text: /*
  Bullet Continuous Collision Detection and Physics Library
  Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
  
  This software is provided 'as-is', without any express or implied warranty.
  In no event will the authors be held liable for any damages arising from the use of this software.
  Permission is granted to anyone to use this software for any purpose, 
  including commercial applications, and to alter it and redistribute it freely, 
  subject to the following restrictions:
  
  1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
  */
  
  #ifndef BT_RIGIDBODY_H
  #define BT_RIGIDBODY_H
  
  #include "LinearMath/btAlignedObjectArray.h"
  #include "LinearMath/btTransform.h"
  #include "BulletCollision/BroadphaseCollision/btBroadphaseProxy.h"
  #include "BulletCollision/CollisionDispatch/btCollisionObject.h"
  
  class btCollisionShape;
  class btMotionState;
  class btTypedConstraint;
  
  
  extern btScalar gDeactivationTime;
  extern bool gDisableDeactivation;
  
  #ifdef BT_USE_DOUBLE_PRECISION
  #define btRigidBodyData	btRigidBodyDoubleData
  #define btRigidBodyDataName	"btRigidBodyDoubleData"
  #else
  #define btRigidBodyData	btRigidBodyFloatData
  #define btRigidBodyDataName	"btRigidBodyFloatData"
  #endif //BT_USE_DOUBLE_PRECISION
  
  
  enum	btRigidBodyFlags
  {
  	BT_DISABLE_WORLD_GRAVITY = 1,
  	///BT_ENABLE_GYROPSCOPIC_FORCE flags is enabled by default in Bullet 2.83 and onwards.
  	///and it BT_ENABLE_GYROPSCOPIC_FORCE becomes equivalent to BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY
  	///See Demos/GyroscopicDemo and computeGyroscopicImpulseImplicit
  	BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT = 2,
  	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_WORLD=4,
  	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY=8,
  	BT_ENABLE_GYROPSCOPIC_FORCE = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY,
  };
  
  
  ///The btRigidBody is the main class for rigid body objects. It is derived from btCollisionObject, so it keeps a pointer to a btCollisionShape.
  ///It is recommended for performance and memory use to share btCollisionShape objects whenever possible.
  ///There are 3 types of rigid bodies: 
  ///- A) Dynamic rigid bodies, with positive mass. Motion is controlled by rigid body dynamics.
  ///- B) Fixed objects with zero mass. They are not moving (basically collision objects)
  ///- C) Kinematic objects, which are objects without mass, but the user can move them. There is on-way interaction, and Bullet calculates a velocity based on the timestep and previous and current world transform.
  ///Bullet automatically deactivates dynamic rigid bodies, when the velocity is below a threshold for a given time.
  ///Deactivated (sleeping) rigid bodies don't take any processing time, except a minor broadphase collision detection impact (to allow active objects to activate/wake up sleeping objects)
  class btRigidBody  : public btCollisionObject
  {
  
  	btMatrix3x3	m_invInertiaTensorWorld;
  	btVector3		m_linearVelocity;
  	btVector3		m_angularVelocity;
  	btScalar		m_inverseMass;
  	btVector3		m_linearFactor;
  
  	btVector3		m_gravity;	
  	btVector3		m_gravity_acceleration;
  	btVector3		m_invInertiaLocal;
  	btVector3		m_totalForce;
  	btVector3		m_totalTorque;
  	
  	btScalar		m_linearDamping;
  	btScalar		m_angularDamping;
  
  	bool			m_additionalDamping;
  	btScalar		m_additionalDampingFactor;
  	btScalar		m_additionalLinearDampingThresholdSqr;
  	btScalar		m_additionalAngularDampingThresholdSqr;
  	btScalar		m_additionalAngularDampingFactor;
  
  
  	btScalar		m_linearSleepingThreshold;
  	btScalar		m_angularSleepingThreshold;
  
