.com/turanszkij/WickedEngine
// This is not using any includes or memory allocations, and computes relative memory offsets designed for texture streaming
// Based on DDS specification: https://learn.microsoft.com/en-us/windows/win32/direct3ddds/dx-graphics-dds-pguide#dds-file-layout
//
//	How to read DDS textures:
//		1) Read the whole DDS file, or sizeof(dds::Header) bytes from the beginning of the file
//		2) Use dds::read_header() to parse the header of the DDS texture
//		3) from the dds::Header structure that was created by dds::read_header(), you can compute parameters of the texture required for loading
//		4) any function of the header returning an offset is relative to the beginning of the file, usable for texture streaming to read only the required data from files
//		5) enjoy
//
//	Example:
//		dds::Header header = dds::read_header(filedata, filesize);
//		if(header.is_valid())
//		{
//			TextureDesc desc;
//			desc.width = header.width();
//			desc.mip_levels = header.mip_levels();
//			desc.array_size = header.array_size();
//
//			SubresourceData initdata;
//			initdata.data_ptr = filedata + header.mip_offset(0);
//			initdata.row_pitch = header.row_pitch(0);
//
//			...continue loading texture data...
//		}
// 
//	How to write DDS textures:
//		1) Allocate memory of: sizeof(dds::Header) + your whole texture size
//		2) Use dds::write_header() to write DDS header into memory
//		3) write your texture data into memory manually after allocation + sizeof(dds::Header)
//		4) this only writes to memory, so write the result into file manually if you want to
//		5) enjoy
//
//	Example:
//		std::vector<unsigned8_t> texturedata; // your texture data in a GPU format
//		std::vector<unsigned8_t> filedata; // DDS file data container
//		filedata.resize(sizeof(dds::Header) + texturedata.size()); // allocate memory
//		
//		dds::write_header(
//			filedata.data(),
//			dds::DXGI_FORMAT_R8G8B8A8_UNORM,
//			width,
//			height,
//			mip_count,	// optional
//			array_size,	// optional
//			false,		// optional (is_cubemap)
//			depth		// optional
//		);
//		std::memcpy(filedata.data() + sizeof(dds::Header), texturedata.data(), texturedata.size());
//
//	...Or you can just freely use the structures here to write your own DDS header
//
//	Note: texture data need to be in the following layout in the DDS file, tightly packed:
//		- Array slice 0 / cubemap face +X
//			- mipmap 0
//				- depth slice 0
//				- depth slice 1
//				- ...
//			- mipmap 1
//				- depth slice 0
//				- depth slice 1
//				- ...
//			- ...
//		- Array slice 1 / cubemap face -X
//			- mipmap 0
//				- depth slice 0
//				- depth slice 1
//				- ...
//			- mipmap 1
//				- depth slice 0
//				- depth slice 1
//				- ...
//			- ...
//		- ...
//	Note: This is similar to how you would provide the texture with DirectX 11 API's D3D11_SUBRESOURCE_DATA when creating textures
//
//	Support:
//		- This will only create DX10 version of DDS, doesn't support legacy
//		- Tested with Texture 1D, Texture 2D, Texture 2D Array, Cubemap, Cubemap array, 3D Texture
//		- Tested with uncompressed formats and block compressed
//		- mipmaps: Yes
//		- arrays: Yes
//
// 
//	Contributors:
//		- Jon Jansen
//
//	MIT License (see the end of this file)

