Hi there, I''m trying to create an OpenGL application that runs in a dialog. I manage to create a rendering context, but I really don''t know how I should swap the buffers. I use code something like the following (sorry, don''t have the exact code here) HINSTANCE gsInstance; // assigned from WinMain''s hInstance HWND gsWindow; gsWindow = CreateDialog(gsInstance, MAKEINTRESOURCE(IDD_DLG_MAIN), DlgProc) I then get the device context for this gsDeviceContext = GetDC(gsWindow) then set the pixel format for this DC, and then create a rendering context. When I check, the rendering context is created fine. (ie. it does not return NULL when created) My problem is that I can''t call SwapBuffers(gsDeviceContext). It seems to be giving an invalid memory access message when this is called. Any ideas (or does anyone know a better way of doing this?) Thanks FReY

Hey there frey!

My idea is, that you create the dialog, but you get a dc for the DIALOG window... I think that what you''d want to do is create a window in the dialog (CreateWindow with hWndParent) and get a DC for THAT... just an idea but i think this ll work.

I dont think that you can render to the dialog parent window, as windows does this...

Hey there, thanks for your response!!

So create a completely new window within the dialog? Would I ever be able to create a static dialog control and then use that?

I''ve tried this and I run into the same problem

HWND gsControlWnd;
HDC gsDeviceContext;

gsControlWnd = GetDlgItem(gsWindow, IDC_STATIC_VIEW);
gsDeviceContext = GetDC(gsControlWnd);

If I created a new window, I''d have to syncronize it to the parent dialog''s position or would this be done automatically?

Thanks again,
FReY

The easiest and most portable way I know of is to make an OpenGL control. Derive from CWnd and override the OnPreCreateWindow, OnCreate, and OnPaint functions to do your OpenGL specific initialization. This way you can resize the OGL window (a CWnd object), and have room for other controls in the dialog (or have multiple OGL controls in a single dialog.

---
K-1 Productions: Come visit us here.

And if I''m not using MFC at all, is this possible?

This will give you some hints in Win32:

