scriptapi_object.cpp

/*
Minetest
Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "scriptapi.h"
#include "scriptapi_object.h"
#include "log.h"
#include "tool.h"
#include "scriptapi_types.h"
#include "scriptapi_inventory.h"
#include "scriptapi_item.h"
#include "scriptapi_entity.h"
#include "scriptapi_common.h"
#include "hud.h"


struct EnumString es_HudElementType[] =
{
	{HUD_ELEM_IMAGE,     "image"},
	{HUD_ELEM_TEXT,      "text"},
	{HUD_ELEM_STATBAR,   "statbar"},
	{HUD_ELEM_INVENTORY, "inventory"},
	{0, NULL},
};

struct EnumString es_HudElementStat[] =
{
	{HUD_STAT_POS,    "pos"},
	{HUD_STAT_NAME,   "name"},
	{HUD_STAT_SCALE,  "scale"},
	{HUD_STAT_TEXT,   "text"},
	{HUD_STAT_NUMBER, "number"},
	{HUD_STAT_ITEM,   "item"},
	{HUD_STAT_DIR,    "direction"},
	{HUD_STAT_ALIGN,  "alignment"},
	{0, NULL},
};


/*
	ObjectRef
*/


ObjectRef* ObjectRef::checkobject(lua_State *L, int narg)
{
	luaL_checktype(L, narg, LUA_TUSERDATA);
	void *ud = luaL_checkudata(L, narg, className);
	if(!ud) luaL_typerror(L, narg, className);
	return *(ObjectRef**)ud;  // unbox pointer
}

ServerActiveObject* ObjectRef::getobject(ObjectRef *ref)
{
	ServerActiveObject *co = ref->m_object;
	return co;
}

LuaEntitySAO* ObjectRef::getluaobject(ObjectRef *ref)
{
	ServerActiveObject *obj = getobject(ref);
	if(obj == NULL)
		return NULL;
	if(obj->getType() != ACTIVEOBJECT_TYPE_LUAENTITY)
		return NULL;
	return (LuaEntitySAO*)obj;
}

PlayerSAO* ObjectRef::getplayersao(ObjectRef *ref)
{
	ServerActiveObject *obj = getobject(ref);
	if(obj == NULL)
		return NULL;
	if(obj->getType() != ACTIVEOBJECT_TYPE_PLAYER)
		return NULL;
	return (PlayerSAO*)obj;
}

Player* ObjectRef::getplayer(ObjectRef *ref)
{
	PlayerSAO *playersao = getplayersao(ref);
	if(playersao == NULL)
		return NULL;
	return playersao->getPlayer();
}

// Exported functions

// garbage collector
int ObjectRef::gc_object(lua_State *L) {
	ObjectRef *o = *(ObjectRef **)(lua_touserdata(L, 1));
	//infostream<<"ObjectRef::gc_object: o="<<o<<std::endl;
	delete o;
	return 0;
}

// remove(self)
int ObjectRef::l_remove(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	verbosestream<<"ObjectRef::l_remove(): id="<<co->getId()<<std::endl;
	co->m_removed = true;
	return 0;
}

// getpos(self)
// returns: {x=num, y=num, z=num}
int ObjectRef::l_getpos(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	v3f pos = co->getBasePosition() / BS;
	lua_newtable(L);
	lua_pushnumber(L, pos.X);
	lua_setfield(L, -2, "x");
	lua_pushnumber(L, pos.Y);
	lua_setfield(L, -2, "y");
	lua_pushnumber(L, pos.Z);
	lua_setfield(L, -2, "z");
	return 1;
}

// setpos(self, pos)
int ObjectRef::l_setpos(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	//LuaEntitySAO *co = getluaobject(ref);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// pos
	v3f pos = checkFloatPos(L, 2);
	// Do it
	co->setPos(pos);
	return 0;
}

// moveto(self, pos, continuous=false)
int ObjectRef::l_moveto(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	//LuaEntitySAO *co = getluaobject(ref);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// pos
	v3f pos = checkFloatPos(L, 2);
	// continuous
	bool continuous = lua_toboolean(L, 3);
	// Do it
	co->moveTo(pos, continuous);
	return 0;
}

// punch(self, puncher, time_from_last_punch, tool_capabilities, dir)
int ObjectRef::l_punch(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ObjectRef *puncher_ref = checkobject(L, 2);
	ServerActiveObject *co = getobject(ref);
	ServerActiveObject *puncher = getobject(puncher_ref);
	if(co == NULL) return 0;
	if(puncher == NULL) return 0;
	v3f dir;
	if(lua_type(L, 5) != LUA_TTABLE)
		dir = co->getBasePosition() - puncher->getBasePosition();
	else
		dir = read_v3f(L, 5);
	float time_from_last_punch = 1000000;
	if(lua_isnumber(L, 3))
		time_from_last_punch = lua_tonumber(L, 3);
	ToolCapabilities toolcap = read_tool_capabilities(L, 4);
	dir.normalize();
	// Do it
	co->punch(dir, &toolcap, puncher, time_from_last_punch);
	return 0;
}

// right_click(self, clicker); clicker = an another ObjectRef
int ObjectRef::l_right_click(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ObjectRef *ref2 = checkobject(L, 2);
	ServerActiveObject *co = getobject(ref);
	ServerActiveObject *co2 = getobject(ref2);
	if(co == NULL) return 0;
	if(co2 == NULL) return 0;
	// Do it
	co->rightClick(co2);
	return 0;
}

// set_hp(self, hp)
// hp = number of hitpoints (2 * number of hearts)
// returns: nil
int ObjectRef::l_set_hp(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	luaL_checknumber(L, 2);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	int hp = lua_tonumber(L, 2);
	/*infostream<<"ObjectRef::l_set_hp(): id="<<co->getId()
			<<" hp="<<hp<<std::endl;*/
	// Do it
	co->setHP(hp);
	// Return
	return 0;
}

// get_hp(self)
// returns: number of hitpoints (2 * number of hearts)
// 0 if not applicable to this type of object
int ObjectRef::l_get_hp(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL){
		// Default hp is 1
		lua_pushnumber(L, 1);
		return 1;
	}
	int hp = co->getHP();
	/*infostream<<"ObjectRef::l_get_hp(): id="<<co->getId()
			<<" hp="<<hp<<std::endl;*/
	// Return
	lua_pushnumber(L, hp);
	return 1;
}

// get_inventory(self)
int ObjectRef::l_get_inventory(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	InventoryLocation loc = co->getInventoryLocation();
	if(get_server(L)->getInventory(loc) != NULL)
		InvRef::create(L, loc);
	else
		lua_pushnil(L); // An object may have no inventory (nil)
	return 1;
}

// get_wield_list(self)
int ObjectRef::l_get_wield_list(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	lua_pushstring(L, co->getWieldList().c_str());
	return 1;
}

// get_wield_index(self)
int ObjectRef::l_get_wield_index(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	lua_pushinteger(L, co->getWieldIndex() + 1);
	return 1;
}

// get_wielded_item(self)
int ObjectRef::l_get_wielded_item(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL){
		// Empty ItemStack
		LuaItemStack::create(L, ItemStack());
		return 1;
	}
	// Do it
	LuaItemStack::create(L, co->getWieldedItem());
	return 1;
}

// set_wielded_item(self, itemstack or itemstring or table or nil)
int ObjectRef::l_set_wielded_item(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	ItemStack item = read_item(L, 2);
	bool success = co->setWieldedItem(item);
	lua_pushboolean(L, success);
	return 1;
}

// set_armor_groups(self, groups)
int ObjectRef::l_set_armor_groups(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	ItemGroupList groups;
	read_groups(L, 2, groups);
	co->setArmorGroups(groups);
	return 0;
}

