vr-input-source

vr-input-source

vr-input-source tracks all positionally-tracked gamepads, and exposes them in an API similar to the XRInputSource defined in the upcoming WebXR API.

The package performs a few key tasks related to using VR input sources. It keeps track of all connected gamepads that report their physical position, and fires events when their buttons are pressed or released. When multiple gamepads are used simultaneously, typically two-handed controllers like Oculus Touch, it tracks which one was most recently used. This allows developers to use that controller as the device that controls the cursor, a behavior commonly seen on VR platforms.

Button Events

The Web Gamepad API relies on polling to get gamepad data, and does not fire events like keyboard or mouse inputs. This requires some code to run on each rendered frame, inspect gamepad state, and determine which buttons changed since the last frame. vr-input-source performs this action for all tracked gamepads, and will fire the following events:

Primary Button Events

Primary buttons are those that perform a selection action, and vary from controller to controller. Due to the wide range of input devices used for VR, it's recommended that developers build interfaces around a single select action, rather than relying on the presence of many buttons. How a button is determined to be primary or secondary is described in a later section.

• selectstart - Triggered when one of the gamepad's primary buttons is pressed down. Similar to mousedown.
• selectend - Triggered when one of the gamepad's primary buttons is released, or the gamepad is disconnected while some buttons are pressed. Similar to mouseup.
• select - Triggered when one of the gamepad's primary buttons is pressed down, then released. Similar to click.

Alternative Button Events

Generic button-press events also exist to track when any button, primary or otherwise, is pressed or released.

• pressstart - Triggered when any of the gamepad's buttons is pressed down. Similar to mousedown.
• pressend - Triggered when any of the gamepad's buttons is released, or the gamepad is disconnected while some buttons are pressed. Similar to mouseup.
• press - Triggered when any of the gamepad's buttons is pressed down, then released. Similar to click.

Capacitive Button Events

Some controllers have capacitive buttons or trackpads

• touchstart - Triggered when the user's finger touches a capacitive button.
• touchend - Triggered when a user's finger stops touching a capacitive button.

Primary vs Secondary

Some gamepads have a single button (Daydream); others have a button and a trigger (Oculus Go); others have many different buttons (Oculus Touch, Vive Wand, Windows MR Motion Controllers). There is rarely a correlation between the reported ordering of the buttons and their intended action. vr-input-source is aware of popular gamepads, and maps their primary actions to the select events. For example, it maps both the A button and main trigger on Oculus Touch as primary actions. For unrecognized gamepads, every button is considered primary. This is to future-proof applications against new input hardware; otherwise, developers would need to upgrade older apps to add mappings for new devices.

The list of recognized gamepad mappings is found in WellKnownGamepads.js, and can be updated to support new input types.

Controller Events

The top-level VRInputSource class also fires events related to changes in input devices.

• inputsourceschange - Triggered when the set of connected gamepads with pose changes. This could either be the result of a connection or a disconnection.
• activesourcechange - Triggered when the Active Input Source changes. The active source is the gamepad that was most recently used. This can be used by the application to change which gamepad draws the cursor.