mirror of
https://github.com/appgurueu/modlib.git
synced 2024-08-20 13:24:11 +02:00
190 lines
5.2 KiB
Lua
190 lines
5.2 KiB
Lua
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local assert, tonumber, type, setmetatable, ipairs, unpack
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= assert, tonumber, type, setmetatable, ipairs, unpack
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local math_floor, table_insert, table_concat
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= math.floor, table.insert, table.concat
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local obj = {}
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local metatable = {__index = obj}
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local function read_floats(next_word, n)
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if n == 0 then return end
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local num = next_word()
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assert(num:find"^%-?%d+$" or num:find"^%-?%d+%.%d+$")
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return tonumber(num), read_floats(next_word, n - 1)
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end
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local function read_index(list, index)
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if not index then return end
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index = tonumber(index)
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if index < 0 then
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index = index + #list + 1
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end
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assert(list[index])
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return index
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end
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local function read_indices(self, next_word)
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local word = next_word()
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if not word then return end
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-- TODO optimize this (ideally using a vararg-ish split by `/`)
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local vertex, texcoord, normal
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vertex = word:match"^%-?%d+$"
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if not vertex then
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vertex, texcoord = word:match"^(%-?%d+)/(%-?%d+)$"
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if not vertex then
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vertex, normal = word:match"^(%-?%d+)//(%-?%d+)$"
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if not vertex then
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vertex, texcoord, normal = word:match"^(%-?%d+)/(%-?%d+)/(%-?%d+)$"
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end
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end
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end
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return {
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vertex = read_index(self.vertices, vertex),
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texcoord = read_index(self.texcoords, texcoord),
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normal = read_index(self.normals, normal)
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}, read_indices(self, next_word)
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end
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function obj.read_lines(
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... -- line iterator such as `modlib.text.lines"str"` or `io.lines"filename"`
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)
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local self = {
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vertices = {},
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texcoords = {},
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normals = {},
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groups = {}
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}
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local groups = {}
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local active_group = {name = "default"}
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groups[1] = active_group
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groups.default = active_group
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for line in ... do
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if line:byte() ~= ("#"):byte() then
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local next_word = line:gmatch"%S+"
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local command = next_word()
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if command == "v" or command == "vn" then
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local x, y, z = read_floats(next_word, 3)
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x = -x
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table_insert(self[command == "v" and "vertices" or "normals"], {x, y, z})
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elseif command == "vt" then
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local x, y = read_floats(next_word, 2)
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y = 1 - y
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table_insert(self.texcoords, {x, y})
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elseif command == "f" then
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table_insert(active_group, {read_indices(self, next_word)})
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elseif command == "g" or command == "usemtl" then
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-- TODO consider distinguishing between materials & groups
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local name = next_word() or "default"
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if groups[name] then
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active_group = groups[name]
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else
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active_group = {name = name}
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table_insert(groups, active_group)
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groups[name] = active_group
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end
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assert(not next_word(), "only a single group/material name is supported")
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end
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end
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end
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-- Keep only nonempty groups
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for _, group in ipairs(groups) do
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if group[1] ~= nil then
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table_insert(self.groups, group)
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end
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end
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return setmetatable(self, metatable) -- obj object
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end
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-- Does not close a file handle if passed
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--> obj object
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function obj.read_file(file_or_name)
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if type(file_or_name) == "string" then
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return obj.read_lines(io.lines(file_or_name))
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end
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local handle = file_or_name
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-- `handle.read, handle` can be used as a line iterator
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return obj.read_lines(assert(handle.read), handle)
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end
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--> obj object
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function obj.read_string(str)
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-- Empty lines can be ignored
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return obj.read_lines(str:gmatch"[^\r\n]+")
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end
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local function write_float(float)
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if math_floor(float) == float then
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return ("%d"):format(float)
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end
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return ("%f"):format(float):match"^(.-)0*$" -- strip trailing zeros
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end
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local function write_index(index)
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if index.texcoord then
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if index.normal then
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return("%d/%d/%d"):format(index.vertex, index.texcoord, index.normal)
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end
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return ("%d/%d"):format(index.vertex, index.texcoord)
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end if index.normal then
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return ("%d//%d"):format(index.vertex, index.normal)
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end
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return ("%d"):format(index.vertex)
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end
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-- Callback/"caller"-style iterator; use `iterator.for_generator` to turn this into a callee-style iterator
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function obj:write_lines(
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write_line -- function(line: string) to write a line
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)
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local function write_v3f(type, v3f)
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local x, y, z = unpack(v3f)
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x = -x
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write_line(("%s %s %s %s"):format(type, write_float(x), write_float(y), write_float(z)))
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end
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for _, vertex in ipairs(self.vertices) do
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write_v3f("v", vertex)
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end
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for _, normal in ipairs(self.normals) do
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write_v3f("vn", normal)
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end
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for _, texcoord in ipairs(self.texcoords) do
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local x, y = texcoord[1], texcoord[2]
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y = 1 - y
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write_line(("vt %s %s"):format(write_float(x), write_float(y)))
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end
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for _, group in ipairs(self.groups) do
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write_line("g " .. group.name) -- this will convert `usemtl` into `g` but that shouldn't matter
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for _, face in ipairs(group) do
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local command = {"f"}
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for i, index in ipairs(face) do
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command[i + 1] = write_index(index)
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end
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write_line(table_concat(command, " "))
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end
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end
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end
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-- Write `self` to a file
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-- Does not close or flush a file handle if passed
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function obj:write_file(file_or_name)
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if type(file_or_name) == "string" then
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file_or_name = io.open(file_or_name)
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end
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self:write_lines(function(line)
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file_or_name:write(line)
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file_or_name:write"\n"
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end)
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end
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-- Write `self` to a string
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function obj:write_string()
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local rope = {}
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self:write_lines(function(line)
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table_insert(rope, line)
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end)
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table_insert(rope, "") -- trailing newline for good measure
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return table_concat(rope, "\n") -- string representation of `self`
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end
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return obj
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