namespace dds
{
	enum DDS_PIXELFORMAT_FLAGS
	{
		DDPF_ALPHAPIXELS = 0x1,		// Texture contains alpha data; dwRGBAlphaBitMask contains valid data.
		DDPF_ALPHA = 0x2,			// Used in some older DDS files for alpha channel only uncompressed data (dwRGBBitCount contains the alpha channel bitcount; dwABitMask contains valid data)
		DDPF_FOURCC = 0x4,			// Texture contains compressed RGB data; dwFourCC contains valid data.
		DDPF_RGB = 0x40,			// Texture contains uncompressed RGB data; dwRGBBitCount and the RGB masks (dwRBitMask, dwGBitMask, dwBBitMask) contain valid data.
		DDPF_YUV = 0x200,			// Used in some older DDS files for YUV uncompressed data (dwRGBBitCount contains the YUV bit count; dwRBitMask contains the Y mask, dwGBitMask contains the U mask, dwBBitMask contains the V mask)
		DDPF_LUMINANCE = 0x20000	// Used in some older DDS files for single channel color uncompressed data (dwRGBBitCount contains the luminance channel bit count; dwRBitMask contains the channel mask). Can be combined with DDPF_ALPHAPIXELS for a two channel DDS file.
	};
	struct DDS_PIXELFORMAT {
		unsigned dwSize;
		unsigned dwFlags;
		unsigned dwFourCC;
		unsigned dwRGBBitCount;
		unsigned dwRBitMask;
		unsigned dwGBitMask;
		unsigned dwBBitMask;
		unsigned dwABitMask;
	};
	enum DDSD_CAPS
	{
		DDSD_CAPS = 0x1,			// Required in every .dds file.
		DDSD_HEIGHT = 0x2,			// Required in every .dds file.
		DDSD_WIDTH = 0x4,			// Required in every .dds file.
		DDSD_PITCH = 0x8,			// Required when pitch is provided for an uncompressed texture.
		DDSD_PIXELFORMAT = 0x1000,	// Required in every .dds file.
		DDSD_MIPMAPCOUNT = 0x20000,	// Required in a mipmapped texture.
		DDSD_LINEARSIZE = 0x80000,	// Required when pitch is provided for a compressed texture.
		DDSD_DEPTH = 0x800000		// Required in a depth texture.
	};
	enum DDSCAPS
	{
		DDSCAPS_COMPLEX = 0x8,		// Optional; must be used on any file that contains more than one surface (a mipmap, a cubic environment map, or mipmapped volume texture).
		DDSCAPS_MIPMAP = 0x400000,	// Optional; should be used for a mipmap.
		DDSCAPS_TEXTURE = 0x1000,	// Required
	};
	enum DDSCAPS2
	{
		DDSCAPS2_CUBEMAP = 0x200,			// Required for a cube map.
		DDSCAPS2_CUBEMAP_POSITIVEX = 0x400,	// Required when these surfaces are stored in a cube map.
		DDSCAPS2_CUBEMAP_NEGATIVEX = 0x800,	// Required when these surfaces are stored in a cube map.
		DDSCAPS2_CUBEMAP_POSITIVEY = 0x1000,// Required when these surfaces are stored in a cube map.
		DDSCAPS2_CUBEMAP_NEGATIVEY = 0x2000,// Required when these surfaces are stored in a cube map.
		DDSCAPS2_CUBEMAP_POSITIVEZ = 0x4000,// Required when these surfaces are stored in a cube map.
		DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x8000,// Required when these surfaces are stored in a cube map.
		DDSCAPS2_VOLUME = 0x200000,			// Required for a volume texture.
	};
	typedef struct {
		unsigned dwSize;
		unsigned dwFlags;
		unsigned dwHeight;
		unsigned dwWidth;
		unsigned dwPitchOrLinearSize;
		unsigned dwDepth;
		unsigned dwMipMapCount;
		unsigned dwReserved1[11];
		DDS_PIXELFORMAT ddspf;
		unsigned dwCaps;
		unsigned dwCaps2;
		unsigned dwCaps3;
		unsigned dwCaps4;
		unsigned dwReserved2;
	} DDS_HEADER;
	enum DXGI_FORMAT {
		DXGI_FORMAT_UNKNOWN = 0,
		DXGI_FORMAT_R32G32B32A32_TYPELESS = 1,
		DXGI_FORMAT_R32G32B32A32_FLOAT = 2,
		DXGI_FORMAT_R32G32B32A32_UINT = 3,
		DXGI_FORMAT_R32G32B32A32_SINT = 4,
		DXGI_FORMAT_R32G32B32_TYPELESS = 5,
		DXGI_FORMAT_R32G32B32_FLOAT = 6,
		DXGI_FORMAT_R32G32B32_UINT = 7,
		DXGI_FORMAT_R32G32B32_SINT = 8,
		DXGI_FORMAT_R16G16B16A16_TYPELESS = 9,
		DXGI_FORMAT_R16G16B16A16_FLOAT = 10,
		DXGI_FORMAT_R16G16B16A16_UNORM = 11,
		DXGI_FORMAT_R16G16B16A16_UINT = 12,
		DXGI_FORMAT_R16G16B16A16_SNORM = 13,
		DXGI_FORMAT_R16G16B16A16_SINT = 14,
		DXGI_FORMAT_R32G32_TYPELESS = 15,
		DXGI_FORMAT_R32G32_FLOAT = 16,
		DXGI_FORMAT_R32G32_UINT = 17,
		DXGI_FORMAT_R32G32_SINT = 18,
		DXGI_FORMAT_R32G8X24_TYPELESS = 19,
		DXGI_FORMAT_D32_FLOAT_S8X24_UINT = 20,
		DXGI_FORMAT_R32_FLOAT_X8X24_TYPELESS = 21,
		DXGI_FORMAT_X32_TYPELESS_G8X24_UINT = 22,
		DXGI_FORMAT_R10G10B10A2_TYPELESS = 23,
		DXGI_FORMAT_R10G10B10A2_UNORM = 24,
		DXGI_FORMAT_R10G10B10A2_UINT = 25,
		DXGI_FORMAT_R11G11B10_FLOAT = 26,
		DXGI_FORMAT_R8G8B8A8_TYPELESS = 27,
		DXGI_FORMAT_R8G8B8A8_UNORM = 28,
		DXGI_FORMAT_R8G8B8A8_UNORM_SRGB = 29,