Main

// windowopengl.cpp : Defines the entry point for the application.//#include "stdafx.h"#include "resource.h"#include <gl\glut.h>#include <gl\gl.h>#include <gl\glaux.h>#define MAX_LOADSTRING 100// Global Variables:HINSTANCE hInst;								// current instanceTCHAR szTitle[MAX_LOADSTRING];					// The title bar textTCHAR szWindowClass[MAX_LOADSTRING];			// The title bar textint TheEnd;										// Flag used by thread to end		int xrot;										// rotation// Foward declarations of functions included in this code module:ATOM				MyRegisterClass(HINSTANCE hInstance);BOOL				InitInstance(HINSTANCE, int);LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);LRESULT CALLBACK	About(HWND, UINT, WPARAM, LPARAM);LRESULT CALLBACK	OpenGL(HWND, UINT, WPARAM, LPARAM);DWORD WINAPI		InitGL(HWND);int					MySetPixelFormat(HDC hdc);void			    RenderScene(int);int APIENTRY WinMain(HINSTANCE hInstance,                     HINSTANCE hPrevInstance,                     LPSTR     lpCmdLine,                     int       nCmdShow){ 	// TODO: Place code here.	MSG msg;	HACCEL hAccelTable;	// Initialize global strings	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);	LoadString(hInstance, IDC_WINDOWOPENGL, szWindowClass, MAX_LOADSTRING);	MyRegisterClass(hInstance);	// Perform application initialization:	if (!InitInstance (hInstance, nCmdShow)) 	{		return FALSE;	}	hAccelTable = LoadAccelerators(hInstance, (LPCTSTR)IDC_WINDOWOPENGL);	// Main message loop:	while (GetMessage(&msg, NULL, 0, 0)) 	{		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) 		{			TranslateMessage(&msg);			DispatchMessage(&msg);		}	}	return msg.wParam;}////  FUNCTION: MyRegisterClass()////  PURPOSE: Registers the window class.////  COMMENTS:////    This function and its usage is only necessary if you want this code//    to be compatible with Win32 systems prior to the ''RegisterClassEx''//    function that was added to Windows 95. It is important to call this function//    so that the application will get ''well formed'' small icons associated//    with it.//ATOM MyRegisterClass(HINSTANCE hInstance){	WNDCLASSEX wcex;	wcex.cbSize = sizeof(WNDCLASSEX); 	wcex.style			= CS_HREDRAW | CS_VREDRAW;	wcex.lpfnWndProc	= (WNDPROC)WndProc;	wcex.cbClsExtra		= 0;	wcex.cbWndExtra		= 0;	wcex.hInstance		= hInstance;	wcex.hIcon			= LoadIcon(hInstance, (LPCTSTR)IDI_WINDOWOPENGL);	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);	wcex.lpszMenuName	= (LPCSTR)IDC_WINDOWOPENGL;	wcex.lpszClassName	= szWindowClass;	wcex.hIconSm		= LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);	return RegisterClassEx(&wcex);}////   FUNCTION: InitInstance(HANDLE, int)////   PURPOSE: Saves instance handle and creates main window////   COMMENTS:////        In this function, we save the instance handle in a global variable and//        create and display the main program window.//BOOL InitInstance(HINSTANCE hInstance, int nCmdShow){   HWND hWnd;   hInst = hInstance; // Store instance handle in our global variable   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);   if (!hWnd)   {      return FALSE;   }   ShowWindow(hWnd, nCmdShow);   UpdateWindow(hWnd);   return TRUE;}////  FUNCTION: WndProc(HWND, unsigned, WORD, LONG)////  PURPOSE:  Processes messages for the main window.