Getting DC of opengl backbuffer

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2 comments, last by Drew_Benton 19 years, 3 months ago
Hi I'm no game programmer, but this has been bugging me for quite some time now and was hoping someone here might beable to help How can I get the Device Context of an OpenGL backbuffer from ANOTHER application or even from my own. Once I have this, is it possible to Blit the contents using BitBlt to another dc in another application? Thnx in advance for any help
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Ok I'm no expert in this - but here's a shot.

1. I do not think you can get access to the OpenGL backbuffer. I may be wrong though.

2. To get the DC of another OpenGL program, I know you can do that. You do it in the same way you get the DC of your own program, but you just must have the HWND of the other program. To do that take a look at my recent post here.

HDC hDC = GetDC(hWnd);


You will have to replace hWnd with the HWND variable that you use to get the program's hwnd.

Quote:Once I have this, is it possible to Blit the contents using BitBlt to another dc in another application?


I am not sure - but I do not see why not! The only thing is that the original program might always clear the screen after you call your blit function - so you will have to think about that as well.

I hope this helps some!

- Drew
Thanx for that...but im really (really) hoping that the backbuffer can be refered to in some way

I did try what you said already and i got nothing, although that might be a mistake on my part...
Quote:Original post by _Paulus_
Thanx for that...but im really (really) hoping that the backbuffer can be refered to in some way

I did try what you said already and i got nothing, although that might be a mistake on my part...


Ok after more research I still belive that you cannot obtain the backbuffer, but you can draw to the front buffer. Anyways I have made a quick little program showing what you want to do as proof. I'm sorry they are messy and I did not make a project file - but this was a quick little endevor.

This is just NeHe's lesson6 - but I took out the texture loading stuff so you can make a quick little test.

