text: /*
  * Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
  *
  * 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 B2_BODY_H
  #define B2_BODY_H
  
  #include <Box2D/Common/b2Math.h>
  #include <Box2D/Collision/Shapes/b2Shape.h>
  #include <memory>
  
  class b2Fixture;
  class b2Joint;
  class b2Contact;
  class b2Controller;
  class b2World;
  struct b2FixtureDef;
  struct b2JointEdge;
  struct b2ContactEdge;
  
  /// The body type.
  /// static: zero mass, zero velocity, may be manually moved
  /// kinematic: zero mass, non-zero velocity set by user, moved by solver
  /// dynamic: positive mass, non-zero velocity determined by forces, moved by solver
  enum b2BodyType
  {
      b2_staticBody = 0,
      b2_kinematicBody,
      b2_dynamicBody
  
      // TODO_ERIN
      //b2_bulletBody,
  };
  
  /// A body definition holds all the data needed to construct a rigid body.
  /// You can safely re-use body definitions. Shapes are added to a body after construction.
  struct b2BodyDef
  {
      /// This constructor sets the body definition default values.
      b2BodyDef()
      {
          userData = NULL;
          position.Set(0.0f, 0.0f);
          angle = 0.0f;
          linearVelocity.Set(0.0f, 0.0f);
          angularVelocity = 0.0f;
          linearDamping = 0.0f;
          angularDamping = 0.0f;
          allowSleep = true;
          awake = true;
          fixedRotation = false;
          bullet = false;
          type = b2_staticBody;
          active = true;
          gravityScale = 1.0f;
      }
  
      /// The body type: static, kinematic, or dynamic.
      /// Note: if a dynamic body would have zero mass, the mass is set to one.
      b2BodyType type;
  
      /// The world position of the body. Avoid creating bodies at the origin
      /// since this can lead to many overlapping shapes.
      b2Vec2 position;
  
      /// The world angle of the body in radians.
      float32 angle;
  
      /// The linear velocity of the body's origin in world co-ordinates.
      b2Vec2 linearVelocity;
  
      /// The angular velocity of the body.
      float32 angularVelocity;
  
      /// Linear damping is use to reduce the linear velocity. The damping parameter
      /// can be larger than 1.0f but the damping effect becomes sensitive to the
      /// time step when the damping parameter is large.
      float32 linearDamping;
  
      /// Angular damping is use to reduce the angular velocity. The damping parameter
      /// can be larger than 1.0f but the damping effect becomes sensitive to the
      /// time step when the damping parameter is large.
      float32 angularDamping;
  
      /// Set this flag to false if this body should never fall asleep. Note that
      /// this increases CPU usage.
      bool allowSleep;
  
      /// Is this body initially awake or sleeping?
      bool awake;
  
      /// Should this body be prevented from rotating? Useful for characters.
      bool fixedRotation;
  
      /// Is this a fast moving body that should be prevented from tunneling through
      /// other moving bodies? Note that all bodies are prevented from tunneling through
      /// kinematic and static bodies. This setting is only considered on dynamic bodies.
      /// @warning You should use this flag sparingly since it increases processing time.
      bool bullet;
  
      /// Does this body start out active?
      bool active;
  
      /// Use this to store application specific body data.
      void* userData;
  
      /// Scale the gravity applied to this body.
      float32 gravityScale;
  };
  
  /// A rigid body. These are created via b2World::CreateBody.
  class b2Body
  {
  public:
      /// Creates a fixture and attach it to this body. Use this function if you need
      /// to set some fixture parameters, like friction. Otherwise you can create the
      /// fixture directly from a shape.
      /// If the density is non-zero, this function automatically updates the mass of the body.
      /// Contacts are not created until the next time step.
      /// @param def the fixture definition.
      /// @warning This function is locked during callbacks.
      b2Fixture* CreateFixture(const b2FixtureDef* def);
  
      /// Creates a fixture from a shape and attach it to this body.
      /// This is a convenience function. Use b2FixtureDef if you need to set parameters
      /// like friction, restitution, user data, or filtering.
      /// If the density is non-zero, this function automatically updates the mass of the body.
      /// @param shape the shape to be cloned.
      /// @param density the shape density (set to zero for static bodies).
      /// @warning This function is locked during callbacks.
      b2Fixture* CreateFixture(const b2Shape* shape, float32 density);
  
