I was recently looking thru the API and noticed the setBackgroundColor(Color color) of TextDisplay entity uses Bukkit's color class, which does not have an option for the Alpha channel.

As per McWiki for Text Display entities:

""

•  background: The background color, arranged by ARGB. Since pixel with an alpha channel less than 0.1 are discarded when rendering in vanilla shader, the background becomes fully transparent when A is less than 26 (0x1A). Defaults to 1073741824 (0x40000000). Interpolated.

""

I would love to see something here get added, as Im sure many people will find the transparency for these to be quite useful.

 

Thank you for reading!