Make an Add-on

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Add-ons are made by members of Celestia community who are not necessarily developers of Celestia program. Making an add-on doesn't require extensive programming knowledge. You can make them too!

Read the Wiki

Addon Tutorials for Beginners is a good place to start. It introduces the basic concepts of making add-ons, what you can change in Celestia with add-ons, etc.

Start with an Existing Add-on

After understanding the file formats used by Celestia, it is recommended to modify an existing add-on to get a head start. Download an add-on inside the app and follow Use Add-ons and Scripts to find out where the add-on is installed. Explore by changing a few fields in the files that you are interested in. Run the app again to see if changes are effective.

Special Notes

1. Use a supported texture file format. For example, an .heic image from iPhone camera capture is not supported and must be converted first.
2. Check texture resolutions. Textures should be in power of 2 (e.g. 1024x1024, 1024x2048). Not all devices support textures with resolutions that are not power of 2.
3. Format your catalog files. For example, check if the brackets are balanced.
4. Check File names. Avoid having special characters in file and directory names.
5. Ensure file references (for example, referencing texture file in a catalog file) match the exact casing of the source filename. On case-sensitive filesystems, it is required for file lookup.

Share Your Add-on

Zip up your add-on (only .zip archive is supported) and you can upload your add-on to the in-app add-on categories with celestia-addon-validator.