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Diffstat (limited to 'Source/external/Box2D/Dynamics/Joints/b2RevoluteJoint.h')
| -rw-r--r-- | Source/external/Box2D/Dynamics/Joints/b2RevoluteJoint.h | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/Source/external/Box2D/Dynamics/Joints/b2RevoluteJoint.h b/Source/external/Box2D/Dynamics/Joints/b2RevoluteJoint.h new file mode 100644 index 0000000..06b1455 --- /dev/null +++ b/Source/external/Box2D/Dynamics/Joints/b2RevoluteJoint.h @@ -0,0 +1,204 @@ +/* +* 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_REVOLUTE_JOINT_H +#define B2_REVOLUTE_JOINT_H + +#include "Box2D/Dynamics/Joints/b2Joint.h" + +/// Revolute joint definition. This requires defining an +/// anchor point where the bodies are joined. The definition +/// uses local anchor points so that the initial configuration +/// can violate the constraint slightly. You also need to +/// specify the initial relative angle for joint limits. This +/// helps when saving and loading a game. +/// The local anchor points are measured from the body's origin +/// rather than the center of mass because: +/// 1. you might not know where the center of mass will be. +/// 2. if you add/remove shapes from a body and recompute the mass, +/// the joints will be broken. +struct b2RevoluteJointDef : public b2JointDef +{ + b2RevoluteJointDef() + { + type = e_revoluteJoint; + localAnchorA.Set(0.0f, 0.0f); + localAnchorB.Set(0.0f, 0.0f); + referenceAngle = 0.0f; + lowerAngle = 0.0f; + upperAngle = 0.0f; + maxMotorTorque = 0.0f; + motorSpeed = 0.0f; + enableLimit = false; + enableMotor = false; + } + + /// Initialize the bodies, anchors, and reference angle using a world + /// anchor point. + void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor); + + /// The local anchor point relative to bodyA's origin. + b2Vec2 localAnchorA; + + /// The local anchor point relative to bodyB's origin. + b2Vec2 localAnchorB; + + /// The bodyB angle minus bodyA angle in the reference state (radians). + float32 referenceAngle; + + /// A flag to enable joint limits. + bool enableLimit; + + /// The lower angle for the joint limit (radians). + float32 lowerAngle; + + /// The upper angle for the joint limit (radians). + float32 upperAngle; + + /// A flag to enable the joint motor. + bool enableMotor; + + /// The desired motor speed. Usually in radians per second. + float32 motorSpeed; + + /// The maximum motor torque used to achieve the desired motor speed. + /// Usually in N-m. + float32 maxMotorTorque; +}; + +/// A revolute joint constrains two bodies to share a common point while they +/// are free to rotate about the point. The relative rotation about the shared +/// point is the joint angle. You can limit the relative rotation with +/// a joint limit that specifies a lower and upper angle. You can use a motor +/// to drive the relative rotation about the shared point. A maximum motor torque +/// is provided so that infinite forces are not generated. +class b2RevoluteJoint : public b2Joint +{ +public: + b2Vec2 GetAnchorA() const override; + b2Vec2 GetAnchorB() const override; + + /// The local anchor point relative to bodyA's origin. + const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; } + + /// The local anchor point relative to bodyB's origin. + const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; } + + /// Get the reference angle. + float32 GetReferenceAngle() const { return m_referenceAngle; } + + /// Get the current joint angle in radians. + float32 GetJointAngle() const; + + /// Get the current joint angle speed in radians per second. + float32 GetJointSpeed() const; + + /// Is the joint limit enabled? + bool IsLimitEnabled() const; + + /// Enable/disable the joint limit. + void EnableLimit(bool flag); + + /// Get the lower joint limit in radians. + float32 GetLowerLimit() const; + + /// Get the upper joint limit in radians. + float32 GetUpperLimit() const; + + /// Set the joint limits in radians. + void SetLimits(float32 lower, float32 upper); + + /// Is the joint motor enabled? + bool IsMotorEnabled() const; + + /// Enable/disable the joint motor. + void EnableMotor(bool flag); + + /// Set the motor speed in radians per second. + void SetMotorSpeed(float32 speed); + + /// Get the motor speed in radians per second. + float32 GetMotorSpeed() const; + + /// Set the maximum motor torque, usually in N-m. + void SetMaxMotorTorque(float32 torque); + float32 GetMaxMotorTorque() const { return m_maxMotorTorque; } + + /// Get the reaction force given the inverse time step. + /// Unit is N. + b2Vec2 GetReactionForce(float32 inv_dt) const override; + + /// Get the reaction torque due to the joint limit given the inverse time step. + /// Unit is N*m. + float32 GetReactionTorque(float32 inv_dt) const override; + + /// Get the current motor torque given the inverse time step. + /// Unit is N*m. + float32 GetMotorTorque(float32 inv_dt) const; + + /// Dump to b2Log. + void Dump() override; + +protected: + + friend class b2Joint; + friend class b2GearJoint; + + b2RevoluteJoint(const b2RevoluteJointDef* def); + + void InitVelocityConstraints(const b2SolverData& data) override; + void SolveVelocityConstraints(const b2SolverData& data) override; + bool SolvePositionConstraints(const b2SolverData& data) override; + + // Solver shared + b2Vec2 m_localAnchorA; + b2Vec2 m_localAnchorB; + b2Vec3 m_impulse; + float32 m_motorImpulse; + + bool m_enableMotor; + float32 m_maxMotorTorque; + float32 m_motorSpeed; + + bool m_enableLimit; + float32 m_referenceAngle; + float32 m_lowerAngle; + float32 m_upperAngle; + + // Solver temp + int32 m_indexA; + int32 m_indexB; + b2Vec2 m_rA; + b2Vec2 m_rB; + b2Vec2 m_localCenterA; + b2Vec2 m_localCenterB; + float32 m_invMassA; + float32 m_invMassB; + float32 m_invIA; + float32 m_invIB; + b2Mat33 m_mass; // effective mass for point-to-point constraint. + float32 m_motorMass; // effective mass for motor/limit angular constraint. + b2LimitState m_limitState; +}; + +inline float32 b2RevoluteJoint::GetMotorSpeed() const +{ + return m_motorSpeed; +} + +#endif |