      /// Destroy a fixture. This removes the fixture from the broad-phase and
      /// destroys all contacts associated with this fixture. This will
      /// automatically adjust the mass of the body if the body is dynamic and the
      /// fixture has positive density.
      /// All fixtures attached to a body are implicitly destroyed when the body is destroyed.
      /// @param fixture the fixture to be removed.
      /// @warning This function is locked during callbacks.
      void DestroyFixture(b2Fixture* fixture);
  
      /// Set the position of the body's origin and rotation.
      /// This breaks any contacts and wakes the other bodies.
      /// Manipulating a body's transform may cause non-physical behavior.
      /// @param position the world position of the body's local origin.
      /// @param angle the world rotation in radians.
      void SetTransform(const b2Vec2& position, float32 angle);
  
  	void SetPosition(const b2Vec2& position);
  
  
      /// Get the body transform for the body's origin.
      /// @return the world transform of the body's origin.
      const b2Transform& GetTransform() const;
  
      /// Get the world body origin position.
      /// @return the world position of the body's origin.
      const b2Vec2& GetPosition() const;
  
      /// Get the angle in radians.
      /// @return the current world rotation angle in radians.
      float32 GetAngle() const;
  
      /// Get the world position of the center of mass.
      const b2Vec2& GetWorldCenter() const;
  
      /// Get the local position of the center of mass.
      const b2Vec2& GetLocalCenter() const;
  
      /// Set the linear velocity of the center of mass.
      /// @param v the new linear velocity of the center of mass.
      void SetLinearVelocity(const b2Vec2& v);
  
      /// Get the linear velocity of the center of mass.
      /// @return the linear velocity of the center of mass.
      b2Vec2 GetLinearVelocity() const;
  
      /// Set the angular velocity.
      /// @param omega the new angular velocity in radians/second.
      void SetAngularVelocity(float32 omega);
  
      /// Get the angular velocity.
      /// @return the angular velocity in radians/second.
      float32 GetAngularVelocity() const;
  
      /// Apply a force at a world point. If the force is not
      /// applied at the center of mass, it will generate a torque and
      /// affect the angular velocity. This wakes up the body.
      /// @param force the world force vector, usually in Newtons (N).
      /// @param point the world position of the point of application.
      void ApplyForce(const b2Vec2& force, const b2Vec2& point);
  
      /// Apply a force to the center of mass. This wakes up the body.
      /// @param force the world force vector, usually in Newtons (N).
      void ApplyForceToCenter(const b2Vec2& force);
  
      /// Apply a torque. This affects the angular velocity
      /// without affecting the linear velocity of the center of mass.
      /// This wakes up the body.
      /// @param torque about the z-axis (out of the screen), usually in N-m.
      void ApplyTorque(float32 torque);
  
      /// Apply an impulse at a point. This immediately modifies the velocity.
      /// It also modifies the angular velocity if the point of application
      /// is not at the center of mass. This wakes up the body.
      /// @param impulse the world impulse vector, usually in N-seconds or kg-m/s.
      /// @param point the world position of the point of application.
      void ApplyLinearImpulse(const b2Vec2& impulse, const b2Vec2& point);
  
      /// Apply an angular impulse.
      /// @param impulse the angular impulse in units of kg*m*m/s
      void ApplyAngularImpulse(float32 impulse);
  
      /// Get the total mass of the body.
      /// @return the mass, usually in kilograms (kg).
      float32 GetMass() const;
  
      /// Get the rotational inertia of the body about the local origin.
      /// @return the rotational inertia, usually in kg-m^2.
      float32 GetInertia() const;
  
      /// Get the mass data of the body.
      /// @return a struct containing the mass, inertia and center of the body.
      void GetMassData(b2MassData* data) const;
  
      /// Set the mass properties to override the mass properties of the fixtures.
      /// Note that this changes the center of mass position.
      /// Note that creating or destroying fixtures can also alter the mass.
      /// This function has no effect if the body isn't dynamic.
      /// @param massData the mass properties.
      void SetMassData(const b2MassData* data);
  
