To render UI and react to input from the users in the Game view, connect the UXML Documents to a Panel Settings asset by a UI Document component.
Every UI Document component references a UXML Document that defines the UI and a Panel Settings that renders it. You can connect more than one UXML Document to a single Panel Settings asset.
A Panel Settings asset defines a panel in the Scene. The panel provides the root visual element that UI hierarchies are attached to, and draws the UI in the Scene at runtime. How you configure the Panel Settings asset determines how the UI is rendered. It also determines how the UI reacts to input. For example, the panel that’s visually in the front intercepts clicks from the user before the panels that are visually in the back.
You can configure the Panel Settings asset to do the following:
To configure a panel:
A panel can display UI from more than one UXML Document component. Each UI Document has a Sort Order property that sets the UXML Document rendering order:
To connect more than one UXML Document to a panel:
Select or create a GameObject to host the UI.
Select Component > UI Toolkit > UI Document to add a UI Document component.
In the Inspector window of the UIDocument, do the following:
Repeat the process for each UXML Document.
Note: If there are multiple UI document components attached to the same Panel Settings, all these documents have a common focus navigation context. If they have distinct Panel Settings, navigation won’t jump automatically from one to the other even if you arrange them side by side. To make navigation jump from one to the other, you must set the focusController of the Panel Settings to the FocusController of the UI Document component you want to jump to.
Unity loads a UI Document component’s source UXML documents when it calls the OnEnable() method on the component. To ensure the visual tree loads correctly, add logic to interact with the controls inside the OnEnable() method. This means your script must respond to OnEnable() and OnDisable() to safely reference visual elements from your UXML documents.
A UI Document component clears its contents when it responds to the OnEnable() and OnDisable() methods. This approach removes UI elements that the UI Document won’t reuse soon and effectively clears the associated resources. Additionally, if a UI Document component isn’t assigned with a Panel Settings asset, it automatically clears its contents.
To hide a UI element that’s likely to be reused soon or needs to appear quickly to avoid an initialization penalty, set the display of the UIDocument.rootVisualElement to none. You can also use this to hide a UI element component that’s part of a larger UI hierarchy.