如何使用Unity从URL加载图像？

Question

请救我脱离疯狂。

无论我多少次谷歌，我总是得到以下代码的（通常已弃用）版本：

IEnumerator setImage(string url) {
    Texture2D texture = profileImage.canvasRenderer.GetMaterial().mainTexture as Texture2D;

    WWW www = new WWW(url);
    yield return www;

    Debug.Log("Why on earh is this never called?");

    www.LoadImageIntoTexture(texture);
    www.Dispose();
    www = null;
}

我使用的是Unity 5而不是4.我正在尝试加载的URL存在。请对我有所启发。

如何通过HTTP加载图像并将其显示在UnityEngine.UI.Image中？

Answer 1

快速澄清：https://docs.unity3d.com/ScriptReference/MonoBehaviour.StartCoroutine.html

public void yourMethod()
{
   StartCoroutine(setImage("http://url/image.jpg")); //balanced parens CAS
}

IEnumerator setImage(string url) {
    Texture2D texture = profileImage.canvasRenderer.GetMaterial().mainTexture as Texture2D;

    WWW www = new WWW(url);
    yield return www;

    // calling this function with StartCoroutine solves the problem
    Debug.Log("Why on earh is this never called?");

    www.LoadImageIntoTexture(texture);
    www.Dispose();
    www = null;
}

Answer 2

对于Unity 2018+，使用UnityWebRequest替换WWW类。

void Start(){    
    StartCoroutine(DownloadImage(url));
}

IEnumerator DownloadImage(string MediaUrl)
{   
    UnityWebRequest request = UnityWebRequestTexture.GetTexture(MediaUrl);
    yield return request.SendWebRequest();
    if(request.isNetworkError || request.isHttpError) 
        Debug.Log(request.error);
    else
        YourRawImage.texture = ((DownloadHandlerTexture) request.downloadHandler).texture
} 

Answer 3

当你想要异步时：

using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.Networking;

public static async Task<Texture2D> GetRemoteTexture ( string url )
{
    using( UnityWebRequest www = UnityWebRequestTexture.GetTexture( url ) )
    {
        //begin requenst:
        var asyncOp = www.SendWebRequest();

        //await until it's done: 
        while( asyncOp.isDone==false )
        {
            await Task.Delay( 1000/30 );//30 hertz
        }

        //read results:
        if( www.isNetworkError || www.isHttpError )
        {
            //log error:
            #if DEBUG
            Debug.Log( $"{ www.error }, URL:{ www.url }" );
            #endif

            //nothing to return on error:
            return null;
        }
        else
        {
            //return valid results:
            return DownloadHandlerTexture.GetContent( www );
        }
    }
}

用法示例：

[SerializeField] string _imageUrl;
[SerializeField] Material _material;

async void Start ()
{
    Texture2D texture = await GetRemoteTexture( _imageUrl );
    _material.mainTexture = texture;
}

Answer 4

感谢Umair M提出的问题，我发现需要使用unity的StartCoroutine来调用此方法。

Answer 5

public void OnStart()
{
    StartCoroutine(setImage("http://drive.google.com/myimage.jpg")); 
}

IEnumerator setImage(string url) 
{
    Texture2D texture = null;
    WWW www = new WWW(url);
    yield return www;

    Debug.Log("Why on earh is this never called?");
    texture = WWW.texture;
    //end show Image in texture 2D
}