      /// This resets the mass properties to the sum of the mass properties of the fixtures.
      /// This normally does not need to be called unless you called SetMassData to override
      /// the mass and you later want to reset the mass.
      void ResetMassData();
  
      /// Get the world coordinates of a point given the local coordinates.
      /// @param localPoint a point on the body measured relative the the body's origin.
      /// @return the same point expressed in world coordinates.
      b2Vec2 GetWorldPoint(const b2Vec2& localPoint) const;
  
      /// Get the world coordinates of a vector given the local coordinates.
      /// @param localVector a vector fixed in the body.
      /// @return the same vector expressed in world coordinates.
      b2Vec2 GetWorldVector(const b2Vec2& localVector) const;
  
      /// Gets a local point relative to the body's origin given a world point.
      /// @param a point in world coordinates.
      /// @return the corresponding local point relative to the body's origin.
      b2Vec2 GetLocalPoint(const b2Vec2& worldPoint) const;
  
      /// Gets a local vector given a world vector.
      /// @param a vector in world coordinates.
      /// @return the corresponding local vector.
      b2Vec2 GetLocalVector(const b2Vec2& worldVector) const;
  
      /// Get the world linear velocity of a world point attached to this body.
      /// @param a point in world coordinates.
      /// @return the world velocity of a point.
      b2Vec2 GetLinearVelocityFromWorldPoint(const b2Vec2& worldPoint) const;
  
      /// Get the world velocity of a local point.
      /// @param a point in local coordinates.
      /// @return the world velocity of a point.
      b2Vec2 GetLinearVelocityFromLocalPoint(const b2Vec2& localPoint) const;
  
      /// Get the linear damping of the body.
      float32 GetLinearDamping() const;
  
      /// Set the linear damping of the body.
      void SetLinearDamping(float32 linearDamping);
  
      /// Get the angular damping of the body.
      float32 GetAngularDamping() const;
  
      /// Set the angular damping of the body.
      void SetAngularDamping(float32 angularDamping);
  
      /// Get the gravity scale of the body.
      float32 GetGravityScale() const;
  
      /// Set the gravity scale of the body.
      void SetGravityScale(float32 scale);
  
      /// Set the type of this body. This may alter the mass and velocity.
      void SetType(b2BodyType type);
  
      /// Get the type of this body.
      b2BodyType GetType() const;
  
      /// Should this body be treated like a bullet for continuous collision detection?
      void SetBullet(bool flag);
  
      /// Is this body treated like a bullet for continuous collision detection?
      bool IsBullet() const;
  
      /// You can disable sleeping on this body. If you disable sleeping, the
      /// body will be woken.
      void SetSleepingAllowed(bool flag);
  
      /// Is this body allowed to sleep
      bool IsSleepingAllowed() const;
  
      /// Set the sleep state of the body. A sleeping body has very
      /// low CPU cost.
      /// @param flag set to true to put body to sleep, false to wake it.
      void SetAwake(bool flag);
  
      /// Get the sleeping state of this body.
      /// @return true if the body is sleeping.
      bool IsAwake() const;
  
      /// Set the active state of the body. An inactive body is not
      /// simulated and cannot be collided with or woken up.
      /// If you pass a flag of true, all fixtures will be added to the
      /// broad-phase.
      /// If you pass a flag of false, all fixtures will be removed from
      /// the broad-phase and all contacts will be destroyed.
      /// Fixtures and joints are otherwise unaffected. You may continue
      /// to create/destroy fixtures and joints on inactive bodies.
      /// Fixtures on an inactive body are implicitly inactive and will
      /// not participate in collisions, ray-casts, or queries.
      /// Joints connected to an inactive body are implicitly inactive.
      /// An inactive body is still owned by a b2World object and remains
      /// in the body list.
      void SetActive(bool flag);
  
      /// Get the active state of the body.
      bool IsActive() const;
  
      /// Set this body to have fixed rotation. This causes the mass
      /// to be reset.
      void SetFixedRotation(bool flag);
  
      /// Does this body have fixed rotation?
      bool IsFixedRotation() const;
  