		DXGI_FORMAT_R8G8B8A8_UINT = 30,
		DXGI_FORMAT_R8G8B8A8_SNORM = 31,
		DXGI_FORMAT_R8G8B8A8_SINT = 32,
		DXGI_FORMAT_R16G16_TYPELESS = 33,
		DXGI_FORMAT_R16G16_FLOAT = 34,
		DXGI_FORMAT_R16G16_UNORM = 35,
		DXGI_FORMAT_R16G16_UINT = 36,
		DXGI_FORMAT_R16G16_SNORM = 37,
		DXGI_FORMAT_R16G16_SINT = 38,
		DXGI_FORMAT_R32_TYPELESS = 39,
		DXGI_FORMAT_D32_FLOAT = 40,
		DXGI_FORMAT_R32_FLOAT = 41,
		DXGI_FORMAT_R32_UINT = 42,
		DXGI_FORMAT_R32_SINT = 43,
		DXGI_FORMAT_R24G8_TYPELESS = 44,
		DXGI_FORMAT_D24_UNORM_S8_UINT = 45,
		DXGI_FORMAT_R24_UNORM_X8_TYPELESS = 46,
		DXGI_FORMAT_X24_TYPELESS_G8_UINT = 47,
		DXGI_FORMAT_R8G8_TYPELESS = 48,
		DXGI_FORMAT_R8G8_UNORM = 49,
		DXGI_FORMAT_R8G8_UINT = 50,
		DXGI_FORMAT_R8G8_SNORM = 51,
		DXGI_FORMAT_R8G8_SINT = 52,
		DXGI_FORMAT_R16_TYPELESS = 53,
		DXGI_FORMAT_R16_FLOAT = 54,
		DXGI_FORMAT_D16_UNORM = 55,
		DXGI_FORMAT_R16_UNORM = 56,
		DXGI_FORMAT_R16_UINT = 57,
		DXGI_FORMAT_R16_SNORM = 58,
		DXGI_FORMAT_R16_SINT = 59,
		DXGI_FORMAT_R8_TYPELESS = 60,
		DXGI_FORMAT_R8_UNORM = 61,
		DXGI_FORMAT_R8_UINT = 62,
		DXGI_FORMAT_R8_SNORM = 63,
		DXGI_FORMAT_R8_SINT = 64,
		DXGI_FORMAT_A8_UNORM = 65,
		DXGI_FORMAT_R1_UNORM = 66,
		DXGI_FORMAT_R9G9B9E5_SHAREDEXP = 67,
		DXGI_FORMAT_R8G8_B8G8_UNORM = 68,
		DXGI_FORMAT_G8R8_G8B8_UNORM = 69,
		DXGI_FORMAT_BC1_TYPELESS = 70,
		DXGI_FORMAT_BC1_UNORM = 71,
		DXGI_FORMAT_BC1_UNORM_SRGB = 72,
		DXGI_FORMAT_BC2_TYPELESS = 73,
		DXGI_FORMAT_BC2_UNORM = 74,
		DXGI_FORMAT_BC2_UNORM_SRGB = 75,
		DXGI_FORMAT_BC3_TYPELESS = 76,
		DXGI_FORMAT_BC3_UNORM = 77,
		DXGI_FORMAT_BC3_UNORM_SRGB = 78,
		DXGI_FORMAT_BC4_TYPELESS = 79,
		DXGI_FORMAT_BC4_UNORM = 80,
		DXGI_FORMAT_BC4_SNORM = 81,
		DXGI_FORMAT_BC5_TYPELESS = 82,
		DXGI_FORMAT_BC5_UNORM = 83,
		DXGI_FORMAT_BC5_SNORM = 84,
		DXGI_FORMAT_B5G6R5_UNORM = 85,
		DXGI_FORMAT_B5G5R5A1_UNORM = 86,
		DXGI_FORMAT_B8G8R8A8_UNORM = 87,
		DXGI_FORMAT_B8G8R8X8_UNORM = 88,
		DXGI_FORMAT_R10G10B10_XR_BIAS_A2_UNORM = 89,
		DXGI_FORMAT_B8G8R8A8_TYPELESS = 90,
		DXGI_FORMAT_B8G8R8A8_UNORM_SRGB = 91,
		DXGI_FORMAT_B8G8R8X8_TYPELESS = 92,
		DXGI_FORMAT_B8G8R8X8_UNORM_SRGB = 93,
		DXGI_FORMAT_BC6H_TYPELESS = 94,
		DXGI_FORMAT_BC6H_UF16 = 95,
		DXGI_FORMAT_BC6H_SF16 = 96,
		DXGI_FORMAT_BC7_TYPELESS = 97,
		DXGI_FORMAT_BC7_UNORM = 98,
		DXGI_FORMAT_BC7_UNORM_SRGB = 99,
		DXGI_FORMAT_AYUV = 100,
		DXGI_FORMAT_Y410 = 101,
		DXGI_FORMAT_Y416 = 102,
		DXGI_FORMAT_NV12 = 103,
		DXGI_FORMAT_P010 = 104,
		DXGI_FORMAT_P016 = 105,
		DXGI_FORMAT_420_OPAQUE = 106,
		DXGI_FORMAT_YUY2 = 107,
		DXGI_FORMAT_Y210 = 108,
		DXGI_FORMAT_Y216 = 109,
		DXGI_FORMAT_NV11 = 110,
		DXGI_FORMAT_AI44 = 111,
		DXGI_FORMAT_IA44 = 112,
		DXGI_FORMAT_P8 = 113,
		DXGI_FORMAT_A8P8 = 114,
		DXGI_FORMAT_B4G4R4A4_UNORM = 115,
		DXGI_FORMAT_P208 = 130,
		DXGI_FORMAT_V208 = 131,
		DXGI_FORMAT_V408 = 132,
		DXGI_FORMAT_SAMPLER_FEEDBACK_MIN_MIP_OPAQUE,
		DXGI_FORMAT_SAMPLER_FEEDBACK_MIP_REGION_USED_OPAQUE,
		D3DFMT_R8G8B8, // Note: you will need to handle conversion of this legacy format yourself
		DXGI_FORMAT_FORCE_DWORD = 0xffffffff
	};
	enum D3D10_RESOURCE_DIMENSION {
		D3D10_RESOURCE_DIMENSION_UNKNOWN = 0,
		D3D10_RESOURCE_DIMENSION_BUFFER = 1,
		D3D10_RESOURCE_DIMENSION_TEXTURE1D = 2,
		D3D10_RESOURCE_DIMENSION_TEXTURE2D = 3,
		D3D10_RESOURCE_DIMENSION_TEXTURE3D = 4
	};
	enum DDS_RESOURCE_MISC_TEXTURECUBE
	{
		DDS_RESOURCE_MISC_TEXTURECUBE = 0x4,	// Indicates a 2D texture is a cube-map texture.
	};
	enum DDS_ALPHA_MODE
	{
		DDS_ALPHA_MODE_UNKNOWN = 0x0,		// Alpha channel content is unknown. This is the value for legacy files, which typically is assumed to be 'straight' alpha.
		DDS_ALPHA_MODE_STRAIGHT = 0x1,		// Any alpha channel content is presumed to use straight alpha.
		DDS_ALPHA_MODE_PREMULTIPLIED = 0x2,	// Any alpha channel content is using premultiplied alpha. The only legacy file formats that indicate this information are 'DX2' and 'DX4'.
		DDS_ALPHA_MODE_OPAQUE = 0x3,		// Any alpha channel content is all set to fully opaque.
		DDS_ALPHA_MODE_CUSTOM = 0x4,		// Any alpha channel content is being used as a 4th channel and is not intended to represent transparency (straight or premultiplied).
	};
	typedef struct {
		DXGI_FORMAT dxgiFormat;
		D3D10_RESOURCE_DIMENSION resourceDimension;
		unsigned miscFlag;
		unsigned arraySize;
		unsigned miscFlags2;
	} DDS_HEADER_DXT10;

