I have written a new simple example mod with many code comments as an example of good lua mapgen code.
Browse code here https://github.com/paramat/lvm_example
Download https://github.com/paramat/lvm_example/ ... master.zip
This mod should work with Minetest 0.4.13 or later.
Code: Select all
-- Set the 3D noise parameters for the terrain.
local np_terrain = {
offset = 0,
scale = 1,
spread = {x = 384, y = 192, z = 384},
seed = 5900033,
octaves = 5,
persist = 0.63,
lacunarity = 2.0,
--flags = ""
}
-- Set singlenode mapgen (air nodes only).
-- Disable the engine lighting calculation since that will be done for a
-- mapchunk of air nodes and will be incorrect after we place nodes.
minetest.set_mapgen_params({mgname = "singlenode", flags = "nolight"})
-- Get the content IDs for the nodes used.
local c_sandstone = minetest.get_content_id("default:sandstone")
local c_water = minetest.get_content_id("default:water_source")
-- Initialize noise object to nil. It will be created once only during the
-- generation of the first mapchunk, to minimise memory use.
local nobj_terrain = nil
-- Localise noise buffer table outside the loop, to be re-used for all
-- mapchunks, therefore minimising memory use.
local nvals_terrain = {}
-- Localise data buffer table outside the loop, to be re-used for all
-- mapchunks, therefore minimising memory use.
local data = {}
-- On generated function.
-- 'minp' and 'maxp' are the minimum and maximum positions of the mapchunk that
-- define the 3D volume.
minetest.register_on_generated(function(minp, maxp, seed)
-- Start time of mapchunk generation.
local t0 = os.clock()
-- Noise stuff.
-- Side length of mapchunk.
local sidelen = maxp.x - minp.x + 1
-- Required dimensions of the 3D noise perlin map.
local permapdims3d = {x = sidelen, y = sidelen, z = sidelen}
-- Create the perlin map noise object once only, during the generation of
-- the first mapchunk when 'nobj_terrain' is 'nil'.
nobj_terrain = nobj_terrain or
minetest.get_perlin_map(np_terrain, permapdims3d)
-- Create a flat array of noise values from the perlin map, with the
-- minimum point being 'minp'.
-- Set the buffer parameter to use and reuse 'nvals_terrain' for this.
nobj_terrain:get3dMap_flat(minp, nvals_terrain)
-- Voxelmanip stuff.
-- Load the voxelmanip with the result of engine mapgen. Since 'singlenode'
-- mapgen is used this will be a mapchunk of air nodes.
local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
-- 'area' is used later to get the voxelmanip indexes for positions.
local area = VoxelArea:new{MinEdge = emin, MaxEdge = emax}
-- Get the content ID data from the voxelmanip in the form of a flat array.
-- Set the buffer parameter to use and reuse 'data' for this.
vm:get_data(data)
-- Generation loop.
-- Noise index for the flat array of noise values.
local ni = 1
-- Process the content IDs in 'data'.
-- The most useful order is a ZYX loop because:
-- 1. This matches the order of the 3D noise flat array.
-- 2. This allows a simple +1 incrementing of the voxelmanip index along x
-- rows.
for z = minp.z, maxp.z do
for y = minp.y, maxp.y do
-- Voxelmanip index for the flat array of content IDs.
-- Initialise to first node in this x row.
local vi = area:index(minp.x, y, z)
for x = minp.x, maxp.x do
-- Consider a 'solidness' value for each node,
-- let's call it 'density', where
-- density = density noise + density gradient.
local density_noise = nvals_terrain[ni]
-- Density gradient is a value that is 0 at water level (y = 1)
-- and falls in value with increasing y. This is necessary to
-- create a 'world surface' with only solid nodes deep underground
-- and only air high above water level.
-- Here '128' determines the typical maximum height of the terrain.
local density_gradient = (1 - y) / 128
-- Place solid nodes when 'density' > 0.
if density_noise + density_gradient > 0 then
data[vi] = c_sandstone
-- Otherwise if at or below water level place water.
elseif y <= 1 then
data[vi] = c_water
end
-- Increment noise index.
ni = ni + 1
-- Increment voxelmanip index along x row.
-- The voxelmanip index increases by 1 when
-- moving by 1 node in the +x direction.
vi = vi + 1
end
end
end
-- After processing, write content ID data back to the voxelmanip.
vm:set_data(data)
-- Calculate lighting for what has been created.
vm:calc_lighting()
-- Write what has been created to the world.
vm:write_to_map()
-- Liquid nodes were placed so set them flowing.
vm:update_liquids()
-- Print generation time of this mapchunk.
local chugent = math.ceil((os.clock() - t0) * 1000)
print ("[lvm_example] Mapchunk generation time " .. chugent .. " ms")
end)
