Subnautica Below Zero: map export

mass_convert.bat

@echo off

rem edit paths (input and output)
set MESH_DIR=b:\sub
set WORK_DIR=d:\tmp\subnautica\zero_work
set LUA=E:\devel\lua_x64\lua.exe

set LUA_DIR=%~dp0%

:convert
if exist %WORK_DIR%\obj rmdir /q /s %WORK_DIR%\obj
mkdir %WORK_DIR%\obj
pushd %WORK_DIR%\obj
for /r %MESH_DIR% %%i in (*.dat) do (
    %LUA% "%LUA_DIR%\mesh2obj.lua" "%%i"
)
popd

:merge
if exist %WORK_DIR%\level rmdir /q /s %WORK_DIR%\level
mkdir %WORK_DIR%\level
pushd %WORK_DIR%\level
for /l %%i in (0 1 24) do (
    echo %%i
    copy /y "%WORK_DIR%\obj\*-%%i-*.obj" level-%%i.obj
)
popd

:eof
pause

mesh2obj.lua

assert(_VERSION == "Lua 5.3")

local function convert(fn)

    local r
    local su = string.unpack

    local function uint16()
        local res, _ = su("H", r:read(2))
        return res
    end
    local function uint32()
        local res, _ = su("I4", r:read(4))
        return res
    end
    local function str(len)
        return r:read(len)
    end
    local function float()
        local res, _ = su("f", r:read(4))
        if res ~= res then res = 0.0 end
        return res
    end

    r = assert(io.open(fn, "rb"))

    local point = {}
    local normal = {}
    local face = {}

    local sz = uint32()
    local name = str(sz)

    local tail = sz % 4
    if tail > 0 then r:read(4 - tail) end
    
    r:read(8)   -- 1, 0
    local idxs = uint32()
    r:read(12)   -- 0, 0, 0
    local points = uint32()
--    local center = { float(), float(), float() }
--    local extent = { float(), float(), float() }
    r:read(60)

    print(("%s\t%d indices, %d points"):format(name, idxs, points))
--    print(("center: %s\nextent: %s"):format(table.concat(center, ", "), table.concat(extent, ", ")))

    sz = uint32()
    local faces = sz // 6
--  print(("%d faces"):format(faces))

    for i = 1, faces do
        local f1, f2, f3 = points-uint16(), points-uint16(), points-uint16()
        table.insert(face, { f1, f3, f2 })
    end
    r:read(64)

    sz = uint32()
    assert(points == sz // 24, "\n\n" .. points .. " != " .. sz // 24 .. "\n\n")

    local X, Y, Z
    for _x, _y, _z in name:gmatch("-(.+)-(.+)-(.+)") do
        X = _x * 32.0
        Y = _y * 32.0
        Z = _z * -32.0
    end

    for i = 1, points do
        local x, y, z = float() + X, float() + Y, Z - float()
        table.insert(point, { x, y, z })
        table.insert(normal, { float(), float(), -float() })
    end
    r:read(16*10+4)

    local center2 = { float(), float(), float() }
    local extent2 = { float(), float(), float() }
--print(("center: %s\nextent: %s"):format(table.concat(center2, ", "), table.concat(extent2, ", ")))
    r:read(4*3)

    r:close()


--[[ write OBJ ]]--
    fn = name:sub(7) .. ".obj"
    local w = assert(io.open(fn, "w+b"))

    local fmt = {
        head = "#o n_%s\n# %d points, %d faces\n",
        point = "v %f %f %f\n",
        normal = "vn %f %f %f\n",
        group = "g g_%s\ns 1\n",
        face = "f -%d//-%d -%d//-%d -%d//-%d\n"
    }

    w:write(fmt.head:format(name, points, faces))
    for i = 1, points do
        local p = point[i]
        w:write(fmt.point:format(p[1], p[2], p[3]))
    end
--    don't export normals, recalculate it the Meshlab
--[[
    for i = 1, points do
        local n = normal[i]
        w:write(fmt.normal:format(n[1], n[2], n[3]))
    end
]]
    w:write(fmt.group:format(name))
    for i = 1, #face do
        local f = face[i]
        w:write(fmt.face:format(f[1], f[1], f[2], f[2], f[3], f[3]))
    end

    w:close()

end

convert(arg[1])