  	//m_optionalMotionState allows to automatic synchronize the world transform for active objects
  	btMotionState*	m_optionalMotionState;
  
  	//keep track of typed constraints referencing this rigid body, to disable collision between linked bodies
  	btAlignedObjectArray<btTypedConstraint*> m_constraintRefs;
  
  	int				m_rigidbodyFlags;
  	
  	int				m_debugBodyId;
  	
  
  protected:
  
  	ATTRIBUTE_ALIGNED16(btVector3		m_deltaLinearVelocity);
  	btVector3		m_deltaAngularVelocity;
  	btVector3		m_angularFactor;
  	btVector3		m_invMass;
  	btVector3		m_pushVelocity;
  	btVector3		m_turnVelocity;
  
  
  public:
  
  
  	///The btRigidBodyConstructionInfo structure provides information to create a rigid body. Setting mass to zero creates a fixed (non-dynamic) rigid body.
  	///For dynamic objects, you can use the collision shape to approximate the local inertia tensor, otherwise use the zero vector (default argument)
  	///You can use the motion state to synchronize the world transform between physics and graphics objects. 
  	///And if the motion state is provided, the rigid body will initialize its initial world transform from the motion state,
  	///m_startWorldTransform is only used when you don't provide a motion state.
  	struct	btRigidBodyConstructionInfo
  	{
  		btScalar			m_mass;
  
  		///When a motionState is provided, the rigid body will initialize its world transform from the motion state
  		///In this case, m_startWorldTransform is ignored.
  		btMotionState*		m_motionState;
  		btTransform	m_startWorldTransform;
  
  		btCollisionShape*	m_collisionShape;
  		btVector3			m_localInertia;
  		btScalar			m_linearDamping;
  		btScalar			m_angularDamping;
  
  		///best simulation results when friction is non-zero
  		btScalar			m_friction;
  		///the m_rollingFriction prevents rounded shapes, such as spheres, cylinders and capsules from rolling forever.
  		///See Bullet/Demos/RollingFrictionDemo for usage
  		btScalar			m_rollingFriction;
          btScalar			m_spinningFriction;//torsional friction around contact normal
          
  		///best simulation results using zero restitution.
  		btScalar			m_restitution;
  
  		btScalar			m_linearSleepingThreshold;
  		btScalar			m_angularSleepingThreshold;
  
  		//Additional damping can help avoiding lowpass jitter motion, help stability for ragdolls etc.
  		//Such damping is undesirable, so once the overall simulation quality of the rigid body dynamics system has improved, this should become obsolete
  		bool				m_additionalDamping;
  		btScalar			m_additionalDampingFactor;
  		btScalar			m_additionalLinearDampingThresholdSqr;
  		btScalar			m_additionalAngularDampingThresholdSqr;
  		btScalar			m_additionalAngularDampingFactor;
  
  		btRigidBodyConstructionInfo(	btScalar mass, btMotionState* motionState, btCollisionShape* collisionShape, const btVector3& localInertia=btVector3(0,0,0)):
  		m_mass(mass),
  			m_motionState(motionState),
  			m_collisionShape(collisionShape),
  			m_localInertia(localInertia),
  			m_linearDamping(btScalar(0.)),
  			m_angularDamping(btScalar(0.)),
  			m_friction(btScalar(0.5)),
  			m_rollingFriction(btScalar(0)),
              m_spinningFriction(btScalar(0)),
  			m_restitution(btScalar(0.)),
  			m_linearSleepingThreshold(btScalar(0.8)),
  			m_angularSleepingThreshold(btScalar(1.f)),
  			m_additionalDamping(false),
  			m_additionalDampingFactor(btScalar(0.005)),
  			m_additionalLinearDampingThresholdSqr(btScalar(0.01)),
  			m_additionalAngularDampingThresholdSqr(btScalar(0.01)),
  			m_additionalAngularDampingFactor(btScalar(0.01))
  		{
  			m_startWorldTransform.setIdentity();
  		}
  	};
  
  	///btRigidBody constructor using construction info
  	btRigidBody(	const btRigidBodyConstructionInfo& constructionInfo);
  
  	///btRigidBody constructor for backwards compatibility. 
  	///To specify friction (etc) during rigid body construction, please use the other constructor (using btRigidBodyConstructionInfo)
  	btRigidBody(	btScalar mass, btMotionState* motionState, btCollisionShape* collisionShape, const btVector3& localInertia=btVector3(0,0,0));
  
  
  	virtual ~btRigidBody()
          { 
                  //No constraints should point to this rigidbody
  		//Remove constraints from the dynamics world before you delete the related rigidbodies. 
                  btAssert(m_constraintRefs.size()==0); 
          }
  
  protected:
  
  	///setupRigidBody is only used internally by the constructor
  	void	setupRigidBody(const btRigidBodyConstructionInfo& constructionInfo);
  
  public:
  
  	void			proceedToTransform(const btTransform& newTrans); 
  	
  	///to keep collision detection and dynamics separate we don't store a rigidbody pointer
  	///but a rigidbody is derived from btCollisionObject, so we can safely perform an upcast
  	static const btRigidBody*	upcast(const btCollisionObject* colObj)
  	{
  		if (colObj->getInternalType()&btCollisionObject::CO_RIGID_BODY)
  			return (const btRigidBody*)colObj;
  		return 0;
  	}
  	static btRigidBody*	upcast(btCollisionObject* colObj)
  	{
  		if (colObj->getInternalType()&btCollisionObject::CO_RIGID_BODY)
  			return (btRigidBody*)colObj;
  		return 0;
  	}
  	
  	/// continuous collision detection needs prediction
  	void			predictIntegratedTransform(btScalar step, btTransform& predictedTransform) ;
  	
  	void			saveKinematicState(btScalar step);
  	
  	void			applyGravity();
  	
  	void			setGravity(const btVector3& acceleration);  
  
  	const btVector3&	getGravity() const
  	{
  		return m_gravity_acceleration;
  	}
  
  	void			setDamping(btScalar lin_damping, btScalar ang_damping);
  
  	btScalar getLinearDamping() const
  	{
  		return m_linearDamping;
  	}
  
  	btScalar getAngularDamping() const
  	{
  		return m_angularDamping;
  	}
  
  	btScalar getLinearSleepingThreshold() const
  	{
  		return m_linearSleepingThreshold;
  	}
  
  	btScalar getAngularSleepingThreshold() const
  	{
  		return m_angularSleepingThreshold;
  	}
  
  	void			applyDamping(btScalar timeStep);
  
  	SIMD_FORCE_INLINE const btCollisionShape*	getCollisionShape() const {
  		return m_collisionShape;
  	}
  
  	SIMD_FORCE_INLINE btCollisionShape*	getCollisionShape() {
  			return m_collisionShape;
  	}
  	
  	void			setMassProps(btScalar mass, const btVector3& inertia);
  	
  	const btVector3& getLinearFactor() const
  	{
  		return m_linearFactor;
  	}
  	void setLinearFactor(const btVector3& linearFactor)
  	{
  		m_linearFactor = linearFactor;
  		m_invMass = m_linearFactor*m_inverseMass;
  	}
  	btScalar		getInvMass() const { return m_inverseMass; }
  	const btMatrix3x3& getInvInertiaTensorWorld() const { 
  		return m_invInertiaTensorWorld; 
  	}
  		
  	void			integrateVelocities(btScalar step);
  
  	void			setCenterOfMassTransform(const btTransform& xform);
  
  	void			applyCentralForce(const btVector3& force)
  	{
  		m_totalForce += force*m_linearFactor;
  	}
  
  	// XXX AMMO local addition to bullet
  	void	applyCentralLocalForce(const btVector3& force)
  	{
  		m_totalForce += m_worldTransform.getBasis() * force * m_linearFactor;
  	}
  
  	const btVector3& getTotalForce() const
  	{
  		return m_totalForce;
  	};
  
  	const btVector3& getTotalTorque() const
  	{
  		return m_totalTorque;
  	};
      
  	const btVector3& getInvInertiaDiagLocal() const
  	{
  		return m_invInertiaLocal;
  	};
  
  	void	setInvInertiaDiagLocal(const btVector3& diagInvInertia)
  	{
  		m_invInertiaLocal = diagInvInertia;
  	}
  
  	void	setSleepingThresholds(btScalar linear,btScalar angular)
  	{
  		m_linearSleepingThreshold = linear;
  		m_angularSleepingThreshold = angular;
  	}
  
  	void	applyTorque(const btVector3& torque)
  	{
  		m_totalTorque += torque*m_angularFactor;
  	}
  	
  	// XXX AMMO local addition to bullet
  	void	applyLocalTorque(const btVector3& torque)
  	{
  		m_totalTorque += m_worldTransform.getBasis() * torque * m_angularFactor;
  	}
  
  	void	applyForce(const btVector3& force, const btVector3& rel_pos) 
  	{
  		applyCentralForce(force);
  		applyTorque(rel_pos.cross(force*m_linearFactor));
  	}
  	
  	void applyCentralImpulse(const btVector3& impulse)
  	{
  		m_linearVelocity += impulse *m_linearFactor * m_inverseMass;
  	}
  	
    	void applyTorqueImpulse(const btVector3& torque)
  	{
  			m_angularVelocity += m_invInertiaTensorWorld * torque * m_angularFactor;
  	}
  	
  	void applyImpulse(const btVector3& impulse, const btVector3& rel_pos) 
  	{
  		if (m_inverseMass != btScalar(0.))
  		{
  			applyCentralImpulse(impulse);
  			if (m_angularFactor)
  			{
  				applyTorqueImpulse(rel_pos.cross(impulse*m_linearFactor));
  			}
  		}
  	}
  
  	void clearForces() 
  	{
  		m_totalForce.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  		m_totalTorque.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  	}
  	
  	void updateInertiaTensor();    
  	
  	const btVector3&     getCenterOfMassPosition() const { 
  		return m_worldTransform.getOrigin(); 
  	}
  	btQuaternion getOrientation() const;
  	
  	const btTransform&  getCenterOfMassTransform() const { 
  		return m_worldTransform; 
  	}
  	const btVector3&   getLinearVelocity() const { 
  		return m_linearVelocity; 
  	}
  	const btVector3&    getAngularVelocity() const { 
  		return m_angularVelocity; 
  	}
  	
  
  	inline void setLinearVelocity(const btVector3& lin_vel)
  	{ 
  		m_updateRevision++;
  		m_linearVelocity = lin_vel; 
  	}
  
  	inline void setAngularVelocity(const btVector3& ang_vel) 
  	{ 
  		m_updateRevision++;
  		m_angularVelocity = ang_vel; 
  	}
  
  	btVector3 getVelocityInLocalPoint(const btVector3& rel_pos) const
  	{
  		//we also calculate lin/ang velocity for kinematic objects
  		return m_linearVelocity + m_angularVelocity.cross(rel_pos);
  
  		//for kinematic objects, we could also use use:
  		//		return 	(m_worldTransform(rel_pos) - m_interpolationWorldTransform(rel_pos)) / m_kinematicTimeStep;
  	}
  
  	void translate(const btVector3& v) 
  	{
  		m_worldTransform.getOrigin() += v; 
  	}
  
  	
  	void	getAabb(btVector3& aabbMin,btVector3& aabbMax) const;
  
  
  
  
  	
