glfw draw line
glColor3f(1.0,0.0,0.0); // red x
glBegin(GL_LINES);
// x aix
glVertex3f(-4.0, 0.0f, 0.0f);
glVertex3f(4.0, 0.0f, 0.0f);
glVertex3f(4.0, 0.0f, 0.0f);
glVertex3f(3.0, 1.0f, 0.0f);
glVertex3f(4.0, 0.0f, 0.0f);
glVertex3f(3.0, -1.0f, 0.0f);
glEnd();
// y
glColor3f(0.0,1.0,0.0); // green y
glBegin(GL_LINES);
glVertex3f(0.0, -4.0f, 0.0f);
glVertex3f(0.0, 4.0f, 0.0f);
glVertex3f(0.0, 4.0f, 0.0f);
glVertex3f(1.0, 3.0f, 0.0f);
glVertex3f(0.0, 4.0f, 0.0f);
glVertex3f(-1.0, 3.0f, 0.0f);
glEnd();
// z
glColor3f(0.0,0.0,1.0); // blue z
glBegin(GL_LINES);
glVertex3f(0.0, 0.0f ,-4.0f );
glVertex3f(0.0, 0.0f ,4.0f );
glVertex3f(0.0, 0.0f ,4.0f );
glVertex3f(0.0, 1.0f ,3.0f );
glVertex3f(0.0, 0.0f ,4.0f );
glVertex3f(0.0, -1.0f ,3.0f );
glEnd();