Add core.spawn_tree_on_vmanip (#15415)

This function works like `core.spawn_tree`, but spawns an L-system tree onto a VoxelManip object instead on the map.

src/mapgen/treegen.cpp

@@ -875,4 +875,15 @@ void make_pine_tree(MMVManip &vmanip, v3s16 p0, const NodeDefManager *ndef,
 	}
 }
 
+std::string error_to_string(error e)
+{
+	switch (e) {
+		case SUCCESS:
+			return "success";
+		case UNBALANCED_BRACKETS:
+			return "closing ']' has no matching opening bracket";
+	}
+	return "unknown error";
+}
+
 }; // namespace treegen

src/mapgen/treegen.h

@@ -68,4 +68,7 @@ namespace treegen {
 	treegen::error make_ltree(MMVManip &vmanip, v3s16 p0, const TreeDef &def);
 	// Helper to spawn it directly on map
 	treegen::error spawn_ltree(ServerMap *map, v3s16 p0, const TreeDef &def);
+
+	// Helper to get a string from the error message
+	std::string error_to_string(error e);
 }; // namespace treegen

src/script/lua_api/l_env.cpp

@@ -1307,11 +1307,7 @@ int ModApiEnv::l_spawn_tree(lua_State *L)
 	ServerMap *map = &env->getServerMap();
 	treegen::error e;
 	if ((e = treegen::spawn_ltree (map, p0, tree_def)) != treegen::SUCCESS) {
-		if (e == treegen::UNBALANCED_BRACKETS) {
-			luaL_error(L, "spawn_tree(): closing ']' has no matching opening bracket");
-		} else {
-			luaL_error(L, "spawn_tree(): unknown error");
-		}
+		throw LuaError("spawn_tree(): " + treegen::error_to_string(e));
 	}
 
 	lua_pushboolean(L, true);
@@ -1614,11 +1610,7 @@ int ModApiEnvVM::l_spawn_tree(lua_State *L)
 
 	treegen::error e;
 	if ((e = treegen::make_ltree(*vm, p0, tree_def)) != treegen::SUCCESS) {
-		if (e == treegen::UNBALANCED_BRACKETS) {
-			throw LuaError("spawn_tree(): closing ']' has no matching opening bracket");
-		} else {
-			throw LuaError("spawn_tree(): unknown error");
-		}
+		throw LuaError("spawn_tree(): " + treegen::error_to_string(e));
 	}
 
 	lua_pushboolean(L, true);

src/script/lua_api/l_mapgen.cpp

@@ -1773,6 +1773,27 @@ int ModApiMapgen::l_place_schematic_on_vmanip(lua_State *L)
 	return 1;
 }
 
+// spawn_tree_on_vmanip(vmanip, pos, treedef)
+int ModApiMapgen::l_spawn_tree_on_vmanip(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	MMVManip *vm = checkObject<LuaVoxelManip>(L, 1)->vm;
+	v3s16 p0 = read_v3s16(L, 2);
+	treegen::TreeDef tree_def;
+	const NodeDefManager *ndef = getGameDef(L)->ndef();
+	if (!read_tree_def(L, 3, ndef, tree_def))
+		return 0;
+
+	treegen::error e = treegen::make_ltree(*vm, p0, tree_def);
+	if (e != treegen::SUCCESS) {
+		throw LuaError("spawn_tree_on_vmanip(): " + treegen::error_to_string(e));
+	}
+
+	lua_pushboolean(L, true);
+	return 1;
+}
+
 
 // serialize_schematic(schematic, format, options={...})
 int ModApiMapgen::l_serialize_schematic(lua_State *L)
@@ -2023,6 +2044,7 @@ void ModApiMapgen::Initialize(lua_State *L, int top)
 	API_FCT(create_schematic);
 	API_FCT(place_schematic);
 	API_FCT(place_schematic_on_vmanip);
+	API_FCT(spawn_tree_on_vmanip);
 	API_FCT(serialize_schematic);
 	API_FCT(read_schematic);
 }
@@ -2049,6 +2071,7 @@ void ModApiMapgen::InitializeEmerge(lua_State *L, int top)
 	API_FCT(generate_ores);
 	API_FCT(generate_decorations);
 	API_FCT(place_schematic_on_vmanip);
+	API_FCT(spawn_tree_on_vmanip);
 	API_FCT(serialize_schematic);
 	API_FCT(read_schematic);
 }

src/script/lua_api/l_mapgen.h

@@ -131,6 +131,9 @@ private:
 	//     replacements, force_placement, flagstring)
 	static int l_place_schematic_on_vmanip(lua_State *L);
 
+	// spawn_tree_on_vmanip(vmanip, pos, treedef)
+	static int l_spawn_tree_on_vmanip(lua_State *L);
+
 	// serialize_schematic(schematic, format, options={...})
 	static int l_serialize_schematic(lua_State *L);