new method -- ObjectMotionState::getBodyLinearVelocityGTSigma

libraries/physics/src/EntityMotionState.cpp

@@ -32,11 +32,6 @@ static const quint8 STEPS_TO_DECIDE_BALLISTIC = 4;
 const uint32_t LOOPS_FOR_SIMULATION_ORPHAN = 50;
 const quint64 USECS_BETWEEN_OWNERSHIP_BIDS = USECS_PER_SECOND / 5;
 
-// NOTE: the threshold to use here relates to the linear displacement threshold (dX) for sending updates
-// to objects that are tracked server-side (e.g. entities which use dX = 2mm).  Hence an object moving 
-// just under this velocity threshold would trigger an update about V/dX times per second.
-const float MIN_LINEAR_SPEED_SQUARED = 0.0036f; // 6 mm/sec
-
 #ifdef WANT_DEBUG_ENTITY_TREE_LOCKS
 bool EntityMotionState::entityTreeIsLocked() const {
     EntityTreeElementPointer element = _entity ? _entity->getElement() : nullptr;
@@ -253,11 +248,7 @@ bool EntityMotionState::remoteSimulationOutOfSync(uint32_t simulationStep) {
         btTransform xform = _body->getWorldTransform();
         _serverPosition = bulletToGLM(xform.getOrigin());
         _serverRotation = bulletToGLM(xform.getRotation());
-        _serverVelocity = getBodyLinearVelocity();
+        _serverVelocity = getBodyLinearVelocityGTSigma();
-        if (glm::length2(_serverVelocity) < MIN_LINEAR_SPEED_SQUARED) {
-            _serverVelocity *= 0.0f;
-        }
-
         _serverAngularVelocity = bulletToGLM(_body->getAngularVelocity());
         _lastStep = simulationStep;
         _serverActionData = _entity->getActionData();
@@ -556,11 +547,7 @@ void EntityMotionState::bump(quint8 priority) {
 void EntityMotionState::resetMeasuredBodyAcceleration() {
     _lastMeasureStep = ObjectMotionState::getWorldSimulationStep();
     if (_body) {
-        _lastVelocity = getBodyLinearVelocity();
+        _lastVelocity = getBodyLinearVelocityGTSigma();
-        // if _lastVelocity is too slow, set it to zero
-        if (glm::length2(_lastVelocity) < MIN_LINEAR_SPEED_SQUARED) {
-            _lastVelocity *= 0.0f;
-        }
     } else {
         _lastVelocity = glm::vec3(0.0f);
     }
@@ -579,10 +566,7 @@ void EntityMotionState::measureBodyAcceleration() {
 
         // Note: the integration equation for velocity uses damping:   v1 = (v0 + a * dt) * (1 - D)^dt
         // hence the equation for acceleration is: a = (v1 / (1 - D)^dt - v0) / dt
-        glm::vec3 velocity = getBodyLinearVelocity();
+        glm::vec3 velocity = getBodyLinearVelocityGTSigma();
-        if (glm::length2(velocity) < MIN_LINEAR_SPEED_SQUARED) {
-            velocity *= 0.0f;
-        }
 
         _measuredAcceleration = (velocity / powf(1.0f - _body->getLinearDamping(), dt) - _lastVelocity) * invDt;
         _lastVelocity = velocity;

libraries/physics/src/ObjectMotionState.cpp

@@ -83,6 +83,19 @@ glm::vec3 ObjectMotionState::getBodyLinearVelocity() const {
     return bulletToGLM(_body->getLinearVelocity());
 }
 
+glm::vec3 ObjectMotionState::getBodyLinearVelocityGTSigma() const {
+    // NOTE: the threshold to use here relates to the linear displacement threshold (dX) for sending updates
+    // to objects that are tracked server-side (e.g. entities which use dX = 2mm).  Hence an object moving 
+    // just under this velocity threshold would trigger an update about V/dX times per second.
+    const float MIN_LINEAR_SPEED_SQUARED = 0.0036f; // 6 mm/sec
+
+    glm::vec3 velocity = bulletToGLM(_body->getLinearVelocity());
+    if (glm::length2(velocity) < MIN_LINEAR_SPEED_SQUARED) {
+        velocity *= 0.0f;
+    }
+    return velocity;
+}
+
 glm::vec3 ObjectMotionState::getObjectLinearVelocityChange() const {
     return glm::vec3(0.0f);  // Subclasses override where meaningful.
 }

libraries/physics/src/ObjectMotionState.h

@@ -89,6 +89,7 @@ public:
     void setBodyGravity(const glm::vec3& gravity) const;
 
     glm::vec3 getBodyLinearVelocity() const;
+    glm::vec3 getBodyLinearVelocityGTSigma() const;
     glm::vec3 getBodyAngularVelocity() const;
     virtual glm::vec3 getObjectLinearVelocityChange() const;