Part of the Khronos Group
OpenGL.org

The Industry's Foundation for High Performance Graphics

from games to virtual reality, mobile phones to supercomputers

Results 1 to 2 of 2

Thread: OpenGL from DLL causing errors

  1. #1
    Junior Member Newbie
    Join Date
    Feb 2011
    Posts
    9

    OpenGL from DLL causing errors

    I have following scenario:

    my GUI is in C#, and it grabs images from an attached camera. The application then pipes the image data pointer to the DLL, which should display the image.

    The point is, I call OpenGLDisplay_Init(), which results in the error returned from glGetError() as 0. The initialization itself seems to work fine, and the image on my second monitor goes black.
    My main application is not using OpenGL in any way. The interesting thing is that in

    void OpenGL_Display:rawNewImage(int width, int height, unsigned char* imageData, bool flip)
    {
    GLenum mError = glGetError();

    BOOL returnVal = wglMakeCurrent(hDC, hRC);
    mError = glGetError();

    UpdateGLBuffers(width, height, imageData);
    DrawGLScene(flip);
    SwapBuffers(hDC);
    }

    the first glGetError() already returns 1282, so the OpenGL Context seems to have been invalidated, but I don't know how, and if it did, why I cannot get it back via wglMakeCurrent().
    Can someone help me figure out what's going wrong there?

    Edit: GetLastError() returns 170, saying that the requested resource is in use. Trying to find a way around that. wglGetCurrentDC / wglGetCurrentContext both return NULL, and I cannot do anything so far to "unbusy" those resources.

    .cpp:
    Code :
    /** Based on code by NeHe tutorials
        Adapted to display live camera display with OpenGL
    */
     
     
    #include "OpenGL-Display.h"
     
     
    using namespace OGD;
     
     
    OpenGL_Display::OpenGL_Display()
    {
     
     
    }
     
     
    OpenGL_Display::~OpenGL_Display()
    {
        KillGLWindow();
    }
     
     
    void OpenGL_Display::Init_Display(int width, int height, int posX, int posY)
    {
        if (!CreateGLWindow("Ophthametrics Live Display", width, height, 24, false, posX, posY))
        {
            throw;
        }    
    }
     
     
    LRESULT CALLBACK OpenGL_Display::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_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_SIZE:                                // Resize The OpenGL Window
            {
                oglDisp.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);
    }
     
     
     
     
    bool OpenGL_Display::CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag, int posX, int posY)
    {
        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
     
     
        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 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_Display";                                // Set The Class Name
     
     
        int error = 0;
        if ((error=RegisterClass(&wc))==0)                                    // Attempt To Register The Window Class
        {
            char* message = new char[256];
            sprintf_s(message, 256, "Failed To Register The Window Class. Error: %d", error);
            MessageBox(NULL, message,"ERROR",MB_OK|MB_ICONEXCLAMATION);
            delete message;
            return FALSE;                                            // Return FALSE
        }
     
     
     
     
        dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;            // Window Extended Style
        dwStyle=WS_VISIBLE | WS_POPUP |    WS_CLIPSIBLINGS | WS_CLIPCHILDREN;;                            // Windows Style
     
        AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);        // Adjust Window To True Requested Size
        //HWND hwndC = GetConsoleWindow();
        // Create The Window
        if (!(hWnd=CreateWindowEx(    dwExStyle,                            // Extended Style For The Window
                                    "OpenGL_Display",                    // Class Name
                                    title,                                // Window Title
                                    dwStyle |                            // Defined Window Style
                                    WS_CLIPSIBLINGS |                    // Required Window Style
                                    WS_CLIPCHILDREN,                    // Required Window Style
                                    posX, posY,                            // 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
    }
     
     
     
     
    int OpenGL_Display::LoadGLTextures()                                    // Load Bitmaps And Convert To Textures
    {
        // Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit
     
     
        glGenTextures(1, &texture);                    // Create The Texture
        // Typical Texture Generation Using Data From The Bitmap
        glBindTexture(GL_TEXTURE_2D, texture);
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); // Minimizing filter, in case display is smaller image size
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); // Magnifying filter, in case display is smaller image size
     
        return 1;                                        // Return The Status
    }
     
     
    GLvoid OpenGL_Display::ReSizeGLScene(GLsizei width, GLsizei height)        // Resize And Initialize The GL Window
    {
        if (height==0)                                        // Prevent A Divide By Zero
        {
            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(25.0f,1.0f,0.1f,100.0f);
     
     
        glMatrixMode(GL_MODELVIEW);                            // Select The Modelview Matrix
        glLoadIdentity();                                    // Reset The Modelview Matrix
    }
     
     
    int OpenGL_Display::InitGL(GLvoid)                                        // All Setup For OpenGL Goes Here
    {
        if (!LoadGLTextures())                                // Jump To Texture Loading Routine
        {
            return FALSE;                                    // If Texture Didn't Load Return FALSE
        }
     
