Add z-index management to HUD

doc/lua_api.txt

@@ -1260,6 +1260,11 @@ precisely positioned items in the HUD.
 **Note**: `offset` _will_ adapt to screen DPI as well as user defined scaling
 factor!
 
+The `z_index` field specifies the order of HUD elements from back to front.
+Lower z-index elements are displayed behind higher z-index elements. Elements
+with same z-index are displayed in an arbitrary order. Default 0.
+Supports negative values.
+
 Below are the specific uses for fields in each type; fields not listed for that
 type are ignored.
 
@@ -7322,6 +7327,9 @@ Used by `Player:hud_add`. Returned by `Player:hud_get`.
 
         size = { x=100, y=100 },
         -- Size of element in pixels
+
+        z_index = 0,
+        -- Z index : lower z-index HUDs are displayed behind higher z-index HUDs
     }
 
 Particle definition

src/client/clientevent.h

@@ -131,6 +131,7 @@ struct ClientEvent
 			v2f *offset;
 			v3f *world_pos;
 			v2s32 *size;
+			s16 z_index;
 		} hudadd;
 		struct
 		{

src/client/game.cpp

@@ -2650,6 +2650,7 @@ void Game::handleClientEvent_HudAdd(ClientEvent *event, CameraOrientation *cam)
 	e->offset = *event->hudadd.offset;
 	e->world_pos = *event->hudadd.world_pos;
 	e->size = *event->hudadd.size;
+	e->z_index = event->hudadd.z_index;
 	hud_server_to_client[server_id] = player->addHud(e);
 
 	delete event->hudadd.pos;
@@ -2728,6 +2729,10 @@ void Game::handleClientEvent_HudChange(ClientEvent *event, CameraOrientation *ca
 		case HUD_STAT_SIZE:
 			e->size = *event->hudchange.v2s32data;
 			break;
+
+		case HUD_STAT_Z_INDEX:
+			e->z_index = event->hudchange.data;
+			break;
 	}
 
 	delete event->hudchange.v3fdata;

src/client/hud.cpp

@@ -283,11 +283,25 @@ void Hud::drawLuaElements(const v3s16 &camera_offset)
 {
 	u32 text_height = g_fontengine->getTextHeight();
 	irr::gui::IGUIFont* font = g_fontengine->getFont();
+
+	// Reorder elements by z_index
+	std::vector<size_t> ids;
+
 	for (size_t i = 0; i != player->maxHudId(); i++) {
 		HudElement *e = player->getHud(i);
 		if (!e)
 			continue;
 
+		auto it = ids.begin();
+		while (it != ids.end() && player->getHud(*it)->z_index <= e->z_index)
+			++it;
+
+		ids.insert(it, i);
+	}
+
+	for (size_t i : ids) {
+		HudElement *e = player->getHud(i);
+
 		v2s32 pos(floor(e->pos.X * (float) m_screensize.X + 0.5),
 				floor(e->pos.Y * (float) m_screensize.Y + 0.5));
 		switch (e->type) {

src/hud.cpp

@@ -43,6 +43,8 @@ const struct EnumString es_HudElementStat[] =
 	{HUD_STAT_ALIGN,  "alignment"},
 	{HUD_STAT_OFFSET, "offset"},
 	{HUD_STAT_WORLD_POS, "world_pos"},
+	{HUD_STAT_SIZE,    "size"},
+	{HUD_STAT_Z_INDEX, "z_index"},
 	{0, NULL},
 };
 

src/hud.h

@@ -74,7 +74,8 @@ enum HudElementStat {
 	HUD_STAT_ALIGN,
 	HUD_STAT_OFFSET,
 	HUD_STAT_WORLD_POS,
-	HUD_STAT_SIZE
+	HUD_STAT_SIZE,
+	HUD_STAT_Z_INDEX,
 };
 
 struct HudElement {
@@ -90,6 +91,7 @@ struct HudElement {
 	v2f offset;
 	v3f world_pos;
 	v2s32 size;
+	s16 z_index = 0;
 };
 
 extern const EnumString es_HudElementType[];

src/network/clientpackethandler.cpp

@@ -1081,6 +1081,7 @@ void Client::handleCommand_HudAdd(NetworkPacket* pkt)
 	v2f offset;
 	v3f world_pos;
 	v2s32 size;
+	s16 z_index = 0;
 
 	*pkt >> server_id >> type >> pos >> name >> scale >> text >> number >> item
 		>> dir >> align >> offset;
@@ -1093,6 +1094,11 @@ void Client::handleCommand_HudAdd(NetworkPacket* pkt)
 		*pkt >> size;
 	} catch(SerializationError &e) {};
 
+	try {
+		*pkt >> z_index;
+	}
+	catch(PacketError &e) {}
+
 	ClientEvent *event = new ClientEvent();
 	event->type             = CE_HUDADD;
 	event->hudadd.server_id = server_id;
@@ -1108,6 +1114,7 @@ void Client::handleCommand_HudAdd(NetworkPacket* pkt)
 	event->hudadd.offset    = new v2f(offset);
 	event->hudadd.world_pos = new v3f(world_pos);
 	event->hudadd.size      = new v2s32(size);
+	event->hudadd.z_index   = z_index;
 	m_client_event_queue.push(event);
 }
 

src/network/networkprotocol.h

@@ -563,6 +563,7 @@ enum ToClientCommand
 		v2f1000 offset
 		v3f1000 world_pos
 		v2s32 size
+		s16 z_index
 	*/
 
 	TOCLIENT_HUDRM = 0x4a,

src/script/common/c_content.cpp

@@ -1856,6 +1856,8 @@ void read_hud_element(lua_State *L, HudElement *elem)
 	elem->number  = getintfield_default(L, 2, "number", 0);
 	elem->item    = getintfield_default(L, 2, "item", 0);
 	elem->dir     = getintfield_default(L, 2, "direction", 0);
+	elem->z_index = MYMAX(S16_MIN, MYMIN(S16_MAX,
+			getintfield_default(L, 2, "z_index", 0)));
 
 	// Deprecated, only for compatibility's sake
 	if (elem->dir == 0)
@@ -1921,6 +1923,9 @@ void push_hud_element(lua_State *L, HudElement *elem)
 
 	push_v3f(L, elem->world_pos);
 	lua_setfield(L, -2, "world_pos");
+
+	lua_pushnumber(L, elem->z_index);
+	lua_setfield(L, -2, "z_index");
 }
 
 HudElementStat read_hud_change(lua_State *L, HudElement *elem, void **value)
@@ -1978,6 +1983,10 @@ HudElementStat read_hud_change(lua_State *L, HudElement *elem, void **value)
 			elem->size = read_v2s32(L, 4);
 			*value = &elem->size;
 			break;
+		case HUD_STAT_Z_INDEX:
+			elem->z_index = MYMAX(S16_MIN, MYMIN(S16_MAX, luaL_checknumber(L, 4)));
+			*value = &elem->z_index;
+			break;
 	}
 	return stat;
 }

src/server.cpp

@@ -1654,7 +1654,8 @@ void Server::SendHUDAdd(session_t peer_id, u32 id, HudElement *form)
 
 	pkt << id << (u8) form->type << form->pos << form->name << form->scale
 			<< form->text << form->number << form->item << form->dir
-			<< form->align << form->offset << form->world_pos << form->size;
+			<< form->align << form->offset << form->world_pos << form->size
+			<< form->z_index;
 
 	Send(&pkt);
 }