Meta Quest devices support fixed foveated rendering (FFR). FFR enables the edges of an application-generated frame to be rendered at a lower resolution than the center portion of the frame. This lowers the fidelity of the scene in the viewer’s peripheral vision and likely will not be noticed.

This reduction in rendered pixels can provide several benefits:

Note: FFR does not rely on eye-tracking. Rather, the high-resolution pixels (the fovea) are fixed in the center of the frame. However, the Meta Quest Pro does have eye-tracking cameras, which are required to place high-resolution pixels where the eye is looking. For more information about this, see Eye Tracked Foveated Rendering.

FFR has some tradeoffs:

The image below shows a user’s perception of a 135° field of view (hemisphere), with two 20° arcs highlighted. The 2D plane of the screen that renders this view (horizontal line) is overlaid on top. Notice how, when comparing the 20° arc at the edge of the field of view with the 20° arc at the center, the arc at the edge takes up much more of the screen. This distortion is an unavoidable part of rendering a 3D world on a screen.

More pixels are required to create the post-distortion areas at the edge of the FOV than the center of the FOV, resulting in a higher pixel density at the edge of the FOV than in the middle. This is highly counterproductive, since users generally look toward the center of the screen. On top of that, lenses blur the edge of the field of view, so even though many pixels have been rendered in that part of the eye texture, the sharpness of the image is lost. The GPU spends a lot of time rendering pixels at the edge of the FOV that can’t be clearly seen. This is very inefficient. FFR reclaims wasted GPU resources by lowering the resolution of these screen portions.

Like most mobile computers, Meta Quest headsets use tiled rendering, in which a frame is split into dozens of “tiles” of clustered pixels, and each tile is rendered separately. FFR is implemented by controlling the resolution of individual render tiles on the GPU. When FFR is enabled, tiles that are closer to the edges of the eye buffer are rendered at a lower resolution than tiles closer to the center.

The gains (or losses) provided by FFR typically depend on your application’s pixel shader costs. FFR can result in a 25% gain in performance with pixel-intensive applications. On the other hand, applications with very simple shaders, which are not bound on GPU fill, will likely not see a significant improvement from FFR. A highly ALU-bound application will benefit from this, as shown in the graph below that collects GPU utilization on a scene. Given a 16% GPU utilization coming from timewarp (and therefore not affected by FFR), this graph shows a 6.5% performance improvement from the low setting, 11.5% improvement from medium setting, and a 21% improvement from the high setting.

This demonstrates a best case scenario for using FFR. If you perform the same test on an application that has very simple pixel shaders, it is possible to actually have a net loss on the low setting, due to the fact that the fixed overhead of using FFR can be higher than the rendering savings on a relatively small number of few pixels. In fact, in this situation, you might experience a slight gain with the high setting, but it won’t be worth the image quality loss.

The images below show the FFR resolution multiplier map (also called the fragment density map) for the left eye, and an example tilemap for a frame for the left eye, on a Meta Quest 3, at each FFR setting. Note that the positions and sizes of tiles can change depending on your headset and render settings, but will always approximate the FFR resolution multiplier map. The colors represent the following resolution levels:

Note: The un-calculated (black) pixels on the right edge of the left eye resolution multiplier map are due to rendering with Symmetric Field of View enabled. This is a recommended optimization for Meta Quest devices, in which the left and right eye render at the same field of view, and pixels on the far edge for each eye are not rendered. This results in the same output image as an asymmetric field of view.

Note: The resolution multiplier maps for the right eye are just horizontal mirrors of the displayed left-eye maps.

Note: High Top is not available when using the OpenXR interface (see OpenXR, VRAPI, and LibOVR); setting FFR to High Top will be treated like setting to High. In OpenXR, High Top FFR can be generated by using the verticalOffset parameter on the High FFR level (see OpenXR docs).

Many developers simply use the high FFR setting for their entire app as a general solution for performance, which some have found to have a very noticeable impact on visuals. Here are some tips and best practices on better tuning the FFR settings in-game: