diff options
Diffstat (limited to 'src/3rdparty/Box2D/Dynamics/Joints/b2DistanceJoint.h')
| -rw-r--r-- | src/3rdparty/Box2D/Dynamics/Joints/b2DistanceJoint.h | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/3rdparty/Box2D/Dynamics/Joints/b2DistanceJoint.h b/src/3rdparty/Box2D/Dynamics/Joints/b2DistanceJoint.h new file mode 100644 index 0000000..ba59210 --- /dev/null +++ b/src/3rdparty/Box2D/Dynamics/Joints/b2DistanceJoint.h @@ -0,0 +1,169 @@ +/* +* Copyright (c) 2006-2007 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_DISTANCE_JOINT_H +#define B2_DISTANCE_JOINT_H + +#include "Box2D/Dynamics/Joints/b2Joint.h" + +/// Distance joint definition. This requires defining an +/// anchor point on both bodies and the non-zero length of the +/// distance joint. The definition uses local anchor points +/// so that the initial configuration can violate the constraint +/// slightly. This helps when saving and loading a game. +/// @warning Do not use a zero or short length. +struct b2DistanceJointDef : public b2JointDef +{ + b2DistanceJointDef() + { + type = e_distanceJoint; + localAnchorA.Set(0.0f, 0.0f); + localAnchorB.Set(0.0f, 0.0f); + length = 1.0f; + frequencyHz = 0.0f; + dampingRatio = 0.0f; + } + + /// Initialize the bodies, anchors, and length using the world + /// anchors. + void Initialize(b2Body* bodyA, b2Body* bodyB, + const b2Vec2& anchorA, const b2Vec2& anchorB); + + /// The local anchor point relative to bodyA's origin. + b2Vec2 localAnchorA; + + /// The local anchor point relative to bodyB's origin. + b2Vec2 localAnchorB; + + /// The natural length between the anchor points. + float32 length; + + /// The mass-spring-damper frequency in Hertz. A value of 0 + /// disables softness. + float32 frequencyHz; + + /// The damping ratio. 0 = no damping, 1 = critical damping. + float32 dampingRatio; +}; + +/// A distance joint constrains two points on two bodies +/// to remain at a fixed distance from each other. You can view +/// this as a massless, rigid rod. +class b2DistanceJoint : public b2Joint +{ +public: + + b2Vec2 GetAnchorA() const override; + b2Vec2 GetAnchorB() const override; + + /// Get the reaction force given the inverse time step. + /// Unit is N. + b2Vec2 GetReactionForce(float32 inv_dt) const override; + + /// Get the reaction torque given the inverse time step. + /// Unit is N*m. This is always zero for a distance joint. + float32 GetReactionTorque(float32 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; } + + /// Set/get the natural length. + /// Manipulating the length can lead to non-physical behavior when the frequency is zero. + void SetLength(float32 length); + float32 GetLength() const; + + /// Set/get frequency in Hz. + void SetFrequency(float32 hz); + float32 GetFrequency() const; + + /// Set/get damping ratio. + void SetDampingRatio(float32 ratio); + float32 GetDampingRatio() const; + + /// Dump joint to dmLog + void Dump() override; + +protected: + + friend class b2Joint; + b2DistanceJoint(const b2DistanceJointDef* data); + + void InitVelocityConstraints(const b2SolverData& data) override; + void SolveVelocityConstraints(const b2SolverData& data) override; + bool SolvePositionConstraints(const b2SolverData& data) override; + + float32 m_frequencyHz; + float32 m_dampingRatio; + float32 m_bias; + + // Solver shared + b2Vec2 m_localAnchorA; + b2Vec2 m_localAnchorB; + float32 m_gamma; + float32 m_impulse; + float32 m_length; + + // Solver temp + int32 m_indexA; + int32 m_indexB; + b2Vec2 m_u; + b2Vec2 m_rA; + b2Vec2 m_rB; + b2Vec2 m_localCenterA; + b2Vec2 m_localCenterB; + float32 m_invMassA; + float32 m_invMassB; + float32 m_invIA; + float32 m_invIB; + float32 m_mass; +}; + +inline void b2DistanceJoint::SetLength(float32 length) +{ + m_length = length; +} + +inline float32 b2DistanceJoint::GetLength() const +{ + return m_length; +} + +inline void b2DistanceJoint::SetFrequency(float32 hz) +{ + m_frequencyHz = hz; +} + +inline float32 b2DistanceJoint::GetFrequency() const +{ + return m_frequencyHz; +} + +inline void b2DistanceJoint::SetDampingRatio(float32 ratio) +{ + m_dampingRatio = ratio; +} + +inline float32 b2DistanceJoint::GetDampingRatio() const +{ + return m_dampingRatio; +} + +#endif |