Question

I have an opengl c++ code for reading .ply file. I want to read keyboard arrow keys(up,down,right,left) for move a point on the screen. I used glutKeyboardFunc function but i have an error:

Unhandled exception at 0x1000bb1e in opengl3.exe: 0xC0000005: Access violation reading location 0x00000070.

On this line:

glutKeyboardFunc(keyPressed);

#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glut.h>
 #include <iostream>
#include <stdio.h>
#include <string.h>
#include <cmath>
#include <string>
#include <conio.h>
HWND    hWnd;
HDC     hDC;
HGLRC   hRC;

// Set up pixel format for graphics initialization
void SetupPixelFormat()
{
    PIXELFORMATDESCRIPTOR pfd, *ppfd;
    int pixelformat;

    ppfd = &pfd;

    ppfd->nSize = sizeof(PIXELFORMATDESCRIPTOR);
    ppfd->nVersion = 1;
    ppfd->dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
    ppfd->dwLayerMask = PFD_MAIN_PLANE;
    ppfd->iPixelType = PFD_TYPE_COLORINDEX;
    ppfd->cColorBits = 16;
    ppfd->cDepthBits = 16;
    ppfd->cAccumBits = 0;
    ppfd->cStencilBits = 0;

    pixelformat = ChoosePixelFormat(hDC, ppfd);
    SetPixelFormat(hDC, pixelformat, ppfd);
}

void InitGraphics()
{
    hDC = GetDC(hWnd);

    SetupPixelFormat();

    hRC = wglCreateContext(hDC);
    wglMakeCurrent(hDC, hRC);

    glClearColor(0, 0, 0, 0.5);
    glClearDepth(1.0);
    glEnable(GL_DEPTH_TEST);
}

// Resize graphics to fit window
void ResizeGraphics()
{
    // Get new window size
    RECT rect;
    int width, height;
    GLfloat aspect;

    GetClientRect(hWnd, &rect);
    width = rect.right;
    height = rect.bottom;
    aspect = (GLfloat)width / height;

    // Adjust graphics to window size
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0, aspect, 1.0, 100.0);
    glMatrixMode(GL_MODELVIEW);
}

// Draw frame
void DrawGraphics()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Set location in front of camera
    glLoadIdentity();
    glTranslated(0, 0, -10);

    // Draw a square
    glBegin(GL_QUADS);
    glColor3d(100, 200, 30);
    /*
    glVertex3d(-2, 2, 0);
    glVertex3d(2, 2, 0);
    glVertex3d(2, -2, 0);
    glVertex3d(-2, -2, 0);
    */






    //FILE * file = fopen("D:\\dart.ply","r");
    FILE * file = fopen("mosalas.ply","r");
        if (file!=NULL)
  {
        fseek(file,0,SEEK_END);
        long fileSize = ftell(file);
        float* Vertex_Buffer;
        try
        {
        Vertex_Buffer = (float*) malloc (ftell(file));
        }
        catch (char* )
        {
            //return -1;
        }
        //if (Vertex_Buffer == NULL) return -1;
        fseek(file,0,SEEK_SET); 

       //Faces_Triangles = (float*) malloc(fileSize*sizeof(float));
       //Normals  = (float*) malloc(fileSize*sizeof(float));

       if (file)
       {
            int i = 0;   
            int temp = 0;
            int quads_index = 0;
            int triangle_index = 0;
            int normal_index = 0;
            char buffer[1000];


            fgets(buffer,300,file);         // ply


            // READ HEADER
            // -----------------
            int TotalConnectedPoints;
            // Find number of vertexes
            while (  strncmp( "element vertex", buffer,strlen("element vertex")) != 0  )
            {
                fgets(buffer,300,file);         // format
            }
            strcpy(buffer, buffer+strlen("element vertex"));
            sscanf(buffer,"%i", &TotalConnectedPoints);

            int TotalFaces;
            // Find number of face
            fseek(file,0,SEEK_SET);
            while (  strncmp( "element face", buffer,strlen("element face")) != 0  )
            {
                fgets(buffer,300,file);         // format
            }
            strcpy(buffer, buffer+strlen("element face"));
            sscanf(buffer,"%i", &TotalFaces);


