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// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#ifndef B2_PRISMATIC_JOINT_H
#define B2_PRISMATIC_JOINT_H
#include "b2_api.h"
#include "b2_joint.h"
/// Prismatic joint definition. This requires defining a line of
/// motion using an axis and an anchor point. The definition uses local
/// anchor points and a local axis so that the initial configuration
/// can violate the constraint slightly. The joint translation is zero
/// when the local anchor points coincide in world space. Using local
/// anchors and a local axis helps when saving and loading a game.
struct B2_API b2PrismaticJointDef : public b2JointDef
{
b2PrismaticJointDef()
{
type = e_prismaticJoint;
localAnchorA.SetZero();
localAnchorB.SetZero();
localAxisA.Set(1.0f, 0.0f);
referenceAngle = 0.0f;
enableLimit = false;
lowerTranslation = 0.0f;
upperTranslation = 0.0f;
enableMotor = false;
maxMotorForce = 0.0f;
motorSpeed = 0.0f;
}
/// Initialize the bodies, anchors, axis, and reference angle using the world
/// anchor and unit world axis.
void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor, const b2Vec2& axis);
/// The local anchor point relative to bodyA's origin.
b2Vec2 localAnchorA;
/// The local anchor point relative to bodyB's origin.
b2Vec2 localAnchorB;
/// The local translation unit axis in bodyA.
b2Vec2 localAxisA;
/// The constrained angle between the bodies: bodyB_angle - bodyA_angle.
float referenceAngle;
/// Enable/disable the joint limit.
bool enableLimit;
/// The lower translation limit, usually in meters.
float lowerTranslation;
/// The upper translation limit, usually in meters.
float upperTranslation;
/// Enable/disable the joint motor.
bool enableMotor;
/// The maximum motor torque, usually in N-m.
float maxMotorForce;
/// The desired motor speed in radians per second.
float motorSpeed;
};
/// A prismatic joint. This joint provides one degree of freedom: translation
/// along an axis fixed in bodyA. Relative rotation is prevented. You can
/// use a joint limit to restrict the range of motion and a joint motor to
/// drive the motion or to model joint friction.
class B2_API b2PrismaticJoint : public b2Joint
{
public:
b2Vec2 GetAnchorA() const override;
b2Vec2 GetAnchorB() const override;
b2Vec2 GetReactionForce(float inv_dt) const override;
float GetReactionTorque(float inv_dt) 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; }
/// The local joint axis relative to bodyA.
const b2Vec2& GetLocalAxisA() const { return m_localXAxisA; }
/// Get the reference angle.
float GetReferenceAngle() const { return m_referenceAngle; }
/// Get the current joint translation, usually in meters.
float GetJointTranslation() const;
/// Get the current joint translation speed, usually in meters per second.
float GetJointSpeed() const;
/// Is the joint limit enabled?
bool IsLimitEnabled() const;
/// Enable/disable the joint limit.
void EnableLimit(bool flag);
/// Get the lower joint limit, usually in meters.
float GetLowerLimit() const;
/// Get the upper joint limit, usually in meters.
float GetUpperLimit() const;
/// Set the joint limits, usually in meters.
void SetLimits(float lower, float upper);
/// Is the joint motor enabled?
bool IsMotorEnabled() const;
/// Enable/disable the joint motor.
void EnableMotor(bool flag);
/// Set the motor speed, usually in meters per second.
void SetMotorSpeed(float speed);
/// Get the motor speed, usually in meters per second.
float GetMotorSpeed() const;
/// Set the maximum motor force, usually in N.
void SetMaxMotorForce(float force);
float GetMaxMotorForce() const { return m_maxMotorForce; }
/// Get the current motor force given the inverse time step, usually in N.
float GetMotorForce(float inv_dt) const;
/// Dump to b2Log
void Dump() override;
///
void Draw(b2Draw* draw) const override;
protected:
friend class b2Joint;
friend class b2GearJoint;
b2PrismaticJoint(const b2PrismaticJointDef* def);
void InitVelocityConstraints(const b2SolverData& data) override;
void SolveVelocityConstraints(const b2SolverData& data) override;
bool SolvePositionConstraints(const b2SolverData& data) override;
b2Vec2 m_localAnchorA;
b2Vec2 m_localAnchorB;
b2Vec2 m_localXAxisA;
b2Vec2 m_localYAxisA;
float m_referenceAngle;
b2Vec2 m_impulse;
float m_motorImpulse;
float m_lowerImpulse;
float m_upperImpulse;
float m_lowerTranslation;
float m_upperTranslation;
float m_maxMotorForce;
float m_motorSpeed;
bool m_enableLimit;
bool m_enableMotor;
// Solver temp
int32 m_indexA;
int32 m_indexB;
b2Vec2 m_localCenterA;
b2Vec2 m_localCenterB;
float m_invMassA;
float m_invMassB;
float m_invIA;
float m_invIB;
b2Vec2 m_axis, m_perp;
float m_s1, m_s2;
float m_a1, m_a2;
b2Mat22 m_K;
float m_translation;
float m_axialMass;
};
inline float b2PrismaticJoint::GetMotorSpeed() const
{
return m_motorSpeed;
}
#endif
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