////  EntityMotionState.cpp//  libraries/entities/src////  Created by Andrew Meadows on 2014.11.06//  Copyright 2013 High Fidelity, Inc.////  Distributed under the Apache License, Version 2.0.//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html// #include <EntityItem.h>#include <EntityEditPacketSender.h>#include <PhysicsCollisionGroups.h> #include "BulletUtil.h"#include "EntityMotionState.h"#include "PhysicsEngine.h"#include "PhysicsHelpers.h"#include "PhysicsLogging.h" static const float ACCELERATION_EQUIVALENT_EPSILON_RATIO = 0.1f;static const quint8 STEPS_TO_DECIDE_BALLISTIC = 4;  EntityMotionState::EntityMotionState(btCollisionShape* shape, EntityItemPointer entity) :    ObjectMotionState(shape),    _entity(entity),    _sentActive(false),    _numNonMovingUpdates(0),    _lastStep(0),    _serverPosition(0.0f),    _serverRotation(),    _serverVelocity(0.0f),    _serverAngularVelocity(0.0f),    _serverGravity(0.0f),    _serverAcceleration(0.0f),    _accelerationNearlyGravityCount(0),    _candidateForOwnership(false),    _loopsSinceOwnershipBid(0),    _loopsWithoutOwner(0){    _type = MOTIONSTATE_TYPE_ENTITY;    assert(_entity != nullptr);    setMass(_entity->computeMass());} EntityMotionState::~EntityMotionState() {    // be sure to clear _entity before calling the destructor    assert(!_entity);} void EntityMotionState::updateServerPhysicsVariables() {    _serverPosition = _entity->getPosition();    _serverRotation = _entity->getRotation();    _serverVelocity = _entity->getVelocity();    _serverAngularVelocity = _entity->getAngularVelocity();    _serverAcceleration = _entity->getAcceleration();} // virtualvoid EntityMotionState::handleEasyChanges(uint32_t flags) {    updateServerPhysicsVariables();    ObjectMotionState::handleEasyChanges(flags);    if (flags & EntityItem::DIRTY_SIMULATOR_ID) {        _loopsWithoutOwner = 0;        _candidateForOwnership = 0;        if (_entity->getSimulatorID().isNull()                && !_entity->isMoving()                && _body->isActive()) {            // remove the ACTIVATION flag because this object is coming to rest            // according to a remote simulation and we don't want to wake it up again            flags &= ~EntityItem::DIRTY_PHYSICS_ACTIVATION;            _body->setActivationState(WANTS_DEACTIVATION);        } else {            auto nodeList = DependencyManager::get<NodeList>();            const QUuid& sessionID = nodeList->getSessionUUID();            if (_entity->getSimulatorID() != sessionID) {                _loopsSinceOwnershipBid = 0;            }        }    }    if ((flags & EntityItem::DIRTY_PHYSICS_ACTIVATION) && !_body->isActive()) {        _body->activate();    }}  // virtualvoid EntityMotionState::handleHardAndEasyChanges(uint32_t flags, PhysicsEngine* engine) {    updateServerPhysicsVariables();    ObjectMotionState::handleHardAndEasyChanges(flags, engine);} void EntityMotionState::clearObjectBackPointer() {    ObjectMotionState::clearObjectBackPointer();    _entity = nullptr;} MotionType EntityMotionState::computeObjectMotionType() const {    if (!_entity) {        return MOTION_TYPE_STATIC;    }    if (_entity->getCollisionsWillMove()) {        return MOTION_TYPE_DYNAMIC;    }    return _entity->isMoving() ?  MOTION_TYPE_KINEMATIC : MOTION_TYPE_STATIC;} bool EntityMotionState::isMoving() const {    return _entity && _entity->isMoving();} // This callback is invoked by the physics simulation in two cases:// (1) when the RigidBody is first added to the world//     (irregardless of MotionType: STATIC, DYNAMIC, or KINEMATIC)// (2) at the beginning of each simulation step for KINEMATIC RigidBody's --//     it is an opportunity for outside code to update the object's simulation positionvoid EntityMotionState::getWorldTransform(btTransform& worldTrans) const {    if (!