# Celestia/Display Options
## Introduction

When Celestia starts, by default it shows a 3D image in a window on the computer's main screen. Depending on its user interface, Celestia may be able to occupy the entire screen.
Image quality can be improved somewhat, too.

### Size
#### Linux

Celestia starts in a window, you can exter/exit fullscreen mode by typing Alt-Enter.

#### Mac OS X

Celestia starts in a window whose position and size are saved. Enter/exit fullscreen mode by typing Cmd(Apple)+F. Move your mouse to the top of the screen when in fullscreen mode to access the menu bar.
Right-clicking (control-clicking) on objects to bring up a context menu, switching to other applications, hide, and opening panels like Preferences and Help continue to work 100% in full screen mode. Multiple screens should be detected properly, although when switching to fullscreen mode Celestia currently only targets the screen which is most covered by the Celestia window.
Various display options can be accessed from Celestia > Preferences or the Display menu.

#### Windows XP, Vista and 7

Celestia starts in a window which is located in the same place and at the same size as when Celestia previously exited. The menu "Render / Select display mode..." provides access to the list of full-screen resolutions claimed to be supported by the graphics display. Once the default resolution has been configured using that menu, you can exter and exit fullscreen mode by typing Alt-Enter.

### Edges

By default, Celestia does not enable anti-aliasing. This means that you'll see stair-step jaggies and moving dots on the edges of objects, especially on diagonal lines. Turning on anti-aliasing will make the display run more slowly, but objects will look better.
Celestia includes two different anti-aliasing options: a menu and keyboard option to smooth the orbital path lines, and a configuration file option to enable full-screen anti-aliasing.
You can separately enable various levels of full-screen antialiasing in the controls for your graphics hardware. This will affect all 3D programs, not just Celestia.

#### Menu and keyboard (orbit smoothing)

The Windows menu option Render/Antialiasing turns on hardware smoothing of the orbital path lines.
(What are the corresponding Linux, and MacOS menu options?)
The keyboard command Ctrl-X is available in all versions of Celestia to toggle this display rendering option.

#### celestia.cfg (full screen)

To enable full-screen antialiasing within Celestia, edit the file celestia.cfg. Find the line which currently says
# AntialiasingSamples 4
and delete the #. If your graphics hardware supports higher levels of antialiasing, you can increase its value appropriately. This feature will work only if your graphics hardware has been configured to allow application control of antialiasing.

#### hardware control panel (full screen)

Alternatively, you can open the software control panel for your graphics hardware and turn on its antialiasing features permanently. This will affect all 3D programs, not just Celestia.
In either case, while the edges of objects will look much better, Celestia will run more slowly. The framerate reduction will depend on the quality of your graphics hardware.