Pointer: don't put a vanished panel back in the visibility map

The panel-edge test read visible[edgeKey], and when the last panel the cursor touched was
gone from the overlay list, that added it back as hidden. The map then had more entries than
there are handles, which made the 50 ms visibility poll run every frame, and since the last
commit it also counted as a visibility change each time, so unchanged frames were never
reused. The edge test now looks the key up without adding it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/design.md

@@ -116,9 +116,9 @@ The driver starts disconnected, because holding the right-hand role while SteamV
 
 ### The cursor
 
-Mouse motion turns into yaw and pitch around an anchor, the head position at the last recenter. A ray from the anchor is tested against every visible overlay with `ComputeOverlayIntersection`. On a hit, the cursor sits on that surface; otherwise it floats at `POINTER_DISTANCE`. Since the anchor isn't your current eye position, a second test runs along your line of sight to the cursor point, and anything nearer wins, so the cursor always lands on what you see under it. Overlays in `POINTER_IGNORE` are left out of both tests. A display-only panel, like a performance overlay locked to your view, has no input method, so SteamVR's laser passes through it, but `ComputeOverlayIntersection` still hits it, and the cursor stuck to it. The laser starts just before the cursor point, so an ignored panel nearer to you doesn't catch it either.
+Mouse motion turns into yaw and pitch around an anchor, the head position at the last recenter. A ray from the anchor is tested against every visible overlay with `ComputeOverlayIntersection`. On a hit, the cursor sits on that surface; otherwise it floats at `POINTER_DISTANCE`. Since the anchor isn't your current eye position, a second test runs along your line of sight to the cursor point, and anything nearer wins, so the cursor always lands on what you see under it. Overlays in `POINTER_IGNORE` are left out of both tests. A display-only panel, like a performance overlay locked to your view, has no input method, so SteamVR's laser passes through it, but `ComputeOverlayIntersection` still hits it, and the cursor stuck to it. The laser starts just before the cursor point, so an ignored panel nearer to you doesn't catch it either. Both tests ask SteamVR about every visible overlay, so a frame where nothing moved (the mouse, the anchor, the eye by more than 5 mm, which overlays show) reuses the last result, for up to 100 ms, since overlays can also move on their own. The dots' overlay settings go to SteamVR only when they change, and the pose goes to the driver, which keeps the last one, only when the laser would land 0.1 mm or more elsewhere, and at least every 100 ms.
 
-OpenVR has no call to list other programs' overlays, so the helper runs `vrcmd --overlays` in the background. It includes hidden overlays, because a floating window's controls only appear while something hovers the window, and the cursor has to find them immediately.
+OpenVR has no call to list other programs' overlays, so the helper runs `vrcmd --overlays` in the background. It includes hidden overlays, because a floating window's controls only appear while something hovers the window, and the cursor has to find them immediately. Each run is a shell and a new SteamVR client, about 30 ms of CPU, and it ran every second while the pointer was awake, which in gaze mode is all the time. Now it runs every 20 seconds, and at once when the pointer wakes, when the dashboard opens or closes, when a game starts or ends, and when a left click hits nothing (a panel that came up since). An overlay already on the list showing or hiding needs no new list: the helper checks the visibility of the ones it knows every 50 ms.
 
 The laser starts partway along your line of sight to the cursor rather than at your eye. SteamVR sizes its hit dot by distance from the laser's origin, and a laser from the eye still shows a beam in each eye. Starting it close to the target makes the beam and the dot tiny, while `POINTER_ORIGIN_MARGIN` keeps the origin in front of the small window controls, which float a few centimetres in front of their panels. The helper's own white dot is the visible cursor. In empty space it's an interactive overlay that the laser lands on, so SteamVR never draws a laser into nothing.
 
@@ -141,7 +141,7 @@ Replacing a loaded driver's files, as re-running the installer used to do, leave
 
 The dashboard follows whichever device summoned it or last pressed its trigger. Frametop adds "last used wins": moving a real controller releases the pointer, and the next mouse movement takes the laser back. Moving means faster than 0.35 m/s or 2 rad/s (both times `POINTER_CONTROLLER_PICKUP`, 1 by default) for 100 ms in a row, while the controller is tracked normally. A single sample over the limit used to be enough, and controllers resting on a desk took the laser back on a knock or a tracking jump while the mouse was in use. Small movements don't count; waking needs `POINTER_WAKE_COUNTS` of mouse motion within a second, so desk jitter doesn't steal the laser. While the pointer is awake, a tiny transparent overlay with `MakeOverlaysInteractiveIfVisible` keeps SteamVR's laser mouse on, since otherwise the first click would only switch the laser on.
 
-When the headset comes off, SteamVR reports its activity level as idle at once and turns the displays off 5 seconds later (`power.turnOffScreensTimeout`), unless something keeps it awake. An awake pointer did, and so did the helper's `vrcmd` runs: each is a new SteamVR client, and a new client every second kept SteamVR out of standby. The helper now releases the pointer as soon as the headset is idle, ignores the mouse until you're wearing it again, and pauses the overlay list whenever the pointer is off.
+When the headset comes off, SteamVR reports its activity level as idle at once and turns the displays off 5 seconds later (`power.turnOffScreensTimeout`), unless something keeps it awake. An awake pointer did, and so did the helper's `vrcmd` runs: each is a new SteamVR client, and a new client every second kept SteamVR out of standby. The helper now releases the pointer as soon as the headset is idle, ignores the mouse until you're wearing it again, and pauses the overlay list whenever the pointer is off. With the pointer off it also stops running its loop every 8 ms, about 116 wakeups a second for nothing: it waits up to 250 ms for a command on its socket (20 ms while it reads mapped controller buttons, which SteamVR input only offers by polling), and leaves the overlay lookups until the pointer wakes.
 
 ### Moving floating windows
 
@@ -153,6 +153,8 @@ SteamVR opens every input device only when it starts. When a Bluetooth mouse sle
 
 Keyboards aren't grabbed by default, because a grabbed keyboard's keys went into a virtual keyboard nothing typed from; the relay forwards them to ft-screens instead.
 
+The relay never waits on the pointer helper. Its socket to the helper used to block, so when the helper stalled (a layout placement or `grabprobe` holds it for seconds, and the gaze service fills its socket 90 times a second meanwhile), the whole relay stopped with it: keyboards, the volume keys, and pausing. Now what the helper doesn't take waits in order and goes out on the next loops. Mouse moves add up into one while they wait, and a scroll notch is dropped, since scrolling seconds late is no use; presses and releases are kept, so no button stays down. Mouse motion goes to the helper at most every 4 ms, rather than once per report, which from a 1000 Hz mouse was 1000 datagrams a second to a helper that runs every 8 ms; a button sends the motion before it first, so the click lands where the pointer was.
+
 An ungrabbed keyboard reaches both sides at once. In VR, gamescope reads every input device itself (the SteamOS build's `InputStealer`, libinput with udev hotplug, so new devices too) and types into its focused app, and ft-screens types the same keys into the desktop. So Space in the desktop also paused Spotify on the dashboard. Typing now follows the last click. ft-screens sees clicks on its own screens, from the mouse or a controller. A click anywhere else is only visible for the mouse: overlay apps get SteamVR's `OverlayFocusChanged` (which panel the laser is on) but no controller button events, so the pointer helper reports the panel under the dot on each left press. ft-screens tells the relay where typing goes every second, from an unbound socket so the relay's replies can't loop back into its control socket, and the relay grabs pass-through keyboards while it's the desktop. A grab waits until the keyboard has no key down, so no key stays held on either side, and the relay lets go if ft-screens stops reporting. A program that reads every keyboard for a hotkey (a dictation tool, say) loses a grabbed keyboard. Repeating the keys on another input device doesn't work: gamescope reads that device too, whether it's the relay's virtual keyboard or one created later, and every Space, typed or dictated, paused Spotify again. So with `SHARE_KEYS=1` the relay sends a grabbed keyboard's keys to `@frametop_keys` as datagrams (`key <code> <value> <device name>`). It's off by default, because the relay can't tell who is listening: abstract sockets have no permissions, and any local process that binds the name first gets every key typed into the desktop, passwords included. A listener should accept only its own user (`SO_PASSCRED`) and skip any keyboard of its own that the relay grabs too.
 
 Volume keys must never reach gamescope. With the openvr backend, gamescope sends volume up and down to Steam by moving keyboard focus to Steam for the key and then back to the previously focused surface. When nothing had focus, the one it moves back to is null, and wlroots aborts on a null focus surface (`wlr_seat_keyboard_notify_enter: Assertion 'surface' failed`), which ends the whole VR session. Keyboard focus is often empty while you work in VR, so one press of the headset's volume button could take everything down. gamescope reads the headset's buttons and every keyboard itself (`InputStealer`), as do SteamVR's processes, so the relay has to stop volume keys at the device. Grabbing `gpio-keys` would also take the headset's click button, so the relay remaps the volume entries in each device's keymap (`EVIOCSKEYCODE`) and handles the stand-in codes itself. That fix covers every device at once, including keyboards that aren't grabbed.
@@ -195,7 +197,7 @@ Hiding the screens during a game kept them out of view, but Frametop kept using
 
