Question

我正在尝试在C＃中使用opengl。我有以下代码失败，错误2000 ERROR_INVALID_PIXEL_FORMAT
第一个定义：

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
public static extern IntPtr GetDC(IntPtr hWnd);

[StructLayout(LayoutKind.Sequential)]
    public struct PIXELFORMATDESCRIPTOR
    {
        public void Init()
        {
            nSize = (ushort) Marshal.SizeOf(typeof (PIXELFORMATDESCRIPTOR));
            nVersion = 1;
            dwFlags = PFD_FLAGS.PFD_DRAW_TO_WINDOW | PFD_FLAGS.PFD_SUPPORT_OPENGL | PFD_FLAGS.PFD_DOUBLEBUFFER | PFD_FLAGS.PFD_SUPPORT_COMPOSITION;
            iPixelType = PFD_PIXEL_TYPE.PFD_TYPE_RGBA;
            cColorBits = 24;
            cRedBits = cRedShift = cGreenBits = cGreenShift = cBlueBits = cBlueShift = 0;
            cAlphaBits = cAlphaShift = 0;
            cAccumBits = cAccumRedBits = cAccumGreenBits = cAccumBlueBits = cAccumAlphaBits = 0;
            cDepthBits = 32;
            cStencilBits = cAuxBuffers = 0;
            iLayerType = PFD_LAYER_TYPES.PFD_MAIN_PLANE;
            bReserved = 0;
            dwLayerMask = dwVisibleMask = dwDamageMask = 0;
        }
        ushort nSize;
        ushort nVersion;
        PFD_FLAGS dwFlags;
        PFD_PIXEL_TYPE iPixelType;
        byte cColorBits;
        byte cRedBits;
        byte cRedShift;
        byte cGreenBits;
        byte cGreenShift;
        byte cBlueBits;
        byte cBlueShift;
        byte cAlphaBits;
        byte cAlphaShift;
        byte cAccumBits;
        byte cAccumRedBits;
        byte cAccumGreenBits;
        byte cAccumBlueBits;
        byte cAccumAlphaBits;
        byte cDepthBits;
        byte cStencilBits;
        byte cAuxBuffers;
        PFD_LAYER_TYPES iLayerType;
        byte bReserved;
        uint dwLayerMask;
        uint dwVisibleMask;
        uint dwDamageMask;
    }

    [Flags]
    public enum PFD_FLAGS : uint 
    {
        PFD_DOUBLEBUFFER = 0x00000001,
        PFD_STEREO = 0x00000002,
        PFD_DRAW_TO_WINDOW = 0x00000004,
        PFD_DRAW_TO_BITMAP = 0x00000008,
        PFD_SUPPORT_GDI = 0x00000010,
        PFD_SUPPORT_OPENGL = 0x00000020,
        PFD_GENERIC_FORMAT = 0x00000040,
        PFD_NEED_PALETTE = 0x00000080,
        PFD_NEED_SYSTEM_PALETTE = 0x00000100,
        PFD_SWAP_EXCHANGE = 0x00000200,
        PFD_SWAP_COPY = 0x00000400,
        PFD_SWAP_LAYER_BUFFERS = 0x00000800,
        PFD_GENERIC_ACCELERATED = 0x00001000,
        PFD_SUPPORT_DIRECTDRAW = 0x00002000,
        PFD_DIRECT3D_ACCELERATED = 0x00004000,
        PFD_SUPPORT_COMPOSITION = 0x00008000,
        PFD_DEPTH_DONTCARE = 0x20000000,
        PFD_DOUBLEBUFFER_DONTCARE = 0x40000000,
        PFD_STEREO_DONTCARE = 0x80000000
    }

    public enum PFD_LAYER_TYPES : byte
    {
        PFD_MAIN_PLANE = 0,
        PFD_OVERLAY_PLANE = 1,
        PFD_UNDERLAY_PLANE = 255
    }

    public enum PFD_PIXEL_TYPE : byte
    {
        PFD_TYPE_RGBA = 0,
        PFD_TYPE_COLORINDEX = 1
    }

    [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
    public static extern int ChoosePixelFormat(IntPtr hdc, [In] ref PIXELFORMATDESCRIPTOR ppfd);

    [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
    public static extern bool SetPixelFormat(IntPtr hdc, int iPixelFormat, ref PIXELFORMATDESCRIPTOR ppfd);
[DllImport("opengl32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
    public static extern IntPtr wglCreateContext(IntPtr hDC);

