Lay out hands/ like Frametop's other components

trackd/ becomes track/, and the calibration helper the Python tools
import moves from the prototype's folder into tools/. The model
development tools (nettest and the scripts that compare it with the
Python models or cut int8 calibration crops) stay in frame-hands with
the prototype they need.

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

hands/track/pinch.cpp

@@ -0,0 +1,153 @@
+#include "pinch.h"
+
+#include "io.h"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <algorithm>
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
+
+namespace {
+
+constexpr int kThumbTip = 4, kIndexTip = 8;
+
+void put3(float out[3], V3 v) {
+    for (int k = 0; k < 3; ++k) out[k] = float(v[k]);
+}
+
+}  // namespace
+
+void Pinch::update(const std::vector<const Hand *> &hands, const std::vector<Seen> &views, int64_t t_ns) {
+    events.clear();
+    for (int s = 0; s < 2; ++s) {
+        fh_pinch_t &o = side_[s];
+        const bool down = o.flags & FH_PINCH_DOWN;
+        // the hand: while down, the one the pinch began on; else the best tracked hand of this side
+        const Hand *h = nullptr;
+        for (const Hand *c : hands) {
+            if (down ? c->id != follow_[s] : c->right() != (s == 1)) continue;
+            if (!h || c->frames > h->frames) h = c;
+        }
+        world_d[s] = tri_d[s] = -1;
+        if (!h) {
+            o.flags &= ~FH_PINCH_TRACKED;
+            if (down && (t_ns - seen_ns_[s]) / 1e9 > p_.grace_s) end(s, t_ns, true);
+            continue;
+        }
+        seen_ns_[s] = t_ns;
+        tri_d[s] = norm(h->pts[kThumbTip] - h->pts[kIndexTip]);
+        double sum = 0;
+        int n = 0;
+        for (const Seen &v : views) {
+            if (v.hand != h->id) continue;
+            const V3 a{v.lm.world[kThumbTip][0], v.lm.world[kThumbTip][1], v.lm.world[kThumbTip][2]};
+            const V3 b{v.lm.world[kIndexTip][0], v.lm.world[kIndexTip][1], v.lm.world[kIndexTip][2]};
+            sum += norm(a - b), ++n;
+        }
+        if (n) world_d[s] = sum / n * h->scale;
+        const double d = p_.triangulated || world_d[s] < 0 ? tri_d[s] : world_d[s];
+        const V3 point = (h->smooth[kThumbTip] + h->smooth[kIndexTip]) * 0.5;
+        o.flags |= FH_PINCH_TRACKED;
+        o.hand_id = uint32_t(h->id);
+        o.distance = float(d);
+        o.strength = float(std::clamp((p_.end_m - d) / (p_.end_m - p_.begin_m), 0.0, 1.0));
+        put3(o.point, point);
+        if (!down) {
+            if (d < p_.begin_m) {
+                o.flags = (o.flags | FH_PINCH_DOWN) & ~FH_PINCH_LOST;
+                ++o.begins;
+                o.begin_ns = uint64_t(t_ns);
+                put3(o.begin_point, point);
+                follow_[s] = h->id;
+                open_frames_[s] = 0;
+                events.push_back({s, "begin", t_ns, d, point});
+            }
+        } else if (d > p_.end_m) {
+            if (++open_frames_[s] >= p_.end_frames) end(s, t_ns, false);
+        } else {
+            open_frames_[s] = 0;
+        }
+    }
+}
+
+void Pinch::end(int s, int64_t t_ns, bool lost) {
+    fh_pinch_t &o = side_[s];
+    o.flags = (o.flags & ~FH_PINCH_DOWN) | (lost ? FH_PINCH_LOST : 0);
+    ++o.ends;
+    o.end_ns = uint64_t(t_ns);
+    follow_[s] = 0;
+    events.push_back({s, lost ? "lost" : "end", t_ns, o.distance, {o.point[0], o.point[1], o.point[2]}});
+}
+
+void Pinch::release(int64_t t_ns) {
+    events.clear();
+    for (int s = 0; s < 2; ++s) {
+        side_[s].flags &= ~FH_PINCH_TRACKED;
+        if (side_[s].flags & FH_PINCH_DOWN) end(s, t_ns, true);
+    }
+}
+
+bool Pinch::engaged() const {
+    for (const fh_pinch_t &o : side_)
+        if ((o.flags & FH_PINCH_DOWN) || ((o.flags & FH_PINCH_TRACKED) && o.strength > 0.3f)) return true;
+    return false;
+}
+
+bool GesturePublisher::open(const Pinch &pinch, std::string &err) {
+    const char *run = std::getenv("XDG_RUNTIME_DIR");
+    const std::string dir = std::string(run ? run : "/run/user/" + std::to_string(getuid())) + "/frame-hands";
+    mkdir(dir.c_str(), 0700);
+    chmod(dir.c_str(), 0700);
+    const std::string path = dir + "/gestures";
+    const int fd = ::open(path.c_str(), O_RDWR | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
+    if (fd < 0 || ftruncate(fd, sizeof(fh_gestures_t)) < 0) return err = path + ": " + std::strerror(errno), false;
+    void *m = mmap(nullptr, sizeof(fh_gestures_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    close(fd);
+    if (m == MAP_FAILED) return err = path + ": can't map it", false;
+    out_ = static_cast<fh_gestures_t *>(m);
+    // keep the counters a previous tracker left, so a reader doesn't see them jump back
+    const bool ours = !std::memcmp(out_->magic, FH_GESTURES_MAGIC, 8) && out_->version == FH_GESTURES_VERSION;
+    if (!ours) {
+        std::memset(out_, 0, sizeof *out_);
+        std::memcpy(out_->magic, FH_GESTURES_MAGIC, 8);
+        out_->version = FH_GESTURES_VERSION;
+        out_->size = sizeof(fh_gestures_t);
+    }
+    seq_ = out_->seq / 2 + 1;
+    // a pinch the last tracker left down (it crashed) is over: count its end, as lost
+    __atomic_store_n(&out_->seq, 2 * ++seq_ - 1, __ATOMIC_RELAXED);
+    __atomic_thread_fence(__ATOMIC_RELEASE);
+    for (fh_pinch_t &o : out_->pinch)
+        if (o.begins != o.ends) {
+            o.ends = o.begins;
+            o.end_ns = mono_ns();
+            o.flags = (o.flags & ~FH_PINCH_DOWN) | FH_PINCH_LOST;
+        }
+    __atomic_store_n(&out_->seq, 2 * seq_, __ATOMIC_RELEASE);
+    out_->begin_m = float(pinch.params().begin_m);
+    out_->end_m = float(pinch.params().end_m);
+    return true;
+}
+
+void GesturePublisher::write(const Pinch &pinch, uint64_t capture_ns) {
+    __atomic_store_n(&out_->seq, 2 * ++seq_ - 1, __ATOMIC_RELAXED);
+    __atomic_thread_fence(__ATOMIC_RELEASE);
+    for (int s = 0; s < 2; ++s) {
+        // counters carry on from what's in the file (a restarted tracker starts its own at 0)
+        const fh_pinch_t &in = pinch.side(s);
+        fh_pinch_t &o = out_->pinch[s];
+        const uint32_t base_b = o.begins - last_begins_[s], base_e = o.ends - last_ends_[s];
+        o = in;
+        o.begins = base_b + in.begins;
+        o.ends = base_e + in.ends;
+        last_begins_[s] = in.begins, last_ends_[s] = in.ends;
+    }
+    out_->capture_ns = capture_ns;
+    out_->publish_ns = mono_ns();
+    __atomic_store_n(&out_->seq, 2 * seq_, __ATOMIC_RELEASE);
+}