Remove MyAvatar "squat" recenter from ad6bbc7ff6

The "squat" recenter pre-dates the sit/stand detection, but the current version basically came from ad6bbc7ff6 in 2018.  I'm removing it because it doesn't seem useful anymore (with or without the other changes in this branch).

What it did (on the current master) :
- If "Avatar leaning behavior" was "Auto"
- and the user was standing
- but their head was more than 5cm below standing height
- and their chest was upright
- for 30 seconds
- do a vertical recenter so that the avatar stands straight (instead of having knees bent).
When the user stood up straight after that recenter, the avatar would hover off the ground until the next recenter (eg. walking).

interface/src/avatar/MyAvatar.cpp

@@ -652,8 +652,6 @@ void MyAvatar::update(float deltaTime) {
     // update moving average of HMD facing in xz plane.
     const float HMD_FACING_TIMESCALE = getRotationRecenterFilterLength();
     const float PERCENTAGE_WEIGHT_HEAD_VS_SHOULDERS_AZIMUTH = 0.0f; // 100 percent shoulders
-    const float COSINE_THIRTY_DEGREES = 0.866f;
-    const float SQUATTY_TIMEOUT = 30.0f; // 30 seconds
     const float HEIGHT_FILTER_COEFFICIENT = 0.01f;
 
     float tau = deltaTime / HMD_FACING_TIMESCALE;
@@ -720,29 +718,6 @@ void MyAvatar::update(float deltaTime) {
         setAverageHeadRotation(computeAverageHeadRotation(getControllerPoseInAvatarFrame(controller::Action::HEAD)));
     }
 
-    // if the spine is straight and the head is below the default position by 5 cm then increment squatty count.
-    const float SQUAT_THRESHOLD = 0.05f;
-    glm::vec3 headDefaultPositionAvatarSpace = getAbsoluteDefaultJointTranslationInObjectFrame(getJointIndex("Head"));
-    glm::quat spine2OrientationAvatarSpace = getAbsoluteJointRotationInObjectFrame(getJointIndex("Spine2"));
-    glm::vec3 upSpine2 = spine2OrientationAvatarSpace * glm::vec3(0.0f, 1.0f, 0.0f);
-    if (glm::length(upSpine2) > 0.0f) {
-        upSpine2 = glm::normalize(upSpine2);
-    }
-    float angleSpine2 = glm::dot(upSpine2, glm::vec3(0.0f, 1.0f, 0.0f));
-
-    if (getHMDCrouchRecenterEnabled() &&
-        getControllerPoseInAvatarFrame(controller::Action::HEAD).getTranslation().y < (headDefaultPositionAvatarSpace.y - SQUAT_THRESHOLD) &&
-        (angleSpine2 > COSINE_THIRTY_DEGREES)) {
-
-        _squatTimer += deltaTime;
-        if (_squatTimer > SQUATTY_TIMEOUT) {
-            _squatTimer = 0.0f;
-            _follow._squatDetected = true;
-        }
-    } else {
-        _squatTimer = 0.0f;
-    }
-
     // put update sit stand state counts here
     updateSitStandState(newHeightReading.getTranslation().y, deltaTime);
 
@@ -5363,7 +5338,6 @@ void MyAvatar::setIsInWalkingState(bool isWalking) {
 // Specify whether the user is sitting or standing in the real world.
 void MyAvatar::setIsInSittingState(bool isSitting) {
     _sitStandStateTimer = 0.0f;
-    _squatTimer = 0.0f;
     // on reset height we need the count to be more than one in case the user sits and stands up quickly.
     _isInSittingState.set(isSitting);
     setResetMode(true);
@@ -5811,10 +5785,6 @@ bool MyAvatar::FollowHelper::shouldActivateVertical(const MyAvatar& myAvatar,
         } else {
             // in the standing state
             returnValue = (offset.y > CYLINDER_TOP) || (offset.y < CYLINDER_BOTTOM);
-            // finally check for squats in standing
-            if (_squatDetected) {
-                returnValue = true;
-            }
         }
     }
     return returnValue;
@@ -5873,9 +5843,6 @@ void MyAvatar::FollowHelper::prePhysicsUpdate(MyAvatar& myAvatar,
             if (!isActive(CharacterController::FollowType::Vertical) &&
                 (shouldActivateVertical(myAvatar, desiredBodyMatrix, currentBodyMatrix) || hasDriveInput)) {
                 activate(CharacterController::FollowType::Vertical, false);
-                if (_squatDetected) {
-                    _squatDetected = false;
-                }
             }
         }
     } else {

interface/src/avatar/MyAvatar.h

@@ -2920,7 +2920,6 @@ private:
         void setForceActivateHorizontal(bool val);
         bool getToggleHipsFollowing() const;
         void setToggleHipsFollowing(bool followHead);
-        bool _squatDetected { false };
         std::atomic<bool> _forceActivateRotation { false };
         std::atomic<bool> _forceActivateVertical { false };
         std::atomic<bool> _forceActivateHorizontal { false };