_entity) {        return;    }    if (_motionType == MOTION_TYPE_KINEMATIC) {        // This is physical kinematic motion which steps strictly by the subframe count        // of the physics simulation.        uint32_t thisStep = ObjectMotionState::getWorldSimulationStep();        float dt = (thisStep - _lastKinematicStep) * PHYSICS_ENGINE_FIXED_SUBSTEP;        _entity->simulateKinematicMotion(dt);         // bypass const-ness so we can remember the step        const_cast<EntityMotionState*>(this)->_lastKinematicStep = thisStep;    }    worldTrans.setOrigin(glmToBullet(getObjectPosition()));    worldTrans.setRotation(glmToBullet(_entity->getRotation()));} // This callback is invoked by the physics simulation at the end of each simulation step...// iff the corresponding RigidBody is DYNAMIC and has moved.void EntityMotionState::setWorldTransform(const btTransform& worldTrans) {    if (!_entity) {        return;    }    measureBodyAcceleration();    _entity->setPosition(bulletToGLM(worldTrans.getOrigin()) + ObjectMotionState::getWorldOffset());    _entity->setRotation(bulletToGLM(worldTrans.getRotation()));     _entity->setVelocity(getBodyLinearVelocity());    _entity->setAngularVelocity(getBodyAngularVelocity());     _entity->setLastSimulated(usecTimestampNow());     if (_entity->getSimulatorID().isNull()) {        _loopsWithoutOwner++;         const uint32_t OWNERSHIP_BID_DELAY = 50;        if (_loopsWithoutOwner > OWNERSHIP_BID_DELAY) {            //qDebug() << "Warning -- claiming something I saw moving." << getName();            _candidateForOwnership = true;        }    } else {        _loopsWithoutOwner = 0;    }     #ifdef WANT_DEBUG        quint64 now = usecTimestampNow();        qCDebug(physics) << "EntityMotionState::setWorldTransform()... changed entity:" << _entity->getEntityItemID();        qCDebug(physics) << "       last edited:" << _entity->getLastEdited() << formatUsecTime(now - _entity->getLastEdited()) << "ago";        qCDebug(physics) << "    last simulated:" << _entity->getLastSimulated() << formatUsecTime(now - _entity->getLastSimulated()) << "ago";        qCDebug(physics) << "      last updated:" << _entity->getLastUpdated() << formatUsecTime(now - _entity->getLastUpdated()) << "ago";    #endif} // virtual and protectedbtCollisionShape* EntityMotionState::computeNewShape() {    if (_entity) {        ShapeInfo shapeInfo;        _entity->computeShapeInfo(shapeInfo);        return getShapeManager()->getShape(shapeInfo);    }    return nullptr;} bool EntityMotionState::isCandidateForOwnership(const QUuid& sessionID) const {     if (!_body || !_entity) {        return false;    }    return _candidateForOwnership || sessionID == _entity->getSimulatorID();} bool EntityMotionState::remoteSimulationOutOfSync(uint32_t simulationStep) {    assert(_body);    // if we've never checked before, our _lastStep will be 0, and we need to initialize our state    if (_lastStep == 0) {        btTransform xform = _body->getWorldTransform();        _serverPosition = bulletToGLM(xform.getOrigin());        _serverRotation = bulletToGLM(xform.getRotation());        _serverVelocity = bulletToGLM(_body->getLinearVelocity());        _serverAngularVelocity = bulletToGLM(_body->getAngularVelocity());        _lastStep = simulationStep;        _sentActive = false;        return false;    }        #ifdef WANT_DEBUG    glm::vec3 wasPosition = _serverPosition;    glm::quat wasRotation = _serverRotation;    glm::vec3 wasAngularVelocity = _serverAngularVelocity;    #endif     int numSteps = simulationStep - _lastStep;    float dt = (float)(numSteps) * PHYSICS_ENGINE_FIXED_SUBSTEP;     const float INACTIVE_UPDATE_PERIOD = 0.5f;    if (!