File indexing completed on 2024-12-29 03:29:27

 /*
 * Copyright (c) 2006-2012 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_MOTOR_JOINT_H
 #define B2_MOTOR_JOINT_H
 
 #include <Box2D/Dynamics/Joints/b2Joint.h>
 
 /// Motor joint definition.
 struct b2MotorJointDef : public b2JointDef
 {
     b2MotorJointDef()
     {
         type = e_motorJoint;
         linearOffset.SetZero();
         angularOffset = 0.0f;
         maxForce = 1.0f;
         maxTorque = 1.0f;
         correctionFactor = 0.3f;
     }
 
     /// Initialize the bodies and offsets using the current transforms.
     void Initialize(b2Body* bodyA, b2Body* bodyB);
 
     /// Position of bodyB minus the position of bodyA, in bodyA's frame, in meters.
     b2Vec2 linearOffset;
 
     /// The bodyB angle minus bodyA angle in radians.
     float32 angularOffset;
     
     /// The maximum motor force in N.
     float32 maxForce;
 
     /// The maximum motor torque in N-m.
     float32 maxTorque;
 
     /// Position correction factor in the range [0,1].
     float32 correctionFactor;
 };
 
 /// A motor joint is used to control the relative motion
 /// between two bodies. A typical usage is to control the movement
 /// of a dynamic body with respect to the ground.
 class b2MotorJoint : public b2Joint
 {
 public:
     b2Vec2 GetAnchorA() const;
     b2Vec2 GetAnchorB() const;
 
     b2Vec2 GetReactionForce(float32 inv_dt) const;
     float32 GetReactionTorque(float32 inv_dt) const;
 
     /// Set/get the target linear offset, in frame A, in meters.
     void SetLinearOffset(const b2Vec2& linearOffset);
     const b2Vec2& GetLinearOffset() const;
 
     /// Set/get the target angular offset, in radians.
     void SetAngularOffset(float32 angularOffset);
     float32 GetAngularOffset() const;
 
     /// Set the maximum friction force in N.
     void SetMaxForce(float32 force);
 
     /// Get the maximum friction force in N.
     float32 GetMaxForce() const;
 
     /// Set the maximum friction torque in N*m.
     void SetMaxTorque(float32 torque);
 
     /// Get the maximum friction torque in N*m.
     float32 GetMaxTorque() const;
 
     /// Set the position correction factor in the range [0,1].
     void SetCorrectionFactor(float32 factor);
 
     /// Get the position correction factor in the range [0,1].
     float32 GetCorrectionFactor() const;
 
     /// Dump to b2Log
     void Dump();
 
 protected:
 
     friend class b2Joint;
 
     b2MotorJoint(const b2MotorJointDef* def);
 
     void InitVelocityConstraints(const b2SolverData& data);
     void SolveVelocityConstraints(const b2SolverData& data);
     bool SolvePositionConstraints(const b2SolverData& data);
 
     // Solver shared
     b2Vec2 m_linearOffset;
     float32 m_angularOffset;
     b2Vec2 m_linearImpulse;
     float32 m_angularImpulse;
     float32 m_maxForce;
     float32 m_maxTorque;
     float32 m_correctionFactor;
 
     // Solver temp
     int32 m_indexA;
     int32 m_indexB;
     b2Vec2 m_rA;
     b2Vec2 m_rB;
     b2Vec2 m_localCenterA;
     b2Vec2 m_localCenterB;
     b2Vec2 m_linearError;
     float32 m_angularError;
     float32 m_invMassA;
     float32 m_invMassB;
     float32 m_invIA;
     float32 m_invIB;
     b2Mat22 m_linearMass;
     float32 m_angularMass;
 };
 
 #endif