diff options
Diffstat (limited to 'source/external/Box2D/Dynamics/Joints/b2PulleyJoint.h')
| -rw-r--r-- | source/external/Box2D/Dynamics/Joints/b2PulleyJoint.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/source/external/Box2D/Dynamics/Joints/b2PulleyJoint.h b/source/external/Box2D/Dynamics/Joints/b2PulleyJoint.h new file mode 100644 index 0000000..71c759b --- /dev/null +++ b/source/external/Box2D/Dynamics/Joints/b2PulleyJoint.h @@ -0,0 +1,152 @@ +/* +* 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_PULLEY_JOINT_H +#define B2_PULLEY_JOINT_H + +#include "Box2D/Dynamics/Joints/b2Joint.h" + +const float32 b2_minPulleyLength = 2.0f; + +/// Pulley joint definition. This requires two ground anchors, +/// two dynamic body anchor points, and a pulley ratio. +struct b2PulleyJointDef : public b2JointDef +{ + b2PulleyJointDef() + { + type = e_pulleyJoint; + groundAnchorA.Set(-1.0f, 1.0f); + groundAnchorB.Set(1.0f, 1.0f); + localAnchorA.Set(-1.0f, 0.0f); + localAnchorB.Set(1.0f, 0.0f); + lengthA = 0.0f; + lengthB = 0.0f; + ratio = 1.0f; + collideConnected = true; + } + + /// Initialize the bodies, anchors, lengths, max lengths, and ratio using the world anchors. + void Initialize(b2Body* bodyA, b2Body* bodyB, + const b2Vec2& groundAnchorA, const b2Vec2& groundAnchorB, + const b2Vec2& anchorA, const b2Vec2& anchorB, + float32 ratio); + + /// The first ground anchor in world coordinates. This point never moves. + b2Vec2 groundAnchorA; + + /// The second ground anchor in world coordinates. This point never moves. + b2Vec2 groundAnchorB; + + /// The local anchor point relative to bodyA's origin. + b2Vec2 localAnchorA; + + /// The local anchor point relative to bodyB's origin. + b2Vec2 localAnchorB; + + /// The a reference length for the segment attached to bodyA. + float32 lengthA; + + /// The a reference length for the segment attached to bodyB. + float32 lengthB; + + /// The pulley ratio, used to simulate a block-and-tackle. + float32 ratio; +}; + +/// The pulley joint is connected to two bodies and two fixed ground points. +/// The pulley supports a ratio such that: +/// length1 + ratio * length2 <= constant +/// Yes, the force transmitted is scaled by the ratio. +/// Warning: the pulley joint can get a bit squirrelly by itself. They often +/// work better when combined with prismatic joints. You should also cover the +/// the anchor points with static shapes to prevent one side from going to +/// zero length. +class b2PulleyJoint : public b2Joint +{ +public: + b2Vec2 GetAnchorA() const override; + b2Vec2 GetAnchorB() const override; + + b2Vec2 GetReactionForce(float32 inv_dt) const override; + float32 GetReactionTorque(float32 inv_dt) const override; + + /// Get the first ground anchor. + b2Vec2 GetGroundAnchorA() const; + + /// Get the second ground anchor. + b2Vec2 GetGroundAnchorB() const; + + /// Get the current length of the segment attached to bodyA. + float32 GetLengthA() const; + + /// Get the current length of the segment attached to bodyB. + float32 GetLengthB() const; + + /// Get the pulley ratio. + float32 GetRatio() const; + + /// Get the current length of the segment attached to bodyA. + float32 GetCurrentLengthA() const; + + /// Get the current length of the segment attached to bodyB. + float32 GetCurrentLengthB() const; + + /// Dump joint to dmLog + void Dump() override; + + /// Implement b2Joint::ShiftOrigin + void ShiftOrigin(const b2Vec2& newOrigin) override; + +protected: + + friend class b2Joint; + b2PulleyJoint(const b2PulleyJointDef* data); + + void InitVelocityConstraints(const b2SolverData& data) override; + void SolveVelocityConstraints(const b2SolverData& data) override; + bool SolvePositionConstraints(const b2SolverData& data) override; + + b2Vec2 m_groundAnchorA; + b2Vec2 m_groundAnchorB; + float32 m_lengthA; + float32 m_lengthB; + + // Solver shared + b2Vec2 m_localAnchorA; + b2Vec2 m_localAnchorB; + float32 m_constant; + float32 m_ratio; + float32 m_impulse; + + // Solver temp + int32 m_indexA; + int32 m_indexB; + b2Vec2 m_uA; + b2Vec2 m_uB; + 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; +}; + +#endif |