I'm working on adding grass to my terrain system. I'm using three cross-aligned billboard, to represent a grass "blade". Now I'm wondering what a good method for storing grass patches, so that I can load them into the game? I'm currently using a heightmap for the topology and a "weight" map for which kind of texture to apply to where. I want the artist to have control over where to place grass and where not to, so any suggestions for a format to store this information? Should I e.g. store an 2d array for each smallest possible unit on my terrain with 0-9, determining what kind of grass is at this position? This doesn't seem optimal in size, so any other suggestions is welcome!