Box2D 2.4.1
A 2D physics engine for games
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b2_wheel_joint.h
1// MIT License
2
3// Copyright (c) 2019 Erin Catto
4
5// Permission is hereby granted, free of charge, to any person obtaining a copy
6// of this software and associated documentation files (the "Software"), to deal
7// in the Software without restriction, including without limitation the rights
8// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9// copies of the Software, and to permit persons to whom the Software is
10// furnished to do so, subject to the following conditions:
11
12// The above copyright notice and this permission notice shall be included in all
13// copies or substantial portions of the Software.
14
15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21// SOFTWARE.
22
23#ifndef B2_WHEEL_JOINT_H
24#define B2_WHEEL_JOINT_H
25
26#include "b2_api.h"
27#include "b2_joint.h"
28
35struct B2_API b2WheelJointDef : public b2JointDef
36{
38 {
39 type = e_wheelJoint;
40 localAnchorA.SetZero();
41 localAnchorB.SetZero();
42 localAxisA.Set(1.0f, 0.0f);
43 enableLimit = false;
44 lowerTranslation = 0.0f;
45 upperTranslation = 0.0f;
46 enableMotor = false;
47 maxMotorTorque = 0.0f;
48 motorSpeed = 0.0f;
49 stiffness = 0.0f;
50 damping = 0.0f;
51 }
52
55 void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor, const b2Vec2& axis);
56
59
62
65
68
71
74
77
80
83
85 float stiffness;
86
88 float damping;
89};
90
95class B2_API b2WheelJoint : public b2Joint
96{
97public:
98 b2Vec2 GetAnchorA() const override;
99 b2Vec2 GetAnchorB() const override;
100
101 b2Vec2 GetReactionForce(float inv_dt) const override;
102 float GetReactionTorque(float inv_dt) const override;
103
105 const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
106
108 const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
109
111 const b2Vec2& GetLocalAxisA() const { return m_localXAxisA; }
112
114 float GetJointTranslation() const;
115
117 float GetJointLinearSpeed() const;
118
120 float GetJointAngle() const;
121
123 float GetJointAngularSpeed() const;
124
126 bool IsLimitEnabled() const;
127
129 void EnableLimit(bool flag);
130
132 float GetLowerLimit() const;
133
135 float GetUpperLimit() const;
136
138 void SetLimits(float lower, float upper);
139
141 bool IsMotorEnabled() const;
142
144 void EnableMotor(bool flag);
145
147 void SetMotorSpeed(float speed);
148
150 float GetMotorSpeed() const;
151
153 void SetMaxMotorTorque(float torque);
154 float GetMaxMotorTorque() const;
155
157 float GetMotorTorque(float inv_dt) const;
158
160 void SetStiffness(float stiffness);
161 float GetStiffness() const;
162
164 void SetDamping(float damping);
165 float GetDamping() const;
166
168 void Dump() override;
169
171 void Draw(b2Draw* draw) const override;
172
173protected:
174
175 friend class b2Joint;
176 b2WheelJoint(const b2WheelJointDef* def);
177
178 void InitVelocityConstraints(const b2SolverData& data) override;
179 void SolveVelocityConstraints(const b2SolverData& data) override;
180 bool SolvePositionConstraints(const b2SolverData& data) override;
181
182 b2Vec2 m_localAnchorA;
183 b2Vec2 m_localAnchorB;
184 b2Vec2 m_localXAxisA;
185 b2Vec2 m_localYAxisA;
186
187 float m_impulse;
188 float m_motorImpulse;
189 float m_springImpulse;
190
191 float m_lowerImpulse;
192 float m_upperImpulse;
193 float m_translation;
194 float m_lowerTranslation;
195 float m_upperTranslation;
196
197 float m_maxMotorTorque;
198 float m_motorSpeed;
199
200 bool m_enableLimit;
201 bool m_enableMotor;
202
203 float m_stiffness;
204 float m_damping;
205
206 // Solver temp
207 int32 m_indexA;
208 int32 m_indexB;
209 b2Vec2 m_localCenterA;
210 b2Vec2 m_localCenterB;
211 float m_invMassA;
212 float m_invMassB;
213 float m_invIA;
214 float m_invIB;
215
216 b2Vec2 m_ax, m_ay;
217 float m_sAx, m_sBx;
218 float m_sAy, m_sBy;
219
220 float m_mass;
221 float m_motorMass;
222 float m_axialMass;
223 float m_springMass;
224
225 float m_bias;
226 float m_gamma;
227
228};
229
230inline float b2WheelJoint::GetMotorSpeed() const
231{
232 return m_motorSpeed;
233}
234
235inline float b2WheelJoint::GetMaxMotorTorque() const
236{
237 return m_maxMotorTorque;
238}
239
240#endif
A rigid body. These are created via b2World::CreateBody.
Definition b2_body.h:129
Definition b2_draw.h:49
Definition b2_joint.h:110
Definition b2_wheel_joint.h:96
float GetJointAngle() const
Get the current joint angle in radians.
void Draw(b2Draw *draw) const override
Debug draw this joint.
float GetReactionTorque(float inv_dt) const override
Get the reaction torque on bodyB in N*m.
void SetStiffness(float stiffness)
Access spring stiffness.
b2Vec2 GetAnchorA() const override
Get the anchor point on bodyA in world coordinates.
float GetJointAngularSpeed() const
Get the current joint angular speed in radians per second.
const b2Vec2 & GetLocalAnchorA() const
The local anchor point relative to bodyA's origin.
Definition b2_wheel_joint.h:105
float GetLowerLimit() const
Get the lower joint translation limit, usually in meters.
const b2Vec2 & GetLocalAxisA() const
The local joint axis relative to bodyA.
Definition b2_wheel_joint.h:111
float GetMotorTorque(float inv_dt) const
Get the current motor torque given the inverse time step, usually in N-m.
b2Vec2 GetAnchorB() const override
Get the anchor point on bodyB in world coordinates.
float GetMotorSpeed() const
Get the motor speed, usually in radians per second.
Definition b2_wheel_joint.h:230
void EnableLimit(bool flag)
Enable/disable the joint translation limit.
void EnableMotor(bool flag)
Enable/disable the joint motor.
float GetJointTranslation() const
Get the current joint translation, usually in meters.
void Dump() override
Dump to b2Log.
bool IsLimitEnabled() const
Is the joint limit enabled?
void SetDamping(float damping)
Access damping.
void SetMotorSpeed(float speed)
Set the motor speed, usually in radians per second.
void SetLimits(float lower, float upper)
Set the joint translation limits, usually in meters.
float GetJointLinearSpeed() const
Get the current joint linear speed, usually in meters per second.
void SetMaxMotorTorque(float torque)
Set/Get the maximum motor force, usually in N-m.
float GetUpperLimit() const
Get the upper joint translation limit, usually in meters.
const b2Vec2 & GetLocalAnchorB() const
The local anchor point relative to bodyB's origin.
Definition b2_wheel_joint.h:108
bool IsMotorEnabled() const
Is the joint motor enabled?
b2Vec2 GetReactionForce(float inv_dt) const override
Get the reaction force on bodyB at the joint anchor in Newtons.
Joint definitions are used to construct joints.
Definition b2_joint.h:72
Solver Data.
Definition b2_time_step.h:68
A 2D column vector.
Definition b2_math.h:42
Definition b2_wheel_joint.h:36
float motorSpeed
The desired motor speed in radians per second.
Definition b2_wheel_joint.h:82
bool enableLimit
Enable/disable the joint limit.
Definition b2_wheel_joint.h:67
float stiffness
Suspension stiffness. Typically in units N/m.
Definition b2_wheel_joint.h:85
float upperTranslation
The upper translation limit, usually in meters.
Definition b2_wheel_joint.h:73
float lowerTranslation
The lower translation limit, usually in meters.
Definition b2_wheel_joint.h:70
b2Vec2 localAnchorB
The local anchor point relative to bodyB's origin.
Definition b2_wheel_joint.h:61
bool enableMotor
Enable/disable the joint motor.
Definition b2_wheel_joint.h:76
b2Vec2 localAnchorA
The local anchor point relative to bodyA's origin.
Definition b2_wheel_joint.h:58
float damping
Suspension damping. Typically in units of N*s/m.
Definition b2_wheel_joint.h:88
float maxMotorTorque
The maximum motor torque, usually in N-m.
Definition b2_wheel_joint.h:79
b2Vec2 localAxisA
The local translation axis in bodyA.
Definition b2_wheel_joint.h:64
void Initialize(b2Body *bodyA, b2Body *bodyB, const b2Vec2 &anchor, const b2Vec2 &axis)