Question

我正在尝试使用Visual C ++ .NET 2008中的OpenGL创建一个带纹理的Cube。经过一些去角质，使用GLU后，我发现必须使用gluBuild2DMipmaps。

问题是，我使用System :: Drawing :: Bitmap.FromFile（）读取位图

现在，如何将此托管的Bitmap对象传递给gluBuild2DMipmaps，它接受const void *参数???

我已经使用这些代码尝试了LockBits：

BYTE * data;
/*ambil raw data*/
System::Drawing::Rectangle rect =  System::Drawing::Rectangle(0,0,b->Width,b->Height);
System::Drawing::Imaging::BitmapData ^  bitmapData;
    b->LockBits(
        rect,
        System::Drawing::Imaging::ImageLockMode::ReadWrite, 
        b->PixelFormat ,bitmapData);

    ::memcpy(data,bitmapData->Scan0.ToPointer(),b->Width * b->Height);
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, width, height,
                   GL_RGB, GL_UNSIGNED_BYTE, data);

使用一个24bpp的BMP文件，它卡在行锁定位上，并显示消息System.ArgumentException：附加信息：参数无效。

我做错了什么????

我刚刚找到了正确的解决方案。这是因为有几个问题：

我使用了错误的重载功能。请参阅我如何调用lockBits
我没有初始化指针dataBitmap。
而且，由于GLuint * texture;是托管指针，我必须使用pin_pointer将其转换为非托管指针。

谢谢，这是正确的方法：

void CBox::LoadTextureRaw(String ^ filename, int wrap)
{
    //GLuint texture;

    System::Drawing::Bitmap ^ bitmap = gcnew Bitmap(filename);  
    int h = bitmap->Height;
    int w = bitmap->Width;
    int s = w * h;
    dataTexture = new BYTE[s * 3];

    System::Drawing::Rectangle rect =  System::Drawing::Rectangle(0,0,bitmap->Width,bitmap->Height);
    System::Drawing::Imaging::BitmapData ^  bitmapData = 
        bitmap->LockBits(rect,System::Drawing::Imaging::ImageLockMode::ReadWrite , System::Drawing::Imaging::PixelFormat::Format24bppRgb);

    ::memcpy(dataTexture,bitmapData->Scan0.ToPointer(),s);


    bitmap->UnlockBits(bitmapData); 
    pin_ptr<GLuint*> pt = &texture;//pin managed pointer, to be unmanaged... asyeeeem
    **pt = gluBuild2DMipmaps(GL_TEXTURE_2D, 3, w, h,GL_RGB, GL_UNSIGNED_BYTE, dataTexture);     
}

Answer 1

我使用以下代码复制 Bitmap 数据：

Image image = null;
Bitmap iBitmap = new Bitmap(fs);
BitmapData iBitmapData;
GCHandle hImageData;

if ((iBitmap.Flags & (int)ImageFlags.ColorSpaceRgb) != 0) {
    switch (iBitmap.PixelFormat) {
        case PixelFormat.Format1bppIndexed:
        case PixelFormat.Format4bppIndexed:
        case PixelFormat.Format8bppIndexed:
            // Allocate image raster
            image = new RasterImage<ColorBGR8>(iBitmap.Width, iBitmap.Height);
            break;
        case PixelFormat.Format16bppRgb565:
            // Allocate image raster
            image = new RasterImage<ColorBGR16>(iBitmap.Width, iBitmap.Height);
            break;
        case PixelFormat.Format24bppRgb:
            // Allocate image raster
            image = new RasterImage<ColorBGR24>(iBitmap.Width, iBitmap.Height);
            break;
        case PixelFormat.Format32bppRgb:
            // Allocate image raster
            image = new RasterImage<ColorBGR32>(iBitmap.Width, iBitmap.Height);
            break;
        case PixelFormat.Format32bppArgb:
            // Allocate image raster
            image = new RasterImage<ColorABGR32>(iBitmap.Width, iBitmap.Height);
            break;
        default:
            throw new Exception("Image RGB pixel format not supported");
    }
} else if ((iBitmap.Flags & (int)ImageFlags.ColorSpaceGray) != 0) {
    switch (iBitmap.PixelFormat) {
        case PixelFormat.Format1bppIndexed:
        case PixelFormat.Format4bppIndexed:
        case PixelFormat.Format8bppIndexed:
            // Allocate image raster
            image = new RasterImage<ColorY8>(iBitmap.Width, iBitmap.Height);
            break;
        default:
            throw new Exception("Image GRAY pixel format not supported");
    }

    if (RenderContext.Caps.TextureSwizzle == false) {
        throw new Exception("unable to load GRAY pixel format image (ARB_texture_swizzle extension not supported)");
    }
} else if ((iBitmap.Flags & (int)ImageFlags.ColorSpaceYcbcr) != 0) {
    throw new Exception("Image YCbCr pixel format not supported");
} else if ((iBitmap.Flags & (int)ImageFlags.ColorSpaceYcck) != 0) {
    throw new Exception("Image YCCK pixel format not supported");
} else if ((iBitmap.Flags & (int)ImageFlags.ColorSpaceCmyk) != 0) {
    throw new Exception("Image CMYK pixel format not supported");
} else
    throw new Exception("Image pixel format not supported");

// Obtain source and destination data pointers
iBitmapData = iBitmap.LockBits(new Rectangle(0, 0, iBitmap.Width, iBitmap.Height), ImageLockMode.ReadOnly, iBitmap.PixelFormat);
hImageData = GCHandle.Alloc(image.GetPixelData(), GCHandleType.Pinned);

    // Alternative without using custom Image class:
    //T[,] buffer = new ColorRGB24[iBitmap.Width, iBitmap.Height];
    //hImageData = GCHandle.Alloc(buffer, GCHandleType.Pinned);

// Copy Bitmap data to Image
memcpy(hImageData.AddrOfPinnedObject(), iBitmapData.Scan0, iBitmapData.Stride*iBitmapData.Height);

hImageData.Free();
iBitmap.UnlockBits(iBitmapData);

return (image);

您可以注意到我必须通过P / Invoke memcpy 例程来复制锁定的内存。

Image 类是我的项目中定义的类，它将方法 GetPixelData（）定义为返回 T [，]的简单例程，其中 T 是如下结构

[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct ColorRGB24 : IColorRGB<byte>
{
    public byte r;
    public byte g;
    public byte b;
}

阅读以下引用：

Using System.Drawing.Imaging.PixelFormat values, such as Indexed and Gdi, will throw an System.ArgumentException

因此，请确保没有索引或 Gdi 像素格式值。

如何正确地将托管位图转换为非托管位图？

1 个答案: