Using Foveation in Your App

The Foveation feature enables an application to gain rendering performance improvement by reducing the pixel density of areas in the peripheral vision. The areas near the focal point still sustains the original pixel density than periphery.

Supported Platforms and Devices
Specification
Environment Settings
Golden Sample
See Also

Supported Platforms and Devices

Platform		Headset	Supported	Plugin Version
PC	PC Streaming	Focus 3/XR Elite/Focus Vision	X
	Pure PC	Vive Cosmos	X
	Pure PC	Vive Pro series	X
AIO		Focus 3	V	2.0.0 and above
		XR Elite	V	2.0.0 and above
		Focus Vision	V	2.0.0 and above

Specification

This chapter will explore how to create more immersive experiences using the Foveation feature within the Foveation extension.

Environment Settings

Check your VIVE OpenXR Plugin version

In Window > Package Manager, make sure your VIVE OpenXR Plugin 2.0.0 or newer.

Enable the Foveation feature

In Edit > Project Settings > XR Plug-in Management > OpenXR, enable the VIVE XR Foveation feature.

Mode Combinations

Fixed Mode
- Set XR_FOVEATION_DYNAMIC_CLEAR_FOV_ENABLED_BIT_HTC only
- Behavior: Foveation remains static, with no dynamic adjustment based on user movement.
Head Motion Mode
- Set XR_FOVEATION_DYNAMIC_CLEAR_FOV_ENABLED_BIT_HTC + XR_FOVEATION_DYNAMIC_LEVEL_ENABLED_BIT_HTC
- Behavior: The foveation region dynamically follows the user’s head movements.
Eye Tracking Mode
- Set XR_FOVEATION_DYNAMIC_CLEAR_FOV_ENABLED_BIT_HTC + XR_FOVEATION_DYNAMIC_FOCAL_CENTER_OFFSET_ENABLED_BIT_HTC
- Behavior: The foveation region dynamically follows the user’s gaze.
Full Dynamic Mode
- Set all three flags: XR_FOVEATION_DYNAMIC_CLEAR_FOV_ENABLED_BIT_HTC + XR_FOVEATION_DYNAMIC_LEVEL_ENABLED_BIT_HTC + XR_FOVEATION_DYNAMIC_FOCAL_CENTER_OFFSET_ENABLED_BIT_HTC
- Behavior: The foveation region adjusts dynamically based on both head movement and eye tracking.

Golden Sample

This article shows how to enable, disable, and customize the foveation in your app.

Create a script and attach it onto any GameObject in the scene.

In the script, first add a using namespace.

using VIVE.OpenXR.ViveFoveation;

Declare a XrFoveationModeHTC named UsingMode.

[SerializeField] XrFoveationModeHTC UsingMode;

The type of foveation creates in your app will depend on UsingMode. There are three type modes, Fixed, Dynamic, and Custom. The Fixed mode means the clear field of view will always be in the center of both eyes. On the contrary, when using the Dynamic mode, the clear field of view will follow the player's eyes, if eye gaze is enable. Finally, the Custom mode let you set the foveation yourself, including the position of clear field of view, the clarity, and the size of clear field of view.

Then, declare an array of XrFoveationConfigurationHTC with size of two.

XrFoveationConfigurationHTC[] Configs = new XrFoveationConfigurationHTC[2];

Configs is used to store the setting of the foveation when using Custom mode.

In Start, set the configuration and use ApplyFoveationHTC() to enable the foveation.

void Start()
{

    bool FoveationIsDynamic_bit01 = true;
    bool FoveationIsDynamic_bit02 = true;
    bool FoveationIsDynamic_bit04 = true;

    /////////////////////Setting for left eye/////////////////////////////
    Configs[0].level = XrFoveationLevelHTC.XR_FOVEATION_LEVEL_HIGH_HTC; //
    Configs[0].clearFovDegree = 0;                                      //
    Configs[0].focalCenterOffset.x = 0.0f;                              // 
    Configs[0].focalCenterOffset.y = 0.0f;                              //
    //////////////////////////////////////////////////////////////////////

    ////////////////////Setting for right eye/////////////////////////////
    Configs[1].level = XrFoveationLevelHTC.XR_FOVEATION_LEVEL_HIGH_HTC; //
    Configs[1].clearFovDegree = 0;                                      //
    Configs[1].focalCenterOffset.x = 0.0f;                              //
    Configs[1].focalCenterOffset.y = 0.0f;                              //
    //////////////////////////////////////////////////////////////////////

    UInt64 flags = (FoveationIsDynamic_bit01 ? ViveFoveation.XR_FOVEATION_DYNAMIC_LEVEL_ENABLED_BIT_HTC : 0x00) |
            (FoveationIsDynamic_bit02 ? ViveFoveation.XR_FOVEATION_DYNAMIC_CLEAR_FOV_ENABLED_BIT_HTC : 0x00) |
            (FoveationIsDynamic_bit04 ? ViveFoveation.XR_FOVEATION_DYNAMIC_FOCAL_CENTER_OFFSET_ENABLED_BIT_HTC : 0x00);


    switch (UsingMode)
    {
        //XR_FOVEATION_MODE_FIXED_HTC: The position of foveation is fixed
        case XrFoveationModeHTC.XR_FOVEATION_MODE_FIXED_HTC:
            ViveFoveation.ApplyFoveationHTC(XrFoveationModeHTC.XR_FOVEATION_MODE_FIXED_HTC, 0, null);
            break;
        //XR_FOVEATION_MODE_DYNAMIC_HTC: the position of foveation can be adjust
        case XrFoveationModeHTC.XR_FOVEATION_MODE_DYNAMIC_HTC:
            VViveFoveation.ApplyFoveationHTC(XrFoveationModeHTC.XR_FOVEATION_MODE_DYNAMIC_HTC, 0, null, flags);
            break;
        //XR_FOVEATION_MODE_CUSTOM_HTC: the foveation will use the custom setting
        case XrFoveationModeHTC.XR_FOVEATION_MODE_CUSTOM_HTC:
            ViveFoveation.ApplyFoveationHTC(UsingMode, 2, Configs);
            break;
    }
}

now if you run the app, you will be able to see the foveation.

Display with foveation

Display without foveation

If you want to disable the foveation, execute the following code.

ViveFoveation.ApplyFoveationHTC(XrFoveationModeHTC.XR_FOVEATION_MODE_DISABLE_HTC, 0, null);