 - A hidden screen still cost as much as a visible one. ft-screens sent every committed screen its frame callback at 90 Hz whether its overlay showed or not, so KWin kept drawing, and its apps with it. Paused, ft-screens sends the callbacks once a second. A Wayland client draws again only after its last frame's callback, so KWin's output stalls, KWin's own clients stop getting theirs, and the whole desktop idles, without anything losing its connection. A second's pace, rather than none, keeps any client that waits on a callback from waiting forever. Stopping KWin or the apps with SIGSTOP would free the same, but a Wayland peer that stops reading overflows the other side's 4 KB socket buffer, which ends the connection: that's how the live desktop died once when its KWin stalled (`Data too big for buffer`). They also sit in different cgroups (KWin under steam.service when the VR launcher starts it, ft-screens in the dev container's), so no single freeze stops them together.
 - The relay does the pausing because it's the one part that always runs, and the pointer helper keeps running because stopping it leaves its virtual controller connected with its last pose (the driver has no staleness timeout), maybe holding a hand role, with the 3D mouse dead. Releasing it does the job. The helper already checks for a scene app twice a second, so it's what tells the relay a game started.
-- The gesture has to work during a game, but SteamVR input reaches only the app with input focus, and an overlay with global input (`steamvr/globalActionSetPriority`) takes the buttons it binds from the game. vrserver's web socket on 127.0.0.1:27062, which its controller binding page uses for the live view, reports every controller component whatever has focus, and reading it takes nothing. The game sees the clicks too, so the default is a gesture games hardly use: both thumbsticks, together, twice. "Together" means within 0.3 seconds of each other, so a stick held down to sprint while the other clicks doesn't count. The stream is about 160 messages a second, nearly all capacitive sensing, so the reader parses only the few that mention a gesture's button. A controller's root path changes while the 3D mouse holds its hand role (`/devices/cv/<serial>` instead of `/user/hand/right`), so the reader looks the controllers up again every 3 seconds.
+- The gesture has to work during a game, but SteamVR input reaches only the app with input focus, and an overlay with global input (`steamvr/globalActionSetPriority`) takes the buttons it binds from the game. vrserver's web socket on 127.0.0.1:27062, which its controller binding page uses for the live view, reports every controller component whatever has focus, and reading it takes nothing. The game sees the clicks too, so the default is a gesture games hardly use: both thumbsticks, together, twice. "Together" means within 0.3 seconds of each other, so a stick held down to sprint while the other clicks doesn't count. The stream is about 160 messages a second, nearly all capacitive sensing, so the reader parses only the few that mention a gesture's button. A controller's root path changes while the 3D mouse holds its hand role (`/devices/cv/<serial>` instead of `/user/hand/right`), so the reader looks the controllers up again (an HTTP request to vrserver): when the relay's 3D mouse connects or lets go, when a message comes from a device it doesn't know, and every 30 seconds. It used to be every 3 seconds.
 - Resuming starts remote desktop through `systemd-run --scope`: started straight from the relay, it would join the relay's cgroup and end with the next relay restart.
 
 ## SteamOS updates

input/game_pause.py

@@ -65,6 +65,18 @@ RESUME_DELAY = 5.0  # after a VR game ends: loading the next one can end one sce
 GAME_STALE = 12.0  # the helper repeats "vrgame" every 5 s; silence this long means no game (or no SteamVR)
 CHORD_WINDOW = 0.3  # a two-button gesture's buttons go down within this of each other
 DOUBLE_WINDOW = 0.7  # a double press's second press comes within this of the first
+LOOKUP_EVERY = 30.0  # the controllers are looked up again this often (and sooner when they may have changed)
+LOOKUP_GAP = 3.0  # but not more often than this for a message from a device it doesn't know
+
+
+def device_of(text):
+    """A web socket message's "device", without parsing all of it (there are about 160 a second)."""
+    at = text.find('"device"')
+    if at < 0:
+        return None
+    start = text.find('"', text.find(":", at) + 1)
+    end = text.find('"', start + 1)
+    return text[start + 1:end] if 0 <= start < end else None
 
 
 def gesture_of(rules, buttons):
@@ -137,6 +149,12 @@ class ControllerWatch(threading.Thread):
         self.changed = threading.Event()
         self.connected = False
         self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+        self.lookup_at = None  # look the controllers up again then (see recheck)
+
+    def recheck(self, delay=1.5):
+        """The controllers' root paths may change soon: the 3D mouse's virtual controller is taking
+        or giving back its hand role. SteamVR takes a moment to hand the role over."""
+        self.lookup_at = time.monotonic() + delay
 
     def set_gesture(self, spec):
         """(buttons, presses), or None for no gesture."""
@@ -176,15 +194,22 @@ class ControllerWatch(threading.Thread):
             ws.open(f"frametop_pause_{os.getpid()}")
             sides = {}  # root path -> side
             next_poll = 0.0
+            last_poll = 0.0
             while True:
                 g = self.current()
                 if g is None:
                     return
                 now = time.monotonic()
+                lookup_at = self.lookup_at
+                if lookup_at is not None and now >= lookup_at:
+                    self.lookup_at = None
+                    next_poll = now
                 if now >= next_poll:
                     # A controller connects later, or changes its root path when the 3D mouse's
-                    # virtual controller takes or gives back its hand role.
+                    # virtual controller takes or gives back its hand role. Each lookup is an HTTP
-                    next_poll = now + 3.0
+                    # request to vrserver, so it's at connect, every LOOKUP_EVERY, when a message
+                    # comes from a device not on the list, and when the relay says (recheck).
+                    next_poll, last_poll = now + LOOKUP_EVERY, now
                     found = vrws.controllers()
                     if found != sides:
                         for path in sides.keys() - found.keys():
@@ -199,6 +224,9 @@ class ControllerWatch(threading.Thread):
                                  f"controller{'s' if len(sides) != 1 else ''} on SteamVR's web socket")
                 wanted = {b: (b.split("/", 1)[0], f"/input/{b.split('/', 1)[1]}/click") for b in g.buttons}
                 for text in ws.messages(timeout=1.0):
+                    device = device_of(text)
+                    if device and device not in sides:
+                        next_poll = min(next_poll, last_poll + LOOKUP_GAP)  # its root path changed, maybe
                     # About 160 messages a second, nearly all capacitive sensing: parse only the
                     # few that carry one of the gesture's buttons.
                     if not any(c in text for _, c in wanted.values()):
@@ -470,6 +498,10 @@ class GamePause:
             return max(0.05, self.resume_at - now)
         return 1.0 if self.game else 3600.0
 
+    def controllers_changed(self):
+        """The 3D mouse took or gave back its hand role, which changes a controller's root path."""
+        self.watch.recheck()
+
     def helper_started(self):
         """The pointer helper (re)started, so SteamVR did too, maybe with the gaze service."""
         if self.paused:

input/input-relay.py

@@ -128,6 +128,7 @@ kernel's evdev and uinput interfaces.
 """
 import array
 import atexit
+import collections
 import errno
 import fcntl
 import json
@@ -459,14 +460,22 @@ class Pointer:
     CLAIM_PULSE = 0.06  # seconds the claim button (switchlaserhand, no click) is held
     RESUME_PAUSE = 1.5  # mouse idle this long, then moving again, re-claims the laser
     WAKE_WINDOW = 1.0  # seconds in which WAKE_COUNTS of motion must add up
+    QUEUE_MAX = 512  # commands kept while the helper is behind (see send)
+    MOVE_EVERY = 0.004  # mouse motion goes to the helper at most this often (see flush)
 
     def __init__(self, sensitivity, idle, wake_counts=40):
-        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+        # Never blocks (see send): a stalled helper must not stall the keyboard, volume keys and pausing.
+        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM | socket.SOCK_NONBLOCK)
+        # Commands the helper's full socket didn't take yet, in order: text, or [dyaw, dpitch] for
+        # mouse moves, which add up into one while they wait.
+        self.queue = collections.deque()
+        self.behind_logged = -60.0
         self.sensitivity = sensitivity  # degrees per mouse count
         self.idle = idle
         self.active = False
         self.last_used = 0.0
         self.dx = self.dy = 0
+        self.move_at = 0.0  # motion last went to the helper then
         self.scroll_until = None
         self.claim_at = None  # when to press the claim button
         self.claim_release = None
@@ -479,11 +488,59 @@ class Pointer:
         self.pending_since = 0.0
         self.gaze_awake_until = 0.0  # the helper's gaze mode keeps the pointer until then
 
-    def send(self, command):
+    def send(self, command, droppable=False):
-        try:
+        """To the helper, in order, without blocking. While the helper doesn't keep up (place and
-            self.sock.sendto(command.encode(), HELPER)
+        grabprobe hold it for seconds, and ft-gazed's 90 Hz gaze fills its socket meanwhile), commands
-        except OSError:
+        wait in the queue and go out from tick(). A droppable one (a scroll notch: scrolling seconds
-            pass  # helper not running (SteamVR not running)
+        late is no use) is dropped instead; presses, releases and the rest are kept, so no button
+        stays down. Moves add up (_move)."""
+        if not self.queue:
+            try:
+                self.sock.sendto(command.encode(), HELPER)
+                return
+            except BlockingIOError:
+                pass
+            except OSError:
+                return  # helper not running (SteamVR not running)
+        if not droppable:
+            self._queue(command)
+
+    def _move(self, dyaw, dpitch):
+        if self.queue and isinstance(self.queue[-1], list):
+            self.queue[-1][0] += dyaw
+            self.queue[-1][1] += dpitch
+            return
+        if not self.queue:
+            try:
+                self.sock.sendto(f"move {dyaw:.4f} {dpitch:.4f}".encode(), HELPER)
+                return
+            except BlockingIOError:
+                pass
+            except OSError:
+                return
+        self._queue([dyaw, dpitch])
+
+    def _queue(self, item):
+        if not self.queue and time.monotonic() - self.behind_logged > 60:
+            self.behind_logged = time.monotonic()
+            log("pointer helper is behind: holding its commands (logged once a minute)")
+        self.queue.append(item)
+        if len(self.queue) > self.QUEUE_MAX:
+            self.queue.popleft()  # stalled for long: the oldest goes
+
+    def drain(self):
+        """Send what waits, in order, as far as the helper takes it."""
+        while self.queue:
+            item = self.queue[0]
+            text = f"move {item[0]:.4f} {item[1]:.4f}" if isinstance(item, list) else item
+            try:
+                self.sock.sendto(text.encode(), HELPER)
+            except BlockingIOError:
+                return
+            except OSError:
+                self.queue.clear()  # the helper went away: nothing to deliver to
+                return
+            self.queue.popleft()
 
     def wake(self, now):
         if not self.active:
@@ -511,7 +568,7 @@ class Pointer:
         elif code == REL_Y:
             self.dy += value
         elif code == REL_WHEEL and value:
-            self.send(f"scroll 0 {1 if value > 0 else -1}")
+            self.send(f"scroll 0 {1 if value > 0 else -1}", droppable=True)
             self.scroll_until = now + self.SCROLL_PULSE
 
     def action(self, name, value, now, source="mouse"):
@@ -543,7 +600,7 @@ class Pointer:
             return  # the rest act on press
         elif name in ("scroll_up", "scroll_down"):
             self.wake(now)
-            self.send(f"scroll 0 {1 if name == 'scroll_up' else -1}")
+            self.send(f"scroll 0 {1 if name == 'scroll_up' else -1}", droppable=True)
             self.scroll_until = now + self.SCROLL_PULSE
         elif name == "dashboard":
             self.dashboard(now)
@@ -582,11 +639,16 @@ class Pointer:
             self.sensitivity *= 1.25 if name == "sens_up" else 0.8
             log(f"sensitivity {self.sensitivity:.4f} deg/count")
 
