b2WeldJoint.h
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上传日期:2022-01-07
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- /*
- * Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
- *
- * 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_WELD_JOINT_H
- #define B2_WELD_JOINT_H
- #include <Box2D/Dynamics/Joints/b2Joint.h>
- /// Weld joint definition. You need to specify local anchor points
- /// where they are attached and the relative body angle. The position
- /// of the anchor points is important for computing the reaction torque.
- struct b2WeldJointDef : public b2JointDef
- {
- b2WeldJointDef()
- {
- type = e_weldJoint;
- localAnchorA.Set(0.0f, 0.0f);
- localAnchorB.Set(0.0f, 0.0f);
- referenceAngle = 0.0f;
- }
- /// Initialize the bodies, anchors, and reference angle using a world
- /// anchor point.
- void Initialize(b2Body* body1, b2Body* body2, const b2Vec2& anchor);
- /// The local anchor point relative to body1's origin.
- b2Vec2 localAnchorA;
- /// The local anchor point relative to body2's origin.
- b2Vec2 localAnchorB;
- /// The body2 angle minus body1 angle in the reference state (radians).
- float32 referenceAngle;
- };
- /// A weld joint essentially glues two bodies together. A weld joint may
- /// distort somewhat because the island constraint solver is approximate.
- class b2WeldJoint : public b2Joint
- {
- public:
- b2Vec2 GetAnchorA() const;
- b2Vec2 GetAnchorB() const;
- b2Vec2 GetReactionForce(float32 inv_dt) const;
- float32 GetReactionTorque(float32 inv_dt) const;
- protected:
- friend class b2Joint;
- b2WeldJoint(const b2WeldJointDef* def);
- void InitVelocityConstraints(const b2TimeStep& step);
- void SolveVelocityConstraints(const b2TimeStep& step);
- bool SolvePositionConstraints(float32 baumgarte);
- b2Vec2 m_localAnchorA;
- b2Vec2 m_localAnchorB;
- float32 m_referenceAngle;
- b2Vec3 m_impulse;
- b2Mat33 m_mass;
- };
- #endif