16. Online Location Information Synchronization

//mmo_game/pb/msg.proto

// Player information
message Player {
    int32 Pid = 1;
    Position P = 2;
}

// Synchronize player display data
message SyncPlayers {
    repeated Player ps = 1;
}

//mmo_game/core/player.go

// Broadcast one's own location to players in the surrounding (nine-grid) area to make them visible
func (p *Player) SyncSurrounding() {
    // 1. Get the player PIDs within the nine-grid area based on one's own position
    pids := WorldMgrObj.AoiMgr.GetPidsByPos(p.X, p.Z)

    // 2. Get all player objects based on PIDs
    players := make([]*Player, 0, len(pids))

    // 3. Send MsgID:200 messages to these players to make oneself appear in their field of view
    for _, pid := range pids {
        players = append(players, WorldMgrObj.GetPlayerByPid(int32(pid)))
    }

    // 3.1. Build MsgId200 protobuf data
    msg := &pb.BroadCast{
        Pid: p.Pid,
        Tp:  2, // TP2 represents broadcasting coordinates
        Data: &pb.BroadCast_P{
            P: &pb.Position{
                X: p.X,
                Y: p.Y,
                Z: p.Z,
                V: p.V,
            },
        },
    }

    // 3.2. Send the 200 message to each player's respective client to display the character
    for _, player := range players {
        player.SendMsg(200, msg)
    }

    // 4. Make players within the nine-grid area appear in one's own field of view
    // 4.1. Create Message SyncPlayers data
    playersData := make([]*pb.Player, 0, len(players))
    for _, player := range players {
        p := &pb.Player{
            Pid: player.Pid,
            P: &pb.Position{
                X: player.X,
                Y: player.Y,
                Z: player.Z,
                V: player.V,
            },
        }
        playersData = append(playersData, p)
    }

    // 4.2. Encapsulate SyncPlayer protobuf data
    SyncPlayersMsg := &pb.SyncPlayers{
        Ps: playersData[:],
    }

    // 4.3. Send all player data that needs to be displayed in the vicinity to the current player
    p.SendMsg(202, SyncPlayersMsg)
}

//mmo_game/server.go

// Hook function when a client establishes a connection
func OnConnecionAdd(conn ziface.IConnection) {
    // Create a player
    player := core.NewPlayer(conn)

    // Synchronize the current PlayerID to the client, using MsgID:1 message
    player.SyncPid()

    // Synchronize the initial coordinate information of the current player to the client, using MsgID:200 message
    player.BroadCastStartPosition()

    // Add the newly logged-in player to the World Manager
    core.WorldMgrObj.AddPlayer(player)

    // Bind the "pid" property to this connection
    conn.SetProperty("pid", player.Pid)

    // New: Synchronize the online information of surrounding players and display the information of surrounding players
    player.SyncSurrounding()

    fmt.Println("=====> Player with pidId = ", player.Pid, " has arrived ====")
}

$ go run server.go