-    def flush(self):
+    def flush(self, now=None):
-        if self.dx or self.dy:
+        """Send the motion so far. With now (a mouse's SYN_REPORT), only once MOVE_EVERY has passed
-            # Mouse right turns the ray right (negative yaw); mouse down tilts it down.
+        since the last: a 1000 Hz mouse sent the helper, which runs every 8 ms, 1000 datagrams a
-            self.send(f"move {-self.dx * self.sensitivity:.4f} {-self.dy * self.sensitivity:.4f}")
+        second. tick() sends the rest when it's due; a button sends it first, so it lands there."""
-            self.dx = self.dy = 0
+        if not (self.dx or self.dy) or (now is not None and now - self.move_at < self.MOVE_EVERY):
+            return
+        self.move_at = time.monotonic() if now is None else now
+        # Mouse right turns the ray right (negative yaw); mouse down tilts it down.
+        self._move(-self.dx * self.sensitivity, -self.dy * self.sensitivity)
+        self.dx = self.dy = 0
 
     def dashboard(self, now=None):
         """Toggle the SteamVR dashboard with the virtual controller's system button.
@@ -601,6 +663,8 @@ class Pointer:
         self.system_at = now + (0.4 if woke else 0.0)
 
     def tick(self, now):
+        self.drain()
+        self.flush(now)
         if self.system_at is not None and now >= self.system_at:
             self.send("btn system 1")
             self.system_at = None
@@ -625,7 +689,10 @@ class Pointer:
 
     def timeout(self):
         pending = (self.scroll_until, self.claim_at, self.claim_release, self.system_at, self.system_release)
-        return 0.02 if any(t is not None for t in pending) else 0.5
+        wait = 0.02 if self.queue or any(t is not None for t in pending) else 0.5
+        if self.dx or self.dy:  # motion held back by flush
+            wait = max(0.0, min(wait, self.move_at + self.MOVE_EVERY - time.monotonic()))
+        return wait
 
     def stand_down(self):
         """Frametop is pausing: a pulse under way ends now, and the pointer lets go."""
@@ -729,7 +796,8 @@ def main():
     # pointer: the 3D mouse while it's in use, pointer_conf: the one the config asks for (they
     # differ while Frametop is paused).
     state = {"pointer": None, "pointer_conf": None, "rules": {}, "share_keys": False,
-             "desktop_until": 0.0, "typing_applied": None, "vr_capture_until": 0.0}
+             "desktop_until": 0.0, "typing_applied": None, "vr_capture_until": 0.0, "vr_bind_retry": False,
+             "pointer_holding": False}
 
     def pause_changed(paused):
         """Frametop paused or resumed (game_pause.py): the relay's own part."""
@@ -779,8 +847,11 @@ def main():
                                and a not in GAZE_ACTIONS and (not pause.paused or works_paused(a))) or "-"
             if state["rules"].get("controller_in_games"):
                 buttons = "+games " + buttons
+        state["vr_bind_retry"] = False
         try:
             screens_sock.sendto(f"vrbind {buttons}".encode(), HELPER)
+        except BlockingIOError:
+            state["vr_bind_retry"] = True  # the helper is behind: again on the next loop
         except OSError:
             pass  # helper not running; it says vrhello when it starts
 
@@ -1233,11 +1304,21 @@ def main():
             if added:
                 apply_roles()
 
+        # The 3D mouse connecting or letting go moves a hand role, so the pause gesture's reader
+        # looks the controllers up again (game_pause.py).
+        holding = bool(state["pointer_conf"] and state["pointer_conf"].active)
+        if holding != state["pointer_holding"]:
+            state["pointer_holding"] = holding
+            pause.controllers_changed()
         ready, _, _ = select.select(list(nodes) + [control], [], [],
                                     min(volume.timeout(now, pointer.timeout() if pointer else 0.5), pause.timeout(now)))
         now = time.monotonic()
         if pointer:
             pointer.tick(now)
+        elif state["pointer_conf"]:
+            state["pointer_conf"].drain()  # paused: what waited still goes, in order
+        if state["vr_bind_retry"]:
+            vr_bind(now)
         volume.tick(now)
         pause.tick(now)
         if state["vr_capture_until"] and now >= state["vr_capture_until"]:
@@ -1319,7 +1400,7 @@ def main():
                         mouse.emit(etype, code, value)
                 elif etype == EV_SYN and code == SYN_REPORT:
                     if pointer:
-                        pointer.flush()
+                        pointer.flush(now)
                     mouse.sync()
                     keyboard.sync()
 

input/test/keys-test.py

@@ -56,7 +56,7 @@ class StubPause:
     def configure(self, *args):
         pass
 
-    game_state = tick = helper_started = configure
+    game_state = tick = helper_started = controllers_changed = configure
 
 
 stub = {}

pointer/driver/driver_ft_pointer.cpp

@@ -12,7 +12,7 @@
 //   aim <yaw_deg> <pitch_deg>   absolute direction (yaw 0 = -Z, the SteamVR forward)
 //   gaze                         follow the head (origin and direction) again
 //   distance <metres>            cursor distance from the anchor (default 1.5)
-//   pose <x> <y> <z> <yaw> <pitch>  exact pose, sent every frame by the ft-pointer helper
+//   pose <x> <y> <z> <yaw> <pitch>  exact pose, from the ft-pointer helper when it changes (it holds)
 //   posq <x> <y> <z> <qw> <qx> <qy> <qz>  exact pose with a full rotation (tilting a panel while moving it)
 //   btn <name> <0|1>             name: trigger, b, x, system, joystick, a (a = claim the laser, no click)
 //   scroll <x> <y>               joystick deflection -1..1
@@ -224,12 +224,23 @@ public:
         pose.result = ok ? TrackingResult_Running_OK : TrackingResult_Uninitialized;
         pose.deviceIsConnected = snapshot.visible;
         pose_ = pose;
-        VRServerDriverHost()->TrackedDevicePoseUpdated(objectId_, pose_, sizeof(DriverPose_t));
+        // Connected, the pose goes out every frame, as SteamVR expects of a tracked device.
+        // Disconnected, once: it says the same thing every frame after.
+        if (snapshot.visible || !reportedOff_) {
+            VRServerDriverHost()->TrackedDevicePoseUpdated(objectId_, pose_, sizeof(DriverPose_t));
+            reportedOff_ = !snapshot.visible;
+        }
 
+        // Inputs only when they change (and all of them the first time).
         auto input = VRDriverInput();
-        for (int i = 0; i < kButtons; ++i) input->UpdateBooleanComponent(buttons_[i], snapshot.buttons[i], 0);
+        for (int i = 0; i < kButtons; ++i)
-        input->UpdateScalarComponent(scrollX_, snapshot.scrollX, 0);
+            if (!inputsSent_ || snapshot.buttons[i] != sentButtons_[i])
-        input->UpdateScalarComponent(scrollY_, snapshot.scrollY, 0);
+                input->UpdateBooleanComponent(buttons_[i], sentButtons_[i] = snapshot.buttons[i], 0);
+        if (!inputsSent_ || snapshot.scrollX != sentScrollX_)
+            input->UpdateScalarComponent(scrollX_, sentScrollX_ = snapshot.scrollX, 0);
+        if (!inputsSent_ || snapshot.scrollY != sentScrollY_)
+            input->UpdateScalarComponent(scrollY_, sentScrollY_ = snapshot.scrollY, 0);
+        inputsSent_ = true;
     }
 
 private:
@@ -239,6 +250,10 @@ private:
     int32_t role_ = TrackedControllerRole_RightHand;
     bool hinted_ = false;  // whether the role hint currently claims role_
     DriverPose_t pose_{};
+    bool reportedOff_ = false;  // the disconnected pose has gone out (it isn't repeated)
+    // What the input components were last set to.
+    bool inputsSent_ = false, sentButtons_[kButtons] = {};
+    float sentScrollX_ = 0.f, sentScrollY_ = 0.f;
     VRInputComponentHandle_t buttons_[kButtons] = {};
     VRInputComponentHandle_t scrollX_ = 0, scrollY_ = 0;
 };
@@ -293,65 +308,102 @@ private:
         }
     }
 
