diff --git a/gnome/src/devicedatastream.js b/gnome/src/devicedatastream.js
index 4d88ff7..0ced9d1 100644
--- a/gnome/src/devicedatastream.js
+++ b/gnome/src/devicedatastream.js
@@ -40,6 +40,32 @@ const POSE_ORIENTATION = [dataViewEnd(EPOCH_MS), FLOAT_SIZE, 16];
const IMU_PARITY_BYTE = [dataViewEnd(POSE_ORIENTATION), UINT8_SIZE, 1];
const DATA_VIEW_LENGTH = dataViewEnd(IMU_PARITY_BYTE);
+// Flatten a packed pose-orientation buffer (mat4 as 16 floats: orientation
+// quaternions at floats [0..3] and [4..7], timestamps at [12..15]) to yaw-only.
+// Uses a swing-twist decomposition about the NWU up-axis (Z): keep the Z and W
+// components, zero X and Y, then renormalize. This removes all pitch and roll
+// from the rendered orientation, so the display tracks only horizontal (yaw)
+// head movement. The identity quaternion [0,0,0,1] is preserved.
+function applyHorizonLock(poseOrientation) {
+ for (const offset of [0, 4]) {
+ const z = poseOrientation[offset + 2];
+ const w = poseOrientation[offset + 3];
+ const norm = Math.hypot(z, w);
+ poseOrientation[offset] = 0;
+ poseOrientation[offset + 1] = 0;
+ if (norm < 1e-6) {
+ // Yaw is undefined here (a pure 180-degree pitch/roll pose); fall
+ // back to identity rather than emitting a zero (non-unit) quaternion.
+ poseOrientation[offset + 2] = 0;
+ poseOrientation[offset + 3] = 1;
+ } else {
+ poseOrientation[offset + 2] = z / norm;
+ poseOrientation[offset + 3] = w / norm;
+ }
+ }
+ return poseOrientation;
+}
+
function checkParityByte(dataView) {
const parityByte = dataViewUint8(dataView, IMU_PARITY_BYTE);
let parity = 0;
@@ -132,6 +158,13 @@ export const DeviceDataStream = GObject.registerClass({
'Debug mode that allows for testing with moving IMU values without a device connected',
GObject.ParamFlags.READWRITE,
false
+ ),
+ 'horizon-lock': GObject.ParamSpec.boolean(
+ 'horizon-lock',
+ 'Horizon lock',
+ 'Flatten the head pose to yaw-only (ignore pitch and roll) so the display only tracks horizontal head movement',
+ GObject.ParamFlags.READWRITE,
+ false
)
}
}, class DeviceDataStream extends GObject.Object {
@@ -212,9 +245,13 @@ export const DeviceDataStream = GObject.registerClass({
const version = dataViewUint8(dataView, VERSION);
const enabled = dataViewUint8(dataView, ENABLED) !== 0 && version === DATA_LAYOUT_VERSION && validData;
let poseOrientation = dataViewFloatArray(dataView, POSE_ORIENTATION);
+ if (this.horizon_lock) applyHorizonLock(poseOrientation);
let posePosition = dataViewFloatArray(dataView, POSE_POSITION);
let smoothFollowEnabled = !this.legacy_follow_mode && dataViewUint8(dataView, SMOOTH_FOLLOW_ENABLED) !== 0;
let smoothFollowOrigin = dataViewFloatArray(dataView, SMOOTH_FOLLOW_ORIGIN_DATA);
+ // The shader renders from the smooth-follow origin when follow is
+ // active, so horizon lock must flatten it too (same packed layout).
