C++ OpenGL wireframe cube rendering blank

Question

I'm just trying to draw a bunch of lines that make up a "cube". I can't for the life of me figure out why this is producing a black screen. The debugger does not break at any point.

I'm sure it's a problem with my pointers, as I'm only decent at them in regular c++ and in OpenGL it gets even worse.

const char* vertexSource = 
    "#version 150\n"
    "in vec3 position;"
    "void main() {"
    "   gl_Position = vec4(position, 1.0);"
    "}";

const char* fragmentSource = 
    "#version 150\n"
    "out vec4 outColor;"
    "void main() {"
    "   outColor = vec4(1.0, 1.0, 1.0, 1.0);"
    "}";

int main() {

    initializeGLFW();

    // Initialize GLEW
    glewExperimental = GL_TRUE;
    glewInit();

    // Create Vertex Array Object
    GLuint vao;
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);

    // Create a Vertex Buffer Object and copy the vertex data to it
    GLuint vbo;
    glGenBuffers( 1, &vbo );

    float vertices[] = {
         1.0f,  1.0f,  1.0f, // Vertex 0 (X, Y, Z)
        -1.0f,  1.0f,  1.0f, // Vertex 1 (X, Y, Z)
        -1.0f, -1.0f,  1.0f, // Vertex 2 (X, Y, Z)
         1.0f, -1.0f,  1.0f, // Vertex 3 (X, Y, Z)
         1.0f,  1.0f, -1.0f, // Vertex 4 (X, Y, Z)
        -1.0f,  1.0f, -1.0f, // Vertex 5 (X, Y, Z)
        -1.0f, -1.0f, -1.0f, // Vertex 6 (X, Y, Z)
         1.0f, -1.0f, -1.0f  // Vertex 7 (X, Y, Z)
    };

    GLuint indices[] = {
        0, 1,
        1, 2,
        2, 3,
        3, 0,
        4, 5,
        5, 6,
        6, 7,
        7, 4,
        0, 4,
        1, 5,
        2, 6,
        3, 7
    };

    glBindBuffer( GL_ARRAY_BUFFER, vbo );
    glBufferData( GL_ARRAY_BUFFER, sizeof( vertices ), vertices, GL_STATIC_DRAW );
    //glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vbo);
    //glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof( indices ), indices, GL_STATIC_DRAW );

    // Create and compile the vertex shader
    GLuint vertexShader = glCreateShader( GL_VERTEX_SHADER );
    glShaderSource( vertexShader, 1, &vertexSource, NULL );
    glCompileShader( vertexShader );

    // Create and compile the fragment shader
    GLuint fragmentShader = glCreateShader( GL_FRAGMENT_SHADER );
    glShaderSource( fragmentShader, 1, &fragmentSource, NULL );
    glCompileShader( fragmentShader );

    // Link the vertex and fragment shader into a shader program
    GLuint shaderProgram = glCreateProgram();
    glAttachShader( shaderProgram, vertexShader );
    glAttachShader( shaderProgram, fragmentShader );
    glBindFragDataLocation( shaderProgram, 0, "outColor" );
    glLinkProgram (shaderProgram);
    glUseProgram( shaderProgram);

    // Specify the layout of the vertex data
    GLint posAttrib = glGetAttribLocation( shaderProgram, "position" );
    glEnableVertexAttribArray( posAttrib );
    glVertexAttribPointer( posAttrib, 3, GL_FLOAT, GL_FALSE, 0, 0 );

    // Main loop
    while(glfwGetWindowParam(GLFW_OPENED)) {

        // Clear the screen to black
        glClearColor( 0.0f, 0.0f, 0.0f, 1.0f );
        glClear( GL_COLOR_BUFFER_BIT );

        // Draw lines from 2 vertices
        glDrawElements(GL_LINES, sizeof(indices), GL_UNSIGNED_INT, indices );

        // Swap buffers
        glfwSwapBuffers();
    }

    // Clean up
    glDeleteProgram( shaderProgram );
    glDeleteShader( fragmentShader );
    glDeleteShader( vertexShader );

    //glDeleteBuffers( 1, &ebo );
    glDeleteBuffers( 1, &vbo );

    glDeleteVertexArrays( 1, &vao );

    glfwTerminate();
    exit( EXIT_SUCCESS );
}

Answer 1

You have no view or projection matrix, so your view volume is a cube 2 units wide and 2 units high and centred on the origin.

Coincidentally, you are drawing a cube that is 2 units wide and 2 units high and centred on the origin. So your cube is getting draw just on the outside edge the view volume.

Draw a smaller cube (use +/-0.5f for vertex coords) and you should see something.

That's assuming that the rest of the code is fine...