+    // Parsed first, then applied under the lock, which RunFrame (vrserver's frame) takes too.
     void Handle(const char *cmd) {
-        std::lock_guard<std::mutex> guard(state_.lock);
+        enum { kNone, kPosq, kPose, kMove, kRecenter, kAim, kGaze, kHide, kShow, kRole, kBtn, kDistance, kScroll };
+        int kind = kNone;
         char name[32];
-        float a, b;
+        float f[7];
-        int v;
+        int v = 0, role = 0, button = -1;
-        float x, y, z, qw, qx, qy, qz;
+        if (std::sscanf(cmd, "posq %f %f %f %f %f %f %f", &f[0], &f[1], &f[2], &f[3], &f[4], &f[5], &f[6]) == 7) {
-        if (std::sscanf(cmd, "posq %f %f %f %f %f %f %f", &x, &y, &z, &qw, &qx, &qy, &qz) == 7) {
+            kind = kPosq;
+        } else if (std::sscanf(cmd, "pose %f %f %f %f %f", &f[0], &f[1], &f[2], &f[3], &f[4]) == 5) {
+            kind = kPose;
+        } else if (std::sscanf(cmd, "move %f %f", &f[0], &f[1]) == 2) {
+            kind = kMove;
+        } else if (std::strncmp(cmd, "recenter", 8) == 0) {
+            kind = kRecenter;
+        } else if (std::sscanf(cmd, "aim %f %f", &f[0], &f[1]) == 2) {
+            kind = kAim;
+        } else if (std::strncmp(cmd, "gaze", 4) == 0) {
+            kind = kGaze;
+        } else if (std::strncmp(cmd, "hide", 4) == 0) {
+            kind = kHide;
+        } else if (std::strncmp(cmd, "show", 4) == 0) {
+            kind = kShow;
+        } else if (std::sscanf(cmd, "role %31s", name) == 1) {
+            role = !std::strcmp(name, "left")     ? TrackedControllerRole_LeftHand
+                   : !std::strcmp(name, "right")  ? TrackedControllerRole_RightHand
+                   : !std::strcmp(name, "stylus") ? TrackedControllerRole_Stylus
+                                                  : 0;
+            if (role) kind = kRole;
+        } else if (std::sscanf(cmd, "btn %31s %d", name, &v) == 2) {
+            for (int i = 0; i < kButtons; ++i)
+                if (std::strcmp(name, kButtonNames[i]) == 0) button = i;
+            if (button >= 0) kind = kBtn;
+        } else if (std::sscanf(cmd, "distance %f", &f[0]) == 1) {
+            kind = kDistance;
+        } else if (std::sscanf(cmd, "scroll %f %f", &f[0], &f[1]) == 2) {
+            kind = kScroll;
+        }
+        if (kind == kNone) return;
+
+        std::lock_guard<std::mutex> guard(state_.lock);
+        switch (kind) {
+        case kPosq:
             state_.explicitPose = true;
             state_.hasQuat = true;
             state_.gaze = false;
-            state_.pos[0] = x;
+            std::memcpy(state_.pos, f, sizeof state_.pos);
-            state_.pos[1] = y;
+            std::memcpy(state_.quat, f + 3, sizeof state_.quat);
-            state_.pos[2] = z;
+            break;
-            state_.quat[0] = qw;
+        case kPose:
-            state_.quat[1] = qx;
-            state_.quat[2] = qy;
-            state_.quat[3] = qz;
-        } else if (std::sscanf(cmd, "pose %f %f %f %f %f", &x, &y, &z, &a, &b) == 5) {
             state_.explicitPose = true;
             state_.hasQuat = false;
             state_.gaze = false;
-            state_.pos[0] = x;
+            std::memcpy(state_.pos, f, sizeof state_.pos);
-            state_.pos[1] = y;
+            state_.yaw = f[3];
-            state_.pos[2] = z;
+            state_.pitch = f[4];
-            state_.yaw = a;
+            break;
-            state_.pitch = b;
+        case kMove:
-        } else if (std::sscanf(cmd, "move %f %f", &a, &b) == 2) {
             state_.explicitPose = false;
             if (state_.gaze) state_.recenter = true;  // first move starts from the gaze
-            state_.yaw += a;  // wrap by hand: libm remainder() is GLIBC_2.43 in the build container
+            state_.yaw += f[0];  // wrap by hand: libm remainder() is GLIBC_2.43 in the build container
             while (state_.yaw > 180.f) state_.yaw -= 360.f;
             while (state_.yaw < -180.f) state_.yaw += 360.f;
-            state_.pitch = std::fmax(-85.f, std::fmin(85.f, state_.pitch + b));
+            state_.pitch = std::fmax(-85.f, std::fmin(85.f, state_.pitch + f[1]));
-        } else if (std::strncmp(cmd, "recenter", 8) == 0) {
+            break;
+        case kRecenter:
             state_.explicitPose = false;
             state_.recenter = true;
-        } else if (std::sscanf(cmd, "aim %f %f", &a, &b) == 2) {
+            break;
+        case kAim:
             state_.gaze = false;
-            state_.yaw = a;
+            state_.yaw = f[0];
-            state_.pitch = b;
+            state_.pitch = f[1];
-        } else if (std::strncmp(cmd, "gaze", 4) == 0) {
+            break;
+        case kGaze:
             state_.gaze = true;
-        } else if (std::strncmp(cmd, "hide", 4) == 0) {
+            break;
+        case kHide:
             state_.visible = false;
-        } else if (std::strncmp(cmd, "show", 4) == 0) {
+            break;
+        case kShow:
             state_.visible = true;
-        } else if (std::sscanf(cmd, "role %31s", name) == 1) {
+            break;
-            state_.role = !std::strcmp(name, "left")     ? TrackedControllerRole_LeftHand
+        case kRole:
-                          : !std::strcmp(name, "right")  ? TrackedControllerRole_RightHand
+            state_.role = role;
-                          : !std::strcmp(name, "stylus") ? TrackedControllerRole_Stylus
+            break;
-                                                         : state_.role;
+        case kBtn:
-        } else if (std::sscanf(cmd, "btn %31s %d", name, &v) == 2) {
+            state_.buttons[button] = v != 0;
-            for (int i = 0; i < kButtons; ++i)
+            break;
-                if (std::strcmp(name, kButtonNames[i]) == 0) state_.buttons[i] = v != 0;
+        case kDistance:
-        } else if (std::sscanf(cmd, "distance %f", &a) == 1) {
+            state_.distance = std::fmax(0.3f, std::fmin(10.f, f[0]));
-            state_.distance = std::fmax(0.3f, std::fmin(10.f, a));
+            break;
-        } else if (std::sscanf(cmd, "scroll %f %f", &a, &b) == 2) {
+        case kScroll:
-            state_.scrollX = a;
+            state_.scrollX = f[0];
-            state_.scrollY = b;
+            state_.scrollY = f[1];
+            break;
         }
     }
 

pointer/helper/ft-pointer.cpp

@@ -36,6 +36,22 @@
 // pointer is off the helper also stops listing overlays with vrcmd, whose connection every
 // second kept SteamVR from going to standby.
 //
+// Idle: while the pointer is off (and hand gestures are off), the main loop waits for a command
+// on its socket for up to 250 ms instead of running every 8 ms, or 20 ms while it reads mapped
+// Frame controller buttons (vrbuttons.h), which have no event to wait for. What has to go on
+// meanwhile still does: the headset's activity level, the game check and the relay's "vrgame"
+// and "gazeawake" repeats, and a mouse command wakes it at once. The overlay lookups (the 50 ms
+// visibility poll, the once-a-second handles) wait for the pointer to wake, and run right then.
+//
+// Unchanged frames: while the pointer is awake, a frame where nothing moved reuses the last one's
+// result. The collision passes (ComputeOverlayIntersection on every visible overlay, twice) run
+// again when the mouse or the anchor moved, the eye moved 5 mm, an overlay showed or hid, or
+// 100 ms have passed (overlays also move by themselves), and always while dragging. The dots'
+// setters go to SteamVR only when their value changes, and a dot's placement only when it moved
+// 0.2 mm or the eye 5 mm (its facing and size then change by well under 1%). The pose goes to the
+// driver, which keeps the last one, when the laser's origin moved 0.2 mm or its direction 0.04
+// deg (0.1 mm where it lands, 15 cm on), and at least every 100 ms.
+//
 // Last used wins: when a real controller moves (picked up), the pointer is released
 // (driver "hide", which also drops its hand role hint), so the controller gets
 // its role and laser back. The next mouse input reconnects and claims the laser again.
@@ -311,6 +327,7 @@ extern "C" {
 #include <atomic>
 #include <chrono>
 #include <cmath>
+#include <condition_variable>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
@@ -328,6 +345,7 @@ extern "C" {
 #include <fcntl.h>
 #include <fnmatch.h>
 
