Pointer: skip unchanged work while the pointer is awake

Every frame (about 116 a second) the helper tested the cursor ray against every visible
overlay twice with ComputeOverlayIntersection, set the dot's alpha, width, transform and
visibility (five calls into SteamVR), and sent the driver a pose datagram, even with the
mouse and the head still.

Now a frame reuses the last collision result when the mouse, the anchor (1 mm) and the
eye (5 mm) haven't moved and no overlay showed, hid, or changed handle. The passes still run
at least every 100 ms, since overlays move on their own (a floating window's controls follow
it), and always while dragging. The dots' setters go to SteamVR only when their value changes:
the placement when the dot moved 0.2 mm or the eye 5 mm, which turns or resizes it by well
under 1%, and the width on a 0.5% change. The plain pose goes to the driver only 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; the driver keeps the last pose and reports it every frame. A tilt's
pose, a placement, or waking sends the next one regardless.

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

pointer/helper/ft-pointer.cpp

@@ -43,6 +43,15 @@
 // 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.
@@ -665,6 +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);
@@ -848,6 +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);
 
@@ -875,6 +916,26 @@ int main() {
 
     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).
@@ -913,6 +974,7 @@ int main() {
         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
@@ -1154,6 +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 = [&] {
@@ -1165,8 +1228,8 @@ int main() {
     auto borrow = [&] {
         SendTo(out, "ft_pointer", "show");
         overlay->ShowOverlay(laserMode);
-        overlay->HideOverlay(cursor);
-        overlay->HideOverlay(marker);
+        cursorDot.Show(false);
+        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);
@@ -1307,8 +1370,8 @@ int main() {
         if (headsetOff && active) {
             active = false;
             claimPending = claimHeld = false;
-            overlay->HideOverlay(cursor);
-            overlay->HideOverlay(marker);
+            cursorDot.Show(false);
+            markerDot.Show(false);
             SendTo(out, "ft_pointer", "btn a 0");
             SendTo(out, "ft_pointer", "hide");
             std::printf("headset off: pointer released\n");
@@ -1539,6 +1602,7 @@ int main() {
             } 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,
@@ -1556,8 +1620,8 @@ int main() {
                 if (!active) wake(Clock::now());
             } else if (std::strncmp(buf, "hide", 4) == 0) {
                 active = false;
-                overlay->HideOverlay(cursor);
-                overlay->HideOverlay(marker);
+                cursorDot.Show(false);
+                markerDot.Show(false);
                 SendTo(out, "ft_pointer", "hide");
             } else {
                 SendTo(out, "ft_pointer", buf);  // btn, scroll
@@ -1599,8 +1663,8 @@ int main() {
             sys->GetControllerRoleForTrackedDeviceIndex(ours) == vr::TrackedControllerRole_Invalid) {
             active = false;
             claimPending = claimHeld = false;
-            overlay->HideOverlay(cursor);
-            overlay->HideOverlay(marker);
+            cursorDot.Show(false);
+            markerDot.Show(false);
             SendTo(out, "ft_pointer", "btn a 0");
             SendTo(out, "ft_pointer", "hide");
             noWakeUntil = tnow + std::chrono::seconds(2);
@@ -1628,8 +1692,8 @@ int main() {
                 if (tnow - movingSince[i] >= std::chrono::milliseconds(100)) {
                     active = false;
                     claimPending = claimHeld = false;
-                    overlay->HideOverlay(cursor);
-                    overlay->HideOverlay(marker);
+                    cursorDot.Show(false);
+                    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);
@@ -1984,6 +2048,7 @@ int main() {
         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;
@@ -2003,6 +2068,7 @@ int main() {
                 sceneGraph[key] = (tw == 0 || th == 0) && tt == vr::VROverlayTransform_Absolute &&
                                   key.rfind("frametop.", 0) != 0;
             }
+            if (handles != before) ++visibleGen;
             // 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) {
@@ -2014,8 +2080,9 @@ int main() {
 
         if (active && (now - lastVisible > std::chrono::milliseconds(50) || visible.size() != handles.size())) {
             lastVisible = now;
-            visible.clear();
-            for (const auto &[key, h] : handles) visible[key] = overlay->IsOverlayVisible(h);
+            std::map<std::string, bool> seen;
+            for (const auto &[key, h] : handles) seen[key] = overlay->IsOverlayVisible(h);
+            if (seen != visible) visible.swap(seen), ++visibleGen;
         }
 
