glColor4f(1.00f, 0.00f, 0.00f, 1.0f);
    glBegin(GL_LINES);
    glVertex3f( 0.0f,  0.0f,  0.0f);
    glVertex3f( 100.0f,  0.0f,  0.0f);
    glEnd();

    QColor halfGreen(0, 128, 0, 255);
    qglColor(halfGreen);
    glBegin(GL_LINES);
    glVertex3f( 0.0f,  0.0f,  0.0f);
    glVertex3f( 0.0f,  100.0f,  0.0f);

    glColor4f(0.00f, 0.00f, 1.00f, 1.0f);
    glVertex3f( 0.0f,  0.0f,  0.0f);
    glVertex3f( 0.0f,  0.0f,  100.0f);
    glEnd();