/*
 *   ORXONOX - the hottest 3D action shooter ever to exist
 *                    > www.orxonox.net <
 *
 *
 *   License notice:
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation; either version 2
 *   of the License, or (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 *   Author:
 *      Fabian 'x3n' Landau
 *      Reto Grieder (physics)
 *   Co-authors:
 *      ...
 *
 */

#include "OrxonoxStableHeaders.h"
#include "WorldEntity.h"

#include <cassert>
#include <OgreSceneNode.h>
#include <OgreSceneManager.h>
#include "BulletDynamics/Dynamics/btRigidBody.h"

#include "util/Exception.h"
#include "util/Convert.h"
#include "core/CoreIncludes.h"
#include "core/XMLPort.h"

#include "objects/Scene.h"
#include "objects/collisionshapes/CompoundCollisionShape.h"

namespace orxonox
{
    const Vector3 WorldEntity::FRONT = Vector3::NEGATIVE_UNIT_Z;
    const Vector3 WorldEntity::BACK  = Vector3::UNIT_Z;
    const Vector3 WorldEntity::LEFT  = Vector3::NEGATIVE_UNIT_X;
    const Vector3 WorldEntity::RIGHT = Vector3::UNIT_X;
    const Vector3 WorldEntity::DOWN  = Vector3::NEGATIVE_UNIT_Y;
    const Vector3 WorldEntity::UP    = Vector3::UNIT_Y;

    WorldEntity::WorldEntity(BaseObject* creator) : BaseObject(creator), Synchronisable(creator)
    {
        RegisterObject(WorldEntity);

        if (!this->getScene() || !this->getScene()->getRootSceneNode())
            ThrowException(AbortLoading, "Can't create WorldEntity, no scene or no root-scenenode given.");

        this->node_ = this->getScene()->getRootSceneNode()->createChildSceneNode();

        this->parent_ = 0;
        this->parentID_ = OBJECTID_UNKNOWN;

        this->node_->setPosition(Vector3::ZERO);
        this->node_->setOrientation(Quaternion::IDENTITY);

        // Default behaviour does not include physics
        this->physicalBody_ = 0;
        this->bPhysicsActive_ = false;
        this->bPhysicsActiveSynchronised_ = false;
        this->bPhysicsActiveBeforeAttaching_ = false;
        this->collisionShape_ = new CompoundCollisionShape(this);
        // Note: CompoundCollisionShape is a Synchronisable, but must not be synchronised.
        //       All objects will get attached on the client anyway, so we don't need synchronisation.
        this->collisionShape_->setWorldEntityParent(this);
        this->collisionType_ = None;
        this->collisionTypeSynchronised_ = None;
        this->mass_           = 0;
        this->childrenMass_   = 0;
        // Use bullet default values
        this->restitution_    = 0;
        this->angularFactor_  = 1;
        this->linearDamping_  = 0;
        this->angularDamping_ = 0;
        this->friction_       = 0.5;
        this->bCollisionCallbackActive_ = false;

        this->registerVariables();
    }

    WorldEntity::~WorldEntity()
    {
        if (this->isInitialized())
        {
            this->node_->detachAllObjects();

            for (std::set<WorldEntity*>::const_iterator it = this->children_.begin(); it != this->children_.end(); )
                delete (*(it++));

            if (this->parent_)
                this->detachFromParent();

            this->node_->removeAllChildren();

            if (this->physicalBody_)
            {
                this->deactivatePhysics();
                delete this->physicalBody_;
            }
            delete this->collisionShape_;

            if (this->getScene()->getSceneManager())
                this->getScene()->getSceneManager()->destroySceneNode(this->node_->getName());
        }
    }

    void WorldEntity::XMLPort(Element& xmlelement, XMLPort::Mode mode)
    {
        SUPER(WorldEntity, XMLPort, xmlelement, mode);

