Transferring file from user's device to Pixel-Streamed Unreal Applications
In this document we will explain how to enable users to upload files directly from their browser to an Unreal Engine application running on the Eagle 3D Streaming (E3DS) platform.
The E3DS platform automatically handles the file selection dialog and stores the uploaded file in your project’s directory
You can initiate the file transfer using either of the following two methods:
Method 1. Sending a Message Directly
(i) Use the Send Pixel Streaming Response node in Blueprints to send the following JSON object:
{"cmd": "sendLocalFileToUE4","pathToSaveFile": "%AnyPathInsideProjectDirectory%"}(ii) Replace %AnyPathInsideProjectDirectory% with the relative path inside your project directory where you want to store the file.
Paths must be relative to the Project Directory (absolute paths like C:\ are not supported).
Figure 1. Sending a message directly
Method 2. Using the E3DS Features Plugin (Recommended)
Prerequisite:
Before proceeding, ensure you have downloaded and installed the E3DS Features Plugin in your Unreal Engine project. For detailed instructions, refer to:
Download and Install the E3DS Features Plugin
Follow the steps below:
(i) Use the Blueprint function Transfer File from User Browser to Unreal, and specify the destination path (for example: ProjectDirectory/Saved/).
(ii) The plugin will automatically handle the upload process.
Figure 2. Using the E3DS Features Plugin
File Selection and Upload Process
Regardless of the method you choose, once the upload request is sent, the Eagle 3D Streaming platform will open a file selection dialog in the browser, allowing the user to choose the file to upload.
Figure 3. Uploading a file
Verifying the Upload
To confirm the file upload has completed, use the File Exists node.
This node takes a full file path and returns whether the file exists.
For example, if you expect
test.jpgto be located inProjectDirectory/Saved/test.jpg, you can check for its presence and print"Yes"or"No"accordingly.
Figure 4. Verifying whether the file upload is completed
Example Behavior:
Initially,
"No"is printed because the file does not exist.As soon as the upload is complete, the output changes to
"Yes".
Figure 5. Verify whether the File Upload is Completed or Not
Troubleshooting
File selection dialog does not appear
Ensure the in-game event or function that triggers the upload is actually called.
Double-check the JSON message format (if using the manual method).
If unsure, try using the E3DS Features Plugin method.
File is uploaded but Unreal cannot find it
Ensure the file is saved inside your Project Directory only.
Saving files outside the project directory (e.g.,
C:\root or custom folders outside the project) is not supported.All uploaded files are virus scanned — any potentially harmful files will be rejected.
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