glClearColor and glClear under glFrustum

OpenGL OpenGL: Basic Coding
1

Hello gentlemen.

I’ve been working with ortho 2D projections for long time.

Nowadays i’ve started C++ classes to:
-> perform camera operations
-> to use glFrustum as a perspective camera.

All the camera and frustum operations/configuration and visualization are ok. But when i make my camera to zoom out couple of times i see that my background becames smaller than my viewport.

Do the background can be smaller than the viewport ???
Maybe I’m telling something wrong but i believe yes if the camera is out of the box of visualization.

an example of my renderization code is:


void draw( void )
{
    glViewport( 0, 0, window_wid, window_height );

    glMatrixMode( GL_PROJECTION );
       glLoadIdentity();
       glFrustum( my_frustum );

    glMatrixMode( GL_MODELVIEW );
       glLoadIdentity();
       camera->postAttitudeAndTranslation();

    glClearColor( my_bkg_color );
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    for( unsigned i = 0; i < objects.size(); ++i )
    {
        glPushMatrix();
            objects[ i ].callDisplayList();
        glPopMatrix();
    }

    glFlush();
}