// set_physics_override(self, physics_override_speed, physics_override_jump, physics_override_gravity)
int ObjectRef::l_set_physics_override(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	PlayerSAO *co = (PlayerSAO *) getobject(ref);
	if(co == NULL) return 0;
	// Do it
	if(!lua_isnil(L, 2)){
		co->m_physics_override_speed = lua_tonumber(L, 2);
		co->m_physics_override_sent = false;
	}
	if(!lua_isnil(L, 3)){
		co->m_physics_override_jump = lua_tonumber(L, 3);
		co->m_physics_override_sent = false;
	}
	if(!lua_isnil(L, 4)){
		co->m_physics_override_gravity = lua_tonumber(L, 4);
		co->m_physics_override_sent = false;
	}
	return 0;
}

// set_animation(self, frame_range, frame_speed, frame_blend)
int ObjectRef::l_set_animation(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	v2f frames = v2f(1, 1);
	if(!lua_isnil(L, 2))
		frames = read_v2f(L, 2);
	float frame_speed = 15;
	if(!lua_isnil(L, 3))
		frame_speed = lua_tonumber(L, 3);
	float frame_blend = 0;
	if(!lua_isnil(L, 4))
		frame_blend = lua_tonumber(L, 4);
	co->setAnimation(frames, frame_speed, frame_blend);
	return 0;
}

// set_bone_position(self, std::string bone, v3f position, v3f rotation)
int ObjectRef::l_set_bone_position(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	std::string bone = "";
	if(!lua_isnil(L, 2))
		bone = lua_tostring(L, 2);
	v3f position = v3f(0, 0, 0);
	if(!lua_isnil(L, 3))
		position = read_v3f(L, 3);
	v3f rotation = v3f(0, 0, 0);
	if(!lua_isnil(L, 4))
		rotation = read_v3f(L, 4);
	co->setBonePosition(bone, position, rotation);
	return 0;
}

// set_attach(self, parent, bone, position, rotation)
int ObjectRef::l_set_attach(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ObjectRef *parent_ref = checkobject(L, 2);
	ServerActiveObject *co = getobject(ref);
	ServerActiveObject *parent = getobject(parent_ref);
	if(co == NULL) return 0;
	if(parent == NULL) return 0;
	// Do it
	std::string bone = "";
	if(!lua_isnil(L, 3))
		bone = lua_tostring(L, 3);
	v3f position = v3f(0, 0, 0);
	if(!lua_isnil(L, 4))
		position = read_v3f(L, 4);
	v3f rotation = v3f(0, 0, 0);
	if(!lua_isnil(L, 5))
		rotation = read_v3f(L, 5);
	co->setAttachment(parent->getId(), bone, position, rotation);
	return 0;
}

// set_detach(self)
int ObjectRef::l_set_detach(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	// Do it
	co->setAttachment(0, "", v3f(0,0,0), v3f(0,0,0));
	return 0;
}

// set_properties(self, properties)
int ObjectRef::l_set_properties(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	ServerActiveObject *co = getobject(ref);
	if(co == NULL) return 0;
	ObjectProperties *prop = co->accessObjectProperties();
	if(!prop)
		return 0;
	read_object_properties(L, 2, prop);
	co->notifyObjectPropertiesModified();
	return 0;
}

/* LuaEntitySAO-only */

// setvelocity(self, {x=num, y=num, z=num})
int ObjectRef::l_setvelocity(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	v3f pos = checkFloatPos(L, 2);
	// Do it
	co->setVelocity(pos);
	return 0;
}

// getvelocity(self)
int ObjectRef::l_getvelocity(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	v3f v = co->getVelocity();
	pushFloatPos(L, v);
	return 1;
}

// setacceleration(self, {x=num, y=num, z=num})
int ObjectRef::l_setacceleration(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// pos
	v3f pos = checkFloatPos(L, 2);
	// Do it
	co->setAcceleration(pos);
	return 0;
}

// getacceleration(self)
int ObjectRef::l_getacceleration(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	v3f v = co->getAcceleration();
	pushFloatPos(L, v);
	return 1;
}

