手把手带你使用Paint in 3D和Photon撸一个在线涂鸦画板

Paint in 3D

Paint in 3D用于在游戏内和编辑器里绘制所有物体。所有功能已经过深度优化，在WebGL、移动端、VR 以及更多平台用起来都非常好用！

它支持标准管线，以及 LWRP、HDRP 和 URP。通过使用GPU 加速，你的物体将以难以置信的速度被绘制。代码还经过深度优化来防止GC，和将所有绘制操作一起批次完成。

跟贴图系统不同，它是一个纹理绘制解决方案。这意味着你可以绘制你的物体上百万次，还是无帧率丢失，让你创作难以想象的游戏。

它在Unity应用商店上的售价是60美元，地址：https://assetstore.unity.com/packages/tools/painting/paint-in-3d-26286。

Photon

Photon中文翻译为“光子”，为有着15年服务器后端开发经验的德国Exit Games公司开发的高效，稳定，可拓展的网络引擎。为目前世界上用户最广泛，支持游戏类型最多的专业网络引擎之一，也是Unity应用商店里用户评价最高的网络组件。

世界多个知名游戏公司和工作室选用Photon作为其产品的网络支持引擎，其中包括WB华纳，Codemaster, 2K, Glu, 微软游戏工作室，史克威尔艾尼克斯，百代南梦宫，SandBox，雨神电竞等知名企业，也有许多工作室和新创企业正在了解和试用Photon之中。

它在Unity应用商店上有一个免费应用，地址：https://assetstore.unity.com/packages/tools/network/pun-2-free-119922。

当然，Photon需要注册账号、创建应用等操作才能使用，还不了解的同学可以去官方网站查阅相关资料。

温馨提示：Photon的国外服务器在国内使用比较卡，所以最好去中国官网申请国内的服务器，申请地址：https://vibrantlink.com/chinacloudapply/。

下面正式开始。

创建工程

使用Unity Hub创建一个3D项目，然后分别引入Paint in 3D和Photon Unity Networking 2，如下图：

温馨提示：在引入Photon Unity Networking 2后，记得配置AppId。

创建简易画板

为了方便演示，我们创建一个Quad作为画板，然后为其添加P3dPaintable、P3dMaterialCloner和P3dPaintableTexture组件，使用它们的默认配置即可，如下图：

然后，创建一个空的GameObject命名为OneMorePaint，然后向OneMorePaint添加P3dPaintSphere组件，修改P3dPaintSphere组件的Color为红色，其他配置保持默认不变，如下图：

再向OneMorePaint添加P3dHitScreen组件，勾选上P3dHitScreen组件的ConnectHits，其他配置保持默认不变，如下图：

这时候，创建简易画板就做好了，运行以后就可以画画了，如下图：

只不过，还是个单机版，我们加上实时在线功能。

连接PUN2服务器

创建一个C#脚本命名为Launcher，再创建一个空的GameObject命名为LauncherGameObject，把C#脚本Launcher添加到LauncherGameObject中。

编辑C#脚本Launcher为如下内容：

using Photon.Pun;
using Photon.Realtime;
using UnityEngine;

namespace One.More
{
    public class Launcher : MonoBehaviourPunCallbacks
    {
        #region Private Fields
        /// <summary>
        /// This client's version number. Users are separated from each other by gameVersion (which allows you to make breaking changes).
        /// </summary>
        string gameVersion = "1";
        /// <summary>
        /// Keep track of the current process. Since connection is asynchronous and is based on several callbacks from Photon,
        /// we need to keep track of this to properly adjust the behavior when we receive call back by Photon.
        /// Typically this is used for the OnConnectedToMaster() callback.
        /// </summary>
        bool isConnecting;
        #endregion