	static constexpr unsigned fourcc(char a, char b, char c, char d)
	{
		return (((unsigned)(d) << 24) | ((unsigned)(c) << 16) | ((unsigned)(b) << 8) | (unsigned)(a));
	}

	struct Header
	{
		unsigned magic;
		DDS_HEADER header;
		DDS_HEADER_DXT10 header10;

		// Returns true if this structure can be used, false otherwise
		constexpr bool is_valid() const
		{
			return
				magic == fourcc('D', 'D', 'S', ' ') &&
				header.ddspf.dwSize == sizeof(DDS_PIXELFORMAT);
		}
		// Returns true if the header10 member is valid
		constexpr bool is_dx10() const
		{
			return
				(header.ddspf.dwFlags & DDPF_FOURCC) &&
				header.ddspf.dwFourCC == fourcc('D', 'X', '1', '0');
		}
		// returns the width of the texture in pixels
		constexpr unsigned width() const
		{
			return header.dwWidth < 1 ? 1 : header.dwWidth;
		}
		// returns the height of the texture in pixels
		constexpr unsigned height() const
		{
			return header.dwHeight < 1 ? 1 : header.dwHeight;
		}
		// returns the depth of the texture in pixels
		constexpr unsigned depth() const
		{
			return header.dwDepth < 1 ? 1 : header.dwDepth;
		}
		// returns the mipmap levels in the texture per slice
		constexpr unsigned mip_levels() const
		{
			return header.dwMipMapCount > 0 ? header.dwMipMapCount : 1;
		}
		// returns the number of slices in the texture
		constexpr unsigned array_size() const
		{
			if (!is_dx10())
			{
				if (is_cubemap())
					return 6;
				return 1;
			}
			unsigned count = 0;
			if (is_cubemap())
				count = header10.arraySize * 6;
			else
				count = header10.arraySize;
			count = count < 1 ? 1 : count;
			return count;
		}
		// returns the format of the texture in the DXGI_FORMAT that is complatible with DX10, even when the texture is using legacy format
		constexpr DXGI_FORMAT format() const
		{
			if (!is_dx10())
			{
				if (header.ddspf.dwFlags & DDPF_RGB)
				{
					switch (header.ddspf.dwRGBBitCount)
					{
					case 32:
						if (header.ddspf.dwRBitMask == 0x000000ff &&
							header.ddspf.dwGBitMask == 0x0000ff00 &&
							header.ddspf.dwBBitMask == 0x00ff0000 &&
							header.ddspf.dwABitMask == 0xff000000) {
							return DXGI_FORMAT_R8G8B8A8_UNORM;
						}
						if (header.ddspf.dwRBitMask == 0x00ff0000 &&
							header.ddspf.dwGBitMask == 0x0000ff00 &&
							header.ddspf.dwBBitMask == 0x000000ff &&
							header.ddspf.dwABitMask == 0xff000000) {
							return DXGI_FORMAT_B8G8R8A8_UNORM;
						}
						if (header.ddspf.dwRBitMask == 0x00ff0000 &&
							header.ddspf.dwGBitMask == 0x0000ff00 &&
							header.ddspf.dwBBitMask == 0x000000ff &&
							header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_B8G8R8X8_UNORM;
						}

						if (header.ddspf.dwRBitMask == 0x0000ffff &&
							header.ddspf.dwGBitMask == 0xffff0000 &&
							header.ddspf.dwBBitMask == 0x00000000 &&
							header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R16G16_UNORM;
						}

						if (header.ddspf.dwRBitMask == 0xffffffff &&
							header.ddspf.dwGBitMask == 0x00000000 &&
							header.ddspf.dwBBitMask == 0x00000000 &&
							header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R32_FLOAT;
						}
						break;
					case 24:
						return D3DFMT_R8G8B8;
					case 16:
						if (header.ddspf.dwRBitMask == 0x7c00 && header.ddspf.dwGBitMask == 0x03e0 &&
							header.ddspf.dwBBitMask == 0x001f && header.ddspf.dwABitMask == 0x8000) {
							return DXGI_FORMAT_B5G5R5A1_UNORM;
						}
						if (header.ddspf.dwRBitMask == 0xf800 && header.ddspf.dwGBitMask == 0x07e0 &&
							header.ddspf.dwBBitMask == 0x001f && header.ddspf.dwABitMask == 0x0000) {
							return DXGI_FORMAT_B5G6R5_UNORM;
						}