////  WM_COMMAND	- process the application menu//  WM_PAINT	- Paint the main window//  WM_DESTROY	- post a quit message and return////LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){	int wmId, wmEvent;	PAINTSTRUCT ps;	HDC hdc;	TCHAR szHello[MAX_LOADSTRING];	LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);	switch (message) 	{		case WM_COMMAND:			wmId    = LOWORD(wParam); 			wmEvent = HIWORD(wParam); 			// Parse the menu selections:			switch (wmId)			{				case IDM_ABOUT:				   DialogBox(hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, (DLGPROC)About);				   break;				case IDM_EXIT:				   DestroyWindow(hWnd);				   break;				case IDM_OPENGL:				   DialogBox(hInst, (LPCTSTR)IDD_OPENGL, hWnd, (DLGPROC)OpenGL);				   break;				default:				   return DefWindowProc(hWnd, message, wParam, lParam);			}			break;		case WM_PAINT:			hdc = BeginPaint(hWnd, &ps);			// TODO: Add any drawing code here...			RECT rt;			GetClientRect(hWnd, &rt);			DrawText(hdc, szHello, strlen(szHello), &rt, DT_CENTER);			EndPaint(hWnd, &ps);			break;		case WM_DESTROY:			PostQuitMessage(0);			break;		default:			return DefWindowProc(hWnd, message, wParam, lParam);   }   return 0;}// Mesage handler for about box.LRESULT CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam){	switch (message)	{		case WM_INITDIALOG:				return TRUE;		case WM_COMMAND:			if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) 			{				EndDialog(hDlg, LOWORD(wParam));				return TRUE;			}			break;	}    return FALSE;}// Mesage handler for OpenGL box.LRESULT CALLBACK OpenGL(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam){	static HANDLE hOpenGL;	static DWORD lpThreadId;	switch (message)	{		case WM_INITDIALOG:				return TRUE;		case WM_COMMAND:			if (LOWORD(wParam) == IDOK) 			{				TheEnd=1;				Sleep(500);				EndDialog(hDlg, LOWORD(wParam));				return TRUE;			}			if (LOWORD(wParam) == IDRENDER) 			{				EnableWindow(GetDlgItem(hDlg,IDRENDER),FALSE);				hOpenGL=CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)InitGL,hDlg,0,&lpThreadId);			}						break;	}    return FALSE;}// Here, we do the regular initialization of OpenGLDWORD WINAPI InitGL(HWND hDlg){	HDC hDC1,hDC2,hDC3,hDC4;	HWND hEdit1,hEdit2,hEdit3,hEdit4;	HGLRC hglrc1,hglrc2,hglrc3,hglrc4;		// First, let''s get the handle to all the window we created in the Dialog	// with the resource editor	hEdit1=GetDlgItem(hDlg,IDC_EDIT1);	hEdit2=GetDlgItem(hDlg,IDC_EDIT2);	hEdit3=GetDlgItem(hDlg,IDC_EDIT3);	hEdit4=GetDlgItem(hDlg,IDC_EDIT4);	// For every window, we get the HDC	hDC1=GetDC(hEdit1);	hDC2=GetDC(hEdit2);	hDC3=GetDC(hEdit3);	hDC4=GetDC(hEdit4);	// OpenGL Initialization	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	MySetPixelFormat(hDC1);	MySetPixelFormat(hDC2);	MySetPixelFormat(hDC3);	MySetPixelFormat(hDC4);	hglrc1 = wglCreateContext(hDC1);	hglrc2 = wglCreateContext(hDC2);	hglrc3 = wglCreateContext(hDC3);	hglrc4 = wglCreateContext(hDC4);	//render here	while(TheEnd !