        XMLPortParamTemplate(WorldEntity, "position",    setPosition,    getPosition,    xmlelement, mode, const Vector3&);
        XMLPortParamTemplate(WorldEntity, "orientation", setOrientation, getOrientation, xmlelement, mode, const Quaternion&);
        XMLPortParamTemplate(WorldEntity, "scale3D",     setScale3D,     getScale3D,     xmlelement, mode, const Vector3&);
        XMLPortParam        (WorldEntity, "scale",       setScale,       getScale,       xmlelement, mode);
        XMLPortParamLoadOnly(WorldEntity, "lookat",      lookAt_xmlport,       xmlelement, mode);
        XMLPortParamLoadOnly(WorldEntity, "direction",   setDirection_xmlport, xmlelement, mode);
        XMLPortParamLoadOnly(WorldEntity, "yaw",         yaw_xmlport,          xmlelement, mode);
        XMLPortParamLoadOnly(WorldEntity, "pitch",       pitch_xmlport,        xmlelement, mode);
        XMLPortParamLoadOnly(WorldEntity, "roll",        roll_xmlport,         xmlelement, mode);

        // Physics
        XMLPortParam(WorldEntity, "collisionType",  setCollisionTypeStr, getCollisionTypeStr, xmlelement, mode);
        XMLPortParam(WorldEntity, "mass",           setMass,             getMass,             xmlelement, mode);
        XMLPortParam(WorldEntity, "restitution",    setRestitution,      getRestitution,      xmlelement, mode);
        XMLPortParam(WorldEntity, "angularFactor",  setAngularFactor,    getAngularFactor,    xmlelement, mode);
        XMLPortParam(WorldEntity, "linearDamping",  setLinearDamping,    getLinearDamping,    xmlelement, mode);
        XMLPortParam(WorldEntity, "angularDamping", setAngularDamping,   getAngularDamping,   xmlelement, mode);
        XMLPortParam(WorldEntity, "friction",       setFriction,         getFriction,         xmlelement, mode);

        // Other attached WorldEntities
        XMLPortObject(WorldEntity, WorldEntity, "attached", attach, getAttachedObject, xmlelement, mode);
        // Attached collision shapes
        XMLPortObject(WorldEntity, CollisionShape, "collisionShapes", attachCollisionShape, getAttachedCollisionShape, xmlelement, mode);
    }

    void WorldEntity::registerVariables()
    {
        registerVariable(this->mainStateName_,  variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::changedMainState));

        registerVariable(this->bActive_,        variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::changedActivity));
        registerVariable(this->bVisible_,       variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::changedVisibility));

        registerVariable(this->getScale3D(),    variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::scaleChanged));

        // Physics stuff
        registerVariable(this->mass_,           variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::massChanged));
        registerVariable(this->restitution_,    variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::restitutionChanged));
        registerVariable(this->angularFactor_,  variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::angularFactorChanged));
        registerVariable(this->linearDamping_,  variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::linearDampingChanged));
        registerVariable(this->angularDamping_, variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::angularDampingChanged));
        registerVariable(this->friction_,       variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::frictionChanged));
        registerVariable(this->bCollisionCallbackActive_,
                                                variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::collisionCallbackActivityChanged));
        registerVariable((int&)this->collisionTypeSynchronised_,
                                                variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::collisionTypeChanged));
        registerVariable(this->bPhysicsActiveSynchronised_,
                                                variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::physicsActivityChanged));

        // Attach to parent if necessary
        registerVariable(this->parentID_,       variableDirection::toclient, new NetworkCallback<WorldEntity>(this, &WorldEntity::parentChanged));
    }

    void WorldEntity::parentChanged()
    {
        if (this->parentID_ != OBJECTID_UNKNOWN)
        {
            WorldEntity* parent = dynamic_cast<WorldEntity*>(Synchronisable::getSynchronisable(this->parentID_));
            if (parent)
                this->attachToParent(parent);
        }
    }

    void WorldEntity::collisionTypeChanged()
    {
        if (this->collisionTypeSynchronised_ != Dynamic &&
            this->collisionTypeSynchronised_ != Kinematic &&
            this->collisionTypeSynchronised_ != Static &&
            this->collisionTypeSynchronised_ != None)
        {
            CCOUT(1) << "Error when collsion Type was received over network. Unknown enum value:" << this->collisionTypeSynchronised_ << std::endl;
        }
        else if (this->collisionTypeSynchronised_ != collisionType_)
        {
            if (this->parent_)
                CCOUT(2) << "Warning: Network connection tried to set the collision type of an attached WE. Ignoring." << std::endl;
            else
                this->setCollisionType(this->collisionTypeSynchronised_);
        }
    }

