A game project usually consists of a large number of external assets that are produced in various specialized programs for producing graphics, 3D models, sound files, animations and so forth. Defold is built for a workflow where you work in your external tools and then import the assets into Defold as they are finalized.
Defold needs all the assets used in your project to be located somewhere in the project hierarchy. You therefore need to import all assets before you can use them. To import assets, simply drag the files from the file system on your computer and drop them in an appropriate place in the Defold editor Assets pane.
Defold supports images in the PNG and JPEG image formats. PNG images must be in 32 bit RGBA format. Other image formats need to be converted before they can be used.
When the assets are imported into Defold they can be used by the various component types supported by Defold:
Defold does not provide editing tools for images, sound files, models or animations. Such assets need to be created outside of Defold in specialized tools and imported into Defold. Defold automatically detects changes to any asset among your project files and updates the editor view accordingly.
The editor saves all Defold assets in text based files that are merge friendly. They are also easy to create and modify with simple scripts. See this forum thread for more information. Note though that we do not publish our file format details since they do change once in a while. You can also use Editor Scripts to hook into certain life-cycle events in the Editor to run scripts to generate or modify assets.
Extra care should be taken when working with Defold asset files through a text editor or external tool. If you introduce errors those can prevent the file from opening in the Defold editor.