      /// Get the list of all fixtures attached to this body.
      b2Fixture* GetFixtureList();
      const b2Fixture* GetFixtureList() const;
  
      /// Get the list of all joints attached to this body.
      b2JointEdge* GetJointList();
      const b2JointEdge* GetJointList() const;
  
      /// Get the list of all contacts attached to this body.
      /// @warning this list changes during the time step and you may
      /// miss some collisions if you don't use b2ContactListener.
      b2ContactEdge* GetContactList();
      const b2ContactEdge* GetContactList() const;
  
      /// Get the next body in the world's body list.
      b2Body* GetNext();
      const b2Body* GetNext() const;
  
      /// Get the user data pointer that was provided in the body definition.
      void* GetUserData() const;
  
      /// Set the user data. Use this to store your application specific data.
      void SetUserData(void* data);
  
      /// Get the parent world of this body.
      b2World* GetWorld();
      const b2World* GetWorld() const;
  
      /// Dump this body to a log file
      void Dump();
  
  private:
  
      friend class b2World;
      friend class b2Island;
      friend class b2ContactManager;
      friend class b2ContactSolver;
      friend class b2Contact;
      
      friend class b2DistanceJoint;
      friend class b2GearJoint;
      friend class b2WheelJoint;
      friend class b2MouseJoint;
      friend class b2PrismaticJoint;
      friend class b2PulleyJoint;
      friend class b2RevoluteJoint;
      friend class b2WeldJoint;
      friend class b2FrictionJoint;
      friend class b2RopeJoint;
  
      // m_flags
      enum
      {
          e_islandFlag        = 0x0001,
          e_awakeFlag            = 0x0002,
          e_autoSleepFlag        = 0x0004,
          e_bulletFlag        = 0x0008,
          e_fixedRotationFlag    = 0x0010,
          e_activeFlag        = 0x0020,
          e_toiFlag            = 0x0040
      };
  
      b2Body(const b2BodyDef* bd, b2World* world);
      ~b2Body();
  
      void SynchronizeFixtures();
      void SynchronizeTransform();
  
      // This is used to prevent connected bodies from colliding.
      // It may lie, depending on the collideConnected flag.
      bool ShouldCollide(const b2Body* other) const;
  
      void Advance(float32 t);
  
      b2BodyType m_type;
  
      uint16 m_flags;
  
      int32 m_islandIndex;
  
      b2Transform m_xf;        // the body origin transform
      b2Sweep m_sweep;        // the swept motion for CCD
  
      b2Vec2 m_linearVelocity;
      float32 m_angularVelocity;
  
      b2Vec2 m_force;
      float32 m_torque;
  
      b2World* m_world;
      b2Body* m_prev;
      b2Body* m_next;
  
      b2Fixture* m_fixtureList;
      int32 m_fixtureCount;
  
      b2JointEdge* m_jointList;
      b2ContactEdge* m_contactList;
  
      float32 m_mass, m_invMass;
  
      // Rotational inertia about the center of mass.
      float32 m_I, m_invI;
  
      float32 m_linearDamping;
      float32 m_angularDamping;
      float32 m_gravityScale;
  
      float32 m_sleepTime;
  
      void* m_userData;
  };
  
  inline b2BodyType b2Body::GetType() const
  {
      return m_type;
  }
  
  inline const b2Transform& b2Body::GetTransform() const
  {
      return m_xf;
  }
  
  inline const b2Vec2& b2Body::GetPosition() const
  {
      return m_xf.p;
  }
  
  inline float32 b2Body::GetAngle() const
  {
      return m_sweep.a;
  }
  
  inline const b2Vec2& b2Body::GetWorldCenter() const
  {
      return m_sweep.c;
  }
  
  inline const b2Vec2& b2Body::GetLocalCenter() const
  {
      return m_sweep.localCenter;
  }
  
  inline void b2Body::SetLinearVelocity(const b2Vec2& v)
  {
      if (m_type == b2_staticBody)
      {
          return;
      }
  
      if (b2Dot(v,v) > 0.0f)
      {
          SetAwake(true);
      }
  
      m_linearVelocity = v;
  }
  
  inline b2Vec2 b2Body::GetLinearVelocity() const
  {
      return m_linearVelocity;
  }
  
