Schematic: Add force_placement parameter to minetest.place_structure API

doc/lua_api.txt

@@ -1595,11 +1595,13 @@ minetest.create_schematic(p1, p2, probability_list, filename, slice_prob_list)
    ^ If slice probability list is nil, no slice probabilities are applied.
 ^ Saves schematic in the Minetest Schematic format to filename.
 
-minetest.place_schematic(pos, schematic, rotation, replacements)
+minetest.place_schematic(pos, schematic, rotation, replacements, force_placement)
 ^ Place the schematic specified by schematic (see: Schematic specifier) at pos.
 ^ Rotation can be "0", "90", "180", "270", or "random".
 ^ If the rotation parameter is omitted, the schematic is not rotated.
 ^ replacements = {{"oldname", "convert_to"}, ...}
+^ force_placement is a boolean indicating whether nodes other than air and
+^ ignore are replaced by the schematic
 
 Random:
 minetest.get_connected_players() -> list of ObjectRefs

src/mapgen.cpp

@@ -652,7 +652,7 @@ void DecoSchematic::blitToVManip(v3s16 p, ManualMapVoxelManipulator *vm,
 }
 
 
-void DecoSchematic::placeStructure(Map *map, v3s16 p) {
+void DecoSchematic::placeStructure(Map *map, v3s16 p, bool force_placement) {
 	assert(schematic != NULL);
 	ManualMapVoxelManipulator *vm = new ManualMapVoxelManipulator(map);
 
@@ -673,7 +673,7 @@ void DecoSchematic::placeStructure(Map *map, v3s16 p) {
 	v3s16 bp2 = getNodeBlockPos(p + s - v3s16(1,1,1));
 	vm->initialEmerge(bp1, bp2);
 
-	blitToVManip(p, vm, rot, true);
+	blitToVManip(p, vm, rot, force_placement);
 
 	std::map<v3s16, MapBlock *> lighting_modified_blocks;
 	std::map<v3s16, MapBlock *> modified_blocks;

src/mapgen.h

@@ -313,7 +313,7 @@ class DecoSchematic : public Decoration {
 	void saveSchematicFile(INodeDefManager *ndef);
 
 	bool getSchematicFromMap(Map *map, v3s16 p1, v3s16 p2);
-	void placeStructure(Map *map, v3s16 p);
+	void placeStructure(Map *map, v3s16 p, bool force_placement);
 	void applyProbabilities(v3s16 p0,
 		std::vector<std::pair<v3s16, u8> > *plist,
 		std::vector<std::pair<s16, u8> > *splist);

src/script/lua_api/l_mapgen.cpp

@@ -599,9 +599,8 @@ int ModApiMapgen::l_place_schematic(lua_State *L)
 	dschem.rotation = (Rotation)rot;
 
 	if (lua_istable(L, 4)) {
-		int index = 4;
 		lua_pushnil(L);
-		while (lua_next(L, index) != 0) {
+		while (lua_next(L, 4) != 0) {
 			// key at index -2 and value at index -1
 			lua_rawgeti(L, -1, 1);
 			std::string replace_from = lua_tostring(L, -1);
@@ -615,6 +614,10 @@ int ModApiMapgen::l_place_schematic(lua_State *L)
 		}
 	}
 
+	bool force_placement = true;
+	if (lua_isboolean(L, 5))
+		force_placement = lua_toboolean(L, 5);
+
 	if (!dschem.filename.empty()) {
 		if (!dschem.loadSchematicFile()) {
 			errorstream << "place_schematic: failed to load schematic file '"
@@ -624,7 +627,7 @@ int ModApiMapgen::l_place_schematic(lua_State *L)
 		dschem.resolveNodeNames(ndef);
 	}
 
-	dschem.placeStructure(map, p);
+	dschem.placeStructure(map, p, force_placement);
 
 	return 1;
 }