Question

I have a problem when rendering cubes in OpenGL.I am drawing two cubes, one is a wire cube and is centered around the origin, while the other is offset from the origin and is solid. I have mapped some keys to rotate the objects by some degrees wrt to the origin, so the whole scene can rotate around the origin.

The problem is, when I render the scene, when the wire cube is supposed to be infront of the other solid cube, it does not display itself correctly.

In the image above, the colored cube is supposed to be behind the wire cube. i.e. the green wire cube should be on top.

Also the cube is not behaving properly.

After I rotate it a little bit around the x axis (current horizontal line).

The cube has missing faces and is not rendering correctly.
What am I doing wrong?

I have coded the following
Note that rotateX,rotateY,rotateZ are mapped to keys, and are my global rotation variables.

//The Initialize function, called once:    
void Init(){
    glEnable(GL_TEXTURE_2D); 
    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);                            // Depth Buffer Setup                       // Enables Depth Testing
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  // Really Nice Perspective Calculations
    glEnable(GL_LIGHTING);
}

void draw(){
    //The main draw function
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity ();
    gluPerspective(45, 640/480.0, .5, 100);

    glMatrixMode(GL_MODELVIEW); //select the modelview matrix.
    glLoadIdentity ();
    gluLookAt(0,0,5,
              0,0,0,
              0,1,0);    

    glRotatef(rotateX,1,0,0);
    glRotatef(rotateY,0,1,0);
    glRotatef(rotateZ,0,0,1);
    drawScene();  // this just draws the main axis lines,

    glutWireCube(1);  

    glPopMatrix();
    glPushMatrix();
    glTranslatef(-2,1,0);
    drawNiceCube();
    glPopMatrix();

    glutSwapBuffers();
}

The code for the drawNiceCube() is just using GL_QUADS, while the drawWireCube is built in in GLUT.

EDIT:
I have posted the full code at http://pastebin.com/p1kwPjEM, sorry if it is not well documented.

Answer 1

datenwolf solved my problem. I quote him:

“@JonathanSimbahan: Parts of your code are redundant, but something is missing: You forgot to call Init(); after creating your GLUT window, hence depth testing and all the other state never get enabled. I for one suggest you don’t use Init at all and move it’s code into the drawing code, where it actually belongs.”