wglCreateContext在C#中失败,但在托管C++中没有
wglCreateContext in C# failing but not in managed C++
我正在尝试在C#中使用opengl。我有以下代码失败,错误为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);
现在失败的代码:
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++中的相同代码正在中工作
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);
我在带有ATI图形卡的VIsta 64位和带有Nvidia的Windows XP 32位上都尝试过,在这两种情况下都得到了相同的结果
此外,我想指出的是,我不想使用任何已经编写好的框架。
有人能告诉我导致异常的C#代码中的错误在哪里吗
找到解决方案
这个问题很奇怪,很难看,真的很难找到。我在互联网上发现,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(据说)opengl32.dll覆盖了ChoosePixelFormat和SetPixelFormat函数(可能更多:-)。正如我在我的c++版本中发现的那样,意外地出现了这种情况
嘿,但是如何在C#中实现它
经过几天的搜索,我发现在tao框架中,他们使用kernel32.dll LoadLibrary()函数并在调用SetPixelFormat 之前加载opengl32.dll来解决这个问题
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opengl32.dll必须在gdi32.dll之前加载,还有其他方法吗。过了一会儿,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
}
在应用程序启动时,在调用gdi32.dll之前,我使用以下命令:
GL.glGetString(0);
这两种方法都能解决问题。
我现在无法对此进行测试,但我首先怀疑的是结构封装。您是否尝试在StructLayout属性中将包装设置为1?例如:
[StructLayout(LayoutKind.Sequential, Pack=1)]
干杯,Brian
调用wglCreateContext两次也有帮助。
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());
}
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