_sentActive) {        // we resend the inactive update every INACTIVE_UPDATE_PERIOD        // until it is removed from the outgoing updates         // (which happens when we don't own the simulation and it isn't touching our simulation)        return (dt > INACTIVE_UPDATE_PERIOD);    }     bool isActive = _body->isActive();    if (!isActive) {        // object has gone inactive but our last send was moving --> send non-moving update immediately        return true;    }     _lastStep = simulationStep;    if (glm::length2(_serverVelocity) > 0.0f) {        _serverVelocity += _serverAcceleration * dt;        _serverVelocity *= powf(1.0f - _body->getLinearDamping(), dt);        _serverPosition += dt * _serverVelocity;    }     // Else we measure the error between current and extrapolated transform (according to expected behavior     // of remote EntitySimulation) and return true if the error is significant.     // NOTE: math is done in the simulation-frame, which is NOT necessarily the same as the world-frame     // due to _worldOffset.    // TODO: compensate for _worldOffset offset here     // compute position error     btTransform worldTrans = _body->getWorldTransform();    glm::vec3 position = bulletToGLM(worldTrans.getOrigin());        float dx2 = glm::distance2(position, _serverPosition);     const float MAX_POSITION_ERROR_SQUARED = 0.000004f; //  Sqrt() - corresponds to 2 millimeters    if (dx2 > MAX_POSITION_ERROR_SQUARED) {         #ifdef WANT_DEBUG            qCDebug(physics) << ".... (dx2 > MAX_POSITION_ERROR_SQUARED) ....";            qCDebug(physics) << "wasPosition:" << wasPosition;            qCDebug(physics) << "bullet position:" << position;            qCDebug(physics) << "_serverPosition:" << _serverPosition;            qCDebug(physics) << "dx2:" << dx2;        #endif         return true;    }        if (glm::length2(_serverAngularVelocity) > 0.0f) {        // compute rotation error        float attenuation = powf(1.0f - _body->getAngularDamping(), dt);        _serverAngularVelocity *= attenuation;           // Bullet caps the effective rotation velocity inside its rotation integration step, therefore         // we must integrate with the same algorithm and timestep in order achieve similar results.        for (int i = 0; i < numSteps; ++i) {            _serverRotation = glm::normalize(computeBulletRotationStep(_serverAngularVelocity, PHYSICS_ENGINE_FIXED_SUBSTEP) * _serverRotation);        }    }    const float MIN_ROTATION_DOT = 0.99999f; // This corresponds to about 0.5 degrees of rotation    glm::quat actualRotation = bulletToGLM(worldTrans.getRotation());     #ifdef WANT_DEBUG        if ((fabsf(glm::dot(actualRotation, _serverRotation)) < MIN_ROTATION_DOT)) {            qCDebug(physics) << ".... ((fabsf(glm::dot(actualRotation, _serverRotation)) < MIN_ROTATION_DOT)) ....";                    qCDebug(physics) << "wasAngularVelocity:" << wasAngularVelocity;            qCDebug(physics) << "_serverAngularVelocity:" << _serverAngularVelocity;             qCDebug(physics) << "length wasAngularVelocity:" << glm::length(wasAngularVelocity);            qCDebug(physics) << "length _serverAngularVelocity:" << glm::length(_serverAngularVelocity);             qCDebug(physics) << "wasRotation:" << wasRotation;            qCDebug(physics) << "bullet actualRotation:" << actualRotation;            qCDebug(physics) << "_serverRotation:" << _serverRotation;        }    #endif     return (fabsf(glm::dot(actualRotation, _serverRotation)) < MIN_ROTATION_DOT);} bool EntityMotionState::shouldSendUpdate(uint32_t simulationStep, const QUuid& sessionID) {    // NOTE: we expect _entity and _body to be valid in this context, since shouldSendUpdate() is only called     // after doesNotNeedToSendUpdate() returns false and that call should return 'true' if _entity or _body are NULL.     assert(_entity);    assert(_body);     if (!remoteSimulationOutOfSync(simulationStep)) {        _candidateForOwnership = false;        return false;    }     if (_entity->getSimulatorID() == sessionID) {        // we own the simulation        _candidateForOwnership = false;        return true;    }     