  inline void b2Body::SetAngularVelocity(float32 w)
  {
      if (m_type == b2_staticBody)
      {
          return;
      }
  
      if (w * w > 0.0f)
      {
          SetAwake(true);
      }
  
      m_angularVelocity = w;
  }
  
  inline float32 b2Body::GetAngularVelocity() const
  {
      return m_angularVelocity;
  }
  
  inline float32 b2Body::GetMass() const
  {
      return m_mass;
  }
  
  inline float32 b2Body::GetInertia() const
  {
      return m_I + m_mass * b2Dot(m_sweep.localCenter, m_sweep.localCenter);
  }
  
  inline void b2Body::GetMassData(b2MassData* data) const
  {
      data->mass = m_mass;
      data->I = m_I + m_mass * b2Dot(m_sweep.localCenter, m_sweep.localCenter);
      data->center = m_sweep.localCenter;
  }
  
  inline b2Vec2 b2Body::GetWorldPoint(const b2Vec2& localPoint) const
  {
      return b2Mul(m_xf, localPoint);
  }
  
  inline b2Vec2 b2Body::GetWorldVector(const b2Vec2& localVector) const
  {
      return b2Mul(m_xf.q, localVector);
  }
  
  inline b2Vec2 b2Body::GetLocalPoint(const b2Vec2& worldPoint) const
  {
      return b2MulT(m_xf, worldPoint);
  }
  
  inline b2Vec2 b2Body::GetLocalVector(const b2Vec2& worldVector) const
  {
      return b2MulT(m_xf.q, worldVector);
  }
  
  inline b2Vec2 b2Body::GetLinearVelocityFromWorldPoint(const b2Vec2& worldPoint) const
  {
      return m_linearVelocity + b2Cross(m_angularVelocity, worldPoint - m_sweep.c);
  }
  
  inline b2Vec2 b2Body::GetLinearVelocityFromLocalPoint(const b2Vec2& localPoint) const
  {
      return GetLinearVelocityFromWorldPoint(GetWorldPoint(localPoint));
  }
  
  inline float32 b2Body::GetLinearDamping() const
  {
      return m_linearDamping;
  }
  
  inline void b2Body::SetLinearDamping(float32 linearDamping)
  {
      m_linearDamping = linearDamping;
  }
  
  inline float32 b2Body::GetAngularDamping() const
  {
      return m_angularDamping;
  }
  
  inline void b2Body::SetAngularDamping(float32 angularDamping)
  {
      m_angularDamping = angularDamping;
  }
  
  inline float32 b2Body::GetGravityScale() const
  {
      return m_gravityScale;
  }
  
  inline void b2Body::SetGravityScale(float32 scale)
  {
      m_gravityScale = scale;
  }
  
  inline void b2Body::SetBullet(bool flag)
  {
      if (flag)
      {
          m_flags |= e_bulletFlag;
      }
      else
      {
          m_flags &= ~e_bulletFlag;
      }
  }
  
  inline bool b2Body::IsBullet() const
  {
      return (m_flags & e_bulletFlag) == e_bulletFlag;
  }
  
  inline void b2Body::SetAwake(bool flag)
  {
      if (flag)
      {
          if ((m_flags & e_awakeFlag) == 0)
          {
              m_flags |= e_awakeFlag;
              m_sleepTime = 0.0f;
          }
      }
      else
      {
          m_flags &= ~e_awakeFlag;
          m_sleepTime = 0.0f;
          m_linearVelocity.SetZero();
          m_angularVelocity = 0.0f;
          m_force.SetZero();
          m_torque = 0.0f;
      }
  }
  
  inline bool b2Body::IsAwake() const
  {
      return (m_flags & e_awakeFlag) == e_awakeFlag;
  }
  
  inline bool b2Body::IsActive() const
  {
      return (m_flags & e_activeFlag) == e_activeFlag;
  }
  
  inline void b2Body::SetFixedRotation(bool flag)
  {
      if (flag)
      {
          m_flags |= e_fixedRotationFlag;
      }
      else
      {
          m_flags &= ~e_fixedRotationFlag;
      }
  
