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# Box2D/Box2D/Dynamics/Joints/b2RevoluteJoint.h

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    00001 /*
    00002 * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
    00003 *
    00004 * This software is provided 'as-is', without any express or implied
    00005 * warranty.  In no event will the authors be held liable for any damages
    00006 * arising from the use of this software.
    00007 * Permission is granted to anyone to use this software for any purpose,
    00008 * including commercial applications, and to alter it and redistribute it
    00009 * freely, subject to the following restrictions:
    00010 * 1. The origin of this software must not be misrepresented; you must not
    00011 * claim that you wrote the original software. If you use this software
    00012 * in a product, an acknowledgment in the product documentation would be
    00013 * appreciated but is not required.
    00014 * 2. Altered source versions must be plainly marked as such, and must not be
    00015 * misrepresented as being the original software.
    00016 * 3. This notice may not be removed or altered from any source distribution.
    00017 */
    00018
    00019 #ifndef B2_REVOLUTE_JOINT_H
    00020 #define B2_REVOLUTE_JOINT_H
    00021
    00022 #include <Box2D/Dynamics/Joints/b2Joint.h>
    00023
    00035 struct b2RevoluteJointDef : public b2JointDef
    00036 {
    00037         b2RevoluteJointDef()
    00038         {
    00039                 type = e_revoluteJoint;
    00040                 localAnchorA.Set(0.0f, 0.0f);
    00041                 localAnchorB.Set(0.0f, 0.0f);
    00042                 referenceAngle = 0.0f;
    00043                 lowerAngle = 0.0f;
    00044                 upperAngle = 0.0f;
    00045                 maxMotorTorque = 0.0f;
    00046                 motorSpeed = 0.0f;
    00047                 enableLimit = false;
    00048                 enableMotor = false;
    00049         }
    00050
    00053         void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
    00054
    00056         b2Vec2 localAnchorA;
    00057
    00059         b2Vec2 localAnchorB;
    00060
    00062         float32 referenceAngle;
    00063
    00065         bool enableLimit;
    00066
    00068         float32 lowerAngle;
    00069
    00071         float32 upperAngle;
    00072
    00074         bool enableMotor;
    00075
    00077         float32 motorSpeed;
    00078
    00081         float32 maxMotorTorque;
    00082 };
    00083
    00090 class b2RevoluteJoint : public b2Joint
    00091 {
    00092 public:
    00093         b2Vec2 GetAnchorA() const;
    00094         b2Vec2 GetAnchorB() const;
    00095
    00096         b2Vec2 GetReactionForce(float32 inv_dt) const;
    00097         float32 GetReactionTorque(float32 inv_dt) const;
    00098
    00100         float32 GetJointAngle() const;
    00101
    00103         float32 GetJointSpeed() const;
    00104
    00106         bool IsLimitEnabled() const;
    00107
    00109         void EnableLimit(bool flag);
    00110
    00112         float32 GetLowerLimit() const;
    00113
    00115         float32 GetUpperLimit() const;
    00116
    00118         void SetLimits(float32 lower, float32 upper);
    00119
    00121         bool IsMotorEnabled() const;
    00122
    00124         void EnableMotor(bool flag);
    00125
    00127         void SetMotorSpeed(float32 speed);
    00128
    00130         float32 GetMotorSpeed() const;
    00131
    00133         void SetMaxMotorTorque(float32 torque);
    00134
    00136         float32 GetMotorTorque() const;
    00137
    00138 protected:
    00139
    00140         friend class b2Joint;
    00141         friend class b2GearJoint;
    00142
    00143         b2RevoluteJoint(const b2RevoluteJointDef* def);
    00144
    00145         void InitVelocityConstraints(const b2TimeStep& step);
    00146         void SolveVelocityConstraints(const b2TimeStep& step);
    00147
    00148         bool SolvePositionConstraints(float32 baumgarte);
    00149
    00150         b2Vec2 m_localAnchor1;  // relative
    00151         b2Vec2 m_localAnchor2;
    00152         b2Vec3 m_impulse;
    00153         float32 m_motorImpulse;
    00154
    00155         b2Mat33 m_mass;                 // effective mass for point-to-point constraint.
    00156         float32 m_motorMass;    // effective mass for motor/limit angular constraint.
    00157
    00158         bool m_enableMotor;
    00159         float32 m_maxMotorTorque;
    00160         float32 m_motorSpeed;
    00161
    00162         bool m_enableLimit;
    00163         float32 m_referenceAngle;
    00164         float32 m_lowerAngle;
    00165         float32 m_upperAngle;
    00166         b2LimitState m_limitState;
    00167 };
    00168
    00169 inline float32 b2RevoluteJoint::GetMotorSpeed() const
    00170 {
    00171         return m_motorSpeed;
    00172 }
    00173
    00174 #endif