Zero foundation uses unity3d to develop AR applications and download 3D models remotely

Tools ：Unity Version 2020.1.6f1c1 Personal、EasyAR 4.1

download ：https://unity.cn/releases、https://www.easyar.cn/view/download.html#download-nav2

register ：Unity Register individual developers to obtain licenses ,EasyAR Also register personal free edition .

open Unity, Create a new one Unity3D project , Double-click the downloaded EasyAR Plug in and import ：

Sign in EasyAR Development Center , Create an app ：

Open the project , hold Key Paste in ：

Create a project ： We use EasyAR This plugin , The official website has given a relatively perfect case , We can refer to ：https://www.easyar.cn/view/download.html#download-nav2

preparation ：

We right click on the blank space of the directory to add a C# Script, Put all the code in LoadAR.cs.

The export model （ Preforms ）：

Write export code ：

using UnityEngine;
using System.Collections;
using UnityEditor;
using System.IO;

public class AssetBundleBuilder 
{
    [MenuItem("Assets/Build AssetBundle")]
    static public void BuildAssetBundle()
    {
        Caching.ClearCache ();
        string path = Application.streamingAssetsPath + "/" + "AssetBundles" + "/" + "Machine";
        if (!Directory.Exists (path)) 
        {
            Directory.CreateDirectory(path);
        }
        BuildPipeline.BuildAssetBundles (path,0,EditorUserBuildSettings.activeBuildTarget);
        AssetDatabase.Refresh ();
    }
}

The generated file is in Assets\StreamingAssets\AssetBundles\Machine（ The name depends on your ）

If the server is IIS Of , You can add Web.config The code can be downloaded .a file , Otherwise 404 error ：

    <system.webServer>
        <staticContent>
            <mimeMap fileExtension=".a" mimeType="application/octet-stream" />
        </staticContent>
    </system.webServer>

add controls ：

To write LoadAR.cs Main code ：

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.UI;
using UnityEngine.Networking;
using LitJson;
using System.Net;
using System.IO;
using System.Text;
using easyar;

public class LoadAR : MonoBehaviour
{
    // Game FPS, It can be modified in the attribute window 
    public int targetFrameRate = 300;

    //SessionID, This is used according to the specific business logic , It's not necessary 
    private string sessionId;

    // Create a goal dynamically （ Recognizer ）
    private ImageTargetController imageTargetController;

    // Create models dynamically 
    private GameObject myModel;

    // When the program wakes up 
    void Awake()
    {
        // Modify the current FPS
        //Application.targetFrameRate = targetFrameRate;
        
        // Get remote server information 
        string url = "http://192.168.1.101/Default.aspx";
        string data = "ClientKey=e10adc3949ba59abbe56e057f20f883e";
        string result = HttpGet(url, data);

        // analysis Json file 
        JsonData jdConfig = JsonMapper.ToObject(result);

        sessionId = (string)jdConfig["sessionId"];

        // obtain GUID And it is displayed in the upper left corner of the screen ：
        Text showGUID = GameObject.Find("Canvas").transform.GetChild(0).gameObject.GetComponent<Text>();
        showGUID.text = "GUID: " + sessionId;

        // Load the model dynamically and add it to ImageTarget below 
        //myModel = (GameObject)Instantiate(Resources.Load("Machine-Mask"));
        //myModel.transform.parent = GameObject.Find("ImageTarget").transform;

        // Change button text 
        Button submit = GameObject.Find("Canvas").transform.GetChild(2).gameObject.GetComponent<Button>();
        Text btnSubmitTxt = submit.transform.GetChild(0).gameObject.GetComponent<Text>();
        btnSubmitTxt.text = " change another one ";
        // Add button event 
        submit.onClick.AddListener(ButtonClick);

        imageTargetController = CreateTargetNode("ImageTarget-ID");// Dynamically create recognition objects 
    }

    // The application starts executing 
    void Start()
    {
        
    }

    // amount to Timer, Update every second 
    void Update()
    {
        ShowTime(DateTime.Now.ToString("HH:mm:ss"));
        //LoadModel();
    }
    
    // Button event 
    void ButtonClick()
    {
        LoadModel();
    }

    // Show time text 
    private void ShowTime(string text)
    {
        Text showTime = GameObject.Find("Canvas").transform.GetChild(1).gameObject.GetComponent<Text>();
        showTime.text = text;
    }

    private string loadUrl="";
    private string loadName="";
    // Get the download list remotely 
    private void LoadModel()
    {
        string url = "http://192.168.1.101/GetModel.aspx";
        string data = "SessionID=" + sessionId;
        string result = HttpGet(url, data);

        try
        {
            JsonData jdModel = JsonMapper.ToObject(result);

            if(loadUrl!=(string)jdModel["url"])
            {
                loadUrl=(string)jdModel["url"];
                loadName=(string)jdModel["name"];
                StartCoroutine(LoadAssets(loadUrl,loadName));
            }
        }
        catch
        {

        }
    }

    // Download the model remotely and load it into ImageTarget Next 
    IEnumerator LoadAssets(string url,string name)
    {
        if(url!=null && url!="")
        {
            UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(url);
            yield return request.SendWebRequest();
            AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);

            GameObject go = ab.LoadAsset<GameObject>(name);

            Destroy(myModel);// Destroy the previous model 

            // stay GameObject Add an object under the node , In order to be in target Show when tracked .
            myModel = (GameObject)Instantiate(go);
            myModel.transform.parent = imageTargetController.gameObject.transform;
        }
    }

    // Dynamically create the component properties of the target 
    private ImageTargetController CreateTargetNode(string targetName)
    {
        GameObject go = new GameObject(targetName);
        var targetController = go.AddComponent<ImageTargetController>();
        
        ImageTrackerFrameFilter imageTracker = FindObjectOfType<ImageTrackerFrameFilter>(); // Get trace events 
        imageTracker.enabled = true;
        targetController.Tracker = imageTracker;    
        targetController.SourceType = ImageTargetController.DataSource.ImageFile;
        targetController.ImageFileSource.PathType = PathType.StreamingAssets;
        targetController.ImageFileSource.Path = "idcard.jpg";   // Identify pictures 
        targetController.ImageFileSource.Name = "ID Card";
        targetController.ImageFileSource.Scale = 10;

        return targetController;
    }

    //GET Request and obtain results 
    public static string HttpGet(string Url, string postDataStr)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == "" ? "" : "?") + postDataStr);
        request.Method = "GET";
        request.ContentType = "text/html;charset=UTF-8";

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream myResponseStream = response.GetResponseStream();
        StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.UTF8);
        string retString = myStreamReader.ReadToEnd();
        myStreamReader.Close();
        myResponseStream.Close();

        return retString;
    }
}

Configure Android build environment , Generate APK file ：

Generate APK Under the project root ：

Send it to Android mobile phone to install and run AR application ：

Click on another button , You can download and display another model ：