         if (active && anchored && hmd.bPoseIsValid && tilting) {
@@ -2025,8 +2092,8 @@ int main() {
                 tiltOrigin = lastOrigin;
                 tiltBasis = AimBasis(lastAim);
                 tiltStart = false;  // angles carry on from any earlier tilt in this drag
-                overlay->HideOverlay(cursor);
-                overlay->HideOverlay(marker);
+                cursorDot.Show(false);
+                markerDot.Show(false);
             }
             const double yr = tiltYaw * M_PI / 180, pr = tiltPitch * M_PI / 180;
             const Vec3 up{0, 1, 0}, side = tiltBasis.x;
@@ -2042,6 +2109,7 @@ 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
@@ -2085,85 +2153,97 @@ int main() {
                 }
                 return h;
             };
-            Hit first;
-            if (!dragging) first = nearest(anchor, dir);
-            double best = first.along;
-            std::string bestKey = first.key;
-            bool bestScene = first.scene;
-            Vec3 bestPoint = first.point, bestNormal = first.normal;
-            bool onEdge = false;
-            if (!dragging && best < 1e8 && !bestScene) {
-                edgeKey = bestKey, edgePoint = bestPoint, edgeNormal = Normalize(bestNormal), edgeLast = bestPoint;
-            } else if (!dragging && best >= 1e8 && !edgeKey.empty() && visible[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;
+            // Unchanged frames (see the top): the last pass still holds.
+            const bool reuse = !dragging && pass.valid && tnow - pass.at < std::chrono::milliseconds(100) &&
+                               pass.gen == visibleGen && std::fabs(yaw - pass.yaw) < 1e-6 &&
+                               std::fabs(pitch - pass.pitch) < 1e-6 && Length(anchor - pass.anchor) < 0.001 &&
+                               Length(eye - pass.eye) < 0.005;
+            double best = pass.best, distance = pass.distance;
+            std::string bestKey = pass.key;
+            bool bestScene = pass.scene, onEdge = pass.onEdge, occluded = pass.occluded;
+            Vec3 point = pass.point;
+            if (!reuse) {
+                Hit first;
+                if (!dragging) first = nearest(anchor, dir);
+                best = first.along;
+                bestKey = first.key;
+                bestScene = first.scene;
+                Vec3 bestPoint = first.point, bestNormal = first.normal;
+                onEdge = false;
+                if (!dragging && best < 1e8 && !bestScene) {
+                    edgeKey = bestKey, edgePoint = bestPoint, edgeNormal = Normalize(bestNormal), edgeLast = bestPoint;
+                } else if (!dragging && best >= 1e8 && !edgeKey.empty() && visible[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
-            // the ray meets (see the top).
-            if (leftHeld && !pressKey.empty()) {
-                vr::ETrackingUniverseOrigin uo;
-                vr::HmdMatrix34_t now{};
-                auto it = handles.find(pressKey);
-                bool still = it != handles.end() &&
-                             overlay->GetOverlayTransformAbsolute(it->second, &uo, &now) == vr::VROverlayError_None;
-                for (int i = 0; still && i < 3; ++i)
-                    for (int j = 0; j < 4; ++j)
-                        if (std::fabs(now.m[i][j] - pressPose.m[i][j]) > 0.001f) still = false;
-                if (still) {
-                    Hit h;
-                    for (const auto &[key, handle] : handles) {
-                        if (!visible[key] || !FramePanel(key)) continue;
-                        vr::VROverlayIntersectionParams_t params{};
-                        params.vSource = {float(anchor.x), float(anchor.y), float(anchor.z)};
-                        params.vDirection = {float(dir.x), float(dir.y), float(dir.z)};
-                        params.eOrigin = vr::TrackingUniverseStanding;
-                        vr::VROverlayIntersectionResults_t r{};
-                        if (overlay->ComputeOverlayIntersection(handle, &params, &r) && r.fDistance > 0.05f &&
-                            r.fDistance < h.along)
-                            h.along = r.fDistance, h.key = key;
+                // Held on one of ft-screens' panels that stays where it is: onto whichever of them
+                // the ray meets (see the top).
+                if (leftHeld && !pressKey.empty()) {
+                    vr::ETrackingUniverseOrigin uo;
+                    vr::HmdMatrix34_t now{};
+                    auto it = handles.find(pressKey);
+                    bool still = it != handles.end() &&
+                                 overlay->GetOverlayTransformAbsolute(it->second, &uo, &now) == vr::VROverlayError_None;
+                    for (int i = 0; still && i < 3; ++i)
+                        for (int j = 0; j < 4; ++j)
+                            if (std::fabs(now.m[i][j] - pressPose.m[i][j]) > 0.001f) still = false;
+                    if (still) {
+                        Hit h;
+                        for (const auto &[key, handle] : handles) {
+                            if (!visible[key] || !FramePanel(key)) continue;
+                            vr::VROverlayIntersectionParams_t params{};