// setyaw(self, radians)
int ObjectRef::l_setyaw(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	float yaw = luaL_checknumber(L, 2) * core::RADTODEG;
	// Do it
	co->setYaw(yaw);
	return 0;
}

// getyaw(self)
int ObjectRef::l_getyaw(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	float yaw = co->getYaw() * core::DEGTORAD;
	lua_pushnumber(L, yaw);
	return 1;
}

// settexturemod(self, mod)
int ObjectRef::l_settexturemod(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	std::string mod = luaL_checkstring(L, 2);
	co->setTextureMod(mod);
	return 0;
}

// setsprite(self, p={x=0,y=0}, num_frames=1, framelength=0.2,
//           select_horiz_by_yawpitch=false)
int ObjectRef::l_setsprite(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	v2s16 p(0,0);
	if(!lua_isnil(L, 2))
		p = read_v2s16(L, 2);
	int num_frames = 1;
	if(!lua_isnil(L, 3))
		num_frames = lua_tonumber(L, 3);
	float framelength = 0.2;
	if(!lua_isnil(L, 4))
		framelength = lua_tonumber(L, 4);
	bool select_horiz_by_yawpitch = false;
	if(!lua_isnil(L, 5))
		select_horiz_by_yawpitch = lua_toboolean(L, 5);
	co->setSprite(p, num_frames, framelength, select_horiz_by_yawpitch);
	return 0;
}

// DEPRECATED
// get_entity_name(self)
int ObjectRef::l_get_entity_name(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	std::string name = co->getName();
	lua_pushstring(L, name.c_str());
	return 1;
}

// get_luaentity(self)
int ObjectRef::l_get_luaentity(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	LuaEntitySAO *co = getluaobject(ref);
	if(co == NULL) return 0;
	// Do it
	luaentity_get(L, co->getId());
	return 1;
}

/* Player-only */

// is_player(self)
int ObjectRef::l_is_player(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	lua_pushboolean(L, (player != NULL));
	return 1;
}

// get_player_name(self)
int ObjectRef::l_get_player_name(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL){
		lua_pushlstring(L, "", 0);
		return 1;
	}
	// Do it
	lua_pushstring(L, player->getName());
	return 1;
}

// get_look_dir(self)
int ObjectRef::l_get_look_dir(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL) return 0;
	// Do it
	float pitch = player->getRadPitch();
	float yaw = player->getRadYaw();
	v3f v(cos(pitch)*cos(yaw), sin(pitch), cos(pitch)*sin(yaw));
	push_v3f(L, v);
	return 1;
}

// get_look_pitch(self)
int ObjectRef::l_get_look_pitch(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL) return 0;
	// Do it
	lua_pushnumber(L, player->getRadPitch());
	return 1;
}

// get_look_yaw(self)
int ObjectRef::l_get_look_yaw(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL) return 0;
	// Do it
	lua_pushnumber(L, player->getRadYaw());
	return 1;
}

// set_look_pitch(self, radians)
int ObjectRef::l_set_look_pitch(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	PlayerSAO* co = getplayersao(ref);
	if(co == NULL) return 0;
	float pitch = luaL_checknumber(L, 2) * core::RADTODEG;
	// Do it
	co->setPitch(pitch);
	return 1;
}

// set_look_yaw(self, radians)
int ObjectRef::l_set_look_yaw(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	PlayerSAO* co = getplayersao(ref);
	if(co == NULL) return 0;
	float yaw = luaL_checknumber(L, 2) * core::RADTODEG;
	// Do it
	co->setYaw(yaw);
	return 1;
}

// set_inventory_formspec(self, formspec)
int ObjectRef::l_set_inventory_formspec(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL) return 0;
	std::string formspec = luaL_checkstring(L, 2);

	player->inventory_formspec = formspec;
	get_server(L)->reportInventoryFormspecModified(player->getName());
	lua_pushboolean(L, true);
	return 1;
}

// get_inventory_formspec(self) -> formspec
int ObjectRef::l_get_inventory_formspec(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL) return 0;

	std::string formspec = player->inventory_formspec;
	lua_pushlstring(L, formspec.c_str(), formspec.size());
	return 1;
}

