C＃编码位图到DDS（DXT1，DXT3，DXT5）

Question

我的应用程序中有一个简单的位图。我需要将其保存为DDS（直接绘制的表面）不像带有.DDS扩展名的简单映像，而需要编码像素数据并将其写入.bin文件。 因此，关于MSDN文档（ dds ， dds_header结构 a href =“ https://learn.microsoft.com/en-us/windows/windows/win32/direct3ddds/dds-pixelformat” rel =“ nofollow noreferrer”> dds_pixelformat结构像素格式和编码像素数据（主表面，然后是其他表面 - 不是吗？）。好的，所以我要做的事情：

private const uint DDS_SIGNATURE = 0x20534444;
private const uint DDPF_FOURCC = 0x00000004;

private const int DDSD_CAPS = 0x00000001;
private const int DDSD_HEIGHT = 0x00000002;
private const int DDSD_WIDTH = 0x00000004;
private const int DDSD_PITCH = 0x00000008;
private const int DDSD_PIXELFORMAT = 0x00001000;
private const int DDSD_MIPMAPCOUNT = 0x00020000;
private const int DDSD_LINEARSIZE = 0x00080000;

private const int DDSCAPS_COMPLEX = 0x00000008;
private const int DDSCAPS_TEXTURE = 0x00001000;
private const int DDSCAPS_MIPMAP = 0x00400000;

private const uint FOURCC_DXT1 = 0x31545844;
private const uint FOURCC_DXT2 = 0x32545844;
private const uint FOURCC_DXT3 = 0x33545844;
private const uint FOURCC_DXT4 = 0x34545844;
private const uint FOURCC_DXT5 = 0x35545844;

private static byte[] GetDDSImageBytes(Bitmap image, EDDSCompressionMode format)
{
    if (image is null ||
        (format != EDDSCompressionMode.DXT1
            && format != EDDSCompressionMode.DXT2
            && format != EDDSCompressionMode.DXT3
            && format != EDDSCompressionMode.DXT4
            && format != EDDSCompressionMode.DXT5))
    {
        return null;
    }
    
    var capsMipMap = 0;
    var capsComplex = 0;
    var mipMapsCount = 0;
    var mipMaps = new List<Bitmap>();

    if (format == EDDSCompressionMode.DXT2 || format == EDDSCompressionMode.DXT3) // let's imagine I need MipMaps only for these formats
    {
        capsMipMap = DDSCAPS_MIPMAP;
        capsComplex = DDSCAPS_COMPLEX;
        mipMapsCount = DDSD_MIPMAPCOUNT;

        while (true)
        {
            var width = Math.Max(1, image.Width >> 1);
            var height = Math.Max(1, image.Height >> 1);

            if (width == 1 && height == 1)
            {
                break;
            }

            mipMaps.Add(CreateMipMap(image, width, height));
        }
    }

    var header = new DDSHeader
    {
        Size = 124,
        Flags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT | mipMapsCount | DDSD_LINEARSIZE,
        Height = image.Height,
        Width = image.Width,
        PitchOrLinearSize = image.Width * image.Height, // I'm not sure it's a proper calculation, please correct me if I'm wrong
        Depth = 0,
        MipMapCount = mipMaps.Count,
        Caps = DDSCAPS_TEXTURE | capsMipMap | capsComplex,
        Caps2 = 0,
        Caps3 = 0,
        Caps4 = 0,
        Reserved2 = 0,
    };

    var pixelFormat = new DDSPixelFormat
    {
        Size = 32,
        Flags = DDPF_FOURCC,
        FourCC = format switch
        {
            EDDSCompressionMode.DXT1 => FOURCC_DXT1,
            EDDSCompressionMode.DXT2 => FOURCC_DXT2,
            EDDSCompressionMode.DXT3 => FOURCC_DXT3,
            EDDSCompressionMode.DXT4 => FOURCC_DXT4,
            EDDSCompressionMode.DXT5 or _ => FOURCC_DXT5,
        },
        RGBBitCount = 0,
        RBitMask = 0,
        GBitMask = 0,
        BBitMask = 0,
        ABitMask = 0
    };

    var data = new List<byte>(CreateHeaderAndFormat(header, pixelFormat));

