Let firmware handle roll correction

web/app.js

@@ -464,6 +464,7 @@ function onDisconnected() {
   document.getElementById('badgeCharging').classList.remove('show');
   document.getElementById('badgeFull').classList.remove('show');
   imuSubscribed = false; vizPaused = true; vizUpdateIndicator(); streamDiagReset();
+  document.getElementById('orientLabel').textContent = '— not streaming —';
   document.getElementById('hashMismatchBanner').style.display = 'none';
   clearTelemetry();
   if (!userDisconnected && document.getElementById('autoReconnect').checked && savedDevice) {
@@ -538,47 +539,10 @@ function streamDiagPkt() {
   }
 }
 
-// ── Orientation (boot-pose tilt compensation) ─────────────────────────────────
-// We average the first N accel frames to determine which way gravity points,
-// then build a 2×2 rotation matrix so that "up on screen" stays world-up
-// regardless of how the device is rotated flat on the table.
-const ORIENT_SAMPLES = 30;
-let orientSamples = 0;
-let orientAccum   = [0, 0, 0];
-// 2×2 basis: [row0=[gY→screenX coeff, gZ→screenX coeff],
-//             row1=[gY→screenY coeff, gZ→screenY coeff]]
-// Identity by default (no rotation assumed until samples collected)
-let orientBasis = [[1, 0], [0, 1]];
-
-function buildOrientBasis() {
-  // Average accel vector = gravity direction in device frame
-  const gx = orientAccum[0] / ORIENT_SAMPLES;
-  const gy = orientAccum[1] / ORIENT_SAMPLES;
-  // gz unused — device assumed roughly flat (|gz| ≈ 1g, gx/gy ≈ 0 when flat)
-  // The horizontal tilt (yaw rotation of the device on the table) is the angle
-  // between device-X axis and world horizontal, derived from gx/gy.
-  // Firmware uses gyroZ for screen-X and gyroY for screen-Y.
-  // A device rotated θ clockwise on the table needs gyros counter-rotated by θ.
-  const norm = Math.sqrt(gx*gx + gy*gy) || 1;
-  const sinT =  gx / norm;   // sin of table-yaw angle
-  const cosT = -gy / norm;   // cos of table-yaw angle (negative Y = gravity down)
-  // Rotation matrix for gyro [gyroY, gyroZ] → [screenX, screenY]:
-  // Normally: screenX = -gyroZ, screenY = -gyroY (firmware convention reflected)
-  // With tilt θ: apply 2D rotation by θ to that vector.
-  orientBasis = [
-    [-sinT,  -cosT],  // screenX row
-    [-cosT,   sinT],  // screenY row
-  ];
-  const deg = (Math.atan2(gx, -gy) * 180 / Math.PI).toFixed(1);
-  log(`Orient locked — device yaw ≈ ${deg}° from nominal`, 'info');
-  document.getElementById('orientLabel').textContent = `yaw offset ${deg}° · complementary filter active`;
-}
-
-function resetOrient() {
-  orientSamples = 0;
-  orientAccum   = [0, 0, 0];
-  orientBasis   = [[1, 0], [0, 1]];
-}
+// Roll compensation is done entirely in firmware (calibrateGyroBias computes
+// rollSin/rollCos from boot-pose accel and applies the rotation before moveX/moveY).
+// The web visualiser just uses moveX/moveY directly — no re-rotation needed here.
+function resetOrient() {}  // kept for call-site compatibility
 
 function vizUpdateIndicator() {
   const el = document.getElementById('vizLive');
@@ -599,9 +563,9 @@ async function vizSetPaused(paused) {
   vizPaused = paused;
   if (!paused && chars.imuStream && !imuSubscribed) {
     try {
-      resetOrient();
       await chars.imuStream.startNotifications();
       imuSubscribed = true;
+      document.getElementById('orientLabel').textContent = 'roll correction active (firmware)';
       log('IMU stream subscribed','ok');
     } catch(e) { log(`IMU stream start failed: ${e.message}`,'err'); vizPaused = true; }
   } else if (paused && imuSubscribed) {
@@ -609,6 +573,7 @@ async function vizSetPaused(paused) {
       await chars.imuStream.stopNotifications();
       imuSubscribed = false;
       streamDiagReset();
+      document.getElementById('orientLabel').textContent = '— not streaming —';
     } catch(e) { log(`IMU stream stop failed: ${e.message}`,'err'); }
   }
   vizUpdateIndicator();
@@ -643,29 +608,14 @@ function parseImuStream(dv) {
   const single = !!(flags & 0x02);
   const dbl    = !!(flags & 0x04);
 
-  // Accumulate boot-pose from first ORIENT_SAMPLES accel frames (device flat on table)
-  if (orientSamples < ORIENT_SAMPLES) {
-    orientAccum[0] += accelX;
-    orientAccum[1] += accelY;
-    orientAccum[2] += accelZ;
-    orientSamples++;
-    if (orientSamples === ORIENT_SAMPLES) buildOrientBasis();
-  }
-
-  // Rotate gyro into world frame using boot-pose basis
-  // gyroY → pitch axis, gyroZ → yaw axis (firmware convention)
-  const wX = gyroY * orientBasis[0][0] + gyroZ * orientBasis[0][1];
-  const wY = gyroY * orientBasis[1][0] + gyroZ * orientBasis[1][1];
-
-  updateAxisBar('gy', wX, 30000);
-  updateAxisBar('gz', wY, 30000);
+  // Axis bars: show raw gyro (firmware convention: Z→screen-X, Y→screen-Y)
+  updateAxisBar('gy', -gyroZ, 30000);
+  updateAxisBar('gz', -gyroY, 30000);
 
   if (!idle) {
-    // moveX/moveY already come corrected from firmware; apply same world rotation
-    const wmX = moveX * orientBasis[0][0] + moveY * orientBasis[1][0];
-    const wmY = moveX * orientBasis[0][1] + moveY * orientBasis[1][1];
-    cursorX = Math.max(4, Math.min(canvas.width  - 4, cursorX + wmX * 1.5));
-    cursorY = Math.max(4, Math.min(canvas.height - 4, cursorY + wmY * 1.5));
+    // moveX/moveY are already roll-corrected by firmware — use them directly
+    cursorX = Math.max(4, Math.min(canvas.width  - 4, cursorX + moveX * 1.5));
+    cursorY = Math.max(4, Math.min(canvas.height - 4, cursorY + moveY * 1.5));
   }
   trail.push({x:cursorX, y:cursorY, t:Date.now(), idle});
   if (trail.length > TRAIL_LEN) trail.shift();