        void Start()
        {
            this.Connect();
        }

        #region MonoBehaviourPunCallbacks Callbacks
        public override void OnConnectedToMaster()
        {
            Debug.Log("PUN Basics Tutorial/Launcher: OnConnectedToMaster() was called by PUN");
            // we don't want to do anything if we are not attempting to join a room.
            // this case where isConnecting is false is typically when you lost or quit the game, when this level is loaded, OnConnectedToMaster will be called, in that case
            // we don't want to do anything.
            if (isConnecting)
            {
                // #Critical: The first we try to do is to join a potential existing room. If there is, good, else, we'll be called back with OnJoinRandomFailed()
                PhotonNetwork.JoinRandomRoom();
                isConnecting = false;
            }
        }
        public override void OnDisconnected(DisconnectCause cause)
        {
            Debug.LogWarningFormat("PUN Basics Tutorial/Launcher: OnDisconnected() was called by PUN with reason {0}", cause);
            isConnecting = false;
        }
        public override void OnJoinRandomFailed(short returnCode, string message)
        {
            Debug.Log("PUN Basics Tutorial/Launcher:OnJoinRandomFailed() was called by PUN. No random room available, so we create one.\nCalling: PhotonNetwork.CreateRoom");
            // #Critical: we failed to join a random room, maybe none exists or they are all full. No worries, we create a new room.
            PhotonNetwork.CreateRoom(null, new RoomOptions());
        }
        public override void OnJoinedRoom()
        {
            Debug.Log("PUN Basics Tutorial/Launcher: OnJoinedRoom() called by PUN. Now this client is in a room.");
        }
        #endregion

        #region Public Methods
        /// <summary>
        /// Start the connection process.
        /// - If already connected, we attempt joining a random room
        /// - if not yet connected, Connect this application instance to Photon Cloud Network
        /// </summary>
        public void Connect()
        {
            // we check if we are connected or not, we join if we are , else we initiate the connection to the server.
            if (PhotonNetwork.IsConnected)
            {
                // #Critical we need at this point to attempt joining a Random Room. If it fails, we'll get notified in OnJoinRandomFailed() and we'll create one.
                PhotonNetwork.JoinRandomRoom();
            }
            else
            {
                // #Critical, we must first and foremost connect to Photon Online Server.
                isConnecting = PhotonNetwork.ConnectUsingSettings();
                PhotonNetwork.GameVersion = gameVersion;
            }
        }
        #endregion
    }
}

这时候，就可以连接到连接PUN2服务器了，运行以后我们可以看到如下日志：

实时在线同步

向之前创建的OneMorePaint添加PhotonView组件，使用默认配置即可，如下图：

创建一个C#脚本命名为OnlinePainting，把C#脚本OnlinePainting添加到OneMorePaint中。

编辑C#脚本OnlinePainting为如下内容：

using PaintIn3D;
using Photon.Pun;
using UnityEngine;

namespace One.More
{
    public class OnlinePainting : MonoBehaviour, IHitPoint, IHitLine
    {
        private PhotonView photonView;
        private P3dPaintSphere paintSphere;

        void Start()
        {
            this.photonView = this.GetComponent<PhotonView>();
            this.paintSphere = this.GetComponent<P3dPaintSphere>();
        }

        public void HandleHitPoint(bool preview, int priority, float pressure, int seed, Vector3 position, Quaternion rotation)
        {
            if (preview)
            {
                return;
            }
            if (this.photonView == null)
            {
                Debug.LogError("PhotonView is not found.");
                return;
            }
            this.photonView.RPC("HandleHitPointRpc", RpcTarget.Others, preview, priority, pressure, seed, position, rotation);
        }

        public void HandleHitLine(bool preview, int priority, float pressure, int seed, Vector3 position, Vector3 endPosition, Quaternion rotation, bool clip)
        {
            if (preview)
            {
                return;
            }
            if (this.photonView == null)
            {
                Debug.LogError("PhotonView is not found.");
                return;
            }
            this.photonView.RPC("HandleHitLinetRpc", RpcTarget.Others, preview, priority, pressure, seed, position, endPosition, rotation, clip);
        }

        [PunRPC]
        public void HandleHitPointRpc(bool preview, int priority, float pressure, int seed, Vector3 position, Quaternion rotation)
        {
            if (this.paintSphere == null)
            {
                Debug.LogError("P3dPaintSphere is not found.");
                return;
            }
            this.paintSphere.HandleHitPoint(preview, priority, pressure, seed, position, rotation);
        }

        [PunRPC]
        public void HandleHitLinetRpc(bool preview, int priority, float pressure, int seed, Vector3 position, Vector3 endPosition, Quaternion rotation, bool clip)
        {
            if (this.paintSphere == null)
            {
                Debug.LogError("P3dPaintSphere is not found.");
                return;
            }
            this.paintSphere.HandleHitLine(preview, priority, pressure, seed, position, endPosition, rotation, clip);
        }
    }
}

在线涂鸦画板就制作完成了，我们看看运行效果怎么样？

运行效果

构建以后，同时启动两个客户端，效果如下：

当然，这只是简单的在线涂鸦画板，你还可以再此基础上添加更丰富的功能，比如：修改画笔颜色、修改画笔大小等等。