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btRigidBody.h

/*
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 RIGIDBODY_H
#define RIGIDBODY_H

#include "LinearMath/btAlignedObjectArray.h"
#include "LinearMath/btPoint3.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;


///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)
00042 class btRigidBody  : public btCollisionObject
{

      btMatrix3x3 m_invInertiaTensorWorld;
      btVector3         m_linearVelocity;
      btVector3         m_angularVelocity;
      btScalar          m_inverseMass;
      btScalar          m_angularFactor;

      btVector3         m_gravity;  
      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
      btAlignedObjectArray<btTypedConstraint*> m_constraintRefs;

public:


      ///btRigidBodyConstructionInfo 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.
00083       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.
00089             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
00098             btScalar                m_friction;
            ///best simulation results using zero restitution.
00100             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_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
00161       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;
      }

      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);
      
      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;
      }
    
      const btVector3& getInvInertiaDiagLocal()
      {
            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;
      }
      
      void  applyForce(const btVector3& force, const btVector3& rel_pos) 
      {
            applyCentralForce(force);
            applyTorque(rel_pos.cross(force)*m_angularFactor);
      }
      
      void applyCentralImpulse(const btVector3& impulse)
      {
            m_linearVelocity += impulse * m_inverseMass;
      }
      
      void applyTorqueImpulse(const btVector3& torque)
      {
                  m_angularVelocity += m_invInertiaTensorWorld * torque;
      }
      
      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_angularFactor);
                  }
            }
      }

      //Optimization for the iterative solver: avoid calculating constant terms involving inertia, normal, relative position
      SIMD_FORCE_INLINE void internalApplyImpulse(const btVector3& linearComponent, const btVector3& angularComponent,btScalar impulseMagnitude)
      {
            if (m_inverseMass != btScalar(0.))
            {
                  m_linearVelocity += linearComponent*impulseMagnitude;
                  if (m_angularFactor)
                  {
                        m_angularVelocity += angularComponent*impulseMagnitude*m_angularFactor;
                  }
            }
      }
      
      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 btPoint3&     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)
      { 
            assert (m_collisionFlags != btCollisionObject::CF_STATIC_OBJECT);
            m_linearVelocity = lin_vel; 
      }

      inline void setAngularVelocity(const btVector3& ang_vel) { 
            assert (m_collisionFlags != btCollisionObject::CF_STATIC_OBJECT);
            {
                  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 btPoint3& 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(btScalar angFac)
      {
            m_angularFactor = angFac;
      }
      btScalar    getAngularFactor() const
      {
            return m_angularFactor;
      }

      //is this rigidbody added to a btCollisionWorld/btDynamicsWorld/btBroadphase?
      bool  isInWorld() const
      {
            return (getBroadphaseProxy() != 0);
      }

      virtual bool checkCollideWithOverride(btCollisionObject* co);

      void addConstraintRef(btTypedConstraint* c);
      void removeConstraintRef(btTypedConstraint* c);

      btTypedConstraint* getConstraintRef(int index)
      {
            return m_constraintRefs[index];
      }

      int getNumConstraintRefs()
      {
            return m_constraintRefs.size();
      }

      int   m_debugBodyId;
};



#endif


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