Function decode_header

Source/ThirdParty/ddspp/ddspp.h:731–995

	}

	inline Result decode_header(const unsigned char* sourceData, Descriptor& desc)
	{
		unsigned int magic = *reinterpret_cast<const unsigned int*>(sourceData); // First 4 bytes are the magic DDS number

		if (magic != DDS_MAGIC)
		{
			return ddspp::Error;
		}

		const Header header = *reinterpret_cast<const Header*>(sourceData + sizeof(DDS_MAGIC));
		const PixelFormat& ddspf = header.ddspf;
		bool dxt10Extension = is_dxt10(header);
		const HeaderDXT10 dxt10Header = *reinterpret_cast<const HeaderDXT10*>(sourceData + sizeof(DDS_MAGIC) + sizeof(Header));

		// Read basic data from the header
		desc.width = header.width > 0 ? header.width : 1;
		desc.height = header.height > 0 ? header.height : 1;
		desc.depth = header.depth > 0 ? header.depth : 1;
		desc.numMips = header.mipMapCount > 0 ? header.mipMapCount : 1;

		// Set some sensible defaults
		desc.arraySize = 1;
		desc.srgb = false;
		desc.type = Texture2D;
		desc.format = UNKNOWN;

		if (dxt10Extension)
		{
			desc.format = dxt10Header.dxgiFormat;

			desc.arraySize = dxt10Header.arraySize;

			switch(dxt10Header.resourceDimension)
			{
				case DXGI_Texture1D:
					desc.depth = 1;
					desc.type = Texture1D;
					break;
				case DXGI_Texture2D:
					desc.depth = 1;

					if(dxt10Header.miscFlag & DXGI_MISC_FLAG_CUBEMAP)
					{
						desc.type = Cubemap;
					}
					else
					{
						desc.type = Texture2D;
					}

					break;
				case DXGI_Texture3D:
					desc.type = Texture3D;
					desc.arraySize = 1; // There are no 3D texture arrays
					break;
				default:
					break;
			}