						if (header.ddspf.dwRBitMask == 0x0f00 && header.ddspf.dwGBitMask == 0x00f0 &&
							header.ddspf.dwBBitMask == 0x000f && header.ddspf.dwABitMask == 0xf000) {
							return DXGI_FORMAT_B4G4R4A4_UNORM;
						}
						break;
					default:
						break;
					}
				}
				else if (header.ddspf.dwFlags & DDPF_LUMINANCE) {
					if (8 == header.ddspf.dwRGBBitCount) {
						if (header.ddspf.dwRBitMask == 0x000000ff && header.ddspf.dwGBitMask == 0x00000000 &&
							header.ddspf.dwBBitMask == 0x00000000 && header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R8_UNORM;
						}
						if (header.ddspf.dwRBitMask == 0x000000ff && header.ddspf.dwGBitMask == 0x0000ff00 &&
							header.ddspf.dwBBitMask == 0x00000000 && header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R8G8_UNORM;
						}
					}
					if (16 == header.ddspf.dwRGBBitCount) {
						if (header.ddspf.dwRBitMask == 0x0000ffff && header.ddspf.dwGBitMask == 0x00000000 &&
							header.ddspf.dwBBitMask == 0x00000000 && header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R16_UNORM;
						}
						if (header.ddspf.dwRBitMask == 0x000000ff && header.ddspf.dwGBitMask == 0x0000ff00 &&
							header.ddspf.dwBBitMask == 0x00000000 && header.ddspf.dwABitMask == 0x00000000) {
							return DXGI_FORMAT_R8G8_UNORM;
						}
					}
				}
				else if (header.ddspf.dwFlags & DDPF_ALPHA) {
					if (8 == header.ddspf.dwRGBBitCount) {
						return DXGI_FORMAT_A8_UNORM;
					}
				}
				else if (header.ddspf.dwFlags & DDPF_FOURCC) {
					if (fourcc('D', 'X', 'T', '1') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC1_UNORM;
					}
					if (fourcc('D', 'X', 'T', '3') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC2_UNORM;
					}
					if (fourcc('D', 'X', 'T', '5') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC3_UNORM;
					}

					if (fourcc('D', 'X', 'T', '4') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC2_UNORM;
					}
					if (fourcc('D', 'X', 'T', '5') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC3_UNORM;
					}

					if (fourcc('A', 'T', 'I', '1') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC4_UNORM;
					}
					if (fourcc('B', 'C', '4', 'U') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC4_UNORM;
					}
					if (fourcc('B', 'C', '4', 'S') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC4_SNORM;
					}

					if (fourcc('A', 'T', 'I', '2') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC5_UNORM;
					}
					if (fourcc('B', 'C', '5', 'U') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC5_UNORM;
					}
					if (fourcc('B', 'C', '5', 'S') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_BC5_SNORM;
					}

					if (fourcc('R', 'G', 'B', 'G') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_R8G8_B8G8_UNORM;
					}
					if (fourcc('G', 'R', 'G', 'B') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_G8R8_G8B8_UNORM;
					}

					if (fourcc('Y', 'U', 'Y', '2') == header.ddspf.dwFourCC) {
						return DXGI_FORMAT_YUY2;
					}

					switch (header.ddspf.dwFourCC) {
					case 36:
						return DXGI_FORMAT_R16G16B16A16_UNORM;
					case 110:
						return DXGI_FORMAT_R16G16B16A16_SNORM;
					case 111:
						return DXGI_FORMAT_R16_FLOAT;
					case 112:
						return DXGI_FORMAT_R16G16_FLOAT;
					case 113:
						return DXGI_FORMAT_R16G16B16A16_FLOAT;
					case 114:
						return DXGI_FORMAT_R32_FLOAT;
					case 115:
						return DXGI_FORMAT_R32G32_FLOAT;
					case 116:
						return DXGI_FORMAT_R32G32B32A32_FLOAT;
					}
				}
				return DXGI_FORMAT_UNKNOWN;
			}
			return header10.dxgiFormat;
		}
		// returns tru if the texture is a cubemap, false otherwise
		constexpr bool is_cubemap() const
		{
			if (is_dx10())
			{
				return header10.miscFlag & DDS_RESOURCE_MISC_TEXTURECUBE;
			}
			return
				(header.dwCaps2 & DDSCAPS2_CUBEMAP) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEX) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEX) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEY) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEY) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEZ) &&
				(header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEZ)
				;
		}
		// returns true if the texture is one dimensional, false otherwise
		constexpr bool is_1d() const
		{
			if (!is_dx10())
				return false;
			return header10.resourceDimension == D3D10_RESOURCE_DIMENSION_TEXTURE1D;
		}
		// returns true if the texture is three dimensional, false otherwise
		constexpr bool is_3d() const
		{
			if (!is_dx10())
				return false;
			return
				(header.dwCaps2 & DDSCAPS2_VOLUME) &&
				header10.resourceDimension == D3D10_RESOURCE_DIMENSION_TEXTURE3D
				;
		}
		// returns the number of bits per element. Element refers to a block of pixels if the texture is block compressed, or a single pixel otherwise
		constexpr unsigned bits_per_element() const
		{
			switch (format())
			{
			case DXGI_FORMAT_R32G32B32A32_TYPELESS:
			case DXGI_FORMAT_R32G32B32A32_FLOAT:
			case DXGI_FORMAT_R32G32B32A32_UINT:
			case DXGI_FORMAT_R32G32B32A32_SINT:
				return 128;

			case DXGI_FORMAT_R32G32B32_TYPELESS:
			case DXGI_FORMAT_R32G32B32_FLOAT:
			case DXGI_FORMAT_R32G32B32_UINT:
			case DXGI_FORMAT_R32G32B32_SINT:
				return 96;