+#include <poll.h>
 #include <sys/mman.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
@@ -500,29 +518,62 @@ std::string JsonQuote(const std::string &s) {
 // public call to enumerate other apps' overlays). Hidden ones are listed too: the
 // window controls under a floating panel only appear while something hovers the
 // panel, and the cursor has to find them the moment they do, not a second later.
+// Each vrcmd run is a shell and a new SteamVR client, about 30 ms of CPU, so the list is read
+// every 20 seconds (kEvery) while the pointer is awake, and at once when something says it may
+// have changed (Kick: the pointer waking, the dashboard opening or closing, a click that hit
+// nothing), at most once a second. Showing and hiding the overlays it knows doesn't need a new
+// list: the main loop polls their visibility (IsOverlayVisible) every 50 ms.
 // Paused while the pointer is off: each vrcmd run connects to SteamVR as a new app, and a new
 // app every second kept SteamVR (and the headset's displays) from going to standby.
 // "overlays" requests (Frametop Input Settings' Ignored panels page) refresh the list even
 // while paused, and are answered from this thread once it's fresh.
 class OverlayList {
 public:
+    static constexpr auto kEvery = std::chrono::seconds(20), kGap = std::chrono::seconds(1);
     void Start() {
         out_ = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
         thread_ = std::thread([this] {
+            std::unique_lock<std::mutex> lk(lock_);
             while (running_) {
-                if (!paused_ || requested_) Refresh();
+                // Sleeps while paused (until a request or the wake); otherwise until it's time, or
-                // Wait a second, or less when the pointer wakes (refresh right away then).
+                // a kick once kGap has passed since the last read.
-                for (int i = 0; i < 10 && running_; ++i) {
+                const auto due = std::max(last_ + kGap, kicked_ ? last_ : last_ + kEvery);
-                    const bool wasPaused = paused_;
+                if (!waiting_.empty()) {
-                    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+                } else if (paused_) {
-                    if ((wasPaused && !paused_) || requested_) break;
+                    cv_.wait(lk);
+                    continue;
+                } else if (std::chrono::steady_clock::now() < due) {
+                    cv_.wait_until(lk, due);
+                    continue;
                 }
+                kicked_ = false;
+                lk.unlock();
+                Refresh();
+                lk.lock();
+                last_ = std::chrono::steady_clock::now();
             }
         });
     }
-    void SetPaused(bool paused) { paused_ = paused; }
+    // Unpausing (the pointer woke) reads the list again at once.
+    void SetPaused(bool paused) {
+        std::lock_guard<std::mutex> guard(lock_);
+        if (paused == paused_) return;
+        if (!paused) kicked_ = true, last_ = {};
+        paused_ = paused;
+        cv_.notify_one();
+    }
+    // The list may have changed: read it again soon (not while paused).
+    void Kick() {
+        std::lock_guard<std::mutex> guard(lock_);
+        kicked_ = true;
+        cv_.notify_one();
+    }
     void Stop() {
-        running_ = false;
+        {
+            std::lock_guard<std::mutex> guard(lock_);
+            running_ = false;
+            cv_.notify_one();
+        }
         if (thread_.joinable()) thread_.join();
     }
     std::vector<std::string> Keys() {
@@ -531,12 +582,14 @@ public:
         for (const auto &e : entries_) keys.push_back(e.key);
         return keys;
     }
+    // Goes up by one each time the list is read, so the main loop knows to look the keys up again.
+    unsigned Generation() const { return generation_; }
     // Answer `to` with {"t":"overlays","list":[{"key","name","visible"}...]} after the next refresh.
     void Request(const sockaddr_un &to, socklen_t len) {
         if (len <= offsetof(sockaddr_un, sun_path)) return;
         std::lock_guard<std::mutex> guard(lock_);
         if (waiting_.size() < 8) waiting_.push_back({to, len});
-        requested_ = true;
+        cv_.notify_one();
     }
 
 private:
@@ -545,7 +598,6 @@ private:
         bool visible;
     };
     void Refresh() {
-        requested_ = false;
         FILE *p = popen("LD_LIBRARY_PATH=/opt/steamvr/bin/linuxarm64 /opt/steamvr/bin/linuxarm64/vrcmd --overlays 2>/dev/null", "r");
         if (!p) return;
         std::vector<Entry> entries;
@@ -577,6 +629,7 @@ private:
             entries_ = std::move(entries);
             waiting.swap(waiting_);
         }
+        ++generation_;
         if (waiting.empty()) return;
         std::string msg = "{\"t\":\"overlays\",\"list\":[";
         for (size_t i = 0; i < entries_.size(); ++i)
@@ -589,10 +642,11 @@ private:
 
     std::thread thread_;
     int out_ = -1;
-    std::atomic<bool> paused_{false};
+    std::mutex lock_;  // guards everything below
-    std::atomic<bool> running_{true};
+    std::condition_variable cv_;
-    std::atomic<bool> requested_{false};
+    bool paused_ = false, running_ = true, kicked_ = false;
-    std::mutex lock_;
+    std::chrono::steady_clock::time_point last_{};  // the last read
+    std::atomic<unsigned> generation_{0};
     std::vector<Entry> entries_;  // written only by the thread; the lock guards readers
     std::vector<std::pair<sockaddr_un, socklen_t>> waiting_;
 };
@@ -620,6 +674,36 @@ bool Ignored(const std::vector<std::string> &patterns, const std::string &key) {
     return false;
 }
 
+vr::HmdMatrix34_t Billboard(Vec3 at, Vec3 eye);
+
+// One of our dots, with what was last set on it: each setter goes to SteamVR only when its value
+// changes (see "Unchanged frames" at the top).
+struct DotOverlay {
+    vr::VROverlayHandle_t h = vr::k_ulOverlayHandleInvalid;
+    int shown = -1;  // unknown at first
+    float alpha = -1, width = -1;
+    bool placed = false;
+    Vec3 at, eye;
+    void Show(bool on) {
+        if (shown == int(on)) return;
+        shown = on;
+        if (on) vr::VROverlay()->ShowOverlay(h);
+        else vr::VROverlay()->HideOverlay(h);
+    }
+    void Alpha(float a) {
+        if (a != alpha) vr::VROverlay()->SetOverlayAlpha(h, alpha = a);
+    }
+    // Width w, at `to`, facing `from`: left as it is for a change under 0.5% in width, and while
+    // it moved less than 0.2 mm and the eye less than 5 mm.
+    void Place(Vec3 to, Vec3 from, float w) {
+        if (std::fabs(w - width) > 0.005f * width) vr::VROverlay()->SetOverlayWidthInMeters(h, width = w);
+        if (placed && Length(to - at) < 0.0002 && Length(from - eye) < 0.005) return;
+        placed = true, at = to, eye = from;
+        const auto m = Billboard(to, from);
+        vr::VROverlay()->SetOverlayTransformAbsolute(h, vr::TrackingUniverseStanding, &m);
+    }
+};
+
 vr::HmdMatrix34_t Billboard(Vec3 at, Vec3 eye) {
     // Overlay faces +Z; point +Z at the eye, keep +Y roughly up.
     const Vec3 z = Normalize(eye - at);
@@ -803,6 +887,8 @@ int main() {
     below.m[1][3] = -50;
     overlay->SetOverlayTransformTrackedDeviceRelative(laserMode, vr::k_unTrackedDeviceIndex_Hmd, &below);
     bool laserModeShown = false;
+    DotOverlay cursorDot, markerDot;  // the setters for `cursor` and `marker` (see "Unchanged frames" at the top)
+    cursorDot.h = cursor, markerDot.h = marker;
     // Controller beams keep the user's width; nothing here changes it any more.
     vr::VRSettings()->SetFloat("dashboard", "laserRayWidthScale", laserWidth);
 
@@ -822,12 +908,34 @@ int main() {
     std::map<std::string, bool> sceneGraph;  // no texture: plane test instead of ComputeOverlayIntersection
     std::map<std::string, bool> visible;     // refreshed every 50 ms
     auto lastVisible = std::chrono::steady_clock::now();
+    auto lastSlow = std::chrono::steady_clock::now() - std::chrono::seconds(10);
+    unsigned listGeneration = 0;  // the overlay list the handles were looked up from
     // The plane of the last panel the cursor was on, and the last point on it (panel edges).
     Vec3 edgePoint, edgeNormal, edgeLast;
     std::string edgeKey;
 
     bool active = false, recenter = false, anchored = false;
     using Clock = std::chrono::steady_clock;
+    // Unchanged frames (see the top): visibleGen goes up when an overlay shows or hides or the
+    // handles change; pass is the last collision pass, posed the last plain pose sent.
+    unsigned visibleGen = 0;
+    struct Pass {
+        bool valid = false;
+        Clock::time_point at{};
+        unsigned gen = 0;
+        double yaw = 0, pitch = 0;
+        Vec3 anchor, eye;
+        double best = 1e9, distance = 0;
+        std::string key;
+        bool scene = false, onEdge = false, occluded = false;
+        Vec3 point;
+    } pass;
+    struct Posed {
+        bool valid = false;
+        Clock::time_point at{};
+        Vec3 origin;
+        double yaw = 0, pitch = 0;
+    } posed;
     Clock::time_point lastMouse{}, claimAt{}, claimRelease{}, wokeAt{}, noWakeUntil{};
     bool claimPending = false, claimHeld = false;
     // Last used wins: since when each controller has been moving (zero: it isn't).
@@ -864,6 +972,9 @@ int main() {
         wokeAt = t;
         active = true;
         recenter = true;
+        // Overlay handles and visibility weren't looked at while it was off (see "Idle" at the top).
+        lastSlow = lastVisible = t - std::chrono::seconds(10);
+        pass.valid = posed.valid = false;
         SendTo(out, "ft_pointer", "role " + role);  // POINTER_ROLE, before it takes it
         SendTo(out, "ft_pointer", "show");
         claimPending = true;  // take the laser without clicking, once SteamVR has bound the device
@@ -965,6 +1076,8 @@ int main() {
             if (debug) std::fflush(stdout);
         }
         nudging = confirmLesson = false;
+        // A click on nothing: maybe on an overlay that came up since the list was read.
+        if (lastHit.empty()) overlays.Kick();
         leftHeld = true;
         dragDistance = lastDistance;
         pressKey.clear();
@@ -1088,7 +1201,6 @@ int main() {
         return gazeOn && gazeMouseHeld && !inGame && !headsetOff && Clock::now() - gz.at < std::chrono::seconds(1) &&
                !aimHeld && !leftHeld && !tilting && hold.src == Src::None && !clickPress && !clickRelease;
     };
-    auto lastSlow = std::chrono::steady_clock::now() - std::chrono::seconds(10);
 