/* *		This Code Was Created By Jeff Molofee 2000 *		A HUGE Thanks To Fredric Echols For Cleaning Up *		And Optimizing The Base Code, Making It More Flexible! *		If You've Found This Code Useful, Please Let Me Know. *		Visit My Site At nehe.gamedev.net */#include <windows.h>		// Header File For Windows#include <stdio.h>			// Header File For Standard Input/Output#include <gl\gl.h>			// Header File For The OpenGL32 Library#include <gl\glu.h>			// Header File For The GLu32 Library#include <gl\glaux.h>		// Header File For The Glaux Library#pragma comment( lib,"opengl32.lib")#pragma comment( lib,"glu32.lib")#pragma comment( lib,"glaux.lib")HDC			hDC=NULL;		// Private GDI Device ContextHGLRC		hRC=NULL;		// Permanent Rendering ContextHWND		hWnd=NULL;		// Holds Our Window HandleHINSTANCE	hInstance;		// Holds The Instance Of The Applicationbool	keys[256];			// Array Used For The Keyboard Routinebool	active=TRUE;		// Window Active Flag Set To TRUE By Defaultbool	fullscreen=TRUE;	// Fullscreen Flag Set To Fullscreen Mode By DefaultGLfloat	xrot;				// X Rotation ( NEW )GLfloat	yrot;				// Y Rotation ( NEW )GLfloat	zrot;				// Z Rotation ( NEW )LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	// Declaration For WndProcGLvoid ReSizeGLScene(GLsizei width, GLsizei height)		// Resize And Initialize The GL Window{	if (height==0)										// Prevent A Divide By Zero By	{		height=1;										// Making Height Equal One	}	glViewport(0,0,width,height);						// Reset The Current Viewport	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix	glLoadIdentity();									// Reset The Projection Matrix	// Calculate The Aspect Ratio Of The Window	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix	glLoadIdentity();									// Reset The Modelview Matrix}int InitGL(GLvoid)										// All Setup For OpenGL Goes Here{	glShadeModel(GL_SMOOTH);							// Enable Smooth Shading	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);				// Black Background	glClearDepth(1.0f);									// Depth Buffer Setup	glEnable(GL_DEPTH_TEST);							// Enables Depth Testing	glDepthFunc(GL_LEQUAL);								// The Type Of Depth Testing To Do	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations	return TRUE;										// Initialization Went OK}int DrawGLScene(GLvoid)									// Here's Where We Do All The Drawing{	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear The Screen And The Depth Buffer	glLoadIdentity();									// Reset The View	glTranslatef(0.0f,0.0f,-5.0f);	glRotatef(xrot,1.0f,0.0f,0.0f);	glRotatef(yrot,0.0f,1.0f,0.0f);	glRotatef(zrot,0.0f,0.0f,1.0f);	glBegin(GL_QUADS);		// Front Face		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);		// Back Face		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);		// Top Face		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);		// Bottom Face		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);		// Right face		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);		// Left Face		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);	glEnd();	xrot+=0.3f;	yrot+=0.2f;	zrot+=0.4f;	return TRUE;										// Keep Going}GLvoid KillGLWindow(GLvoid)								// Properly Kill The Window{	if (fullscreen)										// Are We In Fullscreen Mode?	{		ChangeDisplaySettings(NULL,0);					// If So Switch Back To The Desktop		ShowCursor(TRUE);								// Show Mouse Pointer	}	if (hRC)											// Do We Have A Rendering Context?	{		if (!wglMakeCurrent(NULL,NULL))					// Are We Able To Release The DC And RC Contexts?		{			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		}		if (!wglDeleteContext(hRC))						// Are We Able To Delete The RC?		{			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		}		hRC=NULL;										// Set RC To NULL	}	if (hDC && !ReleaseDC(hWnd,hDC))					// Are We Able To Release The DC	{		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hDC=NULL;										// Set DC To NULL	}	if (hWnd && !DestroyWindow(hWnd))					// Are We Able To Destroy The Window?	{		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hWnd=NULL;										// Set hWnd To NULL	}	if (!UnregisterClass("OpenGL",hInstance))			// Are We Able To Unregister Class	{		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);		hInstance=NULL;									// Set hInstance To NULL	}}/*	This Code Creates Our OpenGL Window.  