Don't fetch lots of axes state information for rendering if object is not visible. * gl-render.cc (opengl_renderer::draw_axes_planes): Check axes color and visibility and return immediately from function if there is nothing to do. * gl-render.cc (opengl_renderer::draw_axes_boxes): Check axes visibility and return immediately from function if there is nothing to do. * gl-render.cc (opengl_renderer::draw_axes_x_grid, drax_axes_y_grid, draw_axes_z_grid): Check axes state and visibility before bothering to fetch any more state data. * gl-render.cc (miscellaneous): Clean up comments. Change lines to wrap at < 80 chars. * graphics.cc (axes::properties::update_axes_layout): Use std::swap instead of intermediate temporary variable for clearer coding style.