Add basic engine with cave shaper

pull/1/head
Bram van den Heuvel 2024-04-18 10:49:45 +02:00
parent e2955959a2
commit 0a11882395
2 changed files with 273 additions and 0 deletions

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@ -10,3 +10,9 @@ noordstar_caves = {}
-- Load features to influence cave shapes
load("shape")
-- Start engine to generate caves
load("engine")
-- For show, the following code COULD in theory be run elsewhere

267
lua/engine.lua Normal file
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@ -0,0 +1,267 @@
-- Convert 3d relative coordinates to an index on a flat array
local function from_3d_to_flat(dx, dy, dz, nx, ny)
return (nx * ny * dz) + (nx * dy) + dx + 1
end
-- Convert an index on a flat array to 3d relative coordinates
local function from_flat_to_3d(i, nx, ny)
return {
dx = (i - 1) % nx,
dy = (i - 1) // nx % ny,
dz = (i - 1) // nx // ny
}
end
-- Iterate over a 3d area, both indexing by the index and the ansolute position
local function iter_3d_area(minp, maxp, callback)
local nx = maxp.x - minp.x + 1
local ny = maxp.y - minp.y + 1
local nz = maxp.z - minp.z + 1
for i = 1, nx * ny * nz do
local dpos = from_flat_to_3d(i, nx, ny)
local pos = {
x = minp.x + dpos.x,
y = minp.y + dpos.y,
z = minp.z + dpos.z,
}
callback(i, pos)
end
end
-- Get an enhanced function from the def function that warns us when the
-- function does not behave properly
local function enhanced_func(def)
if type(def.name) ~= "string" then
error("Invalid nameless shape definition")
elseif type(def.func) ~= "function" then
error(
"Invalid shape definition misses an adjustment function"
)
else
return function(pos, n)
local out = def.func(pos, n)
if type(out) == "number" then
return out
elseif n == nil then
error(
"Shape " .. def.name .. " function must return a number. The input `n` was nil. Perhaps your `noise_params` field is invalid?"
)
else
error("Shape " .. def.name .. " function must return a number.")
end
end
end
end
-- Get a flat array of cave shape noise values from a given cave shape def
local function get_flat_from_shape_def(def, minp, maxp)
local f = enhanced_func(def)
local nx = maxp.x - minp.x + 1
local ny = maxp.y - minp.y + 1
local nz = maxp.z - minp.z + 1
local noise_flat_map = {}
-- If noise parameters have been defined, fill the table with noise
-- If not, all values remain nil
if def.noise_params ~= nil then
local p = PerlinNoiseMap(def.noise_params, { x = nx, y = ny, z = nz })
if nz == 1 then
p:get_2d_map_flat(minp, noise_flat_map)
else
p:get_3d_map_flat(minp, noise_flat_map)
end
end
iter_3d_area(minp, maxp, function(i, pos)
noise_flat_map[i] = f(pos, noise_flat_map[i])
end)
return noise_flat_map
end
local function get_flat_from_noise_params(minp, maxp, noise_params)
local nx = maxp.x - minp.x + 1
local ny = maxp.y - minp.y + 1
local nz = maxp.z - minp.z + 1
local buffer = {}
local p = PerlinNoiseMap(noise_params, { x = nx, y = ny, z = nz })
if nz == 1 then
p:get_2d_map_flat(minp, buffer)
else
p:get_3d_map_flat(minp, buffer)
end
return buffer
end
-- Based on the number of cave shapes, calculate how quickly connectivity is
-- meant to change
local function get_connectivity_noise_params(shape_size)
local factor = math.max(math.abs(shape_size) ^ 0.5, 1)
return {
offset = 50,
scale = 50,
spread = { x = factor * 250, y = factor * 100, z = factor * 250 },
seed = 297948,
octaves = 2,
persistence = 0.2,
lacunarity = 2.0,
flags = "eased"
}
end
-- Based on the number of cave shapes, calculate how quickly verticality is
-- meant to change
local function get_verticality_noise_params(shape_size)