     // --- Panel placement (see "Placement" at the top of the file) ---
     // Device pose, given in the standing universe, sent to the driver in raw space.
@@ -1104,6 +1216,7 @@ int main() {
         char msg[200];
         std::snprintf(msg, sizeof msg, "posq %.5f %.5f %.5f %.6f %.6f %.6f %.6f", o.x, o.y, o.z, q[0], q[1], q[2], q[3]);
         SendTo(out, "ft_pointer", msg);
+        posed.valid = false;
     };
     auto sleepMs = [](int ms) { std::this_thread::sleep_for(std::chrono::milliseconds(ms)); };
     auto headPos = [&] {
@@ -1115,8 +1228,8 @@ int main() {
     auto borrow = [&] {
         SendTo(out, "ft_pointer", "show");
         overlay->ShowOverlay(laserMode);
-        overlay->HideOverlay(cursor);
+        cursorDot.Show(false);
-        overlay->HideOverlay(marker);
+        markerDot.Show(false);
         sleepMs(active ? 50 : 400);  // a fresh connect needs SteamVR to bind the device
         SendTo(out, "ft_pointer", "btn a 1");
         sleepMs(60);
@@ -1243,6 +1356,36 @@ int main() {
         return msg;
     };
 
+    // "move <dyaw> <dpitch>" from the relay.
+    auto mouseMove = [&](double a, double b) {
+        // A move held back (POINTER_GAZE_MOUSE_MOVE=held) only wakes the pointer: it isn't using
+        // the mouse, so a drifting mouse doesn't keep the gaze from taking the pointer back.
+        const bool heldBack = mouseMoveHeld();
+        if (!heldBack) lastMouse = Clock::now();
+        // Any mouse input wakes the pointer (after a controller took over, or a helper restart).
+        if (!active) wake(Clock::now());
+        if (heldBack) return;
+        if (tilting) {
+            tiltYaw += a;
+            tiltPitch = std::clamp(tiltPitch + b, -80.0, 80.0);
+            return;
+        }
+        lastMove = Clock::now();  // the dot shows while the mouse moves it (gaze mode)
+        if (gazeOn && gazeOwns) {
+            // The mouse takes the pointer from the gaze, from where the gaze left it.
+            gazeOwns = false;
+            nudging = haveHead && Clock::now() - gz.at < std::chrono::milliseconds(200);
+            nudgeRawHy = gz.rhy, nudgeRawHp = gz.rhp, nudgeHead = lastHead;
+            nudgeAt = Clock::now(), nudgeMoved = 0;
+        }
+        if (nudging || aimHeld) nudgeMoved += std::hypot(a, b);
+        if (!anchored) recenter = true;
+        yaw += a;
+        while (yaw > 180) yaw -= 360;
+        while (yaw < -180) yaw += 360;
+        pitch = std::clamp(pitch + b, -85.0, 85.0);
+    };
+
     std::printf("ft-pointer running: free distance %.2f m, dot %.2f deg\n", freeDistance, cursorDeg);
     std::fflush(stdout);
 
@@ -1257,8 +1400,8 @@ int main() {
         if (headsetOff && active) {
             active = false;
             claimPending = claimHeld = false;
-            overlay->HideOverlay(cursor);
+            cursorDot.Show(false);
-            overlay->HideOverlay(marker);
+            markerDot.Show(false);
             SendTo(out, "ft_pointer", "btn a 0");
             SendTo(out, "ft_pointer", "hide");
             std::printf("headset off: pointer released\n");
@@ -1308,6 +1451,12 @@ int main() {
                 if (senderLen > offsetof(sockaddr_un, sun_path))
                     sendto(out, msg.data(), msg.size(), 0, reinterpret_cast<const sockaddr *>(&sender), senderLen);
             };
+            // Mouse moves first, the most frequent command.
+            double mx, my;
+            if (std::strncmp(buf, "move ", 5) == 0 && std::sscanf(buf + 5, "%lf %lf", &mx, &my) == 2) {
+                mouseMove(mx, my);
+                continue;
+            }
             // The gaze, from ft-gazed: not mouse input, it never wakes the pointer.
             double g[4];
             if (std::sscanf(buf, "gz %lf %lf %lf %lf", &g[0], &g[1], &g[2], &g[3]) == 4) {
@@ -1396,16 +1545,11 @@ int main() {
                     reply(gazeOn ? "ok on" : "ok off");
                 continue;
             }
-            const bool mouseInput = std::strncmp(buf, "move", 4) == 0 || std::strncmp(buf, "btn", 3) == 0 ||
+            // (Moves were taken first, above.)
-                                    std::strncmp(buf, "scroll", 6) == 0;
+            const bool mouseInput = std::strncmp(buf, "btn", 3) == 0 || std::strncmp(buf, "scroll", 6) == 0;
-            // A move held back (POINTER_GAZE_MOUSE_MOVE=held) only wakes the pointer: it isn't using
+            if (mouseInput) lastMouse = Clock::now();
-            // the mouse, so a drifting mouse doesn't keep the gaze from taking the pointer back.
-            const bool moveHeldBack = std::strncmp(buf, "move", 4) == 0 && mouseMoveHeld();
-            if (mouseInput && !moveHeldBack) lastMouse = Clock::now();
             // Any mouse input wakes the pointer (after a controller took over, or a helper restart).
             if (!active && mouseInput) wake(Clock::now());
-            if (moveHeldBack) continue;
-            double a, b;
             char key[128];
             double px, py, pz, pyaw, ppitch, proll = 0, pgrab = -1;
             if (std::sscanf(buf, "grabprobe %127s", key) == 1) {
@@ -1464,31 +1608,12 @@ int main() {
                 tilting = swallowedRight = false;
                 continue;
             }
-            if (tilting && std::sscanf(buf, "move %lf %lf", &a, &b) == 2) {
+            if (std::strncmp(buf, "recenter", 8) == 0) {
-                tiltYaw += a;
-                tiltPitch = std::clamp(tiltPitch + b, -80.0, 80.0);
-                continue;
-            }
-            if (std::sscanf(buf, "move %lf %lf", &a, &b) == 2) {
-                lastMove = Clock::now();  // the dot shows while the mouse moves it (gaze mode)
-                if (gazeOn && gazeOwns) {
-                    // The mouse takes the pointer from the gaze, from where the gaze left it.
-                    gazeOwns = false;
-                    nudging = haveHead && Clock::now() - gz.at < std::chrono::milliseconds(200);
-                    nudgeRawHy = gz.rhy, nudgeRawHp = gz.rhp, nudgeHead = lastHead;
-                    nudgeAt = Clock::now(), nudgeMoved = 0;
-                }
-                if (nudging || aimHeld) nudgeMoved += std::hypot(a, b);
-                if (!anchored) recenter = true;
-                yaw += a;
-                while (yaw > 180) yaw -= 360;
-                while (yaw < -180) yaw += 360;
-                pitch = std::clamp(pitch + b, -85.0, 85.0);
-            } else if (std::strncmp(buf, "recenter", 8) == 0) {
                 recenter = true;
             } else if (std::strncmp(buf, "reload", 6) == 0) {
                 loadConfig();
                 lastSlow = Clock::now() - std::chrono::seconds(10);  // apply POINTER_IGNORE now
+                pass.valid = false;
                 std::printf("reloaded: free distance %.2f m, dot %.2f deg, origin %.2f, head follow %s, leash %.0f deg, "
                             "controller pickup %.1fx, %zu ignored\n",
                             freeDistance, cursorDeg, originFraction, follow ? "on" : "off", leashDeg, pickupScale,
@@ -1506,8 +1631,8 @@ int main() {
                 if (!active) wake(Clock::now());
             } else if (std::strncmp(buf, "hide", 4) == 0) {
                 active = false;
-                overlay->HideOverlay(cursor);
+                cursorDot.Show(false);
-                overlay->HideOverlay(marker);
+                markerDot.Show(false);
                 SendTo(out, "ft_pointer", "hide");
             } else {
                 SendTo(out, "ft_pointer", buf);  // btn, scroll
@@ -1549,8 +1674,8 @@ int main() {
             sys->GetControllerRoleForTrackedDeviceIndex(ours) == vr::TrackedControllerRole_Invalid) {
             active = false;
             claimPending = claimHeld = false;
-            overlay->HideOverlay(cursor);
+            cursorDot.Show(false);
-            overlay->HideOverlay(marker);
+            markerDot.Show(false);
             SendTo(out, "ft_pointer", "btn a 0");
             SendTo(out, "ft_pointer", "hide");
             noWakeUntil = tnow + std::chrono::seconds(2);
@@ -1578,8 +1703,8 @@ int main() {
                 if (tnow - movingSince[i] >= std::chrono::milliseconds(100)) {
                     active = false;
                     claimPending = claimHeld = false;
-                    overlay->HideOverlay(cursor);
+                    cursorDot.Show(false);
-                    overlay->HideOverlay(marker);
+                    markerDot.Show(false);
                     SendTo(out, "ft_pointer", "btn a 0");
                     SendTo(out, "ft_pointer", "hide");
                     std::printf("controller %u moved (%.2f m/s, %.1f rad/s): pointer released\n", i, speed, spin);
@@ -1629,7 +1754,7 @@ int main() {
         }
 
         // Hands (see the top): pinches and grips from ft-hands.
-        {
+        if (handsOn) {
             vr::TrackedDevicePose_t h0;
             sys->GetDeviceToAbsoluteTrackingPose(vr::TrackingUniverseStanding, 0, &h0, 1);
             if (h0.bPoseIsValid) poses.Add(tnow, h0.mDeviceToAbsoluteTracking);
@@ -1928,10 +2053,13 @@ int main() {
         }
         followAt = tnow;
 