    void WorldEntity::physicsActivityChanged()
    {
        if (this->bPhysicsActiveSynchronised_)
            this->activatePhysics();
        else
            this->deactivatePhysics();
    }

    void WorldEntity::collisionCallbackActivityChanged()
    {
        if (this->hasPhysics())
        {
            if (bCollisionCallbackActive_)
                this->physicalBody_->setCollisionFlags(this->physicalBody_->getCollisionFlags() |
                    btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
            else
                this->physicalBody_->setCollisionFlags(this->physicalBody_->getCollisionFlags() &
                    ~btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
        }
    }

    void WorldEntity::attachNode(Ogre::SceneNode* node)
    {
        Ogre::Node* parent = node->getParent();
        if (parent)
            parent->removeChild(node);
        this->node_->addChild(node);
    }

    void WorldEntity::detachNode(Ogre::SceneNode* node)
    {
        this->node_->removeChild(node);
//        this->getScene()->getRootSceneNode()->addChild(node);
    }

    void WorldEntity::attachToNode(Ogre::SceneNode* node)
    {
        Ogre::Node* parent = this->node_->getParent();
        if (parent)
            parent->removeChild(this->node_);
        node->addChild(this->node_);
    }

    void WorldEntity::detachFromNode(Ogre::SceneNode* node)
    {
        node->removeChild(this->node_);
//        this->getScene()->getRootSceneNode()->addChild(this->node_);
    }

    void WorldEntity::attach(WorldEntity* object)
    {
        if (object == this)
        {
            COUT(2) << "Warning: Can't attach a WorldEntity to itself." << std::endl;
            return;
        }

        if (!object->notifyBeingAttached(this))
            return;

        this->attachNode(object->node_);
        this->children_.insert(object);

        this->attachCollisionShape(object->getCollisionShape());
        // mass
        this->childrenMass_ += object->getMass();
        recalculateMassProps();
    }

    bool WorldEntity::notifyBeingAttached(WorldEntity* newParent)
    {
        // check first whether attaching is even allowed
        if (this->hasPhysics())
        {
            if (!newParent->hasPhysics())
            {
                COUT(2) << "Warning: Cannot attach a physical object to a non physical one." << std::endl;
                return false;
            }
            else if (this->isDynamic())
            {
                COUT(2) << "Warning: Cannot attach a dynamic object to a WorldEntity." << std::endl;
                return false;
            }
            else if (this->isKinematic() && newParent->isDynamic())
            {
                COUT(2) << "Warning: Cannot attach a kinematic object to a dynamic one." << std::endl;
                return false;
            }
            else if (this->isKinematic())
            {
                COUT(2) << "Warning: Cannot attach a kinematic object to a static or kinematic one: Not yet implemented." << std::endl;
                return false;
            }
        }

        if (this->isPhysicsActive())
            this->bPhysicsActiveBeforeAttaching_ = true;
        this->deactivatePhysics();

        if (this->parent_)
            this->detachFromParent();

        this->parent_ = newParent;
        this->parentID_ = newParent->getObjectID();

        // apply transform to collision shape
        this->collisionShape_->setPosition(this->getPosition());
        this->collisionShape_->setOrientation(this->getOrientation());
        // TODO: Scale
        
        return true;
    }

    void WorldEntity::detach(WorldEntity* object)
    {
        if (this->children_.find(object) == this->children_.end())
        {
            CCOUT(2) << "Warning: Cannot detach an object that is not a child." << std::endl;
            return;
        }

        // collision shapes
        this->detachCollisionShape(object->getCollisionShape());

        // mass
        if (object->getMass() > 0.0f)
        {
            this->childrenMass_ -= object->getMass();
            recalculateMassProps();
        }

        this->detachNode(object->node_);
        this->children_.erase(object);

        object->notifyDetached();
    }

    void WorldEntity::notifyDetached()
    {
        this->parent_ = 0;
        this->parentID_ = OBJECTID_UNKNOWN;

        // reset orientation of the collisionShape (cannot be set within a WE usually)
        this->collisionShape_->setPosition(Vector3::ZERO);
        this->collisionShape_->setOrientation(Quaternion::IDENTITY);
        // TODO: Scale

        if (this->bPhysicsActiveBeforeAttaching_)
        {
            this->activatePhysics();
            this->bPhysicsActiveBeforeAttaching_ = false;
        }
    }

