Unity metaverse (III), protobuf & socket realize multi person online

---

Protobuf

brief introduction

Google Protocol Buffer（ abbreviation Protobuf） yes Google The company is a portable and efficient structured data storage format , Can be used as data serialize Tools , Often used for Communication protocol , And Json、XML comparison ,Protobuf The advantage is Higher performance , It's smaller 、 faster , With efficient Binary system Way to store , The generated binary messages are very compact , Therefore, the number of bytes transmitted on the network is less .

Use

We use Protobuf As a communication protocol , Creating a protocol class requires the following steps ：

• Write according to grammar rules .proto file ;
• By compiling tools protoc.exe take .proto File compiled into .cs file ;

To write .proto file

The rules of grammar are as follows ：

• Use message Defining classes , amount to c# Medium class;
• Use three field modifiers to decorate fields ：
  • required It means a Mandatory Field , Must be initialized ;
  • optional It means a Optional Field , It can be done without initialization ;
  • repeated Indicates that the field can contain multiple elements , It can be seen as passing a Array Value ;
• Field type , And C# The corresponding relationship is as follows ：

proto	c#	remarks
bool	bool	Boolean type
string	string	String type
double	double	64 Bit floating point
float	float	32 Bit floating point
int32	int	32 An integer
uint32	uint	Unsigned 32 An integer
int64	long	64 An integer
uint64	ulong	Unsigned 64 An integer
sint32	int	Coding is more than usual int32 Efficient
sint64	long	Coding is more than usual int64 Efficient
fixed32	uint	Unsigned 32 An integer
fixed64	ulong	Unsigned 64 An integer
sfixed32	int	Always 4 Bytes
sfixed64	long	Always 8 Bytes
bytes	ByteString	Bytes of data

• Field identification number

Each field has a unique Identification number , These identifiers are used to identify each field in the binary format of the message , After use Can't change .[1,15] The identification number in the code will occupy 1 byte .[16,2047] The ID number inside is occupied 2 byte , So it should be reserved for those frequent message elements [1,15] Identification number inside .
notes ： Not available [19000-19999] Identification number ,protobuf These are reserved in the protocol implementation .

for example , We need to define AvatarProperty The protocol class is right Avatar Character attributes communicate ,proto The documentation is as follows

message AvatarProperty
{
	required string userId = 1;
	required int32 avatarId = 2;
	required string name = 3;
	required float posX = 4;
	required float posY = 5;
	required float posZ = 6;
	required float rotX = 7;
	required float rotY = 8;
	required float rotZ = 9;
	required float speed = 10;
}

compile .proto file

• function cmd,cd open protoc.exe Location path

• Enter the compile command protoc -I=./ --csharp_out=./ AvatarProperty.proto

After successful compilation , You can see AvatarProperty.cs The file has been generated to the directory , Import it into Unity Then you can .

notes ：AvatarProperty.cs from protobuf The compiler tool generates , Import to Unity After that Do not modify the .

Socket

We go through Socket TCP Realize network communication , Using my small development framework SKFramework Network communication module in ：

SKFramework Framework open source address ：Github - SKFramework

The client sends Avatar data

// Send once every certain interval Avatar data 
timer = Timer.EverySeconds(interval, () =>
{
    
    if (GameServer != null)
    {
    
        var ap = new AvatarProperty()
        {
    
            UserId = UserId,
            PosX = AvatarController.transform.position.x,
            PosY = AvatarController.transform.position.y,
            PosZ = AvatarController.transform.position.z,
            RotX = AvatarController.transform.eulerAngles.x,
            RotY = AvatarController.transform.eulerAngles.y,
            RotZ = AvatarController.transform.eulerAngles.z,
            Speed = AvatarController.Instance.Speed,
        };
        // send data 
        GameServer.Send(ap);
    }
});
timer.Launch();

Timer The module is SKFramework Timing tools in the framework , You can also use Packaga Manager download ,EverySeconds Indicates how many seconds the callback function is executed , Here we will internal Set to 0.025, That is to say 1 Seconds will be sent 40 Time data , It can be adjusted appropriately .

Client reception Avatar data

After the client receives the message from the server , The message content will be passed The event system Make a throw ：

// Throw a message 
Messenger.Publish(msg.name, msg.content);

Messenger It is SKFramework The event system in the framework ,Publish Means to publish a message , The first parameter represents the of the message The theme , The second parameter represents the... Of the message Content .

The subscription topic is AvatarProperty The news of , When the news of this topic is released , Subscription events OnAvatarPropertyMsgEvent Will be executed .

// subscribe AvatarProperty news 
Messenger.Subscribe<ByteString>(typeof(AvatarProperty).Name, OnAvatarPropertyMsgEvent);

stay OnAvatarPropertyMsgEvent Incident , According to the news user ID Judge the corresponding Avatar Whether the character instance exists , If it does not exist, create and initialize ：

private void OnAvatarPropertyMsgEvent(ByteString bs)
{
    
    // Deserialization 
    var ap = AvatarProperty.Parser.ParseFrom(bs);
    if (!avatarDic.ContainsKey(ap.UserId))
    {
    
        // Receive this for the first time Avatar data   First create Avatar figure 
        var instance = Object.Instantiate(Resources.Load<AvatarInstance>(typeof(AvatarInstance).Name));
        // Deposit in Avatar Dictionaries 
        avatarDic.Add(ap.UserId, instance);
        // initialization 
        instance.Init(ap);
    }
    // The goal is Avatar
    avatarDic[ap.UserId].Set(ap);
}

AvatarInstance After receiving data , Use interpolation to calculate coordinates 、 rotate , And synchronization Animator Animation information ：

using UnityEngine;
using UnityEngine.UI;

using SK.Framework;

namespace Metaverse
{
    
    /// <summary>
    /// Avatar example 
    /// </summary>
    public class AvatarInstance : MonoBehaviour
    {
    
        public string UserId {
     get; private set; }

        [SerializeField] private Animator animator;
        [SerializeField] private Canvas worldCanvas;
        private Vector3 targetPos;
        private Vector3 targetRot;
        private const float lerpSpeed = 5f;

        /// <summary>
        ///  initialization 
        /// </summary>
        /// <param name="ap"></param>
        public void Init(AvatarProperty ap)
        {
    
            UserId = ap.UserId;
            Camera mainCamera = Camera.main != null ? Camera.main : FindObjectOfType<Camera>();
            worldCanvas.worldCamera = mainCamera;
            // mount Face2Camera Components   Keep it always facing the camera 
            worldCanvas.GetComponent<Face2Camera>().Set(mainCamera, false, false);
            worldCanvas.GetComponentInChildren<Text>().text = UserId;
        }

        /// <summary>
        ///  receive data 
        /// </summary>
        /// <param name="ap"></param>
        public void Set(AvatarProperty ap)
        {
    
            targetPos = new Vector3(ap.PosX, ap.PosY, ap.PosZ);
            targetRot = new Vector3(ap.RotX, ap.RotY, ap.RotZ);
            animator.SetFloat("Speed", ap.Speed);
        }

        private void Update()
        {
    
            // Interpolation operation 
            transform.position = Vector3.Lerp(transform.position, targetPos, Time.deltaTime * lerpSpeed);
            transform.rotation = Quaternion.Lerp(transform.rotation, Quaternion.Euler(targetRot), lerpSpeed);
        }
    }
}

Face2Camera by SKFramework A component tool in , Its function is to make objects always Towards the camera .

synchronicity ：