// get_player_control(self)
int ObjectRef::l_get_player_control(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL){
		lua_pushlstring(L, "", 0);
		return 1;
	}
	// Do it
	PlayerControl control = player->getPlayerControl();
	lua_newtable(L);
	lua_pushboolean(L, control.up);
	lua_setfield(L, -2, "up");
	lua_pushboolean(L, control.down);
	lua_setfield(L, -2, "down");
	lua_pushboolean(L, control.left);
	lua_setfield(L, -2, "left");
	lua_pushboolean(L, control.right);
	lua_setfield(L, -2, "right");
	lua_pushboolean(L, control.jump);
	lua_setfield(L, -2, "jump");
	lua_pushboolean(L, control.aux1);
	lua_setfield(L, -2, "aux1");
	lua_pushboolean(L, control.sneak);
	lua_setfield(L, -2, "sneak");
	lua_pushboolean(L, control.LMB);
	lua_setfield(L, -2, "LMB");
	lua_pushboolean(L, control.RMB);
	lua_setfield(L, -2, "RMB");
	return 1;
}

// get_player_control_bits(self)
int ObjectRef::l_get_player_control_bits(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if(player == NULL){
		lua_pushlstring(L, "", 0);
		return 1;
	}
	// Do it
	lua_pushnumber(L, player->keyPressed);
	return 1;
}

// hud_add(self, form)
int ObjectRef::l_hud_add(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if (player == NULL)
		return 0;

	HudElement *elem = new HudElement;
	
	elem->type = (HudElementType)getenumfield(L, 2, "hud_elem_type",
								es_HudElementType, HUD_ELEM_TEXT);
	
	lua_getfield(L, 2, "position");
	elem->pos = lua_istable(L, -1) ? read_v2f(L, -1) : v2f();
	lua_pop(L, 1);
	
	lua_getfield(L, 2, "scale");
	elem->scale = lua_istable(L, -1) ? read_v2f(L, -1) : v2f();
	lua_pop(L, 1);
	
	elem->name   = getstringfield_default(L, 2, "name", "");
	elem->text   = getstringfield_default(L, 2, "text", "");
	elem->number = getintfield_default(L, 2, "number", 0);
	elem->item   = getintfield_default(L, 2, "item", 0);
	elem->dir    = getintfield_default(L, 2, "direction", 0);

	lua_getfield(L, 2, "alignment");
	elem->align = lua_istable(L, -1) ? read_v2f(L, -1) : v2f();
	lua_pop(L, 1);

	u32 id = get_server(L)->hudAdd(player, elem);
	if (id == (u32)-1) {
		delete elem;
		return 0;
	}

	lua_pushnumber(L, id);
	return 1;
}

// hud_remove(self, id)
int ObjectRef::l_hud_remove(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if (player == NULL)
		return 0;

	u32 id = -1;
	if (!lua_isnil(L, 2))
		id = lua_tonumber(L, 2);
	
	if (!get_server(L)->hudRemove(player, id))
		return 0;

	lua_pushboolean(L, true);
	return 1;
}

// hud_change(self, id, stat, data)
int ObjectRef::l_hud_change(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if (player == NULL)
		return 0;

	u32 id = !lua_isnil(L, 2) ? lua_tonumber(L, 2) : -1;
	if (id >= player->hud.size())
		return 0;
		