=1 )		{			// Select first Window as the rendering context and draw to it			wglMakeCurrent(hDC1, hglrc1);			RenderScene(1);			SwapBuffers(hDC1);			// Select second Window as the rendering context and draw to it			wglMakeCurrent(hDC2, hglrc2);			RenderScene(2);			SwapBuffers(hDC2);					// Select third Window as the rendering context and draw to it			wglMakeCurrent(hDC3, hglrc3);			RenderScene(2);			SwapBuffers(hDC3);			// Select fourth Window as the rendering context and draw to it			wglMakeCurrent(hDC4, hglrc4);			RenderScene(1);			SwapBuffers(hDC4);			// Throttle the loop. If we don''t put a sleep here, the thread will use 100% cpu						Sleep(1); 		}	wglMakeCurrent(NULL, NULL); 		// Cleanup	ReleaseDC (hDlg, hDC1) ; 	ReleaseDC (hDlg, hDC2) ; 	ReleaseDC (hDlg, hDC3) ; 	ReleaseDC (hDlg, hDC4) ;		wglDeleteContext(hglrc1); 	wglDeleteContext(hglrc2); 	wglDeleteContext(hglrc3); 	wglDeleteContext(hglrc4); 		return TRUE;}// Set up the pixel formatint MySetPixelFormat(HDC hdc){	PIXELFORMATDESCRIPTOR pfd = { 	    sizeof(PIXELFORMATDESCRIPTOR),    // size of this pfd 	    1,                                // version number 	    PFD_DRAW_TO_WINDOW |              // support window 	    PFD_SUPPORT_OPENGL |              // support OpenGL 	    PFD_DOUBLEBUFFER,                 // double buffered 	    PFD_TYPE_RGBA,                    // RGBA type 	    24,                               // 24-bit 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,                       // accum bits ignored 	    32,                               // 32-bit z-buffer     	    0,                                // no stencil buffer 	    0,                                // no auxiliary buffer 	    PFD_MAIN_PLANE,                   // main layer 	    0,                                // reserved 	    0, 0, 0                           // layer masks ignored 	}; 		int  iPixelFormat;  	// get the device context''s best, available pixel format match 	if((iPixelFormat = ChoosePixelFormat(hdc, &pfd)) == 0)	{		MessageBox(NULL, "ChoosePixelFormat Failed", NULL, MB_OK);		return 0;	}	 	// make that match the device context''s current pixel format 	if(SetPixelFormat(hdc, iPixelFormat, &pfd) == FALSE)	{		MessageBox(NULL, "SetPixelFormat Failed", NULL, MB_OK);		return 0;	}	return 1;}// This is where we render, in this case, we will draw a simple 3D-Trianglevoid RenderScene(int axis){			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);			glLoadIdentity();						if(axis==1) glRotatef(xrot,1.0f,0.0f,0.0f);			if(axis==2) glRotatef(xrot,0.0f,1.0f,0.0f);			glBegin(GL_TRIANGLES);			glColor3f(1, 0, 0);						glVertex3f(0, 0.8f, 0);			//top			glColor3f(0, 1, 0);						glVertex3f(-0.5, -0.5, 0.5);	//left			glColor3f(0, 0,1);						glVertex3f(0.5, -0.5, 0.5);		//right			glColor3f(1.0f,0.0f,0.0f);			// Red			glVertex3f( 0.0f, 0.8f, 0.0f);		// Top Of Triangle (Right)			glColor3f(0.0f,0.0f,1.0f);			// Blue			glVertex3f( .5f,-.5f, .5f);			// Left Of Triangle (Right)			glColor3f(0.0f,0.5f,0.0f);			// Green			glVertex3f( 0.5f,-0.5f, -0.5f);		// Right Of Triangle (Right)			glColor3f(1.0f,0.0f,0.0f);			// Red			glVertex3f( 0.0f, 0.8f, 0.0f);		// Top Of Triangle (Back)			glColor3f(0.0f,1.0f,0.0f);			// Green			glVertex3f( 0.5f,-0.5f, -0.5f);		// Left Of Triangle (Back)			glColor3f(0.0f,0.0f,1.0f);			// Blue			glVertex3f(-0.5f,-0.5f, -0.5f);		// Right Of Triangle (Back)			glColor3f(1.0f,0.0f,0.0f);			// Red			glVertex3f( 0.0f, 0.8f, 0.0f);		// Top Of Triangle (Left)			glColor3f(0.0f,0.0f,1.0f);			// Blue			glVertex3f(-0.5f,-0.5f,-0.5f);		// Left Of Triangle (Left)			glColor3f(0.0f,1.0f,0.0f);			// Green			glVertex3f(-0.5f,-0.5f, 0.5f);		// Right Of Triangle (Left)			glEnd();				xrot+=1.5f;}

