To achieve a dynamically scrolling tiled background in UI Toolkit, the backgroundPositionX or backgroundPositionY property must be updated through the IVisualElementScheduler. Directly assigning a StyleBackgroundPosition to your visual element style will not render the visual change effectively unless the assignment is processed by the internal scheduler loop to force a repaint of the background geometry.

1. Ensure the source Texture2D wrap mode is set to Repeat in the asset importer settings.
2. Define a backgroundOffset variable to store the persistent horizontal or vertical displacement.
3. Access the IVisualElementScheduler via your visual element schedule.
4. Within the Execute callback, increment the backgroundOffset using Time.deltaTime and your speed multiplier.
5. Create a new BackgroundPosition instance using the backgroundOffset and a BackgroundPositionKeyword (e.g., BackgroundPositionKeyword.Left).
6. Wrap this value in a StyleBackgroundPosition and assign it to your visual element style backgroundPositionX or backgroundPositionY.
7. Invoke the .Every(16) method on the schedule call to ensure the animation updates at approximately 60 frames per second.

Additional Tips

• Use UsageHints.DynamicTransform on your visual element to optimize performance when the background is modified every frame.
• If the backgroundOffset value increases indefinitely, reset it using a modulo operator based on the texture size to prevent floating point precision issues over long sessions.