Glew problems, unresolved externals

Question

I want to start working with OpenGL 3+ and 4 but I'm having problems getting Glew to work. I have tried to include the glew32.lib in the Additional Dependencies and I have moved the library, and .dll into the main folder so there shouldn't be any path problems. The errors I'm getting are:

Error   5   error LNK2019: unresolved external symbol __imp__glewInit referenced in function "void __cdecl init(void)" (?init@@YAXXZ)   C:\Users\Mike\Desktop\Test Folder\ModelLoader through VBO\ModelLoader\main.obj  ModelLoader
Error   4   error LNK2019: unresolved external symbol __imp__glewGetErrorString referenced in function "void __cdecl init(void)" (?init@@YAXXZ) C:\Users\Mike\Desktop\Test Folder\ModelLoader through VBO\ModelLoader\main.obj  ModelLoader
Error   3   error LNK2001: unresolved external symbol __imp____glewGenBuffers   C:\Users\Mike\Desktop\Test Folder\ModelLoader through VBO\ModelLoader\main.obj  ModelLoader
Error   1   error LNK2001: unresolved external symbol __imp____glewBufferData   C:\Users\Mike\Desktop\Test Folder\ModelLoader through VBO\ModelLoader\main.obj  ModelLoader
Error   2   error LNK2001: unresolved external symbol __imp____glewBindBuffer   C:\Users\Mike\Desktop\Test Folder\ModelLoader through VBO\ModelLoader\main.obj  ModelLoader

And here is most of my code:

#define NOMINMAX

#include <vector>
#include <memory>
#include <string>
#include <iostream>
#include <fstream>
#include <sstream>
#include <Windows.h>
#include <cstdio>
#include <time.h>
#include "GL\glew.h"
#include "glut.h"

#pragma comment(lib, "glew32.lib")
#pragma comment(lib, "opengl32.lib")

using namespace std;

GLsizei screen_width, screen_height;

float camera[3] = {0.0f, 10.0f, -15.0f};

float xPos = 0;
float yPos = 10;
float zPos = -15;
float orbitDegrees = 0;

clock_t sTime;
float fPS;
int fCount;

GLdouble* modelV;
GLdouble* projM;
GLint* vPort;

//Lights settings
GLfloat light_ambient[]= { 0.1f, 0.1f, 0.1f, 0.1f };
GLfloat light_diffuse[]= { 1.0f, 1.0f, 1.0f, 0.0f };
GLfloat light_specular[]= { 1.0f, 1.0f, 1.0f, 0.0f };
GLfloat light_position[]= { 100.0f, 0.0f, -10.0f, 1.0f };

//Materials settings
GLfloat mat_ambient[]= { 0.5f, 0.5f, 0.0f, 0.0f };
GLfloat mat_diffuse[]= { 0.5f, 0.5f, 0.0f, 0.0f };
GLfloat mat_specular[]= { 1.0f, 1.0f, 1.0f, 0.0f };
GLfloat mat_shininess[]= { 1.0f };

typedef struct Vectors {
    float x;
    float y;
    float z;
}Vector;

typedef struct Polys {
    Vector v;
    Vector vt;
    Vector vn;
    int texture;
} Poly;

vector<Vector> vecs;
vector<Vector> normVecs;
vector<Vector> textVecs;

vector<Poly> polyList;


void loadModel(string filepath);
void createTex(string ref);
void render();

// An array of 3 vectors which represents 3 vertices
static const GLfloat g_vertex_buffer_data[] = {
   -1.0f, -1.0f, 0.0f,
   1.0f, -1.0f, 0.0f,
   0.0f,  1.0f, 0.0f,
};

void render()
{
}

void createTex(string ref)
{
}

void loadModel(string filepath)
{
}

void resize (int p_width, int p_height)
{
    if(screen_width==0 && screen_height==0) exit(0);
    screen_width=p_width; // Obtain the new screen width values and store it
    screen_height=p_height; // Height value

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear both the color and the depth buffer so to draw the next frame
    glViewport(0,0,screen_width,screen_height); // Viewport transformation

    glMatrixMode(GL_PROJECTION); // Projection transformation
    glLoadIdentity(); // Initialize the projection matrix as identity
    gluPerspective(45.0f,(GLfloat)screen_width/(GLfloat)screen_height,1.0f,10000.0f);

    glutPostRedisplay(); // This command redraw the scene (it calls the same routine of glutDisplayFunc)
}

