Eye tracking and foveated rendering

Configure foveated rendering on Android XR to reduce GPU load without a noticeable loss of visual quality.

Foveated rendering lowers the resolution of the areas that a user doesn't look at directly. On devices that support eye tracking, gaze-based foveated rendering keeps the high-resolution area centered on the user's gaze. This page supplements Foveated rendering in OpenXR with the settings and permissions that Android XR requires.

Prerequisites

To use foveated rendering on Android XR, do the following:

Set the active build target to Android XR, or use an Android XR build profile.
Enable the Foveated Rendering feature in the OpenXR settings.

When you set the active build target to Android XR, Unity enables the Android XR feature group and the Foveated Rendering feature in the XR Plug-in Management > OpenXR settings. You can set this build target in the Build Profiles window or an Android XR build profile. Unity applies these settings the next time the Unity Editor reloads scripts.

For more information, refer to Android XR build profile in the Unity Manual.

Enable eye tracking and foveated rendering

To enable eye tracking and foveated rendering, configure the following in the OpenXR section of the XR Plug-in Management settings:

Add the Eye Gaze Interaction Profile under Enabled Interaction Profiles.
Enable the Foveated Rendering feature from All Features under OpenXR Feature Groups.

Your application can now use foveated rendering. To use gaze-based foveated rendering, request eye-tracking permission at runtime.

For information about how to configure your interaction profiles and OpenXR features, refer to Configure project settings.

Request eye-tracking permission

Gaze-based foveated rendering requires the android.permission.EYE_TRACKING_FINE permission. When you enable the Foveated Rendering feature, Unity adds this permission to your application's Android manifest at build time, but you must still request it from the user at runtime.

If the user denies the permission, your application uses fixed foveated rendering instead of gaze-based foveated rendering.

For a code example that requests the permission, refer to Permissions.

Optimize rendering at foveation level 0

When you set the foveation level to 0, Android XR can disable fragment density map attachment automatically. Android XR applies this optimization when your project meets the requirements in Prerequisites. You don't need to call additional APIs or enable any other features.

This optimization has no setting in the UI, and Android XR skips it without a warning in either of the following cases:

Your project doesn't use the Android XR build target or build profile.
You disable the Foveated Rendering feature in Project Settings > XR Plug-in Management > OpenXR.

Warm up pipeline state objects

Attaching or detaching the fragment density map changes the render pass, so Unity needs a separate pipeline state object (PSO) for each foveation state. Unity compiles a PSO the first time it renders a shader variant under a given state, then caches it.

Because Unity caches each PSO, later changes between 0 and higher foveation levels reuse the PSOs it already compiled. A shader variant that Unity hasn't rendered before still compiles the first time it appears under either foveation state, which can cause a frame spike.

If your application changes the foveation level to and from 0 during gameplay, warm up both sets of PSOs during a loading screen so that this compilation happens outside active gameplay.

For more information, refer to Warm up PSOs in the Unity Manual.