const uint32_t FRAMES_BETWEEN_OWNERSHIP_CLAIMS = 30;    if (_candidateForOwnership) {        _candidateForOwnership = false;        ++_loopsSinceOwnershipBid;        if (_loopsSinceOwnershipBid > FRAMES_BETWEEN_OWNERSHIP_CLAIMS) {            // we don't own the simulation, but it's time to bid for it            _loopsSinceOwnershipBid = 0;            return true;        }    }     _candidateForOwnership = false;    return false;} void EntityMotionState::sendUpdate(OctreeEditPacketSender* packetSender, const QUuid& sessionID, uint32_t step) {    assert(_entity);     bool active = _body->isActive();    if (!active) {        // make sure all derivatives are zero        glm::vec3 zero(0.0f);        _entity->setVelocity(zero);        _entity->setAngularVelocity(zero);        _entity->setAcceleration(zero);        _sentActive = false;    } else {        float gravityLength = glm::length(_entity->getGravity());        float accVsGravity = glm::abs(glm::length(_measuredAcceleration) - gravityLength);        if (accVsGravity < ACCELERATION_EQUIVALENT_EPSILON_RATIO * gravityLength) {            // acceleration measured during the most recent simulation step was close to gravity.            if (getAccelerationNearlyGravityCount() < STEPS_TO_DECIDE_BALLISTIC) {                // only increment this if we haven't reached the threshold yet.  this is to avoid                // overflowing the counter.                incrementAccelerationNearlyGravityCount();            }        } else {            // acceleration wasn't similar to this entities gravity, so reset the went-ballistic counter            resetAccelerationNearlyGravityCount();        }         // if this entity has been accelerated at close to gravity for a certain number of simulation-steps, let        // the entity server's estimates include gravity.        if (getAccelerationNearlyGravityCount() >= STEPS_TO_DECIDE_BALLISTIC) {            _entity->setAcceleration(_entity->getGravity());        } else {            _entity->setAcceleration(glm::vec3(0.0f));        }         const float DYNAMIC_LINEAR_VELOCITY_THRESHOLD = 0.05f;  // 5 cm/sec        const float DYNAMIC_ANGULAR_VELOCITY_THRESHOLD = 0.087266f;  // ~5 deg/sec        bool movingSlowly = glm::length2(_entity->getVelocity()) < (DYNAMIC_LINEAR_VELOCITY_THRESHOLD * DYNAMIC_LINEAR_VELOCITY_THRESHOLD)            && glm::length2(_entity->getAngularVelocity()) < (DYNAMIC_ANGULAR_VELOCITY_THRESHOLD * DYNAMIC_ANGULAR_VELOCITY_THRESHOLD)            && _entity->getAcceleration() == glm::vec3(0.0f);         if (movingSlowly) {            // velocities might not be zero, but we'll fake them as such, which will hopefully help convince            // other simulating observers to deactivate their own copies            glm::vec3 zero(0.0f);            _entity->setVelocity(zero);            _entity->setAngularVelocity(zero);        }        _sentActive = true;    }     // remember properties for local server prediction    _serverPosition = _entity->getPosition();    _serverRotation = _entity->getRotation();    _serverVelocity = _entity->getVelocity();    _serverAcceleration = _entity->getAcceleration();    _serverAngularVelocity = _entity->getAngularVelocity();     EntityItemProperties properties = _entity->getProperties();     // explicitly set the properties that changed so that they will be packed    properties.setPosition(_serverPosition);    properties.setRotation(_serverRotation);    properties.setVelocity(_serverVelocity);    properties.setAcceleration(_serverAcceleration);    properties.setAngularVelocity(_serverAngularVelocity);     // set the LastEdited of the properties but NOT the entity itself    quint64 now = usecTimestampNow();    properties.setLastEdited(now);     #ifdef WANT_DEBUG        quint64 lastSimulated = _entity->getLastSimulated();        qCDebug(physics) << "EntityMotionState::sendUpdate()";        