The CopperCube Grass Designer 3d game engine editor extension lets you easily create billboard vegetation like grass and flowers on non-terrain custom 3d mesh objects which do not support a vegetation drawing feature like CopperCube built-in terrains do provide. The extension comes with a fully customizable mandatory set of grass tufts asset/prefab, the designer plugin to control the asset/prefab plus over 50 custom grass textures.

https://hadoken-records.itch.io/coppercube-grass-designer