mapgen_rivers/pregenerate.lua
Gaël C 146f009684 Re-organize grid management code for less dependance between files
Remove gridio.lua and move its function to appropriate files
2024-02-01 19:30:07 +01:00

151 lines
3.8 KiB
Lua

-- Generate the grid using terrainlib_lua
-- Only called on first mapgen, if there is no grid yet
-- Constants
local EvolutionModel = dofile(mapgen_rivers.modpath .. '/terrainlib_lua/erosion.lua')
local twist = dofile(mapgen_rivers.modpath .. '/terrainlib_lua/twist.lua')
local blocksize = mapgen_rivers.settings.blocksize
local tectonic_speed = mapgen_rivers.settings.tectonic_speed
local np_base = table.copy(mapgen_rivers.noise_params.base)
np_base.spread = vector.divide(np_base.spread, blocksize)
local evol_params = mapgen_rivers.settings.evol_params
local time = mapgen_rivers.settings.evol_time
local time_step = mapgen_rivers.settings.evol_time_step
local niter = math.ceil(time/time_step)
time_step = time / niter
local use_margin = mapgen_rivers.settings.margin
local margin_width = mapgen_rivers.settings.margin_width / blocksize
local margin_elev = mapgen_rivers.settings.margin_elev
local X = math.floor(mapgen_rivers.settings.map_x_size / blocksize)
local Y = math.floor(mapgen_rivers.settings.map_z_size / blocksize)
local function margin(dem, width, elev)
local X, Y = dem.X, dem.Y
for i=1, width do
local c1 = ((i-1)/width) ^ 0.5
local c2 = (1-c1) * elev
local index = (i-1)*X + 1
for x=1, X do
dem[index] = dem[index] * c1 + c2
index = index + 1
end
index = i
for y=1, Y do
dem[index] = dem[index] * c1 + c2
index = index + X
end
index = X*(Y-i) + 1
for x=1, X do
dem[index] = dem[index] * c1 + c2
index = index + 1
end
index = X-i + 1
for y=1, Y do
dem[index] = dem[index] * c1 + c2
index = index + X
end
end
end
-- Generate grid
minetest.log("action", '[mapgen_rivers] Generating grid, this may take a while...')
if X*Y > 4e6 then
minetest.log("warning", "[mapgen_rivers] You are going to generate a very large grid (>4M nodes). If you experience problems, you should increase blocksize or reduce map size.")
end
local seed = tonumber(minetest.get_mapgen_setting("seed"):sub(-10))
np_base.seed = (np_base.seed or 0) + seed
local nobj_base = PerlinNoiseMap(np_base, {x=X, y=1, z=Y})
local dem = nobj_base:get_3d_map_flat({x=0, y=0, z=0})
dem.X = X
dem.Y = Y
if use_margin then
margin(dem, margin_width, margin_elev)
end
local model = EvolutionModel(evol_params)
model.dem = dem
local ref_dem = model:define_isostasy(dem)
local tectonic_step = tectonic_speed * time_step
collectgarbage()
for i=1, niter do
minetest.log("info", "[mapgen_rivers] Iteration " .. i .. " of " .. niter)
model:diffuse(time_step)
model:flow()
model:erode(time_step)
if i < niter then
if tectonic_step ~= 0 then
nobj_base:get_3d_map_flat({x=0, y=tectonic_step*i, z=0}, ref_dem)
if use_margin then
margin(ref_dem, margin_width, margin_elev)
end
end
model:isostasy()
end
collectgarbage()
end
model:flow()
local mfloor = math.floor
local mmin, mmax = math.min, math.max
local unpk, schar = unpack, string.char
local offset_x, offset_y = twist(model.dirs, model.rivers, 5)
for i=1, X*Y do
offset_x[i] = mmin(mmax(offset_x[i]*256, -128), 127)
offset_y[i] = mmin(mmax(offset_y[i]*256, -128), 127)
end
-- Write data
local datapath = mapgen_rivers.world_data_path
minetest.mkdir(datapath)
local sfile = io.open(datapath .. 'size', "w")
sfile:write(X..'\n'..Y)
sfile:close()
local function write_file(filename, data, bytes)
local file = io.open(datapath .. filename, 'wb')
local bytelist = {}
for j=1, bytes do
bytelist[j] = 0
end
for i=1, #data do
local n = mfloor(data[i])
data[i] = n
for j=bytes, 2, -1 do
bytelist[j] = n % 256
n = mfloor(n / 256)
end
bytelist[1] = n % 256
file:write(schar(unpk(bytelist)))
end
file:close()
end
write_file('dem', model.dem, 2)
write_file('lakes', model.lakes, 2)
write_file('dirs', model.dirs, 1)
write_file('rivers', model.rivers, 4)
write_file('offset_x', offset_x, 1)
write_file('offset_y', offset_y, 1)