	HudElementStat stat = HUD_STAT_NUMBER;
	if (!lua_isnil(L, 3)) {
		int statint;
		std::string statstr = lua_tostring(L, 3);
		stat = string_to_enum(es_HudElementStat, statint, statstr) ?
				(HudElementStat)statint : HUD_STAT_NUMBER;
	}
	
	void *value = NULL;
	HudElement *e = player->hud[id];
	if (!e)
		return 0;
	
	switch (stat) {
		case HUD_STAT_POS:
			e->pos = read_v2f(L, 4);
			value = &e->pos;
			break;
		case HUD_STAT_NAME:
			e->name = lua_tostring(L, 4);
			value = &e->name;
			break;
		case HUD_STAT_SCALE:
			e->scale = read_v2f(L, 4);
			value = &e->scale;
			break;
		case HUD_STAT_TEXT:
			e->text = lua_tostring(L, 4);
			value = &e->text;
			break;
		case HUD_STAT_NUMBER:
			e->number = lua_tonumber(L, 4);
			value = &e->number;
			break;
		case HUD_STAT_ITEM:
			e->item = lua_tonumber(L, 4);
			value = &e->item;
			break;
		case HUD_STAT_DIR:
			e->dir = lua_tonumber(L, 4);
			value = &e->dir;
		case HUD_STAT_ALIGN:
			e->align = read_v2f(L, 4);
			value = &e->align;
	}

	get_server(L)->hudChange(player, id, stat, value);

	lua_pushboolean(L, true);
	return 1;
}

// hud_get(self, id)
int ObjectRef::l_hud_get(lua_State *L)
{
	ObjectRef *ref = checkobject(L, 1);
	Player *player = getplayer(ref);
	if (player == NULL)
		return 0;

	u32 id = lua_tonumber(L, -1);
	if (id >= player->hud.size())
		return 0;
	
	HudElement *e = player->hud[id];
	if (!e)
		return 0;
	
	lua_newtable(L);
	
	lua_pushstring(L, es_HudElementType[(u8)e->type].str);
	lua_setfield(L, -2, "type");
	
	push_v2f(L, e->pos);
	lua_setfield(L, -2, "position");
	
	lua_pushstring(L, e->name.c_str());
	lua_setfield(L, -2, "name");
	
	push_v2f(L, e->scale);
	lua_setfield(L, -2, "scale");
	
	lua_pushstring(L, e->text.c_str());
	lua_setfield(L, -2, "text");
	
	lua_pushnumber(L, e->number);
	lua_setfield(L, -2, "number");
	
	lua_pushnumber(L, e->item);
	lua_setfield(L, -2, "item");
	
	lua_pushnumber(L, e->dir);
	lua_setfield(L, -2, "dir");

	return 1;
}

ObjectRef::ObjectRef(ServerActiveObject *object):
	m_object(object)
{
	//infostream<<"ObjectRef created for id="<<m_object->getId()<<std::endl;
}

ObjectRef::~ObjectRef()
{
	/*if(m_object)
		infostream<<"ObjectRef destructing for id="
				<<m_object->getId()<<std::endl;
	else
		infostream<<"ObjectRef destructing for id=unknown"<<std::endl;*/
}

// Creates an ObjectRef and leaves it on top of stack
// Not callable from Lua; all references are created on the C side.
void ObjectRef::create(lua_State *L, ServerActiveObject *object)
{
	ObjectRef *o = new ObjectRef(object);
	//infostream<<"ObjectRef::create: o="<<o<<std::endl;
	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
	luaL_getmetatable(L, className);
	lua_setmetatable(L, -2);
}

void ObjectRef::set_null(lua_State *L)
{
	ObjectRef *o = checkobject(L, -1);
	o->m_object = NULL;
}

void ObjectRef::Register(lua_State *L)
{
	lua_newtable(L);
	int methodtable = lua_gettop(L);
	luaL_newmetatable(L, className);
	int metatable = lua_gettop(L);

	lua_pushliteral(L, "__metatable");
	lua_pushvalue(L, methodtable);
	lua_settable(L, metatable);  // hide metatable from Lua getmetatable()

	lua_pushliteral(L, "__index");
	lua_pushvalue(L, methodtable);
	lua_settable(L, metatable);

	lua_pushliteral(L, "__gc");
	lua_pushcfunction(L, gc_object);
	lua_settable(L, metatable);

	lua_pop(L, 1);  // drop metatable

	luaL_openlib(L, 0, methods, 0);  // fill methodtable
	lua_pop(L, 1);  // drop methodtable