			case DXGI_FORMAT_R16G16B16A16_TYPELESS:
			case DXGI_FORMAT_R16G16B16A16_FLOAT:
			case DXGI_FORMAT_R16G16B16A16_UNORM:
			case DXGI_FORMAT_R16G16B16A16_UINT:
			case DXGI_FORMAT_R16G16B16A16_SNORM:
			case DXGI_FORMAT_R16G16B16A16_SINT:
			case DXGI_FORMAT_R32G32_TYPELESS:
			case DXGI_FORMAT_R32G32_FLOAT:
			case DXGI_FORMAT_R32G32_UINT:
			case DXGI_FORMAT_R32G32_SINT:
			case DXGI_FORMAT_R32G8X24_TYPELESS:
			case DXGI_FORMAT_D32_FLOAT_S8X24_UINT:
			case DXGI_FORMAT_R32_FLOAT_X8X24_TYPELESS:
			case DXGI_FORMAT_X32_TYPELESS_G8X24_UINT:
			case DXGI_FORMAT_Y416:
			case DXGI_FORMAT_Y210:
			case DXGI_FORMAT_Y216:
				return 64;

			case DXGI_FORMAT_R10G10B10A2_TYPELESS:
			case DXGI_FORMAT_R10G10B10A2_UNORM:
			case DXGI_FORMAT_R10G10B10A2_UINT:
			case DXGI_FORMAT_R11G11B10_FLOAT:
			case DXGI_FORMAT_R8G8B8A8_TYPELESS:
			case DXGI_FORMAT_R8G8B8A8_UNORM:
			case DXGI_FORMAT_R8G8B8A8_UNORM_SRGB:
			case DXGI_FORMAT_R8G8B8A8_UINT:
			case DXGI_FORMAT_R8G8B8A8_SNORM:
			case DXGI_FORMAT_R8G8B8A8_SINT:
			case DXGI_FORMAT_R16G16_TYPELESS:
			case DXGI_FORMAT_R16G16_FLOAT:
			case DXGI_FORMAT_R16G16_UNORM:
			case DXGI_FORMAT_R16G16_UINT:
			case DXGI_FORMAT_R16G16_SNORM:
			case DXGI_FORMAT_R16G16_SINT:
			case DXGI_FORMAT_R32_TYPELESS:
			case DXGI_FORMAT_D32_FLOAT:
			case DXGI_FORMAT_R32_FLOAT:
			case DXGI_FORMAT_R32_UINT:
			case DXGI_FORMAT_R32_SINT:
			case DXGI_FORMAT_R24G8_TYPELESS:
			case DXGI_FORMAT_D24_UNORM_S8_UINT:
			case DXGI_FORMAT_R24_UNORM_X8_TYPELESS:
			case DXGI_FORMAT_X24_TYPELESS_G8_UINT:
			case DXGI_FORMAT_R9G9B9E5_SHAREDEXP:
			case DXGI_FORMAT_R8G8_B8G8_UNORM:
			case DXGI_FORMAT_G8R8_G8B8_UNORM:
			case DXGI_FORMAT_B8G8R8A8_UNORM:
			case DXGI_FORMAT_B8G8R8X8_UNORM:
			case DXGI_FORMAT_R10G10B10_XR_BIAS_A2_UNORM:
			case DXGI_FORMAT_B8G8R8A8_TYPELESS:
			case DXGI_FORMAT_B8G8R8A8_UNORM_SRGB:
			case DXGI_FORMAT_B8G8R8X8_TYPELESS:
			case DXGI_FORMAT_B8G8R8X8_UNORM_SRGB:
			case DXGI_FORMAT_AYUV:
			case DXGI_FORMAT_Y410:
			case DXGI_FORMAT_YUY2:
			case D3DFMT_R8G8B8: // need to be expanded with alpha
				return 32;

			case DXGI_FORMAT_P010:
			case DXGI_FORMAT_P016:
				return 24;

			case DXGI_FORMAT_R8G8_TYPELESS:
			case DXGI_FORMAT_R8G8_UNORM:
			case DXGI_FORMAT_R8G8_UINT:
			case DXGI_FORMAT_R8G8_SNORM:
			case DXGI_FORMAT_R8G8_SINT:
			case DXGI_FORMAT_R16_TYPELESS:
			case DXGI_FORMAT_R16_FLOAT:
			case DXGI_FORMAT_D16_UNORM:
			case DXGI_FORMAT_R16_UNORM:
			case DXGI_FORMAT_R16_UINT:
			case DXGI_FORMAT_R16_SNORM:
			case DXGI_FORMAT_R16_SINT:
			case DXGI_FORMAT_B5G6R5_UNORM:
			case DXGI_FORMAT_B5G5R5A1_UNORM:
			case DXGI_FORMAT_A8P8:
			case DXGI_FORMAT_B4G4R4A4_UNORM:
				return 16;

			case DXGI_FORMAT_NV12:
			case DXGI_FORMAT_NV11:
				return 12;

			case DXGI_FORMAT_R8_TYPELESS:
			case DXGI_FORMAT_R8_UNORM:
			case DXGI_FORMAT_R8_UINT:
			case DXGI_FORMAT_R8_SNORM:
			case DXGI_FORMAT_R8_SINT:
			case DXGI_FORMAT_A8_UNORM:
			case DXGI_FORMAT_AI44:
			case DXGI_FORMAT_IA44:
			case DXGI_FORMAT_P8:
				return 8;

			case DXGI_FORMAT_R1_UNORM:
				return 1;

			case DXGI_FORMAT_BC1_TYPELESS:
			case DXGI_FORMAT_BC1_UNORM:
			case DXGI_FORMAT_BC1_UNORM_SRGB:
			case DXGI_FORMAT_BC4_TYPELESS:
			case DXGI_FORMAT_BC4_UNORM:
			case DXGI_FORMAT_BC4_SNORM:
				return 64;

