Cursor locking and full-screen mode in Web

The Unity Web platform supports features such as cursor locking and full-screen mode that are implemented using the HTML5 APIs, Element.requestPointerLock and Element.requestFullscreen.

Note: As browser support for cursor locking and full-screen mode varies, refer to the Mozilla documentation on cursor locking and full screen.

Cursor locking

Cursor locking lets players lock their mouse cursor to the center of the game window. When the cursor is locked, it appears hidden in Unity and doesn’t move when the mouse moves. This is particularly helpful when playing first-person games, where the mouse cursor is typically used to control the orientation of the player’s angle.

To lock the cursor, use the Cursor.lockState property. For example, the following code shows the cursor in locked state when the user clicks the left mouse button:

void Update()
{
    if (Input.GetMouseButtonDown(0))
    {
        Cursor.lockState = CursorLockMode.Locked;
    }
}

The cursor is automatically unlocked when you press the Esc key.

Sticky cursor lock

Use stickyCursorLock to ensure that the state of Cursor.lockState is persistent, even if the browser releases the cursor lock from the Unity canvas (typically using the Esc key), in which case the cursor is locked again the next time the canvas is in focus. The stickyCursorLock property is commonly used in first-person games, where maintaining the cursor lock mode is particularly beneficial regardless of the browser behavior.

Therefore, if you set WebGLInput._stickyCursorLock to true, the Cursor.lockState remains in CursorLockMode.Locked state even if the Unity canvas HTML element is forced to unlock the cursor. If you set WebGLInput._stickyCursorLock to false, then Cursor.lockState remains synchronized with the browser’s cursor lock state, and changes to CursorLockMode.None if the canvas cursor lock is canceled by pressing the Esc key.

Note: In Web, stickyCursorLock is set to true by default.

Full-screen mode

Use the full-screen mode to use the entire computer screen for your game. You can perform the following actions in full-screen mode:

• Use the entire screen for your game.

• Hide the browser user interface (UI) elements such as the address bar and tabs.

• Hide the Unity player UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
  See in Glossary elements such as the title bar and toolbarA row of buttons and basic controls at the top of the Unity Editor that allows you to interact with the Editor in various ways (e.g. scaling, translation). More info
  See in Glossary.

To enable full-screen mode, use the Screen.fullScreen property. For example, the following code shows the game in full-screen mode when the user presses the F key:

void Update()
{
    if (Input.GetKeyDown(KeyCode.F))
    {
        Screen.fullScreen = true;
    }
}

Note: The Screen.fullScreen property is set to false by default.

To exit full-screen mode, press ESC again, or hover the mouse pointer to the top of the screen to access the address bar and tabs.

Additional considerations

Due to security concerns, browsers allow cursor locking and full-screen mode only in direct response to a user-initiated event such as a mouse-click or key press. Because Unity doesn’t support separate events and rendering loops, it defers event handling until the browser no longer acknowledges full-screen or cursor lock requests issued from Unity scripting as a direct response to the event which triggered it. Therefore, Unity triggers the request on the next user-initiated event, instead of the event that triggered the cursor lock or full-screen request.

To enable cursor lock or full-screen modes with acceptable results, set projects to trigger appropriate requests using mouse/key down events, instead of mouse/key up events. This way you can ensure that the deferred request is guaranteed to be triggered by the corresponding mouse/key up event if not by a user-initiated event earlier.

You can also use Unity’s UI.Button component to achieve the desired behavior by creating a subclass of Button, which overrides the OnPointerDown method.

Note: Some browsers might display a notification message or prompt the user to grant permission before entering full-screen mode or locking the cursor.