     
        glEnable(GL_TEXTURE_2D);                            // Enable Texture Mapping
        glShadeModel(GL_SMOOTH);                            // Enable Smooth Shading
        glClearColor(0.0f, 0.0f, 0.0f, 0.5f);                // Black Background
        glClearDepth(1.0f);                                    // Depth Buffer Setup
        glDisable(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
    }
     
     
    void OpenGL_Display::UpdateGLBuffers(int width, int height, unsigned char* imageData) 
    {
        GLenum mError = glGetError();
        glBindTexture(GL_TEXTURE_2D, texture);
        mError = glGetError();
        glTexImage2D(GL_TEXTURE_2D, 0, GL_INTENSITY, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, imageData);
        mError = glGetError();
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
        mError = glGetError();
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
        mError = glGetError();
    }
     
     
    int OpenGL_Display::DrawGLScene(bool flip)                                    // Here's Where We Do All The Drawing
    {
        GLenum mError = glGetError();
        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);
        mError = glGetError();
        glBindTexture(GL_TEXTURE_2D, texture);
        mError = glGetError();
        glColor4f(1.0, 1.0, 1.0, 1.0);
        mError = glGetError();
        if(flip)
        {
            glBegin(GL_QUADS);
                // Front Face
                glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  0.5f);
                glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  0.5f);
                glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  0.5f);
                glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  0.5f);
            glEnd();
            mError = glGetError();
        }
        else
        {
            glBegin(GL_QUADS);
                // Front Face
                glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, -1.0f,  0.5f);
                glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, -1.0f,  0.5f);
                glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  0.5f);
                glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  0.5f);
            glEnd();
            mError = glGetError();
        }
        mError = glGetError();    
        return TRUE;                                        // Keep Going
    }
     
     
    GLvoid OpenGL_Display::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
        }
    }
     
     
    void OpenGL_Display::DrawNewImage(int width, int height, unsigned char* imageData, bool flip)
    {
        GLenum mError = glGetError();
     
        BOOL returnVal = wglMakeCurrent(hDC, hRC);
        mError = glGetError();
     
        UpdateGLBuffers(width, height, imageData);    
        DrawGLScene(flip);
        SwapBuffers(hDC);
    }
     
     
    extern "C" __declspec(dllexport) void OpenGLDisplay_Init(int width, int height, int posX, int posY)
    {
        oglDisp.Init_Display(width, height, posX, posY);
     
        GLenum mError = glGetError();
    }
     
     
    extern "C" __declspec(dllexport) void OpenGLDisplay_Wrapper(unsigned char* image, int width, int height, bool flip)
    {
        oglDisp.DrawNewImage(width, height, image, flip);    
    }

    .h:
    Code :
    #ifndef __OPENGLDISPLAY
    #define __OPENGLDISPLAY
    #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 <process.h>
     
     
    namespace OGD
    {
        class OpenGL_Display
        {
            public:
                OpenGL_Display();
                ~OpenGL_Display();
                void Init_Display(int width, int height, int posX, int posY);
                void DrawNewImage(int width, int height, unsigned char* imageData, bool flip);
                bool CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag, int posX, int posY);
                GLvoid ReSizeGLScene(GLsizei width, GLsizei height);
                int LoadGLTextures();
                int InitGL(GLvoid);
                void UpdateGLBuffers(int width, int height, unsigned char* imageData);
                int DrawGLScene(bool flip);
                GLvoid KillGLWindow(GLvoid);
                HDC            hDC;        // Private GDI Device Context
     
            protected:
                static LRESULT    CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);    // Declaration For WndProc
     
     
                HGLRC        hRC;        // Permanent Rendering Context
                HWND        hWnd;        // Holds Our Window Handle
                HINSTANCE    hInstance;        // Holds The Instance Of The Application
     
     
                bool    keys[256];            // Array Used For The Keyboard Routine
                bool    active;        // Window Active Flag Set To TRUE By Default
                bool    fullscreen;    // Fullscreen Flag Set To Fullscreen Mode By Default
                bool    g_bExitThread; // end thread
                GLuint    texture;            // Bitmap image buffer
                int        g_iCounter;        // Current buffer being grabbed to
                bool    g_GLdone;    // Counter to make sure no unnecessary updates are made which cause CPU load
        };
    };
     
     
    extern "C" __declspec(dllexport) void OpenGLDisplay_Wrapper(unsigned char* image, int width, int height, bool flip);
    extern "C" __declspec(dllexport) void OpenGLDisplay_Init(int width, int height, int posX, int posY);
     
     
    static OGD::OpenGL_Display oglDisp;
    #endif
    Last edited by SinisterMJ; 01-14-2013 at 09:39 AM.

  2. #2
    Junior Member Newbie
    Join Date
    Feb 2011
    Posts
    9
    I had to call wglMakeCurrent(NULL, NULL); from the initiation now it works fine.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •