public async Task <MeshData> BuildMeshData(Terrain terrain, IReadOnlyCollection <Texture2D> alphaMaps, MassiveGrassGrid.CellIndex index, Rect rect, MassiveGrassProfile profile)
{
var elements = await GenerateElements(terrain, rect, profile, index.hash % 50000);
builder = builder ?? profile.CreateBuilder();
return(await builder.BuildMeshData(terrain, alphaMaps, profile, elements));
}