+ if (this.horizon_lock) applyHorizonLock(smoothFollowOrigin);
const imuResetState = enabled && validData && poseOrientation[0] === 0.0 && poseOrientation[1] === 0.0 && poseOrientation[2] === 0.0 && poseOrientation[3] === 1.0;
const customBannerEnabled = dataViewUint8(dataView, CUSTOM_BANNER_ENABLED) !== 0;
const sbsEnabled = dataViewUint8(dataView, SBS_ENABLED) !== 0;
@@ -281,6 +318,7 @@ export const DeviceDataStream = GObject.registerClass({
dataView = new DataView(buffer);
imuDateMs = dataViewBigUint(dataView, EPOCH_MS);
poseOrientation = dataViewFloatArray(dataView, POSE_ORIENTATION);
+ if (this.horizon_lock) applyHorizonLock(poseOrientation);
posePosition = dataViewFloatArray(dataView, POSE_POSITION);
}
}
diff --git a/gnome/src/extension.js b/gnome/src/extension.js
index 52f41f8..21f786c 100644
--- a/gnome/src/extension.js
+++ b/gnome/src/extension.js
@@ -88,6 +88,7 @@ export default class BreezyDesktopExtension extends Extension {
this.settings.bind('disable-physical-displays', this._monitor_manager, 'disable-physical-displays', Gio.SettingsBindFlags.DEFAULT);
this.settings.bind('legacy-follow-mode', Globals.data_stream, 'legacy-follow-mode', Gio.SettingsBindFlags.DEFAULT);
this.settings.bind('debug-no-device', Globals.data_stream, 'debug-no-device', Gio.SettingsBindFlags.DEFAULT);
+ this.settings.bind('horizon-lock', Globals.data_stream, 'horizon-lock', Gio.SettingsBindFlags.DEFAULT);
this._breezy_desktop_running_connection = Globals.data_stream.connect('notify::breezy-desktop-running',
this._handle_breezy_desktop_running_change.bind(this));
@@ -732,6 +733,7 @@ export default class BreezyDesktopExtension extends Extension {
Gio.Settings.unbind(this.settings, 'headset-as-primary');
Gio.Settings.unbind(this.settings, 'disable-physical-displays');
Gio.Settings.unbind(this.settings, 'debug-no-device');
+ Gio.Settings.unbind(this.settings, 'horizon-lock');
if (this._monitor_manager) {
this._monitor_manager.disable();
diff --git a/ui/data/com.xronlinux.BreezyDesktop.gschema.xml b/ui/data/com.xronlinux.BreezyDesktop.gschema.xml
index 7a9fc9a..c9327a6 100644
--- a/ui/data/com.xronlinux.BreezyDesktop.gschema.xml
+++ b/ui/data/com.xronlinux.BreezyDesktop.gschema.xml
@@ -154,6 +154,15 @@
Enable curved display mode
+
+
+ false
+
+ Horizon lock
+
+ Lock the display to the horizon, tracking only horizontal (yaw) head movement and ignoring pitch (vertical) and roll (tilt)
+
+
-1
diff --git a/ui/src/connecteddevice.py b/ui/src/connecteddevice.py
index f1bf08d..e14be72 100644
--- a/ui/src/connecteddevice.py
+++ b/ui/src/connecteddevice.py
@@ -39,6 +39,7 @@ class ConnectedDevice(Gtk.Box):
follow_threshold_adjustment = Gtk.Template.Child()
follow_mode_switch = Gtk.Template.Child()
curved_display_switch = Gtk.Template.Child()
+ horizon_lock_switch = Gtk.Template.Child()
top_features_group = Gtk.Template.Child()
virtual_displays_row = Gtk.Template.Child()
add_virtual_display_menu = Gtk.Template.Child()
@@ -99,6 +100,7 @@ class ConnectedDevice(Gtk.Box):
self.follow_mode_switch,
self.follow_threshold_scale,
self.curved_display_switch,
+ self.horizon_lock_switch,
self.add_virtual_display_menu,
self.add_virtual_display_button,
self.change_all_displays_distance_button,
@@ -124,6 +126,7 @@ class ConnectedDevice(Gtk.Box):
self.settings.bind('follow-threshold', self.follow_threshold_adjustment, 'value', Gio.SettingsBindFlags.DEFAULT)
# self.settings.bind('widescreen-mode', self.widescreen_mode_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
self.settings.bind('curved-display', self.curved_display_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
+ self.settings.bind('horizon-lock', self.horizon_lock_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
self.settings.bind('headset-display-as-viewport-center', self.headset_display_as_viewport_center_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
self.settings.bind('headset-as-primary', self.headset_as_primary_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
self.settings.bind('remove-virtual-displays-on-disable', self.remove_virtual_displays_on_disable_switch, 'active', Gio.SettingsBindFlags.DEFAULT)
diff --git a/ui/src/gtk/connected-device.ui b/ui/src/gtk/connected-device.ui
index 89fd925..d1c5425 100644
--- a/ui/src/gtk/connected-device.ui
+++ b/ui/src/gtk/connected-device.ui
@@ -88,6 +88,18 @@
+
+
+