  	SIMD_FORCE_INLINE btScalar computeImpulseDenominator(const btVector3& pos, const btVector3& normal) const
  	{
  		btVector3 r0 = pos - getCenterOfMassPosition();
  
  		btVector3 c0 = (r0).cross(normal);
  
  		btVector3 vec = (c0 * getInvInertiaTensorWorld()).cross(r0);
  
  		return m_inverseMass + normal.dot(vec);
  
  	}
  
  	SIMD_FORCE_INLINE btScalar computeAngularImpulseDenominator(const btVector3& axis) const
  	{
  		btVector3 vec = axis * getInvInertiaTensorWorld();
  		return axis.dot(vec);
  	}
  
  	SIMD_FORCE_INLINE void	updateDeactivation(btScalar timeStep)
  	{
  		if ( (getActivationState() == ISLAND_SLEEPING) || (getActivationState() == DISABLE_DEACTIVATION))
  			return;
  
  		if ((getLinearVelocity().length2() < m_linearSleepingThreshold*m_linearSleepingThreshold) &&
  			(getAngularVelocity().length2() < m_angularSleepingThreshold*m_angularSleepingThreshold))
  		{
  			m_deactivationTime += timeStep;
  		} else
  		{
  			m_deactivationTime=btScalar(0.);
  			setActivationState(0);
  		}
  
  	}
  
  	SIMD_FORCE_INLINE bool	wantsSleeping()
  	{
  
  		if (getActivationState() == DISABLE_DEACTIVATION)
  			return false;
  
  		//disable deactivation
  		if (gDisableDeactivation || (gDeactivationTime == btScalar(0.)))
  			return false;
  
  		if ( (getActivationState() == ISLAND_SLEEPING) || (getActivationState() == WANTS_DEACTIVATION))
  			return true;
  
  		if (m_deactivationTime> gDeactivationTime)
  		{
  			return true;
  		}
  		return false;
  	}
  
  
  	
  	const btBroadphaseProxy*	getBroadphaseProxy() const
  	{
  		return m_broadphaseHandle;
  	}
  	btBroadphaseProxy*	getBroadphaseProxy() 
  	{
  		return m_broadphaseHandle;
  	}
  	void	setNewBroadphaseProxy(btBroadphaseProxy* broadphaseProxy)
  	{
  		m_broadphaseHandle = broadphaseProxy;
  	}
  
  	//btMotionState allows to automatic synchronize the world transform for active objects
  	btMotionState*	getMotionState()
  	{
  		return m_optionalMotionState;
  	}
  	const btMotionState*	getMotionState() const
  	{
  		return m_optionalMotionState;
  	}
  	void	setMotionState(btMotionState* motionState)
  	{
  		m_optionalMotionState = motionState;
  		if (m_optionalMotionState)
  			motionState->getWorldTransform(m_worldTransform);
  	}
  
  	//for experimental overriding of friction/contact solver func
  	int	m_contactSolverType;
  	int	m_frictionSolverType;
  
  	void	setAngularFactor(const btVector3& angFac)
  	{
  		m_updateRevision++;
  		m_angularFactor = angFac;
  	}
  
  	void	setAngularFactor(btScalar angFac)
  	{
  		m_updateRevision++;
  		m_angularFactor.setValue(angFac,angFac,angFac);
  	}
  	const btVector3&	getAngularFactor() const
  	{
  		return m_angularFactor;
  	}
  
  	//is this rigidbody added to a btCollisionWorld/btDynamicsWorld/btBroadphase?
  	bool	isInWorld() const
  	{
  		return (getBroadphaseProxy() != 0);
  	}
  
  	void addConstraintRef(btTypedConstraint* c);
  	void removeConstraintRef(btTypedConstraint* c);
  
  	btTypedConstraint* getConstraintRef(int index)
  	{
  		return m_constraintRefs[index];
  	}
  
  	int getNumConstraintRefs() const
  	{
  		return m_constraintRefs.size();
  	}
  
  	void	setFlags(int flags)
  	{
  		m_rigidbodyFlags = flags;
  	}
  
  	int getFlags() const
  	{
  		return m_rigidbodyFlags;
  	}
  
  
  	
