C / C++ / MFC

bool Create(unsigned int width, unsigned int height)
{	

	// Create a p-buffer for off-screen rendering

	m_uiWidth = width;
	m_uiHeight = height;

	m_hWnd = g_pMainApplicationWindow->GetHWND();		

	m_hMainApplicationWindowDC = g_pMainApplicationWindow->GetHDC();
	m_hMainApplicationWindowRC = g_pMainApplicationWindow->GetHGLRC();			
	
	memset(&m_bmi, 0, sizeof(BITMAPINFO));
	m_bmi.bmiHeader.biSize			= sizeof(BITMAPINFOHEADER);
	m_bmi.bmiHeader.biWidth			= m_uiWidth;
	m_bmi.bmiHeader.biHeight		= m_uiHeight;
	m_bmi.bmiHeader.biPlanes		= 1;
	m_bmi.bmiHeader.biBitCount		= 32;
	m_bmi.bmiHeader.biCompression	= BI_RGB;
	m_bmi.bmiHeader.biSizeImage		= m_uiWidth * m_uiHeight * 4;

	// Create DIB
	HDC	hDC = ::GetDC(m_hWnd);
	m_hDib = ::CreateDIBSection(hDC, &m_bmi, DIB_RGB_COLORS, (void**)&m_pTextureData, NULL, (DWORD)0);
	ReleaseDC(m_hWnd, hDC);
	
	m_hMemDC = ::CreateCompatibleDC(NULL);
	if(!m_hMemDC)
	{
		DeleteObject(m_hDib);
		m_hDib = NULL;
		return (false);
	}

	m_hOldDib = SelectObject(m_hMemDC, m_hDib);

	// Setup memory DC's pixel format.
	if (!SetDCPixelFormat(m_hMemDC, PFD_DRAW_TO_BITMAP | PFD_SUPPORT_OPENGL | PFD_STEREO_DONTCARE))
	{
		SelectObject(m_hMemDC, m_hOldDib);
		DeleteObject(m_hDib);
		m_hDib = NULL;
		DeleteDC(m_hMemDC);
		m_hMemDC = NULL;
		return (false);
	}
	
	m_hRC = ::wglCreateContext(m_hMemDC);
	if (!m_hRC)
	{
		SelectObject(m_hMemDC, m_hOldDib);
		DeleteObject(m_hDib);
		m_hDib = NULL;
		DeleteDC(m_hMemDC);
		m_hMemDC = NULL;
		return (false);
	}		
}

bool SetDCPixelFormat(HDC hDC, DWORD dwFlags)
{
	HDC NewHdc = hDC;	

	static PIXELFORMATDESCRIPTOR pixelDesc =
	{
		sizeof(PIXELFORMATDESCRIPTOR),
		1,
		PFD_DRAW_TO_BITMAP |
		PFD_SUPPORT_OPENGL |
		PFD_STEREO_DONTCARE,		
		PFD_TYPE_RGBA,
		32,
		0, 0, 0, 0, 0, 0,
		0,
		0,
		0,
		0, 0, 0, 0,
		16,  
		1, // Use stencil buffer
		0,
		PFD_MAIN_PLANE,
		0,
		0, 0, 0
	};	
		
	GLuint PixelFormat;
	
	int nPixelIndex = ::ChoosePixelFormat(NewHdc, &pixelDesc);
	if (nPixelIndex == 0) // Choose default
	{		
		nPixelIndex = 1;
		if (::DescribePixelFormat(hDC, nPixelIndex, 
			sizeof(PIXELFORMATDESCRIPTOR), &pixelDesc) == 0)
			return false;
	}

	if (!::SetPixelFormat(hDC, nPixelIndex, &pixelDesc))
		return false;

	return true;
}

bool DIBBuffer::StartRendering(void)
{	
	wglMakeCurrent(m_hMemDC, m_hRC);
	BitBlt();

	GLint  texSize;
	glGetIntegerv( GL_MAX_TEXTURE_SIZE, &texSize );

	//i am getting max texture size 1024
	//but when i use the below format i am getting 4096 max texture size

	static PIXELFORMATDESCRIPTOR pfd =
	{
		sizeof(PIXELFORMATDESCRIPTOR),
		1,
		PFD_DRAW_TO_WINDOW |
		PFD_SUPPORT_OPENGL |
		PFD_DOUBLEBUFFER,
		PFD_TYPE_RGBA,
		MAIN_APPLICATION_WINDOW_BITS_PER_PIXEL,
		0, 0, 0, 0, 0, 0,
		0,
		0,
		0,
		0, 0, 0, 0,
		16,  
		1, // Use stencil buffer
		0,
		PFD_MAIN_PLANE,
		0,
		0, 0, 0
	};
}