-        // Slow work, once a second: overlay handles, our device index, laser width.
+        // Slow work, once a second and when the overlay list is new: overlay handles, our device
+        // index. Only while the pointer is awake (see "Idle" at the top).
         const auto now = std::chrono::steady_clock::now();
-        if (now - lastSlow > std::chrono::seconds(1)) {
+        if (active && (now - lastSlow > std::chrono::seconds(1) || overlays.Generation() != listGeneration)) {
             lastSlow = now;
+            listGeneration = overlays.Generation();
+            const auto before = handles;
             handles.clear();
             for (const auto &key : overlays.Keys()) {
                 if (Ignored(ignore, key)) continue;
@@ -1951,19 +2079,21 @@ int main() {
                 sceneGraph[key] = (tw == 0 || th == 0) && tt == vr::VROverlayTransform_Absolute &&
                                   key.rfind("frametop.", 0) != 0;
             }
-            ours = vr::k_unTrackedDeviceIndexInvalid;
+            if (handles != before) ++visibleGen;
-            for (vr::TrackedDeviceIndex_t i = 0; i < vr::k_unMaxTrackedDeviceCount; ++i) {
+            // Our device keeps its index; it's looked for again when a device is activated or
+            // deactivated (the events below).
+            for (vr::TrackedDeviceIndex_t i = 0; ours == vr::k_unTrackedDeviceIndexInvalid && i < vr::k_unMaxTrackedDeviceCount; ++i) {
                 char type[64] = "";
                 sys->GetStringTrackedDeviceProperty(i, vr::Prop_ControllerType_String, type, sizeof type);
                 if (std::strcmp(type, "ft_pointer") == 0) ours = i;
             }
-
         }
 
-        if (now - lastVisible > std::chrono::milliseconds(50) || visible.size() != handles.size()) {
+        if (active && (now - lastVisible > std::chrono::milliseconds(50) || visible.size() != handles.size())) {
             lastVisible = now;
-            visible.clear();
+            std::map<std::string, bool> seen;
-            for (const auto &[key, h] : handles) visible[key] = overlay->IsOverlayVisible(h);
+            for (const auto &[key, h] : handles) seen[key] = overlay->IsOverlayVisible(h);
+            if (seen != visible) visible.swap(seen), ++visibleGen;
         }
 
         if (active && anchored && hmd.bPoseIsValid && tilting) {
@@ -1973,8 +2103,8 @@ int main() {
                 tiltOrigin = lastOrigin;
                 tiltBasis = AimBasis(lastAim);
                 tiltStart = false;  // angles carry on from any earlier tilt in this drag
-                overlay->HideOverlay(cursor);
+                cursorDot.Show(false);
-                overlay->HideOverlay(marker);
+                markerDot.Show(false);
             }
             const double yr = tiltYaw * M_PI / 180, pr = tiltPitch * M_PI / 180;
             const Vec3 up{0, 1, 0}, side = tiltBasis.x;
@@ -1990,6 +2120,7 @@ int main() {
             std::snprintf(msg, sizeof msg, "posq %.5f %.5f %.5f %.6f %.6f %.6f %.6f", originRaw.x, originRaw.y,
                           originRaw.z, q[0], q[1], q[2], q[3]);
             SendTo(out, "ft_pointer", msg);
+            posed.valid = false;
         } else if (active && anchored && hmd.bPoseIsValid) {
             const bool dragging = leftHeld || tnow < dropHoldUntil;
             if (!dragging) tiltYaw = tiltPitch = 0;  // drop finished: back to plain pointing
@@ -2033,85 +2164,98 @@ int main() {
                 }
                 return h;
             };
-            Hit first;
+            // Unchanged frames (see the top): the last pass still holds.
-            if (!dragging) first = nearest(anchor, dir);
+            const bool reuse = !dragging && pass.valid && tnow - pass.at < std::chrono::milliseconds(100) &&
-            double best = first.along;
+                               pass.gen == visibleGen && std::fabs(yaw - pass.yaw) < 1e-6 &&
-            std::string bestKey = first.key;
+                               std::fabs(pitch - pass.pitch) < 1e-6 && Length(anchor - pass.anchor) < 0.001 &&
-            bool bestScene = first.scene;
+                               Length(eye - pass.eye) < 0.005;
-            Vec3 bestPoint = first.point, bestNormal = first.normal;
+            double best = pass.best, distance = pass.distance;
-            bool onEdge = false;
+            std::string bestKey = pass.key;
-            if (!dragging && best < 1e8 && !bestScene) {
+            bool bestScene = pass.scene, onEdge = pass.onEdge, occluded = pass.occluded;
-                edgeKey = bestKey, edgePoint = bestPoint, edgeNormal = Normalize(bestNormal), edgeLast = bestPoint;
+            Vec3 point = pass.point;
-            } else if (!dragging && best >= 1e8 && !edgeKey.empty() && visible[edgeKey]) {
+            if (!reuse) {
-                // Just off a panel: stay on its plane (see "Panel edges" at the top).
+                Hit first;
-                const double denom = Dot(dir, edgeNormal);
+                if (!dragging) first = nearest(anchor, dir);
-                if (std::fabs(denom) > 1e-4) {
+                best = first.along;
-                    const double along = Dot(edgePoint - anchor, edgeNormal) / denom;
+                bestKey = first.key;
-                    const Vec3 at = anchor + dir * along;
+                bestScene = first.scene;
-                    if (along > 0.05 && std::sqrt(Dot(at - edgeLast, at - edgeLast)) <= edgeReach) {
+                Vec3 bestPoint = first.point, bestNormal = first.normal;
-                        best = along;
+                onEdge = false;
-                        bestKey = edgeKey;
+                if (!dragging && best < 1e8 && !bestScene) {
-                        onEdge = true;
+                    edgeKey = bestKey, edgePoint = bestPoint, edgeNormal = Normalize(bestNormal), edgeLast = bestPoint;
+                } else if (!dragging && best >= 1e8 && !edgeKey.empty() && visible.count(edgeKey) &&
+                           visible.at(edgeKey)) {
+                    // Just off a panel: stay on its plane (see "Panel edges" at the top).
+                    const double denom = Dot(dir, edgeNormal);
+                    if (std::fabs(denom) > 1e-4) {
+                        const double along = Dot(edgePoint - anchor, edgeNormal) / denom;
+                        const Vec3 at = anchor + dir * along;
+                        if (along > 0.05 && std::sqrt(Dot(at - edgeLast, at - edgeLast)) <= edgeReach) {
+                            best = along;
+                            bestKey = edgeKey;
+                            onEdge = true;
+                        }
                     }
                 }
-            }
+                // Held on one of ft-screens' panels that stays where it is: onto whichever of them
-            // Held on one of ft-screens' panels that stays where it is: onto whichever of them
+                // the ray meets (see the top).
-            // the ray meets (see the top).
+                if (leftHeld && !pressKey.empty()) {
-            if (leftHeld && !pressKey.empty()) {
+                    vr::ETrackingUniverseOrigin uo;
-                vr::ETrackingUniverseOrigin uo;
+                    vr::HmdMatrix34_t now{};
-                vr::HmdMatrix34_t now{};
+                    auto it = handles.find(pressKey);
-                auto it = handles.find(pressKey);
+                    bool still = it != handles.end() &&
-                bool still = it != handles.end() &&
+                                 overlay->GetOverlayTransformAbsolute(it->second, &uo, &now) == vr::VROverlayError_None;
-                             overlay->GetOverlayTransformAbsolute(it->second, &uo, &now) == vr::VROverlayError_None;
+                    for (int i = 0; still && i < 3; ++i)
-                for (int i = 0; still && i < 3; ++i)
+                        for (int j = 0; j < 4; ++j)
-                    for (int j = 0; j < 4; ++j)
+                            if (std::fabs(now.m[i][j] - pressPose.m[i][j]) > 0.001f) still = false;
-                        if (std::fabs(now.m[i][j] - pressPose.m[i][j]) > 0.001f) still = false;
+                    if (still) {
-                if (still) {
+                        Hit h;
-                    Hit h;
+                        for (const auto &[key, handle] : handles) {
-                    for (const auto &[key, handle] : handles) {
+                            if (!visible[key] || !FramePanel(key)) continue;
-                        if (!visible[key] || !FramePanel(key)) continue;
+                            vr::VROverlayIntersectionParams_t params{};
-                        vr::VROverlayIntersectionParams_t params{};
+                            params.vSource = {float(anchor.x), float(anchor.y), float(anchor.z)};
-                        params.vSource = {float(anchor.x), float(anchor.y), float(anchor.z)};
+                            params.vDirection = {float(dir.x), float(dir.y), float(dir.z)};
-                        params.vDirection = {float(dir.x), float(dir.y), float(dir.z)};
+                            params.eOrigin = vr::TrackingUniverseStanding;
-                        params.eOrigin = vr::TrackingUniverseStanding;
+                            vr::VROverlayIntersectionResults_t r{};
-                        vr::VROverlayIntersectionResults_t r{};
+                            if (overlay->ComputeOverlayIntersection(handle, &params, &r) && r.fDistance > 0.05f &&
-                        if (overlay->ComputeOverlayIntersection(handle, &params, &r) && r.fDistance > 0.05f &&
+                                r.fDistance < h.along)
-                            r.fDistance < h.along)
+                                h.along = r.fDistance, h.key = key;
-                            h.along = r.fDistance, h.key = key;
+                        }
+                        if (h.along < 1e8) dragDistance = h.along, lastHit = h.key;
+                    } else {
+                        pressKey.clear();  // carried: the lock holds for the rest of this press
                     }
-                    if (h.along < 1e8) dragDistance = h.along, lastHit = h.key;
-                } else {
-                    pressKey.clear();  // carried: the lock holds for the rest of this press
                 }
-            }
+                // While dragging: keep the press-time distance and show the non-interactive marker.
-            // While dragging: keep the press-time distance and show the non-interactive marker.
+                // On a scene-graph plane or a panel's edge: the laser-catching dot goes 5 cm behind it.
-            // On a scene-graph plane or a panel's edge: the laser-catching dot goes 5 cm behind it.
+                distance = dragging ? dragDistance : (best < 1e8 ? best : freeDistance);
-            double distance = dragging ? dragDistance : (best < 1e8 ? best : freeDistance);
+                point = anchor + dir * distance;
-            Vec3 point = anchor + dir * distance;
+                occluded = false;
-            bool occluded = false;
+                if (!dragging) {
-            if (!dragging) {
+                    // The cursor lands on what you see under it: the ray above starts at the anchor,
-                // The cursor lands on what you see under it: the ray above starts at the anchor,
+                    // not the eye, so after leaning it can pick a panel that something nearer
-                // not the eye, so after leaning it can pick a panel that something nearer
+                    // covers from where you are now (panels close together in view, at different
-                // covers from where you are now (panels close together in view, at different
+                    // depths). Anything in front of the point on the eye's line of sight wins.
-                // depths). Anything in front of the point on the eye's line of sight wins.
+                    const double toPoint = std::sqrt(Dot(point - eye, point - eye));
-                const double toPoint = std::sqrt(Dot(point - eye, point - eye));
+                    const Hit front = nearest(eye, Normalize(point - eye));
-                const Hit front = nearest(eye, Normalize(point - eye));
+                    if (front.along < toPoint - 0.02) {
-                if (front.along < toPoint - 0.02) {
+                        occluded = true;
-                    occluded = true;
+                        bestKey = front.key, bestScene = front.scene;
-                    bestKey = front.key, bestScene = front.scene;
+                        point = front.point;
-                    point = front.point;
+                        if (!front.scene)
-                    if (!front.scene) edgeKey = front.key, edgePoint = front.point, edgeNormal = Normalize(front.normal),
+                            edgeKey = front.key, edgePoint = front.point, edgeNormal = Normalize(front.normal),
-                                      edgeLast = front.point;
+                            edgeLast = front.point;
-                    distance = std::sqrt(Dot(point - anchor, point - anchor));
+                        distance = std::sqrt(Dot(point - anchor, point - anchor));
-                    best = distance;
+                        best = distance;
-                    onEdge = false;
+                        onEdge = false;
+                    }
+                    lastDistance = distance, lastHit = bestKey;
                 }
-                lastDistance = distance, lastHit = bestKey;
             }
             const bool onScene = !dragging && ((bestScene && best < 1e8) || onEdge);
             const bool onPanel = dragging || (best < 1e8 && !onScene);
             const Vec3 sight = Normalize(point - eye);
-            if (!dragging) {
+            if (!dragging && !reuse) {
                 // SteamVR Settings (see the top): the dashboard's main panel is hidden and its
                 // scene-graph panel shows the page.
                 onVrSettings = false;
@@ -2127,6 +2271,10 @@ int main() {
                     }
                 }
             }
+            if (!reuse) {
+                pass = {!dragging, tnow, visibleGen, yaw, pitch, anchor, eye,
+                        best, distance, bestKey, bestScene, onEdge, occluded, point};
+            }
             if (onVrSettings != catcherHidesHit) {
                 overlay->SetOverlayFlag(cursor, vr::VROverlayFlags_HideLaserIntersection, onVrSettings);
                 catcherHidesHit = onVrSettings;
@@ -2143,20 +2291,16 @@ int main() {
                     alpha = std::clamp(1 - std::min(secs(lastMove) - gazeShow, secs(lastHeld)) / 0.25, 0.0, 1.0);
                 }
                 if (tnow < calPanelUntil) alpha = 0;
-                overlay->SetOverlayAlpha(marker, float(alpha));
+                markerDot.Alpha(float(alpha));
-                overlay->SetOverlayWidthInMeters(marker, float(2 * SETTINGS_DOT * std::tan(cursorDeg * M_PI / 360)));
+                markerDot.Place(near, eye, float(2 * SETTINGS_DOT * std::tan(cursorDeg * M_PI / 360)));
-                auto mm = Billboard(near, eye);
+                cursorDot.Alpha(0);
-                overlay->SetOverlayTransformAbsolute(marker, vr::TrackingUniverseStanding, &mm);
+                cursorDot.Place(far, eye, float(2 * SETTINGS_CATCHER * std::tan(cursorDeg * M_PI / 360)));
-                overlay->SetOverlayAlpha(cursor, 0);
+                markerDot.Show(true);
-                overlay->SetOverlayWidthInMeters(cursor, float(2 * SETTINGS_CATCHER * std::tan(cursorDeg * M_PI / 360)));
+                cursorDot.Show(true);
-                auto mc = Billboard(far, eye);
-                overlay->SetOverlayTransformAbsolute(cursor, vr::TrackingUniverseStanding, &mc);
-                overlay->ShowOverlay(marker);
-                overlay->ShowOverlay(cursor);
             } else {
                 // On a panel: the non-interactive marker, pulled 5 mm toward the eye so it
                 // draws on top. In free space: the interactive dot the laser lands on.
-                const vr::VROverlayHandle_t show = onPanel ? marker : cursor, hide = onPanel ? cursor : marker;
+                DotOverlay &show = onPanel ? markerDot : cursorDot, &hide = onPanel ? cursorDot : markerDot;
                 const Vec3 at = onPanel ? point + Normalize(eye - point) * 0.005 : onScene ? point + dir * 0.05 : point;
                 const double dist = std::sqrt(Dot(at - eye, at - eye));
                 // Gaze mode: a pulse for each click, and with POINTER_GAZE_DOT=moving, shown only
@@ -2173,12 +2317,10 @@ int main() {
                     }
                 }
                 if (tnow < calPanelUntil) alpha = 0;  // the calibration panel is up (see the top)
-                overlay->SetOverlayAlpha(show, float(alpha));
+                show.Alpha(float(alpha));
-                overlay->SetOverlayWidthInMeters(show, float(2 * dist * std::tan(scale * cursorDeg * M_PI / 360)));
+                show.Place(at, eye, float(2 * dist * std::tan(scale * cursorDeg * M_PI / 360)));
-                auto m = Billboard(at, eye);
+                show.Show(true);
-                overlay->SetOverlayTransformAbsolute(show, vr::TrackingUniverseStanding, &m);
+                hide.Show(false);
-                overlay->ShowOverlay(show);
-                overlay->HideOverlay(hide);
             }
 