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // This clear the background color to dark blue
    glMatrixMode(GL_MODELVIEW); // Modeling transformation
    glPushMatrix();
    glLoadIdentity(); // Initialize the model matrix as identity

    gluLookAt(xPos, yPos, zPos, /* look from camera XYZ */
               0, yPos, 0, /* look at the origin */
               0, 1, 0); /* positive Y up vector */

    glRotatef(orbitDegrees, 0.f, 1.0f, 0.0f);
    //glTranslatef(0.0,0.0,-20); // We move the object forward (the model matrix is multiplied by the translation matrix)
    //rotation_x = 30;
    //rotation_x = rotation_x + rotation_x_increment;
   //rotation_y = rotation_y + rotation_y_increment;
       //rotation_z = rotation_z + rotation_z_increment;

   //if (rotation_x > 359) rotation_x = 0;
   //if (rotation_y > 359) rotation_y = 0;
   //if (rotation_z > 359) rotation_z = 0;

   //  glRotatef(rotation_x,1.0,0.0,0.0); // Rotations of the object (the model matrix is multiplied by the rotation matrices)
   //glRotatef(rotation_y,0.0,1.0,0.0);
   //    glRotatef(rotation_z,0.0,0.0,1.0);

    //if (objarray[0]->id_texture!=-1) 
    //{
    //  glBindTexture(GL_TEXTURE_2D, objarray[0]->id_texture); // We set the active texture 
    //    glEnable(GL_TEXTURE_2D); // Texture mapping ON
    //  printf("Txt map ON");
    //}
    //else
    //    glDisable(GL_TEXTURE_2D); // Texture mapping OFF

    glGetDoublev(GL_PROJECTION_MATRIX, modelV);

    glGetDoublev(GL_PROJECTION_MATRIX, projM);

    glGetIntegerv(GL_VIEWPORT, vPort);

    if(clock() > sTime)
    {
        fPS = fCount;
        fCount = 0;
        sTime = clock() + CLOCKS_PER_SEC;
    }

    render();

    glDisable(GL_LIGHTING);

    GLdouble pos[3];

    gluUnProject(100, yPos, -14, modelV, projM, vPort, &pos[0], &pos[1], &pos[2]);

    char buffer2[255];

    int pAmmount = sprintf(buffer2,"FPS: %.2f", fPS);

    //glRasterPos3f(pos[0], pos[1], pos[2]);

    for(int i = 0; i < pAmmount; i++)
    {
        glutBitmapCharacter(GLUT_BITMAP_TIMES_ROMAN_24, buffer2[i]);
    }

    glEnable(GL_LIGHTING);

    /*glPopMatrix();
    glPushMatrix();
    glTranslatef(5.0,0.0,-20.0);
    objarray[1]->render();*/
    glPopMatrix();
    glFlush(); // This force the execution of OpenGL commands
    glutSwapBuffers(); // In double buffered mode we invert the positions of the visible buffer and the writing buffer
    fCount++;
}

void keyboard(unsigned char k, int x, int y)
{
    switch(k)
    {
        case 'w':
                yPos++;
        break;
        case 's':
            yPos--;
        break;
        case 'a':
            xPos--;
        break;
        case 'd':
            xPos++;
        break;
        case 'q':
        orbitDegrees--;
        break;
        case 'e':
            orbitDegrees++;
        break;
        case 'z':
            zPos--;
        break;
        case 'x':
            zPos++;
        break;
    }
}

void initWindow(GLsizei screen_width, GLsizei screen_height)
{
    glClearColor(0.0, 0.0, 0.0, 0.0); // Clear background color to black

    // Viewport transformation
    glViewport(0,0,screen_width,screen_height);

    // Projection transformation
    glMatrixMode(GL_PROJECTION); // Specifies which matrix stack is the target for matrix operations 
    glLoadIdentity(); // We initialize the projection matrix as identity
   gluPerspective(45.0f,(GLfloat)screen_width/(GLfloat)screen_height,1.0f,10000.0f); // We define the "viewing volume"

    gluLookAt(camera[0], camera[1], camera[2], /* look from camera XYZ */
               0, 0, 0, /* look at the origin */
               0, 1, 0); /* positive Y up vector */

    try
    {
        //loadModel("Goku habit dechiré.obj");
        loadModel("Flooring.obj");;
    }
    catch(string& filepath)
    {
        cerr << "Model could not be loaded: " << filepath << endl;

        filepath = "Model could not be loaded: " + filepath;

        wostringstream sString;

        sString << filepath.c_str();