现在代码失败了：

IntPtr dc = Win.GetDC(hwnd);

var pixelformatdescriptor = new GL.PIXELFORMATDESCRIPTOR();
pixelformatdescriptor.Init();

var pixelFormat = GL.ChoosePixelFormat(dc, ref pixelformatdescriptor);
if(!GL.SetPixelFormat(dc, pixelFormat, ref pixelformatdescriptor))
    throw new Win32Exception(Marshal.GetLastWin32Error());
IntPtr hglrc;
if((hglrc = GL.wglCreateContext(dc)) == IntPtr.Zero)
    throw new Win32Exception(Marshal.GetLastWin32Error()); //<----- here I have exception

托管C ++中的相同代码正在运行

HDC dc = GetDC(hWnd);

PIXELFORMATDESCRIPTOR pf;
pf.nSize = sizeof(PIXELFORMATDESCRIPTOR);
pf.nVersion = 1;
pf.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER | PFD_SUPPORT_COMPOSITION;
pf.cColorBits = 24;
pf.cRedBits = pf.cRedShift = pf.cGreenBits = pf.cGreenShift = pf.cBlueBits = pf.cBlueShift = 0;
pf.cAlphaBits = pf.cAlphaShift = 0;
pf.cAccumBits = pf.cAccumRedBits = pf.cAccumGreenBits = pf.cAccumBlueBits = pf.cAccumAlphaBits = 0;
pf.cDepthBits = 32;
pf.cStencilBits = pf.cAuxBuffers = 0;
pf.iLayerType = PFD_MAIN_PLANE;
pf.bReserved = 0;
pf.dwLayerMask = pf.dwVisibleMask = pf.dwDamageMask = 0;

int ipf = ChoosePixelFormat(dc, &pf);
SetPixelFormat(dc, ipf, &pf);

HGLRC hglrc = wglCreateContext(dc);

我已经在64位64位ATI显卡和32位Windows驱动器上使用Nvidia进行了尝试，两种情况都有相同的结果。
另外我想提一下，我不想使用任何已编写的框架。

谁能告诉我C＃代码中导致异常的错误在哪里？

Answer 1

找到解决方案。
问题非常奇怪丑陋而且很难找到。在互联网上的Somwhere我发现当你在编译c ++应用程序时链接opengl32.lib时，它必须放在gdi32.lib之前。原因是（假设）opengl32.dll覆盖了ChoosePixelFormat和SetPixelFormat函数（可能更多:-)。正如我在c ++版本中发现的那样，不小心是这种情况嘿，但是如何在C＃中做到这一点经过几天的搜索，我发现在tao framework中他们使用kernel32.dll LoadLibrary（）函数解决了它并在调用SetPixelFormat之前加载了opengl32.dll

public static bool SetPixelFormat(IntPtr deviceContext, int pixelFormat, ref PIXELFORMATDESCRIPTOR pixelFormatDescriptor) {
        Kernel.LoadLibrary("opengl32.dll");
        return _SetPixelFormat(deviceContext, pixelFormat, ref pixelFormatDescriptor);
    }

所以我们知道必须在gdi32.dll之前加载opengl32.dll，还有其他方法可以做到这一点。之后我想我们可以从opengl32.dll调用一些NOP函数来加载它。例如：

[DllImport("opengl32.dll", EntryPoint = "glGetString", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
static extern IntPtr _glGetString(StringName name);
public static string glGetString(StringName name)
{
    return Marshal.PtrToStringAnsi(_glGetString(name));
}
public enum StringName : uint
{
    GL_VENDOR = 0x1F00,
    GL_RENDERER = 0x1F01,
    GL_VERSION = 0x1F02,
    GL_EXTENSIONS = 0x1F03
}

并且在应用程序启动时，在调用gdi32.dll之前我使用它：

GL.glGetString(0);

两种方式都解决了这个问题。

Answer 2

我现在无法测试，但我的第一个怀疑是结构包装。您是否尝试在StructLayout属性中将打包设置为1？例如：

[StructLayout(LayoutKind.Sequential, Pack=1)]

干杯，布赖恩

Answer 3

两次调用wglCreateContext也有帮助。

if (SetPixelFormat(DC, iPixelformat, ref pfd) == false)
    throw new Win32Exception(Marshal.GetLastWin32Error());

RC = wglCreateContext(DC);
if (RC == HGLRC.Zero)
{   
    if (SetPixelFormat(DC, iPixelformat, ref pfd) == false)
        throw new Win32Exception(Marshal.GetLastWin32Error());
    RC = wglCreateContext(DC);
    if (RC == HGLRC.Zero)
        throw new Win32Exception(Marshal.GetLastWin32Error());
}

C＃中的wglCreateContext失败但在托管C ++中失败

3 个答案: