updated live feedback

correct the user live
- Starting position
- Finishing position
- Second step

app/src/main/java/com/example/jnicpp/bowling/BowlingCameraActivity.kt

@@ -307,10 +307,17 @@ class BowlingCameraActivity : AppCompatActivity(), CameraXController.Callback {
                 // Combined with poseEnabled (rather than posePhase alone) so
                 // the label can tell "pose off" (hidden) apart from "pose on
                 // but not yet in the target posture" (amber prompt) -- both
-                // cases otherwise report a null phase.
+                // cases otherwise report a null phase. poseCorrection rides
+                // along the same collector (rather than its own, like
+                // poseMetrics below) since it directly changes what
+                // renderPosePhase puts in the label -- see that function.
                 launch {
-                    combine(viewModel.poseEnabled, viewModel.posePhase) { enabled, phase -> enabled to phase }
-                        .collect { (enabled, phase) -> renderPosePhase(enabled, phase) }
+                    combine(
+                        viewModel.poseEnabled,
+                        viewModel.posePhase,
+                        viewModel.poseCorrection,
+                    ) { enabled, phase, correction -> Triple(enabled, phase, correction) }
+                        .collect { (enabled, phase, correction) -> renderPosePhase(enabled, phase, correction) }
                 }
                 // Raw angle readout backing the label above -- its own
                 // collector since it's driven by a separate StateFlow
@@ -395,15 +402,24 @@ class BowlingCameraActivity : AppCompatActivity(), CameraXController.Callback {
      *
      * @param poseEnabled Whether pose detection is currently on at all.
      * @param phase The bowler's current delivery phase, or null if none currently validates.
+     * @param correction A specific "here's what to fix" instruction from
+     *        [PosePhaseDetector] when [phase] is null and the bowler is
+     *        being measured against one of the stationary phases (starting
+     *        stance, pushaway, slide & release) -- shown in place of the
+     *        generic "waiting" message when present, so the bowler knows
+     *        exactly what to adjust instead of just that they're not there yet.
      */
-    private fun renderPosePhase(poseEnabled: Boolean, phase: BowlingPhase?) {
+    private fun renderPosePhase(poseEnabled: Boolean, phase: BowlingPhase?, correction: String?) {
         if (!poseEnabled) {
             binding.textPoseFeedback.visibility = View.GONE
             return
         }
         binding.textPoseFeedback.visibility = View.VISIBLE
-        // Every other BowlingPhase falls back to the "waiting" message too --
-        // see PosePhaseDetector's class doc, only STARTING_STANCE is detected today.
+        // Every confirmed phase gets its own label/color below; an
+        // unconfirmed one falls back to a specific correction when
+        // PosePhaseDetector has one (see its class doc), otherwise the
+        // generic "waiting" message -- e.g. mid-approach, where per-frame
+        // correction isn't meaningful.
         when (phase) {
             BowlingPhase.STARTING_STANCE -> {
                 binding.textPoseFeedback.text = getString(R.string.pose_phase_starting_stance)
@@ -430,7 +446,7 @@ class BowlingCameraActivity : AppCompatActivity(), CameraXController.Callback {
                 binding.textPoseFeedback.setBackgroundColor(ContextCompat.getColor(this, R.color.Slide_and_release_ready))
             }
             else -> {
-                binding.textPoseFeedback.text = getString(R.string.pose_phase_waiting)
+                binding.textPoseFeedback.text = correction ?: getString(R.string.pose_phase_waiting)
                 binding.textPoseFeedback.setBackgroundColor(ContextCompat.getColor(this, R.color.Starting_stance_waiting))
             }
         }

app/src/main/java/com/example/jnicpp/bowling/CameraViewModel.kt

@@ -88,6 +88,13 @@ class CameraViewModel(application: Application) : AndroidViewModel(application)
     //This frame's torso/knee/elbow angle readings, or null if pose detection is off.
     val poseMetrics: StateFlow<PosePhaseDetector.Metrics?> = _poseMetrics.asStateFlow()
 
+    // Specific "here's what to fix" instruction while holding one of the
+    // stationary phases (starting stance, pushaway, slide & release) -- see
+    // PosePhaseDetector.correctionFor's doc for why only those three.
+    private val _poseCorrection = MutableStateFlow<String?>(null)
+    /** @brief Live corrective instruction for the current stationary phase, or null if nothing to correct. */
+    val poseCorrection: StateFlow<String?> = _poseCorrection.asStateFlow()
+
     /** @brief Steps detected so far in the current attempt, since the last reset. */
     val stepEvents: StateFlow<List<StepEvent>> get() = stepCountingSession.stepEvents
 
@@ -132,6 +139,7 @@ class CameraViewModel(application: Application) : AndroidViewModel(application)
             posePhaseDetector.reset()
             _posePhase.value = null
             _poseMetrics.value = null
+            _poseCorrection.value = null
         }
     }
 
@@ -153,6 +161,7 @@ class CameraViewModel(application: Application) : AndroidViewModel(application)
         val phaseResult = posePhaseDetector.update(landmarks, angles)
         _posePhase.value = phaseResult.phase
         _poseMetrics.value = phaseResult.metrics
+        _poseCorrection.value = phaseResult.correction
 
