// The purpose of this function is to draw the objects to the screen
void Draw()
{
    glMatrixMode(GL_PROJECTION); // set the view volume shape
    glLoadIdentity();
    glOrtho(-worldx, worldx, -worldy, worldy, 0.1, 100);

    glMatrixMode(GL_MODELVIEW); // position and aim the camera
    glLoadIdentity();

    gluLookAt(eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ);

    // Check if user inputs 'i' or 'I' from the keyboard
    if (original)
    {
        OriginalView();
        original = false;
    }


    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the screen
    for (int i=0; i<37; i++)
    {
        GLfloat mat_ambient[] = {0.0, 0.5, 0.8, 1.0 };
        glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
        cancer.DrawNormalCell(cancer.v[i].x,cancer.v[i].y,cancer.v[i].z);
    }

    if (drawCancer)
    {
        for (int i=0; i<37; i++)
        {
            GLfloat mat_ambient[] = {0.8, 0.0, 0.2, 1.0 };
            glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
            cancer.DrawCancerCell(cancer.v[19].x,cancer.v[19].y,cancer.v[19].z);
    }

    glutSwapBuffers();
}