LuaVoxelManip: Add option to allocate blank data

doc/lua_api.txt

@@ -1594,6 +1594,8 @@ minetest.get_perlin(seeddiff, octaves, persistence, scale)
 ^ Return world-specific perlin noise (int(worldseed)+seeddiff)
 minetest.get_voxel_manip()
 ^ Return voxel manipulator object
+minetest.get_voxel_manip(p1, p2)
+^ Return voxel manipulator object with blank data preallocated
 minetest.set_gen_notify(flags, {deco_ids})
 ^ Set the types of on-generate notifications that should be collected
 ^ flags is a flag field with the available flags:
@@ -2192,6 +2194,7 @@ methods:
 VoxelManip: An interface to the MapVoxelManipulator for Lua
 - Can be created via VoxelManip()
 - Also minetest.get_voxel_manip()
+- Specify a pmin, pmax in either to allocate a blank chunk of data prefilled with cignore
 methods:
 - read_from_map(p1, p2):  Reads a chunk of map from the map containing the region formed by p1 and p2.
   ^ returns actual emerged pmin, actual emerged pmax
@@ -2223,6 +2226,7 @@ methods:
 - update_liquids():  Update liquid flow
 - was_modified(): Returns true or false if the data in the voxel manipulator had been modified since
   the last read from map, due to a call to minetest.set_data() on the loaded area elsewhere
+- get_emerged_area(): Returns actual emerged pmin, actual emerged pmax
 
 VoxelArea: A helper class for voxel areas
 - Can be created via VoxelArea:new{MinEdge=pmin, MaxEdge=pmax}

src/map.cpp

@@ -3597,6 +3597,29 @@ ManualMapVoxelManipulator::~ManualMapVoxelManipulator()
 {
 }
 
+void ManualMapVoxelManipulator::initializeBlank(v3s16 blockpos_min,
+	v3s16 blockpos_max)
+{
+	// Units of these are MapBlocks
+	v3s16 pmin = blockpos_min;
+	v3s16 pmax = blockpos_max;
+
+	VoxelArea block_area_nodes(pmin * MAP_BLOCKSIZE,
+		(pmax + 1) * MAP_BLOCKSIZE - v3s16(1,1,1));
+
+	addArea(block_area_nodes);
+	u32 extent = m_area.getVolume();
+	for (u32 i = 0; i != extent; i++)
+		m_data[i] = MapNode(CONTENT_IGNORE);
+
+	for (s32 z = pmin.Z; z <= pmax.Z; z++)
+	for (s32 y = pmin.Y; y <= pmax.Y; y++)
+	for (s32 x = pmin.X; x <= pmax.X; x++)
+		m_loaded_blocks[v3s16(x, y, z)] = 0;
+
+	m_is_dirty = false;
+}
+
 void ManualMapVoxelManipulator::initialEmerge(v3s16 blockpos_min,
 	v3s16 blockpos_max, bool load_if_inexistent)
 {

src/map.h

@@ -550,6 +550,8 @@ public:
 	void setMap(Map *map)
 	{m_map = map;}
 
+	void initializeBlank(v3s16 pmin, v3s16 pmax);
+
 	void initialEmerge(v3s16 blockpos_min, v3s16 blockpos_max,
 		bool load_if_inexistent = true);
 

src/script/lua_api/l_env.cpp

@@ -638,6 +638,13 @@ int ModApiEnvMod::l_get_voxel_manip(lua_State *L)
 	Map *map = &(env->getMap());
 	LuaVoxelManip *o = new LuaVoxelManip(map);
 
+	if (lua_istable(L, 1) && lua_istable(L, 2)) {
+		v3s16 p1 = getNodeBlockPos(read_v3s16(L, 1));
+		v3s16 p2 = getNodeBlockPos(read_v3s16(L, 2));
+		sortBoxVerticies(p1, p2);
+		o->vm->initializeBlank(p1, p2);
+	}
+
 	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
 	luaL_getmetatable(L, "VoxelManip");
 	lua_setmetatable(L, -2);

src/script/lua_api/l_vmanip.cpp

@@ -345,6 +345,16 @@ int LuaVoxelManip::l_was_modified(lua_State *L)
 	return 1;
 }
 
+int LuaVoxelManip::l_get_emerged_area(lua_State *L)
+{
+	LuaVoxelManip *o = checkobject(L, 1);
+
+	push_v3s16(L, o->vm->m_area.MinEdge);
+	push_v3s16(L, o->vm->m_area.MaxEdge);
+
+	return 2;
+}
+
 LuaVoxelManip::LuaVoxelManip(ManualMapVoxelManipulator *mmvm, bool is_mg_vm)
 {
 	this->vm           = mmvm;
@@ -376,6 +386,13 @@ int LuaVoxelManip::create_object(lua_State *L)
 	Map *map = &(env->getMap());
 	LuaVoxelManip *o = new LuaVoxelManip(map);
 
+	if (lua_istable(L, 1) && lua_istable(L, 2)) {
+		v3s16 p1 = getNodeBlockPos(read_v3s16(L, 1));
+		v3s16 p2 = getNodeBlockPos(read_v3s16(L, 2));
+		sortBoxVerticies(p1, p2);
+		o->vm->initializeBlank(p1, p2);
+	}
+
 	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
 	luaL_getmetatable(L, className);
 	lua_setmetatable(L, -2);
@@ -440,5 +457,6 @@ const luaL_reg LuaVoxelManip::methods[] = {
 	luamethod(LuaVoxelManip, get_param2_data),
 	luamethod(LuaVoxelManip, set_param2_data),
 	luamethod(LuaVoxelManip, was_modified),
+	luamethod(LuaVoxelManip, get_emerged_area),
 	{0,0}
 };

src/script/lua_api/l_vmanip.h

@@ -33,7 +33,6 @@ class ManualMapVoxelManipulator;
  */
 class LuaVoxelManip : public ModApiBase {
 private:
-	ManualMapVoxelManipulator *vm;
 	std::map<v3s16, MapBlock *> modified_blocks;
 	bool is_mapgen_vm;
 
@@ -62,8 +61,11 @@ private:
 	static int l_set_param2_data(lua_State *L);
 
 	static int l_was_modified(lua_State *L);
+	static int l_get_emerged_area(lua_State *L);
 
 public:
+	ManualMapVoxelManipulator *vm;
+
 	LuaVoxelManip(ManualMapVoxelManipulator *mmvm, bool is_mapgen_vm);
 	LuaVoxelManip(Map *map);
 	~LuaVoxelManip();