			case DXGI_FORMAT_BC2_TYPELESS:
			case DXGI_FORMAT_BC2_UNORM:
			case DXGI_FORMAT_BC2_UNORM_SRGB:
			case DXGI_FORMAT_BC3_TYPELESS:
			case DXGI_FORMAT_BC3_UNORM:
			case DXGI_FORMAT_BC3_UNORM_SRGB:
			case DXGI_FORMAT_BC5_TYPELESS:
			case DXGI_FORMAT_BC5_UNORM:
			case DXGI_FORMAT_BC5_SNORM:
			case DXGI_FORMAT_BC6H_TYPELESS:
			case DXGI_FORMAT_BC6H_UF16:
			case DXGI_FORMAT_BC6H_SF16:
			case DXGI_FORMAT_BC7_TYPELESS:
			case DXGI_FORMAT_BC7_UNORM:
			case DXGI_FORMAT_BC7_UNORM_SRGB:
				return 128;
			default:
				return 0;
			}
		}
		// returns 1 for non-block compressed formats, or the block size if it's compressed
		constexpr unsigned block_size() const
		{
			switch (format())
			{
			case DXGI_FORMAT_BC1_TYPELESS:
			case DXGI_FORMAT_BC1_UNORM:
			case DXGI_FORMAT_BC1_UNORM_SRGB:
			case DXGI_FORMAT_BC4_TYPELESS:
			case DXGI_FORMAT_BC4_UNORM:
			case DXGI_FORMAT_BC4_SNORM:
			case DXGI_FORMAT_BC2_TYPELESS:
			case DXGI_FORMAT_BC2_UNORM:
			case DXGI_FORMAT_BC2_UNORM_SRGB:
			case DXGI_FORMAT_BC3_TYPELESS:
			case DXGI_FORMAT_BC3_UNORM:
			case DXGI_FORMAT_BC3_UNORM_SRGB:
			case DXGI_FORMAT_BC5_TYPELESS:
			case DXGI_FORMAT_BC5_UNORM:
			case DXGI_FORMAT_BC5_SNORM:
			case DXGI_FORMAT_BC6H_TYPELESS:
			case DXGI_FORMAT_BC6H_UF16:
			case DXGI_FORMAT_BC6H_SF16:
			case DXGI_FORMAT_BC7_TYPELESS:
			case DXGI_FORMAT_BC7_UNORM:
			case DXGI_FORMAT_BC7_UNORM_SRGB:
				return 4;
			default:
				return 1;
			}
		}
		// returns the size of a specific mipmap in bytes
		constexpr unsigned long long mip_size(unsigned mip) const
		{
			const unsigned long long bpe = bits_per_element();
			const unsigned long long blocksize = block_size();
			unsigned long long num_elements_x = width();
			unsigned long long num_elements_y = height();
			unsigned long long num_elements_z = depth();
			num_elements_x >>= mip;
			num_elements_y >>= mip;
			num_elements_z >>= mip;
			num_elements_x = num_elements_x < 1 ? 1 : num_elements_x;
			num_elements_y = num_elements_y < 1 ? 1 : num_elements_y;
			num_elements_z = num_elements_z < 1 ? 1 : num_elements_z;
			const unsigned long long num_blocks_x = (num_elements_x + blocksize - 1) / blocksize;
			const unsigned long long num_blocks_y = (num_elements_y + blocksize - 1) / blocksize;
			return num_blocks_x * num_blocks_y * num_elements_z * bpe / 8ull;
		}
		// returns the size of one slice in bytes
		constexpr unsigned long long slice_size() const
		{
			const unsigned mips = mip_levels();
			unsigned long long size = 0;
			for (unsigned mip = 0; mip < mips; ++mip)
			{
				size += mip_size(mip);
			}
			return size;
		}
		// returns the size of the whole pixel data in bytes, including all slices and mipmaps
		constexpr unsigned long long data_size() const
		{
			return array_size() * slice_size();
		}
		// returns the offset of the pixel data relative to the beginning of the file, in bytes
		constexpr unsigned long long data_offset() const
		{
			unsigned long long offset = sizeof(Header);
			if (!is_dx10())
				offset -= sizeof(Header::header10);
			return offset;
		}
		// returns the offset of a specific slice relative to the beginning of the file, in bytes
		constexpr unsigned long long slice_offset(unsigned slice) const
		{
			return data_offset() + slice_size() * slice;
		}
		// returns the offset of a specific mipmap of a specific slice relative to the beginning of the file, in bytes
		constexpr unsigned long long mip_offset(unsigned mip, unsigned slice = 0) const
		{
			unsigned long long offset = slice_offset(slice);
			for (unsigned i = 0; i < mip; ++i)
			{
				offset += mip_size(i);
			}
			return offset;
		}
		// returns the size of one row in a specific mip level in bytes
		constexpr unsigned row_pitch(unsigned mip) const
		{
			const unsigned long long bpe = bits_per_element();
			const unsigned long long blocksize = block_size();
			unsigned long long num_elements_x = width();
			num_elements_x >>= mip;
			num_elements_x = num_elements_x < 1 ? 1 : num_elements_x;
			const unsigned long long num_blocks_x = (num_elements_x + blocksize - 1) / blocksize;
			return unsigned(num_blocks_x * bpe / 8);
		}
		// returns the size of a specific slice at a specific mip level in bytes
		constexpr unsigned slice_pitch(unsigned mip) const
		{
			const unsigned long long bpe = bits_per_element();
			const unsigned long long blocksize = block_size();
			unsigned long long num_elements_x = width();
			unsigned long long num_elements_y = height();
			num_elements_x >>= mip;
			num_elements_y >>= mip;
			num_elements_x = num_elements_x < 1 ? 1 : num_elements_x;
			num_elements_y = num_elements_y < 1 ? 1 : num_elements_y;
			const unsigned long long num_blocks_x = (num_elements_x + blocksize - 1) / blocksize;
			const unsigned long long num_blocks_y = (num_elements_y + blocksize - 1) / blocksize;
			return unsigned(num_blocks_x * num_blocks_y * bpe / 8ull);
		}
	};