qCDebug(physics) << "        EntityItemId:" << _entity->getEntityItemID()                         << "---------------------------------------------";        qCDebug(physics) << "       lastSimulated:" << debugTime(lastSimulated, now);    #endif //def WANT_DEBUG     if (sessionID == _entity->getSimulatorID()) {        // we think we own the simulation        if (!active) {            // we own the simulation but the entity has stopped, so we tell the server that we're clearing simulatorID            // but we remember that we do still own it...  and rely on the server to tell us that we don't            properties.setSimulatorID(QUuid());        } else {            // explicitly set the property's simulatorID so that it is flagged as changed and will be packed            properties.setSimulatorID(sessionID);        }    } else {        // we don't own the simulation for this entity yet, but we're sending a bid for it        properties.setSimulatorID(sessionID);    }     if (EntityItem::getSendPhysicsUpdates()) {        EntityItemID id(_entity->getID());        EntityEditPacketSender* entityPacketSender = static_cast<EntityEditPacketSender*>(packetSender);        #ifdef WANT_DEBUG            qCDebug(physics) << "EntityMotionState::sendUpdate()... calling queueEditEntityMessage()...";        #endif         entityPacketSender->queueEditEntityMessage(PacketTypeEntityEdit, id, properties);        _entity->setLastBroadcast(usecTimestampNow());    } else {        #ifdef WANT_DEBUG            qCDebug(physics) << "EntityMotionState::sendUpdate()... NOT sending update as requested.";        #endif    }     _lastStep = step;} uint32_t EntityMotionState::getAndClearIncomingDirtyFlags() {     uint32_t dirtyFlags = 0;    if (_body && _entity) {        dirtyFlags = _entity->getDirtyFlags();         _entity->clearDirtyFlags();        // we add DIRTY_MOTION_TYPE if the body's motion type disagrees with entity velocity settings        int bodyFlags = _body->getCollisionFlags();        bool isMoving = _entity->isMoving();        if (((bodyFlags & btCollisionObject::CF_STATIC_OBJECT) && isMoving) ||                (bodyFlags & btCollisionObject::CF_KINEMATIC_OBJECT && !isMoving)) {            dirtyFlags |= EntityItem::DIRTY_MOTION_TYPE;         }    }    return dirtyFlags;}  // virtualQUuid EntityMotionState::getSimulatorID() const {    if (_entity) {        return _entity->getSimulatorID();    }    return QUuid();}  // virtualvoid EntityMotionState::bump() {    _candidateForOwnership = true;} void EntityMotionState::resetMeasuredBodyAcceleration() {    _lastMeasureStep = ObjectMotionState::getWorldSimulationStep();    if (_body) {        _lastVelocity = bulletToGLM(_body->getLinearVelocity());                                                            } else {        _lastVelocity = glm::vec3(0.0f);    }    _measuredAcceleration = glm::vec3(0.0f);}  void EntityMotionState::measureBodyAcceleration() {    // try to manually measure the true acceleration of the object    uint32_t thisStep = ObjectMotionState::getWorldSimulationStep();    uint32_t numSubsteps = thisStep - _lastMeasureStep;    if (numSubsteps > 0) {        float dt = ((float)numSubsteps * PHYSICS_ENGINE_FIXED_SUBSTEP);        float invDt = 1.0f / dt;        _lastMeasureStep = thisStep;        _measuredDeltaTime = dt;         // 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 = bulletToGLM(_body->getLinearVelocity());        _measuredAcceleration = (velocity / powf(1.0f - _body->getLinearDamping(), dt) - _lastVelocity) * invDt;        _lastVelocity = velocity;        if (numSubsteps > PHYSICS_ENGINE_MAX_NUM_SUBSTEPS && !_candidateForOwnership) {            _loopsSinceOwnershipBid = 0;            _loopsWithoutOwner = 0;        }    }}glm::vec3 EntityMotionState::getObjectLinearVelocityChange() const {

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