    WorldEntity* WorldEntity::getAttachedObject(unsigned int index) const
    {
        unsigned int i = 0;
        for (std::set<WorldEntity*>::const_iterator it = this->children_.begin(); it != this->children_.end(); ++it)
        {
            if (i == index)
                return (*it);
            ++i;
        }
        return 0;
    }

    void WorldEntity::attachOgreObject(Ogre::MovableObject* object)
    {
        this->node_->attachObject(object);
    }

    void WorldEntity::detachOgreObject(Ogre::MovableObject* object)
    {
        this->node_->detachObject(object);
    }

    Ogre::MovableObject* WorldEntity::detachOgreObject(const Ogre::String& name)
    {
        return this->node_->detachObject(name);
    }

    void WorldEntity::attachCollisionShape(CollisionShape* shape)
    {
        this->collisionShape_->attach(shape);
        // Note: this->collisionShape_ already notifies us of any changes.
    }

    void WorldEntity::detachCollisionShape(CollisionShape* shape)
    {
        this->collisionShape_->detach(shape);
        // Note: this->collisionShape_ already notifies us of any changes.
    }

    CollisionShape* WorldEntity::getAttachedCollisionShape(unsigned int index) const
    {
        return this->collisionShape_->getAttachedShape(index);
    }

    void WorldEntity::activatePhysics()
    {
        if (this->isActive() && this->hasPhysics() && !this->isPhysicsActive() && !this->parent_)
        {
            this->getScene()->addPhysicalObject(this);
            this->bPhysicsActive_ = true;
        }
    }

    void WorldEntity::deactivatePhysics()
    {
        if (this->isPhysicsActive())
        {
            this->getScene()->removePhysicalObject(this);
            this->bPhysicsActive_ = false;
        }
    }

    bool WorldEntity::addedToPhysicalWorld() const
    {
        return this->physicalBody_ && this->physicalBody_->isInWorld();
    }

#ifndef _NDEBUG
    const Vector3& WorldEntity::getPosition() const
    {
        return this->node_->getPosition();
    }

    const Quaternion& WorldEntity::getOrientation() const
    {
        return this->node_->getOrientation();
    }

    const Vector3& WorldEntity::getScale3D() const
    {
        return this->node_->getScale();
    }
#endif

    const Vector3& WorldEntity::getWorldPosition() const
    {
        return this->node_->_getDerivedPosition();
    }

    const Quaternion& WorldEntity::getWorldOrientation() const
    {
        return this->node_->_getDerivedOrientation();
    }

    void WorldEntity::translate(const Vector3& distance, TransformSpace::Space relativeTo)
    {
        switch (relativeTo)
        {
        case TransformSpace::Local:
            // position is relative to parent so transform downwards
            this->setPosition(this->getPosition() + this->getOrientation() * distance);
            break;
        case TransformSpace::Parent:
            this->setPosition(this->getPosition() + distance);
            break;
        case TransformSpace::World:
            // position is relative to parent so transform upwards
            if (this->node_->getParent())
                setPosition(getPosition() + (node_->getParent()->_getDerivedOrientation().Inverse() * distance)
                    / node_->getParent()->_getDerivedScale());
            else
                this->setPosition(this->getPosition() + distance);
            break;
        }
    }

    void WorldEntity::rotate(const Quaternion& rotation, TransformSpace::Space relativeTo)
    {
        switch(relativeTo)
        {
        case TransformSpace::Local:
            this->setOrientation(this->getOrientation() * rotation);
            break;
        case TransformSpace::Parent:
            // Rotations are normally relative to local axes, transform up
            this->setOrientation(rotation * this->getOrientation());
            break;
        case TransformSpace::World:
            // Rotations are normally relative to local axes, transform up
            this->setOrientation(this->getOrientation() * this->getWorldOrientation().Inverse()
                * rotation * this->getWorldOrientation());
            break;
        }
    }

    void WorldEntity::lookAt(const Vector3& target, TransformSpace::Space relativeTo, const Vector3& localDirectionVector)
    {
        Vector3 origin;
        switch (relativeTo)
        {
        case TransformSpace::Local:
            origin = Vector3::ZERO;
            break;
        case TransformSpace::Parent:
            origin = this->getPosition();
            break;
        case TransformSpace::World:
            origin = this->getWorldPosition();
            break;
        }
        this->setDirection(target - origin, relativeTo, localDirectionVector);
    }

    void WorldEntity::setDirection(const Vector3& direction, TransformSpace::Space relativeTo, const Vector3& localDirectionVector)
    {
        Quaternion savedOrientation(this->getOrientation());
        Ogre::Node::TransformSpace ogreRelativeTo;
        switch (relativeTo)
        {
        case TransformSpace::Local:
            ogreRelativeTo = Ogre::Node::TS_LOCAL; break;
        case TransformSpace::Parent:
            ogreRelativeTo = Ogre::Node::TS_PARENT; break;
        case TransformSpace::World:
            ogreRelativeTo = Ogre::Node::TS_WORLD; break;
        }
        this->node_->setDirection(direction, ogreRelativeTo, localDirectionVector);
        Quaternion newOrientation(this->node_->getOrientation());
        this->node_->setOrientation(savedOrientation);
        this->setOrientation(newOrientation);
    }

    void WorldEntity::setScale3D(const Vector3& scale)
    {
/*
        if (this->hasPhysics() && scale != Vector3::UNIT_SCALE)
        {
            CCOUT(2) << "Warning: Cannot set the scale of a physical object: Not yet implemented." << std::endl;
            return;
        }
*/
        this->node_->setScale(scale);

        this->changedScale();
    }

    const Vector3& WorldEntity::getWorldScale3D() const
    {
        return this->node_->_getDerivedScale();
    }

    float WorldEntity::getWorldScale() const
    {
        Vector3 scale = this->getWorldScale3D();
        return (scale.x == scale.y && scale.x == scale.z) ? scale.x : 1;
    }

    void WorldEntity::setCollisionType(CollisionType type)
    {
        // If we are already attached to a parent, this would be a bad idea..
        if (this->parent_)
        {
            CCOUT(2) << "Warning: Cannot set the collision type of a WorldEntity with a parent." << std::endl;
            return;
        }
        else if (this->addedToPhysicalWorld())
        {
            CCOUT(2) << "Warning: Cannot set the collision type at run time." << std::endl;
            return;
        }

        // Check for type legality. Could be StaticEntity or MobileEntity
        if (!this->isCollisionTypeLegal(type))
            return;
        if (type != None && !this->getScene()->hasPhysics())
        {
            CCOUT(2) << "Warning: Cannot have physical bodies in a non physical scene." << std::endl;
            return;
        }

        // Check whether we have to create or destroy.
        if (type != None && this->collisionType_ == None)
        {
/*
            // Check whether there was some scaling applied.
            if (!this->node_->getScale().positionEquals(Vector3(1, 1, 1), 0.001))
            {
                CCOUT(2) << "Warning: Cannot create a physical body if there is scaling applied to the node: Not yet implemented." << std::endl;
                return;
            }
*/
            // Create new rigid body
            btRigidBody::btRigidBodyConstructionInfo bodyConstructionInfo(0, this, this->collisionShape_->getCollisionShape());
            this->physicalBody_ = new btRigidBody(bodyConstructionInfo);
            this->physicalBody_->setUserPointer(this);
            this->physicalBody_->setActivationState(DISABLE_DEACTIVATION);
        }
        else if (type == None && this->collisionType_ != None)
        {
            // Destroy rigid body
            assert(this->physicalBody_);
            deactivatePhysics();
            delete this->physicalBody_;
            this->physicalBody_ = 0;
            this->collisionType_ = None;
            this->collisionTypeSynchronised_ = None;
            return;
        }

        // Change type
        switch (type)
        {
        case Dynamic:
            this->physicalBody_->setCollisionFlags(this->physicalBody_->getCollisionFlags() & !(btCollisionObject::CF_STATIC_OBJECT | btCollisionObject::CF_KINEMATIC_OBJECT));
            break;
        case Kinematic:
            this->physicalBody_->setCollisionFlags(this->physicalBody_->getCollisionFlags() & !btCollisionObject::CF_STATIC_OBJECT | btCollisionObject::CF_KINEMATIC_OBJECT);
            break;
        case Static:
            this->physicalBody_->setCollisionFlags(this->physicalBody_->getCollisionFlags() & !btCollisionObject::CF_KINEMATIC_OBJECT | btCollisionObject::CF_STATIC_OBJECT);
            break;
        case None:
            return; // this->collisionType_ was None too
        }