Resource IDs

//{{NO_DEPENDENCIES}}// Microsoft Developer Studio generated include file.// Used by windowopengl.rc//#define IDC_MYICON                      2#define IDD_WINDOWOPENGL_DIALOG         102#define IDD_ABOUTBOX                    103#define IDS_APP_TITLE                   103#define IDM_ABOUT                       104#define IDM_EXIT                        105#define IDS_HELLO                       106#define IDI_WINDOWOPENGL                107#define IDI_SMALL                       108#define IDC_WINDOWOPENGL                109#define IDR_MAINFRAME                   128#define IDD_OPENGL                      129#define IDC_EDIT1                       1000#define IDRENDER                        1001#define IDC_EDIT2                       1002#define IDC_EDIT3                       1003#define IDC_EDIT4                       1004#define IDM_OPENGL                      32771#define IDC_STATIC                      -1// Next default values for new objects// #ifdef APSTUDIO_INVOKED#ifndef APSTUDIO_READONLY_SYMBOLS#define _APS_NEXT_RESOURCE_VALUE        130#define _APS_NEXT_COMMAND_VALUE         32772#define _APS_NEXT_CONTROL_VALUE         1002#define _APS_NEXT_SYMED_VALUE           110#endif#endif

Resource Script

//Microsoft Developer Studio generated resource script.//#include "resource.h"#define APSTUDIO_READONLY_SYMBOLS///////////////////////////////////////////////////////////////////////////////// Generated from the TEXTINCLUDE 2 resource.//#define APSTUDIO_HIDDEN_SYMBOLS#include "windows.h"#undef APSTUDIO_HIDDEN_SYMBOLS#include "resource.h"/////////////////////////////////////////////////////////////////////////////#undef APSTUDIO_READONLY_SYMBOLS/////////////////////////////////////////////////////////////////////////////// English (U.S.) resources#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)#ifdef _WIN32LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US#pragma code_page(1252)#endif //_WIN32///////////////////////////////////////////////////////////////////////////////// Icon//// Icon with lowest ID value placed first to ensure application icon// remains consistent on all systems.IDI_WINDOWOPENGL        ICON    DISCARDABLE     "windowopengl.ICO"IDI_SMALL               ICON    DISCARDABLE     "SMALL.ICO"///////////////////////////////////////////////////////////////////////////////// Menu//IDC_WINDOWOPENGL MENU DISCARDABLE BEGIN    POPUP "&File"    BEGIN        MENUITEM "E&xit",                       IDM_EXIT    END    MENUITEM "&OpenGL",                     IDM_OPENGL    POPUP "&Help"    BEGIN        MENUITEM "&About ...",                  IDM_ABOUT    ENDEND///////////////////////////////////////////////////////////////////////////////// Accelerator//IDC_WINDOWOPENGL ACCELERATORS MOVEABLE PURE BEGIN    "?",            IDM_ABOUT,              ASCII,  ALT    "/",            IDM_ABOUT,              ASCII,  ALTEND///////////////////////////////////////////////////////////////////////////////// Dialog//IDD_ABOUTBOX DIALOG DISCARDABLE  22, 17, 230, 75STYLE DS_MODALFRAME | WS_CAPTION | WS_SYSMENUCAPTION "About"FONT 8, "System"BEGIN    ICON            IDI_WINDOWOPENGL,IDC_MYICON,14,9,16,16    LTEXT           "windowopengl Version 1.0",IDC_STATIC,49,10,119,8,                    SS_NOPREFIX    LTEXT           "Copyright (C) 2001",IDC_STATIC,49,20,119,8    DEFPUSHBUTTON   "OK",IDOK,195,6,30,11,WS_GROUPENDIDD_OPENGL DIALOG DISCARDABLE  0, 0, 304, 170STYLE DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENUCAPTION "Window OpenGL example by Chong Hin Ooi, chongooi@mediaone.net"FONT 8, "MS Sans Serif"BEGIN    DEFPUSHBUTTON   "Render",IDRENDER,190,149,50,14    PUSHBUTTON      "OK",IDOK,247,149,50,14    EDITTEXT        IDC_EDIT1,7,7,138,58,ES_AUTOHSCROLL    EDITTEXT        IDC_EDIT2,159,7,138,58,ES_AUTOHSCROLL    EDITTEXT        IDC_EDIT3,7,78,138,58,ES_AUTOHSCROLL    EDITTEXT        IDC_EDIT4,159,78,138,58,ES_AUTOHSCROLLEND#ifdef APSTUDIO_INVOKED///////////////////////////////////////////////////////////////////////////////// TEXTINCLUDE//2 TEXTINCLUDE DISCARDABLE BEGIN    "#define APSTUDIO_HIDDEN_SYMBOLS\r\n"    "#include ""windows.h""\r\n"    "#undef APSTUDIO_HIDDEN_SYMBOLS\r\n"    "#include ""resource.h""\r\n"    "\0"END3 TEXTINCLUDE DISCARDABLE BEGIN    "\r\n"    "\0"END1 TEXTINCLUDE DISCARDABLE BEGIN    "resource.h\0"END#endif    // APSTUDIO_INVOKED///////////////////////////////////////////////////////////////////////////////// DESIGNINFO//#ifdef APSTUDIO_INVOKEDGUIDELINES DESIGNINFO DISCARDABLE BEGIN    IDD_OPENGL, DIALOG    BEGIN        LEFTMARGIN, 7        RIGHTMARGIN, 297        TOPMARGIN, 7        BOTTOMMARGIN, 163    ENDEND#endif    // APSTUDIO_INVOKED///////////////////////////////////////////////////////////////////////////////// String Table//STRINGTABLE DISCARDABLE BEGIN    IDS_APP_TITLE           "windowopengl"    IDS_HELLO               "Window OpenGL example by Chong Hin Ooi"    IDC_WINDOWOPENGL        "WINDOWOPENGL"END#endif    // English (U.S.) resources/////////////////////////////////////////////////////////////////////////////#ifndef APSTUDIO_INVOKED///////////////////////////////////////////////////////////////////////////////// Generated from the TEXTINCLUDE 3 resource.///////////////////////////////////////////////////////////////////////////////#endif    // not APSTUDIO_INVOKED

Basically, get the handle to the object, get the DC, create the rendering contexts, render, swap buffers, and so on.

Hope this helps

Thanks Xiachunyi, that''s looks *very* similar to what I was doing before, but will try :D

Many thanks!
FReY

ehe he...

*clears throat*

... I was forgetting to call wglMakeCurrent... erm..

So, hope y''all learn from this! And tons of thanks and greetings to the guys who helped me out here, you''re all stars.

*saunters off sheepishly*

:D