Parameters Are:					* *	title			- Title To Appear At The Top Of The Window				* *	width			- Width Of The GL Window Or Fullscreen Mode				* *	height			- Height Of The GL Window Or Fullscreen Mode			* *	bits			- Number Of Bits To Use For Color (8/16/24/32)			* *	fullscreenflag	- Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE)	*/ BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag){	GLuint		PixelFormat;			// Holds The Results After Searching For A Match	WNDCLASS	wc;						// Windows Class Structure	DWORD		dwExStyle;				// Window Extended Style	DWORD		dwStyle;				// Window Style	RECT		WindowRect;				// Grabs Rectangle Upper Left / Lower Right Values	WindowRect.left=(long)0;			// Set Left Value To 0	WindowRect.right=(long)width;		// Set Right Value To Requested Width	WindowRect.top=(long)0;				// Set Top Value To 0	WindowRect.bottom=(long)height;		// Set Bottom Value To Requested Height	fullscreen=fullscreenflag;			// Set The Global Fullscreen Flag	hInstance			= GetModuleHandle(NULL);				// Grab An Instance For Our Window	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	// Redraw On Size, And Own DC For Window.	wc.lpfnWndProc		= (WNDPROC) WndProc;					// WndProc Handles Messages	wc.cbClsExtra		= 0;									// No Extra Window Data	wc.cbWndExtra		= 0;									// No Extra Window Data	wc.hInstance		= hInstance;							// Set The Instance	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);			// Load The Default Icon	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);			// Load The Arrow Pointer	wc.hbrBackground	= NULL;									// No Background Required For GL	wc.lpszMenuName		= NULL;									// We Don't Want A Menu	wc.lpszClassName	= "OpenGL";								// Set The Class Name	if (!RegisterClass(&wc))									// Attempt To Register The Window Class	{		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;											// Return FALSE	}		if (fullscreen)												// Attempt Fullscreen Mode?	{		DEVMODE dmScreenSettings;								// Device Mode		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	// Makes Sure Memory's Cleared		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		// Size Of The Devmode Structure		dmScreenSettings.dmPelsWidth	= width;				// Selected Screen Width		dmScreenSettings.dmPelsHeight	= height;				// Selected Screen Height		dmScreenSettings.dmBitsPerPel	= bits;					// Selected Bits Per Pixel		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;		// Try To Set Selected Mode And Get Results.  NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)		{			// If The Mode Fails, Offer Two Options.  Quit Or Use Windowed Mode.			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)			{				fullscreen=FALSE;		// Windowed Mode Selected.  Fullscreen = FALSE			}			else			{				// Pop Up A Message Box Letting User Know The Program Is Closing.				MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);				return FALSE;									// Return FALSE			}		}	}	if (fullscreen)												// Are We Still In Fullscreen Mode?	{		dwExStyle=WS_EX_APPWINDOW;								// Window Extended Style		dwStyle=WS_POPUP;										// Windows Style		ShowCursor(FALSE);										// Hide Mouse Pointer	}	else	{		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;			// Window Extended Style		dwStyle=WS_OVERLAPPEDWINDOW;							// Windows Style	}	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);		// Adjust Window To True Requested Size	// Create The Window	if (!(hWnd=CreateWindowEx(	dwExStyle,							// Extended Style For The Window								"OpenGL",							// Class Name								title,								// Window Title								dwStyle |							// Defined Window Style								WS_CLIPSIBLINGS |					// Required Window Style								WS_CLIPCHILDREN,					// Required Window Style								0, 0,								// Window Position								WindowRect.right-WindowRect.left,	// Calculate Window Width								WindowRect.bottom-WindowRect.top,	// Calculate Window Height								NULL,								// No Parent Window								NULL,								// No Menu								hInstance,							// Instance								NULL)))								// Dont Pass Anything To WM_CREATE	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	static	PIXELFORMATDESCRIPTOR pfd=				// pfd Tells Windows How We Want Things To Be	{		sizeof(PIXELFORMATDESCRIPTOR),				// Size Of This Pixel Format Descriptor		1,											// Version Number		PFD_DRAW_TO_WINDOW |						// Format Must Support Window		PFD_SUPPORT_OPENGL |						// Format Must Support OpenGL		PFD_DOUBLEBUFFER,							// Must Support Double Buffering		PFD_TYPE_RGBA,								// Request An RGBA Format		bits,										// Select Our Color Depth		0, 0, 0, 0, 0, 0,							// Color Bits Ignored		0,											// No Alpha Buffer		0,											// Shift Bit Ignored		0,											// No Accumulation Buffer		0, 0, 0, 0,									// Accumulation Bits Ignored		16,											// 16Bit Z-Buffer (Depth Buffer)  		0,											// No Stencil Buffer		0,											// No Auxiliary Buffer		PFD_MAIN_PLANE,								// Main Drawing Layer		0,											// Reserved		0, 0, 0										// Layer Masks Ignored	};		if (!