def draw_gl( self ): n = self.n r = self.r vt = Vec( 1,2,3 ).norm() if vt == n: vt = Vec( 3,2,1 ).norm() v1 = vt.vcross( n ) v2 = v1.vcross( n ) v1,v2,v3,v4 = r + v1+v2, r + v1-v2, r + v2-v1, r -v1-v2 glBegin( GL_LINES ) glVertex3f( *v1 ) glVertex3f( *v4 ) glVertex3f( *v2 ) glVertex3f( *v3 ) glVertex3f( *v1 ) glVertex3f( *v2 ) glVertex3f( *v1 ) glVertex3f( *v3 ) glVertex3f( *v3 ) glVertex3f( *v4 ) glVertex3f( *v2 ) glVertex3f( *v4 ) glEnd( )