Experimental schematic format

Readme.md

@@ -234,6 +234,12 @@ Dumps local variables, upvalues and the function environment of the function at
 
 Dumps function info & variables for all functions in stack, starting with stacklevel (default `1`).
 
+## `minetest`
+
+### `schematic`
+
+A schematic format with support for metadata and baked light data. **Experimental.**
+
 ## Release Notes
 
 ### `rolling-68`

init.lua

@@ -65,7 +65,8 @@ if minetest then
 		"liquid",
 		"raycast",
 		"wielditem_change",
-		"colorspec"
+		"colorspec",
+		"schematic"
 	}
 	for _, file in pairs{
 		"data",

minetest/schematic.lua

@@ -0,0 +1,110 @@
+schematic = {}
+local metatable = {__index = schematic}
+
+function schematic.setmetatable(self)
+    return setmetatable(self, metatable)
+end
+
+function schematic.create(self, pos_min, pos_max)
+    -- Don't use the metatable for the defaults to force a serialization
+    self.baked_light = self.backed_light or false
+    self.meta_data = self.meta_data or true
+    self.size = vector.subtract(pos_max, pos_min)
+    local voxelmanip = minetest.get_voxel_manip(pos_min, pos_max)
+    local emin, emax = voxelmanip:read_from_map(pos_min, pos_max)
+    local voxelarea = VoxelArea:new{ MinEdge = emin, MaxEdge = emax }
+    local meta_data = {}
+    for _, pos in ipairs(minetest.find_nodes_with_meta(pos_min, pos_max)) do
+        local meta = minetest.get_meta(pos):to_table()
+        if next(meta.fields) ~= nil or next(meta.inventory) ~= nil then
+            meta_data[voxelarea:indexp(pos)] = meta
+        end
+    end
+    local data, light_data, param2_data = voxelmanip:get_data(), self.baked_light and voxelmanip:get_light_data() or {}, voxelmanip:get_param2_data()
+    local nodes = {}
+    for index in voxelarea:iterp(pos_min, pos_max) do
+        table.insert(nodes, {
+            name = minetest.get_name_from_content_id(data[index]),
+            light = light_data[index],
+            param2 = param2_data[index],
+            meta = meta_data[index]
+        })
+    end
+    self.nodes = nodes
+    return schematic.setmetatable(self)
+end
+
+function schematic:write_to_voxelmanip(voxelmanip, pos_min)
+    local pos_max = vector.add(pos_min, self.size)
+    local emin, emax = voxelmanip:read_from_map(pos_min, pos_max)
+    local voxelarea = VoxelArea:new{ MinEdge = emin, MaxEdge = emax }
+    local data, light_data, param2_data = voxelmanip:get_data(), self.baked_light and voxelmanip:get_light_data(), voxelmanip:get_param2_data()
+    for _, pos in ipairs(minetest.find_nodes_with_meta(pos_min, pos_max)) do
+        -- Clear all metadata. Due to an engine bug, nodes will actually have empty metadata.
+        minetest.get_meta(pos):from_table{}
+    end
+    local i = 1
+    for index in voxelarea:iterp(pos_min, pos_max) do
+        local node = self.nodes[i]
+        i = i + 1
+        data[index] = minetest.get_content_id(node.name)
+        if data[index] == nil then
+            error(("unknown node %q"):format(node.name))
+        end
+        if self.baked_light then
+            light_data[index] = node.light
+        end
+        param2_data[index] = node.param2
+        if node.meta then
+            -- TODO consider removing this check by using a separate table [index] = meta for node meta
+            minetest.get_meta(voxelarea:position(index)):from_table(node.meta)
+        end
+    end
+    voxelmanip:set_data(data)
+    if self.baked_light then
+        voxelmanip:set_light_data(light_data)
+    end
+    voxelmanip:set_param2_data(param2_data)
+end
+
+function schematic:place(pos_min)
+    local pos_max = vector.add(pos_min, self.size)
+    local voxelmanip = minetest.get_voxel_manip(pos_min, pos_max)
+    self:write_to_voxelmanip(voxelmanip, pos_min)
+    voxelmanip:write_to_map(not self.baked_light)
+    return voxelmanip
+end
+
+function schematic:write_bluon(path)
+    local file = io.open(path, "w")
+    -- Header, short for "ModLib Bluon Schematic"
+    file:write"MLBS"
+    modlib.bluon:write(self, file)
+    file:close()
+end
+
+function schematic.read_bluon(path)
+    local file = io.open(path, "r")
+    assert(file:read(4) == "MLBS", "not a modlib bluon schematic")
+    local self = modlib.bluon:read(file)
+    assert(not file:read(), "expected EOF")
+    return schematic.setmetatable(self)
+end
+
+function schematic:write_zlib_bluon(path, compression)
+    local file = io.open(path, "w")
+    -- Header, short for "ModLib Zlib-compressed-bluon Schematic"
+    file:write"MLZS"
+    local rope = modlib.table.rope{}
+    modlib.bluon:write(self, rope)
+    local text = rope:to_text()
+    file:write(minetest.compress(text, "deflate", compression or 9))
+    file:close()
+end
+
+function schematic.read_zlib_bluon(path)
+    local file = io.open(path, "r")
+    assert(file:read(4) == "MLZS", "not a modlib zlib compressed bluon schematic")
+    local self = modlib.bluon:read(modlib.text.inputstream(minetest.decompress(file:read"*a", "deflate")))
+    return schematic.setmetatable(self)
+end