        // Only sets this->collisionShape_
        // However the assertion is to ensure that the internal bullet setting is right
        updateCollisionType();
        assert(this->collisionType_ == type);

        // update mass and inertia tensor
        recalculateMassProps();
        resetPhysicsProps();
        collisionCallbackActivityChanged();
        activatePhysics();
    }

    void WorldEntity::setCollisionTypeStr(const std::string& typeStr)
    {
        std::string typeStrLower = getLowercase(typeStr);
        CollisionType type;
        if (typeStrLower == "dynamic")
            type = Dynamic;
        else if (typeStrLower == "static")
            type = Static;
        else if (typeStrLower == "kinematic")
            type = Kinematic;
        else if (typeStrLower == "none")
            type = None;
        else
            ThrowException(ParseError, std::string("Attempting to set an unknown collision type: '") + typeStr + "'.");
        this->setCollisionType(type);
    }

    std::string WorldEntity::getCollisionTypeStr() const
    {
        switch (this->getCollisionType())
        {
            case Dynamic:
                return "dynamic";
            case Kinematic:
                return "kinematic";
            case Static:
                return "static";
            case None:
                return "none";
            default:
                assert(false);
                return "";
        }
    }

    void WorldEntity::updateCollisionType()
    {
        if (!this->physicalBody_)
            this->collisionType_ = None;
        else if (this->physicalBody_->isKinematicObject())
            this->collisionType_ = Kinematic;
        else if (this->physicalBody_->isStaticObject())
            this->collisionType_ = Static;
        else
            this->collisionType_ = Dynamic;
        this->collisionTypeSynchronised_ = this->collisionType_;
    }

    void WorldEntity::notifyChildMassChanged() // Called by a child WE
    {
        // Note: CollisionShape changes of a child get handled over the internal CompoundCollisionShape already
        // Recalculate mass
        this->childrenMass_ = 0.0f;
        for (std::set<WorldEntity*>::const_iterator it = this->children_.begin(); it != this->children_.end(); ++it)
            this->childrenMass_ += (*it)->getMass();
        recalculateMassProps();
        // Notify parent WE
        if (this->parent_)
            parent_->notifyChildMassChanged();
    }

    void WorldEntity::notifyCollisionShapeChanged() // called by this->collisionShape_
    {
        if (hasPhysics())
        {
            // Bullet doesn't like sudden changes of the collision shape, so we remove and add it again
            if (this->addedToPhysicalWorld())
            {
                this->deactivatePhysics();
                this->physicalBody_->setCollisionShape(this->collisionShape_->getCollisionShape());
                this->activatePhysics();
            }
            else
                this->physicalBody_->setCollisionShape(this->collisionShape_->getCollisionShape());
        }
        recalculateMassProps();
    }

    void WorldEntity::recalculateMassProps()
    {
        // Store local inertia for faster access. Evaluates to (0,0,0) if there is no collision shape.
        float totalMass = this->mass_ + this->childrenMass_;
        this->collisionShape_->calculateLocalInertia(totalMass, this->localInertia_);
        if (this->hasPhysics())
        {
            if (this->isStatic())
            {
                // Just set everything to zero
                this->physicalBody_->setMassProps(0.0f, btVector3(0, 0, 0));
            }
            else if ((this->mass_ + this->childrenMass_) == 0.0f)
            {
                // Use default values to avoid very large or very small values
                CCOUT(4) << "Warning: Setting the internal physical mass to 1.0 because mass_ is 0.0." << std::endl;
                btVector3 inertia(0, 0, 0);
                this->collisionShape_->calculateLocalInertia(1.0f, inertia);
                this->physicalBody_->setMassProps(1.0f, inertia);
            }
            else
            {
                this->physicalBody_->setMassProps(totalMass, this->localInertia_);
            }
        }
    }

    void WorldEntity::resetPhysicsProps()
    {
        if (this->hasPhysics())
        {
            this->physicalBody_->setRestitution(this->restitution_);
            this->physicalBody_->setAngularFactor(this->angularFactor_);
            this->physicalBody_->setDamping(this->linearDamping_, this->angularDamping_);
            this->physicalBody_->setFriction(this->friction_);
        }
    }
}