	// Cannot be created from Lua
	//lua_register(L, className, create_object);
}

const char ObjectRef::className[] = "ObjectRef";
const luaL_reg ObjectRef::methods[] = {
	// ServerActiveObject
	luamethod(ObjectRef, remove),
	luamethod(ObjectRef, getpos),
	luamethod(ObjectRef, setpos),
	luamethod(ObjectRef, moveto),
	luamethod(ObjectRef, punch),
	luamethod(ObjectRef, right_click),
	luamethod(ObjectRef, set_hp),
	luamethod(ObjectRef, get_hp),
	luamethod(ObjectRef, get_inventory),
	luamethod(ObjectRef, get_wield_list),
	luamethod(ObjectRef, get_wield_index),
	luamethod(ObjectRef, get_wielded_item),
	luamethod(ObjectRef, set_wielded_item),
	luamethod(ObjectRef, set_armor_groups),
	luamethod(ObjectRef, set_physics_override),
	luamethod(ObjectRef, set_animation),
	luamethod(ObjectRef, set_bone_position),
	luamethod(ObjectRef, set_attach),
	luamethod(ObjectRef, set_detach),
	luamethod(ObjectRef, set_properties),
	// LuaEntitySAO-only
	luamethod(ObjectRef, setvelocity),
	luamethod(ObjectRef, getvelocity),
	luamethod(ObjectRef, setacceleration),
	luamethod(ObjectRef, getacceleration),
	luamethod(ObjectRef, setyaw),
	luamethod(ObjectRef, getyaw),
	luamethod(ObjectRef, settexturemod),
	luamethod(ObjectRef, setsprite),
	luamethod(ObjectRef, get_entity_name),
	luamethod(ObjectRef, get_luaentity),
	// Player-only
	luamethod(ObjectRef, is_player),
	luamethod(ObjectRef, get_player_name),
	luamethod(ObjectRef, get_look_dir),
	luamethod(ObjectRef, get_look_pitch),
	luamethod(ObjectRef, get_look_yaw),
	luamethod(ObjectRef, set_look_yaw),
	luamethod(ObjectRef, set_look_pitch),
	luamethod(ObjectRef, set_inventory_formspec),
	luamethod(ObjectRef, get_inventory_formspec),
	luamethod(ObjectRef, get_player_control),
	luamethod(ObjectRef, get_player_control_bits),
	luamethod(ObjectRef, hud_add),
	luamethod(ObjectRef, hud_remove),
	luamethod(ObjectRef, hud_change),
	luamethod(ObjectRef, hud_get),
	//luamethod(ObjectRef, hud_lock_next_bar),
	//luamethod(ObjectRef, hud_unlock_bar),
	{0,0}
};

// Creates a new anonymous reference if cobj=NULL or id=0
void objectref_get_or_create(lua_State *L,
		ServerActiveObject *cobj)
{
	if(cobj == NULL || cobj->getId() == 0){
		ObjectRef::create(L, cobj);
	} else {
		objectref_get(L, cobj->getId());
	}
}

void objectref_get(lua_State *L, u16 id)
{
	// Get minetest.object_refs[i]
	lua_getglobal(L, "minetest");
	lua_getfield(L, -1, "object_refs");
	luaL_checktype(L, -1, LUA_TTABLE);
	lua_pushnumber(L, id);
	lua_gettable(L, -2);
	lua_remove(L, -2); // object_refs
	lua_remove(L, -2); // minetest
}