(hDC=GetDC(hWnd)))							// Did We Get A Device Context?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))	// Did Windows Find A Matching Pixel Format?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!SetPixelFormat(hDC,PixelFormat,&pfd))		// Are We Able To Set The Pixel Format?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if (!(hRC=wglCreateContext(hDC)))				// Are We Able To Get A Rendering Context?	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!wglMakeCurrent(hDC,hRC))					// Try To Activate The Rendering Context	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	ShowWindow(hWnd,SW_SHOW);						// Show The Window	SetForegroundWindow(hWnd);						// Slightly Higher Priority	SetFocus(hWnd);									// Sets Keyboard Focus To The Window	ReSizeGLScene(width, height);					// Set Up Our Perspective GL Screen	if (!InitGL())									// Initialize Our Newly Created GL Window	{		KillGLWindow();								// Reset The Display		MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	return TRUE;									// Success}LRESULT CALLBACK WndProc(	HWND	hWnd,			// Handle For This Window							UINT	uMsg,			// Message For This Window							WPARAM	wParam,			// Additional Message Information							LPARAM	lParam)			// Additional Message Information{	switch (uMsg)									// Check For Windows Messages	{		case WM_ACTIVATE:							// Watch For Window Activate Message		{			if (!HIWORD(wParam))					// Check Minimization State			{				active=TRUE;						// Program Is Active			}			else			{				active=FALSE;						// Program Is No Longer Active			}			return 0;								// Return To The Message Loop		}		case WM_SYSCOMMAND:							// Intercept System Commands		{			switch (wParam)							// Check System Calls			{				case SC_SCREENSAVE:					// Screensaver Trying To Start?				case SC_MONITORPOWER:				// Monitor Trying To Enter Powersave?				return 0;							// Prevent From Happening			}			break;									// Exit		}		case WM_CLOSE:								// Did We Receive A Close Message?		{			PostQuitMessage(0);						// Send A Quit Message			return 0;								// Jump Back		}		case WM_KEYDOWN:							// Is A Key Being Held Down?		{			keys[wParam] = TRUE;					// If So, Mark It As TRUE			return 0;								// Jump Back		}		case WM_KEYUP:								// Has A Key Been Released?		{			keys[wParam] = FALSE;					// If So, Mark It As FALSE			return 0;								// Jump Back		}		case WM_SIZE:								// Resize The OpenGL Window		{			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));  // LoWord=Width, HiWord=Height			return 0;								// Jump Back		}	}	// Pass All Unhandled Messages To DefWindowProc	return DefWindowProc(hWnd,uMsg,wParam,lParam);}int WINAPI WinMain(	HINSTANCE	hInstance,			// Instance					HINSTANCE	hPrevInstance,		// Previous Instance					LPSTR		lpCmdLine,			// Command Line Parameters					int			nCmdShow)			// Window Show State{	MSG		msg;									// Windows Message Structure	BOOL	done=FALSE;								// Bool Variable To Exit Loop	// Ask The User Which Screen Mode They Prefer	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)	{		fullscreen=FALSE;							// Windowed Mode	}	// Create Our OpenGL Window	if (!CreateGLWindow("Tutorial",640,480,16,fullscreen))	{		return 0;									// Quit If Window Was Not Created	}	while(!done)									// Loop That Runs While done=FALSE	{		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))	// Is There A Message Waiting?		{			if (msg.message==WM_QUIT)				// Have We Received A Quit Message?			{				done=TRUE;							// If So done=TRUE			}			else									// If Not, Deal With Window Messages			{				TranslateMessage(&msg);				// Translate The Message				DispatchMessage(&msg);				// Dispatch The Message			}		}		else										// If There Are No Messages		{			// Draw The Scene.  Watch For ESC Key And Quit Messages From DrawGLScene()			if ((active && !DrawGLScene()) || keys[VK_ESCAPE])	// Active?  Was There A Quit Received?			{				done=TRUE;							// ESC or DrawGLScene Signalled A Quit			}			else									// Not Time To Quit, Update Screen			{				SwapBuffers(hDC);					// Swap Buffers (Double Buffering)			}			if (keys[VK_F1])						// Is F1 Being Pressed?			{				keys[VK_F1]=FALSE;					// If So Make Key FALSE				KillGLWindow();						// Kill Our Current Window				fullscreen=!fullscreen;				// Toggle Fullscreen / Windowed Mode				// Recreate Our OpenGL Window				if (!CreateGLWindow("NeHe's Texture Mapping Tutorial",640,480,16,fullscreen))				{					return 0;						// Quit If Window Was Not Created				}			}		}	}	// Shutdown	KillGLWindow();									// Kill The Window	return (msg.wParam);							// Exit The Program}


This is the code that will draw a yellow square to the NeHe program. It was meant to be a console appliction.

#include <windows.h>		// Header File For Windows#include <stdio.h>			// Header File For Standard Input/Output#include <iostream.h>#include <gl\gl.h>			// Header File For The OpenGL32 Library#include <gl\glu.h>			// Header File For The GLu32 Library#include <gl\glaux.h>		// Header File For The Glaux Library#pragma comment( lib,"opengl32.lib")#pragma comment( lib,"glu32.lib")#pragma comment( lib,"glaux.lib")HDC			hDC=NULL;		// Private GDI Device ContextHGLRC		hRC=NULL;		// Permanent Rendering ContextHWND		hWnd=NULL;		// Holds Our Window HandleHINSTANCE	hInstance;		// Holds The Instance Of The ApplicationGLuint		PixelFormat;			// Holds The Results After Searching For A Matchint main(int argc, char* argv[]){	HWND ogl = FindWindow("OpenGL","Tutorial");	if( !ogl )	{		cout  << "Cannot find window!";		return 0;	}	hDC = ::GetDC(ogl);	static	PIXELFORMATDESCRIPTOR pfd=				// pfd Tells Windows How We Want Things To Be	{		sizeof(PIXELFORMATDESCRIPTOR),				// Size Of This Pixel Format Descriptor		1,											// Version Number		PFD_DRAW_TO_WINDOW |						// Format Must Support Window		PFD_SUPPORT_OPENGL |						// Format Must Support OpenGL		PFD_DOUBLEBUFFER,							// Must Support Double Buffering		PFD_TYPE_RGBA,								// Request An RGBA Format		32,										// Select Our Color Depth		0, 0, 0, 0, 0, 0,							// Color Bits Ignored		0,											// No Alpha Buffer		0,											// Shift Bit Ignored		0,											// No Accumulation Buffer		0, 0, 0, 0,									// Accumulation Bits Ignored		16,											// 16Bit Z-Buffer (Depth Buffer)  		0,											// No Stencil Buffer		0,											// No Auxiliary Buffer		PFD_MAIN_PLANE,								// Main Drawing Layer		0,											// Reserved		0, 0, 0										// Layer Masks Ignored	};		if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))	// Did Windows Find A Matching Pixel Format?	{				MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!SetPixelFormat(hDC,PixelFormat,&pfd))		// Are We Able To Set The Pixel Format?	{										// Reset The Display		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if (!(hRC=wglCreateContext(hDC)))				// Are We Able To Get A Rendering Context?	{										// Reset The Display		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	if(!wglMakeCurrent(hDC,hRC))					// Try To Activate The Rendering Context	{										// Reset The Display		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);		return FALSE;								// Return FALSE	}	glShadeModel(GL_SMOOTH);							// Enable Smooth Shading	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);				// Black Background	glClearDepth(1.0f);									// Depth Buffer Setup	glEnable(GL_DEPTH_TEST);							// Enables Depth Testing	glDepthFunc(GL_LEQUAL);								// The Type Of Depth Testing To Do	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations	glViewport(0,0,640,480);						// Reset The Current Viewport	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix	glLoadIdentity();									// Reset The Projection Matrix	// Calculate The Aspect Ratio Of The Window	gluPerspective(45.0f,(GLfloat)640/(GLfloat)480,0.1f,100.0f);	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix	glLoadIdentity();		cout << "Everything fine up to here\n";	DWORD start = ::GetTickCount();	bool done = 0;	while( !done )	{		if( ::GetTickCount() - start > 1000)		{			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear The Screen And The Depth Buffer			glLoadIdentity();									// Reset The View			glTranslatef(0.0f,0.0f,-15.0f);			glColor3f(1.0f,1.0f,0.0f);				// Set The Color To Blue One Time Only			glBegin(GL_QUADS);					// Start Drawing Quads				glVertex3f(-1.0f, 1.0f, 0.0f);			// Left And Up 1 Unit (Top Left)				glVertex3f( 1.0f, 1.0f, 0.0f);			// Right And Up 1 Unit (Top Right)				glVertex3f( 1.0f,-1.0f, 0.0f);			// Right And Down One Unit (Bottom Right)				glVertex3f(-1.0f,-1.0f, 0.0f);			// Left And Down One Unit (Bottom Left)			glEnd();			//::SendMessage(hWnd,WM_PAINT,0,0); ** note this 			SwapBuffers(hDC);					// Swap Buffers (Double Buffering)		}		else		{			::Sleep(100);		}	}	return 0;}


Ok to do this just make a simple Win32 empty project. Add in the first .cpp file and compile. Everything should work as is - but you may have to hcange the OpenGL directories.

Next you will need to make a little empty Win32 console app. Paste in the second file and compile. Once again everything *should* compile.

Now you need to run the NeHe first. As you will see, it is a white cube spinning. Run the second program and you will see the square drawn to the screen. Of course you will see the flickering because the second program clears the screen and flips the hDC as well as the NeHe.

I hope that can serve as a good start in figuring out what you want to do. You will definitly have a challenge trying to make the drawing appear smother and such - but at least you have a beginning point [wink]. I hope this helps some. Let me know! [smile]

- Drew

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