+                            params.vSource = {float(anchor.x), float(anchor.y), float(anchor.z)};
+                            params.vDirection = {float(dir.x), float(dir.y), float(dir.z)};
+                            params.eOrigin = vr::TrackingUniverseStanding;
+                            vr::VROverlayIntersectionResults_t r{};
+                            if (overlay->ComputeOverlayIntersection(handle, &params, &r) && r.fDistance > 0.05f &&
+                                r.fDistance < h.along)
+                                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.
-            // On a scene-graph plane or a panel's edge: the laser-catching dot goes 5 cm behind it.
-            double distance = dragging ? dragDistance : (best < 1e8 ? best : freeDistance);
-            Vec3 point = anchor + dir * distance;
-            bool occluded = false;
-            if (!dragging) {
-                // 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
-                // 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.
-                const double toPoint = std::sqrt(Dot(point - eye, point - eye));
-                const Hit front = nearest(eye, Normalize(point - eye));
-                if (front.along < toPoint - 0.02) {
-                    occluded = true;
-                    bestKey = front.key, bestScene = front.scene;
-                    point = front.point;
-                    if (!front.scene) edgeKey = front.key, edgePoint = front.point, edgeNormal = Normalize(front.normal),
-                                      edgeLast = front.point;
-                    distance = std::sqrt(Dot(point - anchor, point - anchor));
-                    best = distance;
-                    onEdge = false;
+                // 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.
+                distance = dragging ? dragDistance : (best < 1e8 ? best : freeDistance);
+                point = anchor + dir * distance;
+                occluded = false;
+                if (!dragging) {
+                    // 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
+                    // 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.
+                    const double toPoint = std::sqrt(Dot(point - eye, point - eye));
+                    const Hit front = nearest(eye, Normalize(point - eye));
+                    if (front.along < toPoint - 0.02) {
+                        occluded = true;
+                        bestKey = front.key, bestScene = front.scene;
+                        point = front.point;
+                        if (!front.scene)
+                            edgeKey = front.key, edgePoint = front.point, edgeNormal = Normalize(front.normal),
+                            edgeLast = front.point;
+                        distance = std::sqrt(Dot(point - anchor, point - anchor));
+                        best = distance;
+                        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;
@@ -2179,6 +2259,10 @@ 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;
@@ -2195,20 +2279,16 @@ 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));
-                overlay->SetOverlayWidthInMeters(marker, float(2 * SETTINGS_DOT * std::tan(cursorDeg * M_PI / 360)));
-                auto mm = Billboard(near, eye);
-                overlay->SetOverlayTransformAbsolute(marker, vr::TrackingUniverseStanding, &mm);
-                overlay->SetOverlayAlpha(cursor, 0);
-                overlay->SetOverlayWidthInMeters(cursor, float(2 * SETTINGS_CATCHER * std::tan(cursorDeg * M_PI / 360)));
-                auto mc = Billboard(far, eye);
-                overlay->SetOverlayTransformAbsolute(cursor, vr::TrackingUniverseStanding, &mc);
-                overlay->ShowOverlay(marker);
-                overlay->ShowOverlay(cursor);
+                markerDot.Alpha(float(alpha));
+                markerDot.Place(near, eye, float(2 * SETTINGS_DOT * std::tan(cursorDeg * M_PI / 360)));
+                cursorDot.Alpha(0);
+                cursorDot.Place(far, eye, float(2 * SETTINGS_CATCHER * std::tan(cursorDeg * M_PI / 360)));
+                markerDot.Show(true);
+                cursorDot.Show(true);
             } 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
@@ -2225,12 +2305,10 @@ int main() {
                     }
                 }
                 if (tnow < calPanelUntil) alpha = 0;  // the calibration panel is up (see the top)
-                overlay->SetOverlayAlpha(show, float(alpha));
-                overlay->SetOverlayWidthInMeters(show, float(2 * dist * std::tan(scale * cursorDeg * M_PI / 360)));
-                auto m = Billboard(at, eye);
-                overlay->SetOverlayTransformAbsolute(show, vr::TrackingUniverseStanding, &m);
-                overlay->ShowOverlay(show);
-                overlay->HideOverlay(hide);
+                show.Alpha(float(alpha));
+                show.Place(at, eye, float(2 * dist * std::tan(scale * cursorDeg * M_PI / 360)));
+                show.Show(true);
+                hide.Show(false);
             }
 
             // Controller ray: from the eye, aimed at the cursor point, converted from the
@@ -2275,10 +2353,15 @@ 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};
             }
         }