        MessageBox(HWND_DESKTOP, sString.str().c_str(), L"Error: loadModel(string filepath)", MB_OK);
    }

    //Lights initialization and activation
    glLightfv (GL_LIGHT1, GL_AMBIENT, light_ambient);
    glLightfv (GL_LIGHT1, GL_DIFFUSE, light_diffuse);
    glLightfv (GL_LIGHT1, GL_DIFFUSE, light_specular);
    glLightfv (GL_LIGHT1, GL_POSITION, light_position);    
    glEnable (GL_LIGHT1);
    glEnable (GL_LIGHTING);

    //Materials initialization and activation
    glMaterialfv (GL_FRONT, GL_AMBIENT, mat_ambient);
    glMaterialfv (GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv (GL_FRONT, GL_DIFFUSE, mat_specular);
    glMaterialfv (GL_FRONT, GL_POSITION, mat_shininess);

    //Other initializations
    glShadeModel(GL_SMOOTH); // Type of shading for the polygons
    //glHint (GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Texture mapping perspective correction
    //glEnable(GL_TEXTURE_2D); // Texture mapping ON
    glPolygonMode (GL_FRONT_AND_BACK, GL_FILL); // Polygon rasterization mode (polygon filled)
    glEnable(GL_CULL_FACE); // Enable the back face culling
    glEnable(GL_DEPTH_TEST); // Enable the depth test 
    glEnable(GL_NORMALIZE);

    /*float* matrix = new float[16];

    glGetFloatv(GL_PROJECTION_MATRIX, matrix);

    for(int i = 0; i < 4; i++)
    {
        cout << matrix[0] << " " << matrix[1] << " " << matrix[2] << " " << matrix[3] << endl;
        matrix += 3;
    }*/

    modelV = new GLdouble[16];

    projM = new GLdouble[16];

    vPort = new GLint[4];

    sTime = clock() + CLOCKS_PER_SEC;
}

void init()
{
    GLenum GlewInitResult;

    GlewInitResult = glewInit();

    if (GLEW_OK != GlewInitResult) {
        fprintf(
            stderr,
            "ERROR: %s\n",
            glewGetErrorString(GlewInitResult)
        );
        exit(EXIT_FAILURE);
    }

    // This will identify our vertex buffer
    GLuint vertexbuffer;

    // Generate 1 buffer, put the resulting identifier in vertexbuffer
    glGenBuffers(1, &vertexbuffer);

    // The following commands will talk about our 'vertexbuffer' buffer
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);

    // Give our vertices to OpenGL.
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
}

int main(int argc, char **argv)
{
    screen_width = 800;
    screen_height = 800;

    glutInit(&argc, argv);    
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(screen_width,screen_height);
    glutInitWindowPosition(0,0);
    glutCreateWindow("ModelLoader");    
    glutDisplayFunc(display);
    glutIdleFunc(display);
    glutReshapeFunc (resize);
    glutKeyboardFunc(keyboard);

    //glutKeyboardFunc(keyboard);
    //glutSpecialFunc(keyboard_s);
    initWindow(screen_width, screen_height);
    init();
    glutMainLoop();

    return 0;
}

Answer 1

You have a linkage problem. You are not providing to the linker the correct path to the glew lib file. For this reason the linker is not able to find the compiled code of the functions you are calling.

From your log it seems you are working on Windows. If you are using Visual Studio, right click on you project. Select Linker, and then Input. Verify that Additional dependencies contains the path to glew lib.

Notice that the dll is not required at linking time. This will be loaded only at run time (remember to put it in the same folder as your executable or in a path listed in your system path).

Answer 2

This has been fixed. The problem was only represented on the machine I was using in University. The problem was that the machine had an older .dll which was conflicting with the .dll that I had in the solution files. It was installed in the System files of the machine. As such it was producing these errors.

I should probably check for such a thing next time.

Answer 3

Not sure how it will help you but, you might give a try and statically link your project to a ".a" library. or it's .lib on windows. If there are unresolved symbol it means it tried to link to a library and not really to a dll.

If it was using the dll, it would probably fail at runtime.