Luamap

For an example of how to use the api, see example.lua and my mandeland mod https://content.minetest.net/packages/MisterE/mandeland/

Intro and usage

Luamap is a library for modders to focus on mapgen logic rather than figuruing out how mapgen works. using it is simple: override the luamap.logic function. The goal of the luamap logic function is to return a content id at a point.

Calling the old logic function before running your own logic allows you to add to other mods that use luamap. If you do not save and call the old luamap function, then your mod will completely override any other mapgens made by other mods using luamap.

local c_stone = minetest.get_content_id("default:stone")
local c_water = minetest.get_content_id("default:water_source")
local water_level = 0
local old_logic = luamap.logic
function luamap.logic(noise_vals,x,y,z,seed,original_content)
    -- get any terrain defined in another mod
    local content = old_logic(noise_vals,x,y,z,seed,original_content)
    -- use our own logic to add to that logic 
    -- make any nodes below sea level water and below stone level stone
    if y < water_level then
        content = c_water
    end
    if y < -3 then
        content = c_stone
    end
    return content
end

This would make a flat mapgen covered in a layer of water.

luamap gives you an easy way to make and use 2d and 3d noises in your mapgen:

-- 2d noise mapgen
luamap.register_noise("terrainmap",{
    type = "2d",
    np_vals = {
        offset = 0,
        scale = 1,
        spread = {x=384, y=256, z=384},
        seed = 5900033,
        octaves = 5,
        persist = 0.63,
        lacunarity = 2.0,
        flags = ""
    },
    ymin = -31000,
    ymax = 31000,
})

local c_stone = minetest.get_content_id("default:stone")
local c_water = minetest.get_content_id("default:water_source")
local water_level = 0
local old_logic = luamap.logic
function luamap.logic(noise_vals,x,y,z,seed,original_content)
    -- get any terrain defined in another mod
    local content = old_logic(noise_vals,x,y,z,seed,original_content)

    if y < water_level then
        content = c_water
    end
    if y < noise_vals.terrainmap * 50 then
        content = c_stone
    end

    return content
end

you can also register a 3d noise like so:

luamap.register_noise("terrainmap",{
    type = "3d",
    np_vals = {
        offset = 0,
        scale = 1,
        spread = {x=384, y=384, z=384},
        seed = 5900033,
        octaves = 5,
        persist = 0.63,
        lacunarity = 2.0,
        flags = ""
    },
    ymin = -31000,
    ymax = 31000,
})

API

luamap.logic

luamap.logic(noise_vals,x,y,z,seed,original_content)

DESCRIPTION: Override this function to define mapgen logic. Best practice is to save the original function and call it to get a preset content id from any previously-defined mapgens.

PARAMETERS:

noise_vals

A table indexed by noise names defined with luamap.register_noise(). So, if I have registered 2 noises: terrain_2d and caves_3d then noisevals might be:

{
    ["terrain_2d"] = .7,
    ["caves_3d"] = -.9,
}

x,y,z

The coordinates of the position to set the content for

seed

The seed passed to minetest.register_on_generated()

original_content

The content id that the original mapgen created. Air if set to singlenode.

RETURNS:

should return a content id such as that gotten from minetest.get_content_id("nodename")

NOTES: remember that this function is called for every single node ever generated. Keep your calculations fast or the mapgen will slow down. 2d noise is much faster than 3d noise.

luamap.register_noise

luamap.register_noise(name,data)

DESCRIPTION: creates a mapgen noise that will be calculated and returned in luamap.logic

PARAMETERS:

name

String, the name of the noise

data

table, the noise data:

{
    type = "2d", -- or "3d"
    np_vals = { -- noise params, see minetest lua api
        offset = 0,
        scale = 1,
        spread = {x=384, y=256, z=384},
        seed = 5900033,
        octaves = 5,
        persist = 0.63,
        lacunarity = 2.0,
        flags = ""
    },
    ymin = -31000,
    ymax = 31000,
}

NOTES: ymin and ymax define a range in which to calculate the noise. This is useful for making realms: a noise might not be needed in a certian y-range. Note that if the position passed to luamap.logic is outside of the y-range, then noise_vals will not contain that noise, which saves on calculation times. Be sure to set the y-range to completely encompass the range that you expect to find your noises.

luamap.precalc

luamap.precalc(data, area, vm, minp, maxp, seed)

DESCRIPTION: An overridable function called just before calculating the noise and calling the logic function for each node. Best practice is to save the old function and call it before adding one's own logic, just like with luamap.logic

luamap.postcalc

luamap.postcalc(data, area, vm, minp, maxp, seed)

DESCRIPTION: An overridable function called just before setting the map lighting and data after the noise has been calculated and luamap.logic has been called for each node in the mapblock. It offers compatability with biomegen by Gaël de Sailly, which needs these parameters to function. Best practice is to save the old function and call it before adding one's own logic, just like with luamap.logic

example:

local old_postcalc = luamap.precalc
function luamap.postcalc(data, area, vm, minp, maxp, seed)
    old_postcalc(data, area, vm, minp, maxp, seed)
    biomegen.generate_all(data, area, vm, minp, maxp, seed)
end

luamap.set_singlenode

luamap.set_singlenode()

DESCRIPTION: Sets the mapgen to singlenode. Do not call this if you intend to make a realm, only call if you intend to completely replace engine mapgens

No params, returns nothing.

HELPER FUNCTIONS

luamap.remap

luamap.remap(val, min_val, max_val, min_map, max_map)

DESCRIPTION: remaps a value between a range of values to a new range of values

PARAMETERS:

val value to remap min_val old range minimum max_val old range maximum min_map new range min max_map new range max

NOTES:

Minetest's perlin noises range from -2 to 2. If you want a noise that ranges from 0 to 1, then you can use remap:

mynoise = noisevals.mynoise
mynoise = luamap.remap(mynoise, -2, 2, 0, 1)

luamap.lerp

luamap.lerp(var_a, var_b, ratio, power)

DESCRIPTION: a linear interpolation function Interpolates between 2 values

PARAMETERS: var_a first value to interpolate between

var_b second value to interpolate between

ratio number between 0 and 1 interpolation ratio: 0 is 100% var_a, 1 is 100% var_b, values between 0 and 1 return a mix of var_a and var_b

power (optional, default 1) controls the exponent of the power. By default, it is 1, which gives linear interpolation. 3 would give cubic interpolation. Controls the shape of the interpolation curve.

NOTES:

useful for mixing two noises. If you use a third noise as the ratio, you can have areas that are mostly controlled by one noise, and other areas controlled by another noise.

luamap.coserp

luamap.coserp(var_a,var_b,ratio)

DESCRIPTION: Same as luamap.lerp but uses cosine interpolation for a smoother curve.