             // Controller ray: from the eye, aimed at the cursor point, converted from the
@@ -2223,10 +2365,15 @@ int main() {
                 std::snprintf(msg, sizeof msg, "posq %.5f %.5f %.5f %.6f %.6f %.6f %.6f", oRaw.x, oRaw.y, oRaw.z, q[0],
                               q[1], q[2], q[3]);
                 SendTo(out, "ft_pointer", msg);
-            } else {
+                posed.valid = false;
+            } else if (!posed.valid || tnow - posed.at >= std::chrono::milliseconds(100) ||
+                       Length(eyeRaw - posed.origin) >= 0.0002 || std::fabs(std::remainder(ayaw - posed.yaw, 360.0)) >= 0.04 ||
+                       std::fabs(apitch - posed.pitch) >= 0.04) {
+                // The driver keeps the last pose: only a change goes out (see "Unchanged frames" at the top).
                 char msg[160];
                 std::snprintf(msg, sizeof msg, "pose %.5f %.5f %.5f %.4f %.4f", eyeRaw.x, eyeRaw.y, eyeRaw.z, ayaw, apitch);
                 SendTo(out, "ft_pointer", msg);
+                posed = {true, tnow, eyeRaw, ayaw, apitch};
             }
         }
 
@@ -2275,6 +2422,12 @@ int main() {
 
         vr::VREvent_t ev;
         while (sys->PollNextEvent(&ev, sizeof ev)) {
+            // The dashboard's overlays come and go with it, and a game brings its own.
+            if (ev.eventType == vr::VREvent_DashboardActivated || ev.eventType == vr::VREvent_DashboardDeactivated ||
+                ev.eventType == vr::VREvent_DashboardOverlayCreated || ev.eventType == vr::VREvent_SceneApplicationChanged)
+                overlays.Kick();
+            if (ev.eventType == vr::VREvent_TrackedDeviceActivated || ev.eventType == vr::VREvent_TrackedDeviceDeactivated)
+                ours = vr::k_unTrackedDeviceIndexInvalid;
             if (ev.eventType == vr::VREvent_Quit) {
                 sys->AcknowledgeQuit_Exiting();
 
@@ -2283,6 +2436,15 @@ int main() {
                 return 0;
             }
         }
-        std::this_thread::sleep_for(std::chrono::milliseconds(8));
+        // Idle (see the top): wait for a command instead. Not with anything still to finish (the
+        // claim pulse, a click's release, a press).
+        const bool idle = !active && !handsOn && !claimPending && !claimHeld && !clickRelease && !leftHeld &&
+                          hold.src == Src::None;
+        if (idle) {
+            pollfd p{in, POLLIN, 0};
+            poll(&p, 1, controllerButtons.Watching(inGame) ? 20 : 250);
+        } else {
+            std::this_thread::sleep_for(std::chrono::milliseconds(8));
+        }
     }
 }

pointer/helper/vrbuttons.h

@@ -111,6 +111,14 @@ class ControllerButtons {
         }
     }
 
+    // Whether Poll reads any button now (the main loop can't sleep long while it does).
+    bool Watching(bool inGame) const {
+        if (!ok_ || (inGame && !games_ && !capture_)) return false;
+        for (int i = 0; i < kCount; ++i)
+            if (bound_[i]) return true;
+        return false;
+    }
+
     // {"manifest":true,"global":false,"bound":[...],"active":[...]}: active = bound and
     // delivered (a controller that has the button is on, and SteamVR lets us have it).
     std::string Status() const {