  
  	///perform implicit force computation in world space
  	btVector3 computeGyroscopicImpulseImplicit_World(btScalar dt) const;
  	
  	///perform implicit force computation in body space (inertial frame)
  	btVector3 computeGyroscopicImpulseImplicit_Body(btScalar step) const;
  
  	///explicit version is best avoided, it gains energy
  	btVector3 computeGyroscopicForceExplicit(btScalar maxGyroscopicForce) const;
  	btVector3 getLocalInertia() const;
  
  	///////////////////////////////////////////////
  
  	virtual	int	calculateSerializeBufferSize()	const;
  
  	///fills the dataBuffer and returns the struct name (and 0 on failure)
  	virtual	const char*	serialize(void* dataBuffer,  class btSerializer* serializer) const;
  
  	virtual void serializeSingleObject(class btSerializer* serializer) const;
  
  	// XXX EMSCRIPTEN: clear the rigid body state
  	void clearState() {
  		m_linearVelocity.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  		m_angularVelocity.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  		m_totalForce.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  		m_totalTorque.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
  	}
  
  };
  
  //@todo add m_optionalMotionState and m_constraintRefs to btRigidBodyData
  ///do not change those serialization structures, it requires an updated sBulletDNAstr/sBulletDNAstr64
  struct	btRigidBodyFloatData
  {
  	btCollisionObjectFloatData	m_collisionObjectData;
  	btMatrix3x3FloatData		m_invInertiaTensorWorld;
  	btVector3FloatData		m_linearVelocity;
  	btVector3FloatData		m_angularVelocity;
  	btVector3FloatData		m_angularFactor;
  	btVector3FloatData		m_linearFactor;
  	btVector3FloatData		m_gravity;	
  	btVector3FloatData		m_gravity_acceleration;
  	btVector3FloatData		m_invInertiaLocal;
  	btVector3FloatData		m_totalForce;
  	btVector3FloatData		m_totalTorque;
  	float					m_inverseMass;
  	float					m_linearDamping;
  	float					m_angularDamping;
  	float					m_additionalDampingFactor;
  	float					m_additionalLinearDampingThresholdSqr;
  	float					m_additionalAngularDampingThresholdSqr;
  	float					m_additionalAngularDampingFactor;
  	float					m_linearSleepingThreshold;
  	float					m_angularSleepingThreshold;
  	int						m_additionalDamping;
  };
  
  ///do not change those serialization structures, it requires an updated sBulletDNAstr/sBulletDNAstr64
  struct	btRigidBodyDoubleData
  {
  	btCollisionObjectDoubleData	m_collisionObjectData;
  	btMatrix3x3DoubleData		m_invInertiaTensorWorld;
  	btVector3DoubleData		m_linearVelocity;
  	btVector3DoubleData		m_angularVelocity;
  	btVector3DoubleData		m_angularFactor;
  	btVector3DoubleData		m_linearFactor;
  	btVector3DoubleData		m_gravity;	
  	btVector3DoubleData		m_gravity_acceleration;
  	btVector3DoubleData		m_invInertiaLocal;
  	btVector3DoubleData		m_totalForce;
  	btVector3DoubleData		m_totalTorque;
  	double					m_inverseMass;
  	double					m_linearDamping;
  	double					m_angularDamping;
  	double					m_additionalDampingFactor;
  	double					m_additionalLinearDampingThresholdSqr;
  	double					m_additionalAngularDampingThresholdSqr;
  	double					m_additionalAngularDampingFactor;
  	double					m_linearSleepingThreshold;
  	double					m_angularSleepingThreshold;
  	int						m_additionalDamping;
  	char	m_padding[4];
  };
  
  
  
  #endif //BT_RIGIDBODY_H
  
  