         // Check if the current pose matches the Starting Stance (pure posture query)
         val isStartingStance = (phaseResult.phase == BowlingPhase.STARTING_STANCE)

app/src/main/java/com/example/jnicpp/bowling/PosePhaseDetector.kt

@@ -124,8 +124,16 @@ class PosePhaseDetector(
      * @brief One [update] call's outcome: the classified phase plus the raw angles it was based on.
      * @param phase See [update]'s return doc.
      * @param metrics This frame's raw angle readings, for display regardless of whether [phase] validated.
+     * @param correction A specific corrective instruction (e.g. "Straighten
+     *        your legs") when the bowler is being measured against one of
+     *        [STATIONARY_PHASES] but doesn't currently match it, or null
+     *        when there's nothing to correct -- either because the current
+     *        posture already validates, the target phase is one of the
+     *        moving phases this detector doesn't give live corrections for
+     *        (see [correctionFor]'s doc), or a needed angle wasn't
+     *        confidently read this frame.
      */
-    data class Result(val phase: BowlingPhase?, val metrics: Metrics)
+    data class Result(val phase: BowlingPhase?, val metrics: Metrics, val correction: String? = null)
 
     /**
      * @brief Feeds one frame's landmarks/angles into the detector.
@@ -160,7 +168,11 @@ class PosePhaseDetector(
                 BowlingPhase.PUSHAWAY -> BowlingPhase.BACK_SWING
                 BowlingPhase.BACK_SWING -> BowlingPhase.POWER_STEP
                 BowlingPhase.POWER_STEP -> BowlingPhase.SLIDE_AND_RELEASE
-                else -> currentPhase
+                // The only BowlingPhase not already matched above -- every
+                // other case (including null) is explicit, so reaching here
+                // means currentPhase is SLIDE_AND_RELEASE, there's no phase
+                // after it to advance to.
+                else -> BowlingPhase.SLIDE_AND_RELEASE
             }
         }
 
@@ -172,7 +184,6 @@ class PosePhaseDetector(
             BowlingPhase.BACK_SWING -> isBackSwingValid(metrics)
             BowlingPhase.POWER_STEP -> isPowerStepValid(metrics)
             BowlingPhase.SLIDE_AND_RELEASE -> isSlideAndReleaseValid(metrics)
-            else -> false
         }
 
         if (isTargetValid) {
@@ -210,7 +221,13 @@ class PosePhaseDetector(
             consecutiveInvalidFrames = 0
         }
 
-        return Result(currentPhase, metrics)
+        val correction = if (!isTargetValid && targetPhase in STATIONARY_PHASES) {
+            correctionFor(targetPhase, metrics)
+        } else {
+            null
+        }
+
+        return Result(currentPhase, metrics, correction)
     }
 
     /** @brief Clears all detection state. Call at the start of a new session/attempt. */
@@ -297,11 +314,118 @@ class PosePhaseDetector(
     @Suppress("UNUSED_PARAMETER")
     private fun isPowerStepValid(metrics: Metrics): Boolean = true
 
-    /** @brief Placeholder validation for Slide & Release phase (Step 5). */
-    @Suppress("UNUSED_PARAMETER")
-    private fun isSlideAndReleaseValid(metrics: Metrics): Boolean = true
+    /**
+     * @brief Checks whether this single frame's [Metrics] match the slide &
+     *        release phase (finishing position, step 5).
+     *
+     * Slide & release is characterized by:
+     * - Torso Tilt: 15-45 degrees (the deepest forward lean of any phase --
+     *   the bowler is bent into the slide)
+     * - Knee Angle: at least one knee bent to 90-150 degrees (the
+     *   sliding/front leg lowers the body through the release; requiring
+     *   only one, not both, since we don't know which leg is forward)
+     * - Elbow Angle: at least one elbow extended to 150-180 degrees (the
+     *   swing arm straightens through the release -- same release cue
+     *   [PoseStageAdvisor] already uses for its own final-step check)
+     *
+     * @param metrics This frame's raw angle readings.
+     * @return true if torso tilt, at least one bent knee, and at least one extended elbow all fall within range.
+     */
+    private fun isSlideAndReleaseValid(metrics: Metrics): Boolean {
+        val torsoTilt = metrics.torsoTiltDegrees ?: return false
+        if (torsoTilt !in 15f..45f) return false
+
+        val kneeAngles = listOfNotNull(metrics.leftKneeAngleDegrees, metrics.rightKneeAngleDegrees)
+        if (kneeAngles.isEmpty() || kneeAngles.none { it in 90f..150f }) return false
+
+        val elbowAngles = listOfNotNull(metrics.leftElbowAngleDegrees, metrics.rightElbowAngleDegrees)
+        return elbowAngles.isNotEmpty() && elbowAngles.any { it in 150f..180f }
+    }
+
+    /**
+     * @brief Produces a specific corrective instruction for why [metrics]
+     *        doesn't currently match [targetPhase].
+     *
+     * Only covers [STATIONARY_PHASES] -- the three phases a bowler actually
+     * holds still in long enough for frame-by-frame angle feedback to be
+     * meaningful. The remaining phases (approach, backswing, power step) are
+     * mid-motion by nature, so a per-frame "here's what's wrong" cue would
+     * either be stale by the time it's read or just describe normal
+     * transitional movement as an error; those are left to [update]'s
+     * existing pass/fail phase label instead.
+     *
+     * Checks each phase's conditions in the same order as its `isXValid`
+     * counterpart and returns on the first one that fails, so the bowler
+     * gets one actionable instruction at a time rather than a list.
+     *
+     * @param targetPhase Which stationary phase to check [metrics] against. Must be one of [STATIONARY_PHASES].
+     * @param metrics This frame's raw angle readings.
+     * @return A short corrective instruction, or null if [metrics] already
+     *         validates for [targetPhase] (nothing to correct) or a needed
+     *         angle wasn't confidently read this frame (nothing useful to say yet).
+     */
+    private fun correctionFor(targetPhase: BowlingPhase, metrics: Metrics): String? = when (targetPhase) {
+        BowlingPhase.STARTING_STANCE -> {
+            val torsoTilt = metrics.torsoTiltDegrees
+            val kneeAngles = listOfNotNull(metrics.leftKneeAngleDegrees, metrics.rightKneeAngleDegrees)
+            val elbowAngles = listOfNotNull(metrics.leftElbowAngleDegrees, metrics.rightElbowAngleDegrees)
+            when {
+                torsoTilt == null -> null
+                torsoTilt > torsoTiltMaxDegrees -> "Stand up straighter"
+                torsoTilt < torsoTiltMinDegrees -> "Relax your stance slightly"
+                kneeAngles.isEmpty() -> null
+                kneeAngles.any { it < kneeAngleMinDegrees } -> "Straighten your legs"
+                elbowAngles.isEmpty() -> null
+                elbowAngles.any { it > elbowAngleMaxDegrees } -> "Bring the ball in closer to your body"
+                elbowAngles.any { it < elbowAngleMinDegrees } -> "Relax your arms a little"
+                else -> null
+            }
+        }
+        BowlingPhase.PUSHAWAY -> {
+            val torsoTilt = metrics.torsoTiltDegrees
+            val kneeAngles = listOfNotNull(metrics.leftKneeAngleDegrees, metrics.rightKneeAngleDegrees)
+            val elbowAngles = listOfNotNull(metrics.leftElbowAngleDegrees, metrics.rightElbowAngleDegrees)
+            when {
+                torsoTilt == null -> null
+                torsoTilt < 5f -> "Lean forward slightly as you push away"
+                torsoTilt > 25f -> "Don't lean too far forward yet"
+                kneeAngles.isEmpty() -> null
+                kneeAngles.any { it < 145f } -> "Keep your legs mostly straight here"
+                elbowAngles.isEmpty() -> null
+                elbowAngles.none { it in 130f..180f } -> "Push the ball further out"
+                else -> null
+            }
+        }
+        BowlingPhase.SLIDE_AND_RELEASE -> {
+            val torsoTilt = metrics.torsoTiltDegrees
+            val kneeAngles = listOfNotNull(metrics.leftKneeAngleDegrees, metrics.rightKneeAngleDegrees)
+            val elbowAngles = listOfNotNull(metrics.leftElbowAngleDegrees, metrics.rightElbowAngleDegrees)
+            when {
+                torsoTilt == null -> null
+                torsoTilt < 15f -> "Bend forward more into the slide"
+                torsoTilt > 45f -> "Don't lean in too far"
+                kneeAngles.isEmpty() -> null
+                kneeAngles.none { it in 90f..150f } -> "Bend your sliding knee more"
+                elbowAngles.isEmpty() -> null
+                elbowAngles.none { it in 150f..180f } -> "Extend your swing arm fully"
+                else -> null
+            }
+        }
+        else -> null
+    }
 
     companion object {
+        /**
+         * @brief The phases a bowler holds still in long enough for
+         *        frame-by-frame angle correction to be meaningful -- see
+         *        [correctionFor]'s doc for why the rest are excluded.
+         */
+        private val STATIONARY_PHASES = setOf(
+            BowlingPhase.STARTING_STANCE,
+            BowlingPhase.PUSHAWAY,
+            BowlingPhase.SLIDE_AND_RELEASE,
+        )
+
         /**
          * @brief Maps a 5-step approach step count (0..5) to its corresponding [BowlingPhase].
          *

gradle/wrapper/gradle-wrapper.properties

@@ -1,7 +1,7 @@
 #Fri Apr 10 12:25:49 SGT 2026
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionSha256Sum=b266d5ff6b90eada6dc3b20cb090e3731302e553a27c5d3e4df1f0d76beaff06
+distributionSha256Sum=bbaeb2fef8710818cf0e261201dab964c572f92b942812df0c3620d62a529a01
 distributionUrl=https\://services.gradle.org/distributions/gradle-9.6.0-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true