// Somewhere else, he defined these:rendererWidth = GLsizei(640);rendererHeight = GLsizei(480);fieldOfViewAngle = 45.0f;nearClippingPlane = 1.0f;farClippingPlane = 200.0f;bool RendererOpenGL::bindToWindow(HWND &windowHandle){	//set up pixel format, rendering context	// NOTE: this method uses 'wgl' commands - the MS Windows Operating system binding for OpenGL.	// it must be over-written when porting this renderer to another OS.	// Need to do 5 things before we can use OpenGL	// First - get the device context of the game window (ie. what is the window being shown on eg. graphics adapter)	// Second - set that device to some desired pixel format	// Third - create a rendering context for OpenGL (something OpenGL draws to and maps to the device)	// Fourth - make the rendering context 'current'	// Fifth - Set the size of the OpenGL window.		// First - get the device context of the game window	hWnd = windowHandle;	hDC = GetDC(hWnd); // get the device context of the window		// Second - set the device to some desired pixel format	// This is done be filling out a pixel format descriptor structure	static PIXELFORMATDESCRIPTOR pfd; // pixel format descriptor	// The pixel format discriptor has a lot of memembers (26) !	// luckily we dont need most of them and set them to zero	// we could go through the structure member by member and set them to zero	// but a shortcut way is to use memset to initialise everything to zero	memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR)); // sets all memmbers of pfd to 0	// now we change only the relevant pfd members	pfd.nSize		= sizeof(PIXELFORMATDESCRIPTOR);	pfd.nVersion	= 1;	pfd.dwFlags		= PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;	pfd.cColorBits	= 16;	pfd.cDepthBits	= 16;	// based on the descriptor, choose the closest supported pixel format.	int PixelFormat = ChoosePixelFormat(hDC, &pfd);	if (PixelFormat==0)	{		// error		MessageBox (NULL,"Could not choose pixel format","Error",MB_OK);		return (false);	}	// set the display device (device context) to the pixel format	if (SetPixelFormat(hDC, PixelFormat, &pfd)==0)	{		// error		MessageBox (NULL,"Could not set pixel format","Error",MB_OK);		return (false);	}		// Third - create rendering context 	 hRC = wglCreateContext(hDC); // windows dependent OpenGL function (wgl)	 if (hRC==NULL)	 {		 MessageBox (NULL,"Could not create GL rendering context","Error",MB_OK);		 return (false);	 }	 // Fourth - Make the rendering context current	 	 if (!wglMakeCurrent(hDC, hRC))	 {		 MessageBox (NULL,"Could not make rendering context current","Error",MB_OK);		 return (false);	 }	 // Fifth - set the size of the OpenGL window	 /*	 ***** Note: this step is important, not setting an initial size	 can cause the whole OS to crash (computer is re-set)	 */	 RECT rect; // structure to store the coordinates of the 4 corners of the window	 GetClientRect (hWnd, &rect); // put the window coordinates in the structure	 ResizeCanvas(long(rect.right-rect.left), long(rect.bottom-rect.top));	 	return (true);}void RendererOpenGL::ResizeCanvas(long widthRequest, long heightRequest){	rendererWidth = (GLsizei)widthRequest;	rendererHeight = (GLsizei)heightRequest;    glViewport(0, 0, rendererWidth, rendererHeight);	setUpViewingFrustum();	}void RendererOpenGL::setUpViewingFrustum()  // set up the viewing volume{	// Select projection matrix and reset it to identity, subsequent operations are then performed on this matrix (gluPerspective)	glMatrixMode(GL_PROJECTION);	glLoadIdentity();	// set up the perspective of the window	GLdouble aspectRatio = (GLfloat)rendererWidth/(GLfloat)rendererHeight;	gluPerspective(fieldOfViewAngle, aspectRatio, nearClippingPlane, farClippingPlane);	// select the model-view matrix (to de-select the projection matrix) and reset it to identity	glMatrixMode(GL_MODELVIEW);	glLoadIdentity();}