            // go to end_header
            while (  strncmp( "end_header", buffer,strlen("end_header")) != 0  )
            {
                fgets(buffer,300,file);         // format
            }
            i =0;
            float* ver0,ver1,ver2,ver3;
            //char* key[100];

            for (int iterator = 0; iterator < TotalConnectedPoints; iterator++)
            {
                fgets(buffer,300,file);

                //sscanf(buffer,"%f %f %f", &Vertex_Buffer[i], &Vertex_Buffer[i+1], &Vertex_Buffer[i+2]);
                sscanf(buffer,"%f %f %f", &ver1, &ver2, &ver3);
                glNormal3f(ver1, ver2, ver3);
                glVertex3d(ver1, ver2, ver3);

                //glVertex3f(ver1, ver2, ver3);

                i += 3;
            }

       }

}



    glPushMatrix();
glBegin;
glTranslatef(-10,5,0);
glColor3f(1,1,1);
glRotatef(90,0,1,0); 
glutSolidCone(0.25, 15, 20, 20);
glEnd();
glPopMatrix();
    //glutMouseFunc(0,0,0);







    /*
    glVertex3d(1.000000, 1.000000, 6);
    glVertex3d(3.000000, 0.000000, 4);
    glVertex3d(0.000000, 0.000000, 4);
    glVertex3d(0.000000, 3.000000, 4);
    glVertex3d(1.500000, 0.500000, 0);*/





    glEnd();

    // Show the new scene
    SwapBuffers(hDC);/**/
}
void keyPressed (unsigned char key, int x, int y) {  
}  
// Handle window events and messages
LONG WINAPI MainWndProc (HWND hWnd, UINT uMsg, WPARAM  wParam, LPARAM  lParam)
{
    switch (uMsg)
    {
    case WM_SIZE:
        ResizeGraphics();
        break;

    case WM_CLOSE: 
        DestroyWindow(hWnd);
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    // Default event handler
    default: 
        return DefWindowProc (hWnd, uMsg, wParam, lParam); 
        break; 
    } 

    return 1; 
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{

    const LPCWSTR appname = TEXT("OpenGL Sample");

    WNDCLASS wndclass;
    MSG      msg;

    // Define the window class
    wndclass.style         = 0;
    wndclass.lpfnWndProc   = (WNDPROC)MainWndProc;
    wndclass.cbClsExtra    = 0;
    wndclass.cbWndExtra    = 0;
    wndclass.hInstance     = hInstance;
    wndclass.hIcon         = LoadIcon(hInstance, appname);
    wndclass.hCursor       = LoadCursor(NULL,IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wndclass.lpszMenuName  = appname;
    wndclass.lpszClassName = appname;

    // Register the window class
    if (!RegisterClass(&wndclass)) return FALSE;

    // Create the window
    hWnd = CreateWindow(
            appname,
            appname,
            WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
            CW_USEDEFAULT,
            CW_USEDEFAULT,
            800,
            600,
            NULL,
            NULL,
            hInstance,
            NULL);

    if (!hWnd) return FALSE;

    // Initialize OpenGL
    InitGraphics();

    // Display the window
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
    DrawGraphics();
    // Event loop
    int key;
    int asgh = 0;
    POINT pt;
    /**/while (1)
    {
        if (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE) == TRUE)
        {
            if (!GetMessage(&msg, NULL, 0, 0))
                return TRUE;

            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }



        glutKeyboardFunc(keyPressed);
        DrawGraphics();
    }

    wglDeleteContext(hRC);
    ReleaseDC(hWnd, hDC);


}

Answer 1

The program you posted lacks a call to glutInit().

Furthermore you’re doing all of the platform-specific window management and context creation that GLUT is supposed abstract away.

Bottom line: If you want to use GLUT, use GLUT. If you want to use Win32, use Win32. Don’t try to mix-and-match.