    //TODO: Implement writing binary data

    return data.ToArray();
}

private static Bitmap CreateMipMap(Bitmap image, int width, int height)
{
    var bmp = new Bitmap(width, height);

    using var blitter = Graphics.FromImage(bmp);

    blitter.InterpolationMode = InterpolationMode.HighQualityBicubic;

    using var wrapMode = new ImageAttributes();

    wrapMode.SetWrapMode(WrapMode.TileFlipXY);
    blitter.DrawImage(image, new Rectangle(0, 0, width, height), 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);

    return bmp;
}

private static byte[] CreateHeaderAndFormat(DDSHeader header, DDSPixelFormat pixelFormat)
{
    var data = new List<byte>(BitConverter.GetBytes(DDS_SIGNATURE));

    data.AddRange(BitConverter.GetBytes(header.Size));
    data.AddRange(BitConverter.GetBytes(header.Flags));
    data.AddRange(BitConverter.GetBytes(header.Height));
    data.AddRange(BitConverter.GetBytes(header.Width));
    data.AddRange(BitConverter.GetBytes(header.PitchOrLinearSize));
    data.AddRange(BitConverter.GetBytes(header.Depth));
    data.AddRange(BitConverter.GetBytes(header.MipMapCount));

    for (var i = 0; i < 11; i++)
    {
        data.AddRange(BitConverter.GetBytes((uint)0));
    }

    data.AddRange(BitConverter.GetBytes(pixelFormat.Size));
    data.AddRange(BitConverter.GetBytes(pixelFormat.Flags));
    data.AddRange(BitConverter.GetBytes(pixelFormat.FourCC));
    data.AddRange(BitConverter.GetBytes(pixelFormat.RGBBitCount));
    data.AddRange(BitConverter.GetBytes(pixelFormat.RBitMask));
    data.AddRange(BitConverter.GetBytes(pixelFormat.GBitMask));
    data.AddRange(BitConverter.GetBytes(pixelFormat.BBitMask));
    data.AddRange(BitConverter.GetBytes(pixelFormat.ABitMask));

    data.AddRange(BitConverter.GetBytes(header.Caps));
    data.AddRange(BitConverter.GetBytes(header.Caps2));
    data.AddRange(BitConverter.GetBytes(header.Caps3));
    data.AddRange(BitConverter.GetBytes(header.Caps4));
    data.AddRange(BitConverter.GetBytes(header.Reserved2));

    return data.ToArray();
}

一些其他信息：

public enum EDDSCompressionMode
{
    Unknown = 0,
    DXT1 = 1,
    DXT2 = 2,
    DXT3 = 3,
    DXT4 = 4,
    DXT5 = 5
}

public struct DDSHeader
{
    public int Size;
    public int Flags;
    public int Height;
    public int Width;
    public int PitchOrLinearSize;
    public int Depth;
    public int MipMapCount;
    public int[] Reserved1;
    public int Caps;
    public int Caps2;
    public int Caps3;
    public int Caps4;
    public int Reserved2;
}

public struct DDSPixelFormat
{
    public uint Size;
    public uint Flags;
    public uint FourCC;
    public uint RGBBitCount;
    public uint RBitMask;
    public uint GBitMask;
    public uint BBitMask;
    public uint ABitMask;
}

问题是我不是DDS图像的专家，我不知道如何从我的位图创建适当的二进制数据。寻找一些外部库，但似乎所有这些库都指示保存.DDS文件，而不是返回像素的编码二进制数据。

我发现的另一件事是实现从文件中读取数据（并且它正常工作！）：<​​a href =“ https://github.com/xackery/eqzip/eqzip/blob/blob/master/master/ddsimage.cs” rel =' nofollow noreferrer“> eqzip 。 似乎我只能从上面的链接中重写（IE Invert）DXT1，DXT3和DXT5方法以获取编码的数据，但是再次 - 我不知道该如何正确执行。

有什么建议，想法，建议，技巧等吗？