/*
	ObjectProperties
*/

void read_object_properties(lua_State *L, int index,
		ObjectProperties *prop)
{
	if(index < 0)
		index = lua_gettop(L) + 1 + index;
	if(!lua_istable(L, index))
		return;

	prop->hp_max = getintfield_default(L, -1, "hp_max", 10);

	getboolfield(L, -1, "physical", prop->physical);

	getfloatfield(L, -1, "weight", prop->weight);

	lua_getfield(L, -1, "collisionbox");
	if(lua_istable(L, -1))
		prop->collisionbox = read_aabb3f(L, -1, 1.0);
	lua_pop(L, 1);

	getstringfield(L, -1, "visual", prop->visual);

	getstringfield(L, -1, "mesh", prop->mesh);

	lua_getfield(L, -1, "visual_size");
	if(lua_istable(L, -1))
		prop->visual_size = read_v2f(L, -1);
	lua_pop(L, 1);

	lua_getfield(L, -1, "textures");
	if(lua_istable(L, -1)){
		prop->textures.clear();
		int table = lua_gettop(L);
		lua_pushnil(L);
		while(lua_next(L, table) != 0){
			// key at index -2 and value at index -1
			if(lua_isstring(L, -1))
				prop->textures.push_back(lua_tostring(L, -1));
			else
				prop->textures.push_back("");
			// removes value, keeps key for next iteration
			lua_pop(L, 1);
		}
	}
	lua_pop(L, 1);

	lua_getfield(L, -1, "colors");
	if(lua_istable(L, -1)){
		prop->colors.clear();
		int table = lua_gettop(L);
		lua_pushnil(L);
		while(lua_next(L, table) != 0){
			// key at index -2 and value at index -1
			if(lua_isstring(L, -1))
				prop->colors.push_back(readARGB8(L, -1));
			else
				prop->colors.push_back(video::SColor(255, 255, 255, 255));
			// removes value, keeps key for next iteration
			lua_pop(L, 1);
		}
	}
	lua_pop(L, 1);

	lua_getfield(L, -1, "spritediv");
	if(lua_istable(L, -1))
		prop->spritediv = read_v2s16(L, -1);
	lua_pop(L, 1);

	lua_getfield(L, -1, "initial_sprite_basepos");
	if(lua_istable(L, -1))
		prop->initial_sprite_basepos = read_v2s16(L, -1);
	lua_pop(L, 1);

	getboolfield(L, -1, "is_visible", prop->is_visible);
	getboolfield(L, -1, "makes_footstep_sound", prop->makes_footstep_sound);
	getfloatfield(L, -1, "automatic_rotate", prop->automatic_rotate);
}

/*
	object_reference
*/

void scriptapi_add_object_reference(lua_State *L, ServerActiveObject *cobj)
{
	realitycheck(L);
	assert(lua_checkstack(L, 20));
	//infostream<<"scriptapi_add_object_reference: id="<<cobj->getId()<<std::endl;
	StackUnroller stack_unroller(L);

	// Create object on stack
	ObjectRef::create(L, cobj); // Puts ObjectRef (as userdata) on stack
	int object = lua_gettop(L);

	// Get minetest.object_refs table
	lua_getglobal(L, "minetest");
	lua_getfield(L, -1, "object_refs");
	luaL_checktype(L, -1, LUA_TTABLE);
	int objectstable = lua_gettop(L);

	// object_refs[id] = object
	lua_pushnumber(L, cobj->getId()); // Push id
	lua_pushvalue(L, object); // Copy object to top of stack
	lua_settable(L, objectstable);
}

void scriptapi_rm_object_reference(lua_State *L, ServerActiveObject *cobj)
{
	realitycheck(L);
	assert(lua_checkstack(L, 20));
	//infostream<<"scriptapi_rm_object_reference: id="<<cobj->getId()<<std::endl;
	StackUnroller stack_unroller(L);

	// Get minetest.object_refs table
	lua_getglobal(L, "minetest");
	lua_getfield(L, -1, "object_refs");
	luaL_checktype(L, -1, LUA_TTABLE);
	int objectstable = lua_gettop(L);

	// Get object_refs[id]
	lua_pushnumber(L, cobj->getId()); // Push id
	lua_gettable(L, objectstable);
	// Set object reference to NULL
	ObjectRef::set_null(L);
	lua_pop(L, 1); // pop object

	// Set object_refs[id] = nil
	lua_pushnumber(L, cobj->getId()); // Push id
	lua_pushnil(L);
	lua_settable(L, objectstable);
}