      ResetMassData();
  }
  
  inline bool b2Body::IsFixedRotation() const
  {
      return (m_flags & e_fixedRotationFlag) == e_fixedRotationFlag;
  }
  
  inline void b2Body::SetSleepingAllowed(bool flag)
  {
      if (flag)
      {
          m_flags |= e_autoSleepFlag;
      }
      else
      {
          m_flags &= ~e_autoSleepFlag;
          SetAwake(true);
      }
  }
  
  inline bool b2Body::IsSleepingAllowed() const
  {
      return (m_flags & e_autoSleepFlag) == e_autoSleepFlag;
  }
  
  inline b2Fixture* b2Body::GetFixtureList()
  {
      return m_fixtureList;
  }
  
  inline const b2Fixture* b2Body::GetFixtureList() const
  {
      return m_fixtureList;
  }
  
  inline b2JointEdge* b2Body::GetJointList()
  {
      return m_jointList;
  }
  
  inline const b2JointEdge* b2Body::GetJointList() const
  {
      return m_jointList;
  }
  
  inline b2ContactEdge* b2Body::GetContactList()
  {
      return m_contactList;
  }
  
  inline const b2ContactEdge* b2Body::GetContactList() const
  {
      return m_contactList;
  }
  
  inline b2Body* b2Body::GetNext()
  {
      return m_next;
  }
  
  inline const b2Body* b2Body::GetNext() const
  {
      return m_next;
  }
  
  inline void b2Body::SetUserData(void* data)
  {
      m_userData = data;
  }
  
  inline void* b2Body::GetUserData() const
  {
      return m_userData;
  }
  
  inline void b2Body::ApplyForce(const b2Vec2& force, const b2Vec2& point)
  {
      if (m_type != b2_dynamicBody)
      {
          return;
      }
  
      if (IsAwake() == false)
      {
          SetAwake(true);
      }
  
      m_force += force;
      m_torque += b2Cross(point - m_sweep.c, force);
  }
  
  inline void b2Body::ApplyForceToCenter(const b2Vec2& force)
  {
      if (m_type != b2_dynamicBody)
      {
          return;
      }
  
      if (IsAwake() == false)
      {
          SetAwake(true);
      }
  
      m_force += force;
  }
  
  inline void b2Body::ApplyTorque(float32 torque)
  {
      if (m_type != b2_dynamicBody)
      {
          return;
      }
  
      if (IsAwake() == false)
      {
          SetAwake(true);
      }
  
      m_torque += torque;
  }
  
  inline void b2Body::ApplyLinearImpulse(const b2Vec2& impulse, const b2Vec2& point)
  {
      if (m_type != b2_dynamicBody)
      {
          return;
      }
  
      if (IsAwake() == false)
      {
          SetAwake(true);
      }
      m_linearVelocity += m_invMass * impulse;
      m_angularVelocity += m_invI * b2Cross(point - m_sweep.c, impulse);
  }
  
  inline void b2Body::ApplyAngularImpulse(float32 impulse)
  {
      if (m_type != b2_dynamicBody)
      {
          return;
      }
  
      if (IsAwake() == false)
      {
          SetAwake(true);
      }
      m_angularVelocity += m_invI * impulse;
  }
  
  inline void b2Body::SynchronizeTransform()
  {
      m_xf.q.Set(m_sweep.a);
      m_xf.p = m_sweep.c - b2Mul(m_xf.q, m_sweep.localCenter);
  }
  
  inline void b2Body::Advance(float32 alpha)
  {
      // Advance to the new safe time. This doesn't sync the broad-phase.
      m_sweep.Advance(alpha);
      m_sweep.c = m_sweep.c0;
      m_sweep.a = m_sweep.a0;
      m_xf.q.Set(m_sweep.a);
      m_xf.p = m_sweep.c - b2Mul(m_xf.q, m_sweep.localCenter);
  }
  
  inline b2World* b2Body::GetWorld()
  {
      return m_world;
  }
  
  inline const b2World* b2Body::GetWorld() const
  {
      return m_world;
  }
  
  #endif
  