--generate a flat sandstone map (needs singlenode)

--material to use:
c_mat = minetest.get_content_id("default:sandstone")
----
local genfunction = function (minp,maxp,blockseed)
    local vm, edgemin, edgemax = minetest.get_mapgen_object("voxelmanip")
    local data = vm:get_data()
    local area = VoxelArea:new{MinEdge=edgemin, MaxEdge=emax}

    if minp.x > 0 then return end
    for x = minp.x, maxp.x, 1 do
        for z = minp.z, maxp.z, 1 do
            for y = minp.y, maxp.y, 1 do
                if y < 1 then
                    local pos = area:index(x,y,z)
                    data[pos] = c_mat
                end
            end
        end
    end
    vm:set_data(data)
    vm:calc_lighting()
    vm:write_to_map(data)
end
minetest.register_on_generated(genfunction)