I tried to do off-screen rendering using pbufer WLG_ARB, but I had problems with wglCreatePbufferARB () It always returns NULL. Here is a piece of code.
bool COpenGLWnd::OffscreenRender
( int transitionID, int counts, int directionID,
BYTE* pPixelArray)
{
HDC tmpDC = ::GetDC(NULL);
SetDCPixelFormat(tmpDC);
HGLRC tmpRC = wglCreateContext(tmpDC);
VERIFY(wglMakeCurrent(tmpDC, tmpRC));
HDC hDC = ::GetDC(NULL);
const int attribList[] =
{
WGL_DRAW_TO_PBUFFER_ARB, GL_TRUE,
WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
WGL_COLOR_BITS_ARB, 32,
WGL_DEPTH_BITS_ARB, 24,
WGL_STENCIL_BITS_ARB, 8,
0,
};
int pixelFormat;
UINT numFormats = 1;
if(!wglGetCurrentContext())
{
return false;
}
wglGetExtensionsStringARB = (PFNWGLGETEXTENSIONSSTRINGARBPROC) wglGetProcAddress("wglGetExtensionsStringARB");
if(!wglGetExtensionsStringARB) return false;
const GLubyte* extensions = (const GLubyte*) wglGetExtensionsStringARB(wglGetCurrentDC());
if(!extensions)
{
return false;
}
wglChoosePixelFormatARB = (PFNWGLCHOOSEPIXELFORMATARBPROC) wglGetProcAddress("wglChoosePixelFormatARB");
wglCreatePbufferARB = (PFNWGLCREATEPBUFFERARBPROC) wglGetProcAddress("wglCreatePbufferARB");
wglGetPbufferDCARB = (PFNWGLGETPBUFFERDCARBPROC) wglGetProcAddress("wglGetPbufferDCARB");
VERIFY(wglMakeCurrent(tmpDC, NULL));
wglDeleteContext(tmpRC);
::ReleaseDC(NULL, tmpDC);
if(!wglChoosePixelFormatARB) return false;
if(!wglCreatePbufferARB) return false;
if(!wglGetPbufferDCARB) return false;
wglChoosePixelFormatARB(hDC, attribList, NULL, 1, &pixelFormat, &numFormats);
const int attribTmp[] = {WGL_PBUFFER_LARGEST_ARB, 0, 0};
m_hbuffer = wglCreatePbufferARB(hDC, pixelFormat, m_BmpWidth, m_BmpHeight, attribTmp);
HDC hpbufferDC = wglGetPbufferDCARB(hbuffer);
if(!hpbufferDC) return false;
HGLRC hpbufferRC = wglCreateContext(hpbufferDC);
VERIFY(wglMakeCurrent(hpbufferDC, hpbufferRC));
...
}
As I said, wglCreatePbufferARB returns NULL, so I cannot use wglGetBufferDCARB. Other WGL_ARB extension functions work very well, for example wglGetExtensionsStringARB and wglChoosePixelformetARB. And also the extension got a very normal line, it starts with "WGL_ARB_extensions_string ...". Each parameter used in wglCreatePbufferARB was not NULL, including hDC. Then why is wglCreatePbufferARB still returning NULL and not working, what did I intend?++ p.s.
GetLastError, ERROR_INVALID_DATA. - attribList, ? GetLastError.
++ p.s.
. . !