local factor = math.max(math.abs(shape_size) ^ 0.5, 1)
return {
offset = 50,
scale = 50,
spread = { x = factor * 100, y = factor * 250, z = factor * 100 },
seed = 35644,
octaves = 2,
persistence = 0.2,
lacunarity = 2.0,
flags = "eased"
}
end
-- Get the distance of each cave shape to calculate their weight.
local function shape_distance_weight(shape_size, dx, dy)
local factor = math.max(math.abs(shape_size) ^ 0.5, 1)
local max_distance = 100 / factor
if dx^2 + dy^2 > max_distance^2 then
return 0
else
return 1 / (dx^5 + dy^5)
end
end
-- Get a flat map containing all flat threshold values
local function get_threshold_flat(minp, maxp)
local connectivity = get_flat_from_noise_params(
minp, maxp,
get_connectivity_noise_params(#noordstar_caves.registered_shapes)
)
local verticality = get_flat_from_noise_params(
minp, maxp,
get_verticality_noise_params(#noordstar_caves.registered_shapes)
)
local noise = {}
-- Get noise for all cave shapes
for key, def in pairs(noordstar_caves.registered_shapes) do
noise[key] = {
key = key,
noise = get_flat_from_shape_def(def, minp, maxp),
def = def
}
end
local thresholds = {}
-- Fill the table
iter_3d_area(minp, maxp, function(i, pos)
local total = 0
local count = 0
local x = connectivity[i]
local y = verticality[i]
for _, n in pairs(noise) do
local v = n.noise[i]
local dx = math.abs(x - n.def.connectivity)
local dy = math.abs(y - n.def.verticality)
local w = math.abs(shape_distance_weight(
#noordstar_caves.registered_shapes, dx, dy
))
total = total + v * w
count = count + w
end
if count <= 0 then
thresholds[i] = -1000
else
thresholds[i] = total / count
end
end)
return thresholds
end
-- Old minimum height for the overworld
local old_overworld_min = mcl_vars.mg_overworld_min
-- If another mod doesn't override the maximum world depth, we will assume that
-- the world depth is the following value.
local world_depth = -800
-- Otherwise, this variable can be changed using the following function,
-- which will also update all the other necessary variables
function noordstar_caves.set_world_depth(h)
-- Set world depth variable
world_depth = h
end
noordstar_caves.set_world_depth(world_depth)
-- The `cave_vastness` is a variable that determines the size of caves.
-- The function takes in an x, y and z variable, and returns a number between
-- 0 and 1.
-- Low numbers mean very rare and tiny caves, while high numbers mean massive
-- caves, with massive open spaces.
-- If you wish to overwrite this function, it is good to keep in mind to:
-- - Make sure that the output changes VERY SLOWLY over time
-- - This function will be run a LOT so it is very performance sensitive
noordstar_caves.cave_vastness = function(pos)
return math.abs(pos.y) / world_depth
end
-- Secretly, we're using an internal function that also adds a safe layer for
-- when we're approaching bedrock levels
local function cave_vastness(pos)
if world_depth + 20 < pos.y then
return noordstar_caves.cave_vastness(pos)
elseif world_depth + 5 < pos.y then
return noordstar_caves.cave_vastness(pos) * math.abs(y - world_depth - 5) / 15
else
return -1000
end
end
minetest.register_on_generated(function(minp, maxp, blockseed)
-- Get voxelmanip
local vm = minetest.get_mapgen_object("voxelmanip")
local data = vm:get_data()
-- Get threshold values
local thresholds = get_threshold_flat(minp, maxp)
local air = minetest.get_content_id("air")
iter_3d_area(minp, maxp, function(i, pos)
if thresholds[i] >= cave_vastness(pos) then
data[i] = air
end
end)
-- Write all changes to the Minetest world
vm:set_data(data)
vm:write_to_map()
end)