	// Read DDS header from memory
	//	data:	pointer to memory, this should be the very start of the DDS file (fourcc bytes included)
	//	size:	size of memory that data points to. It should be sizeof(dds::Header) or larger
	//
	//	returns dds::Header, which you can use to determine relative memory offsets and sizes required to reference certain parts of the texture
	inline Header read_header(
		const void* data,
		unsigned long long size
	)
	{
		Header h = {};
		if (data == nullptr)
			return h; // invalid pointer
		if (size < sizeof(Header::magic) + sizeof(Header::header))
			return h; // magic and header is a must have
		h.magic = *(const unsigned*)data;
		if (h.magic != fourcc('D', 'D', 'S', ' '))
			return h; // fourcc is invalid

		h.header = *(const DDS_HEADER*)((const char*)data + sizeof(h.magic));
		if (size >= sizeof(Header) && h.is_dx10())
		{
			h.header10 = (*(const Header*)data).header10;
		}

		return h;
	}

	// Write the DDS header into memory.
	//	dst:		destination file in memory, must be at least of sizeof(dds::Header)
	//	format:		data format of texture data that will be placed after header
	//	width:		width of top mip level
	//	height:		height of top mip level (you can set this to 0 to indicate 1D texture)
	//	mip_levels:	number of mip levels in the file
	//	array_size:	number of slices in the file. For cubemaps, there is one slice for every face. For 3D texture, there is always only 1 slice.
	//	is_cubemap:	whether the texture is a cubemap. If it is a cubemap, it must have at least array_size = 6
	//	depth:		depth of 3D texture (you can set this to 0 to indicate that the texture is not 3D)
	inline void write_header(
		void* dst,
		DXGI_FORMAT format,
		unsigned int width,
		unsigned int height,
		unsigned int mip_levels = 1,
		unsigned int array_size = 1,
		bool is_cubemap = false,
		unsigned int depth = 0
	)
	{
		Header h = {};
		h.magic = fourcc('D', 'D', 'S', ' ');
		h.header.dwSize = sizeof(DDS_HEADER);
		h.header.dwFlags =
			DDSD_CAPS |
			DDSD_WIDTH |
			DDSD_HEIGHT |
			DDSD_PIXELFORMAT |
			DDSD_MIPMAPCOUNT
			;
		h.header.dwWidth = width;
		h.header.dwHeight = height;
		h.header.dwDepth = depth;
		h.header.dwMipMapCount = mip_levels;
		h.header.ddspf.dwSize = sizeof(DDS_PIXELFORMAT);
		h.header.ddspf.dwFlags = DDPF_FOURCC;
		h.header.ddspf.dwFourCC = fourcc('D', 'X', '1', '0');
		h.header.dwCaps = DDSCAPS_TEXTURE;

		h.header10.dxgiFormat = format;
		h.header10.resourceDimension = D3D10_RESOURCE_DIMENSION_TEXTURE2D;
		h.header10.miscFlags2 = DDS_ALPHA_MODE_UNKNOWN;

		if (is_cubemap)
		{
			h.header10.arraySize = array_size / 6;
			h.header.dwCaps |= DDSCAPS_COMPLEX;
			h.header.dwCaps2 =
				DDSCAPS2_CUBEMAP |
				DDSCAPS2_CUBEMAP_POSITIVEX |
				DDSCAPS2_CUBEMAP_NEGATIVEX |
				DDSCAPS2_CUBEMAP_POSITIVEY |
				DDSCAPS2_CUBEMAP_NEGATIVEY |
				DDSCAPS2_CUBEMAP_POSITIVEZ |
				DDSCAPS2_CUBEMAP_NEGATIVEZ
				;
			h.header10.miscFlag = DDS_RESOURCE_MISC_TEXTURECUBE;
		}
		else if (depth > 0)
		{
			h.header10.arraySize = 1;
			h.header10.resourceDimension = D3D10_RESOURCE_DIMENSION_TEXTURE3D;
			h.header.dwCaps2 = DDSCAPS2_VOLUME;
		}
		else
		{
			h.header10.arraySize = array_size;
		}

		if (height == 0)
		{
			h.header10.resourceDimension = D3D10_RESOURCE_DIMENSION_TEXTURE1D;
			h.header.dwHeight = 1;
		}
		if (mip_levels > 1)
		{
			h.header.dwCaps |= DDSCAPS_COMPLEX;
		}

		*(Header*)dst = h;
	}
}

#endif // DDS_H

//Copyright(c) 2024 Turánszki János
//
//Permission is hereby granted, free of charge, to any person obtaining a copy
//of this software and associated documentation files(the "Software"), to deal
//in the Software without restriction, including without limitation the rights
//to use, copy, modify, merge, publish, distribute, sublicense, and /or sell
//copies of the Software, and to permit persons to whom the Software is
//furnished to do so, subject to the following conditions :
//
//The above copyright notice and this permission notice shall be included in
//all copies or substantial portions of the Software.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//THE SOFTWARE.