Texture2D.LoadImage unable to parse bytes

Question

I'm downloading a raw byte array to be used as a Texture2D using a technique by at SO.

 UnityWebRequest www = UnityWebRequest.Get("myurl");
 
 DownloadHandler handle = www.downloadHandler;
 
 yield return www.Send();
 
 if (www.isNetworkError)
 {
 
     UnityEngine.Debug.Log("Error while Receiving: " + www.error);
 }
 else
 {
     UnityEngine.Debug.Log("Success");
 
     Texture2D texture2d = new Texture2D(8, 8);
 
     texture2d.LoadImage(handle.data);
                     
 }

LoadImage, however, can't parse the byte array and gives me 'red question mark' fallback.

Answer 1

Answer by valentin-simian · Jan 30, 2018 at 01:14 AM

So the issue was in LoadImage not being able to parse the image's header. The function starts reading the texture as a bytearray, however first encounters the header, and doesn't know what to do with it.

Furthermore, the image was hosted on an S3 bucket, which assigned a header by default. Removing the header on S3 solved the issue.

Add comment · Share

Answer 2

I know I am reviving a necro-thread, but I am having a similar issue. I have a png on S3 that I am accessing via an API endpoint that retrieves the raw binary via a node.js use of AWS SDK's getObject(). What is returned also fails to parse. I get a byte array on the Unity side fine, but the LoadImage(byteArray) call returns false. I am a bit stuck, not sure how to remove a header, or even check if one is there, etc.

EDIT: I solved my issue, but I have no idea why I had to do it this way. I will share here for others in case they have a similar issue, and maybe those more knowledgeable than me can point out why I ran into this and potentially suggest better solutions.

For background, I am using Node.js Express to expose API endpoints that allow image access. Within this Node code I uses the AWS SDK getObject() function to fetch the PNG and send it back as so (bucket junk in the params):

     s3.getObject(params, function(err, data) {
         res.write(Buffer.from(data.Body));
         res.end(null);
       });

Theoretically, the Buffer.from(data.Body) here should return the byte array I need for LoadImage() in Unity, and sure enough, if I check the length in Node for my test image it is exactly the number of bytes I expect so seems to be correct. When I actually hit the end point in Unity, however, it comes out as a much longer byte[] that won't parse. On the Unity side I was using the following on a successful request (where uwr is the UnityWebRequest that succeeded):

     byte[] binaryImageWeb = uwr.downloadHandler.data;

My workaround (which I don't love because I don't understand why it is needed, but it works) is to more explicitly return the byte array as a stringified JSON array and then process it on the Unity side through deserialization of the text return rather than the provided .data byte[]. The new Node code is as follows:

     s3.getObject(params, function(err, data) {
         res.write(JSON.stringify(Buffer.from(data.Body).toJSON('hex').data));
         res.end(null);
       });

And the Unity code changes to this:

     byte[] binaryImage = JsonConvert.DeserializeObject<byte[]>(uwr.downloadHandler.text);

Using this approach I get the correct expected-length byte array which successfully parses into a Texture.

Texture2D.LoadImage unable to parse bytes

2 Replies

Your answer

Follow this Question

Related Questions