Add z-index management to HUD

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) {