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Diffstat (limited to 'tests/box2d/Box2D/Dynamics/Joints/b2RevoluteJoint.h')
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1 files changed, 214 insertions, 0 deletions
diff --git a/tests/box2d/Box2D/Dynamics/Joints/b2RevoluteJoint.h b/tests/box2d/Box2D/Dynamics/Joints/b2RevoluteJoint.h new file mode 100755 index 00000000..672ef169 --- /dev/null +++ b/tests/box2d/Box2D/Dynamics/Joints/b2RevoluteJoint.h @@ -0,0 +1,214 @@ +/*
+* 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_REVOLUTE_JOINT_H
+#define B2_REVOLUTE_JOINT_H
+
+#include <Box2D/Dynamics/Joints/b2Joint.h>
+
+/// Revolute joint definition. This requires defining an
+/// anchor point where the bodies are joined. The definition
+/// uses local anchor points so that the initial configuration
+/// can violate the constraint slightly. You also need to
+/// specify the initial relative angle for joint limits. This
+/// helps when saving and loading a game.
+/// The local anchor points are measured from the body's origin
+/// rather than the center of mass because:
+/// 1. you might not know where the center of mass will be.
+/// 2. if you add/remove shapes from a body and recompute the mass,
+/// the joints will be broken.
+// emscripten - b2RevoluteJointDef: add functions to set/get base class members
+struct b2RevoluteJointDef : public b2JointDef
+{
+ b2RevoluteJointDef()
+ {
+ type = e_revoluteJoint;
+ localAnchorA.Set(0.0f, 0.0f);
+ localAnchorB.Set(0.0f, 0.0f);
+ referenceAngle = 0.0f;
+ lowerAngle = 0.0f;
+ upperAngle = 0.0f;
+ maxMotorTorque = 0.0f;
+ motorSpeed = 0.0f;
+ enableLimit = false;
+ enableMotor = false;
+ }
+
+ /// Initialize the bodies, anchors, and reference angle using a world
+ /// anchor point.
+ void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
+
+ /// The local anchor point relative to bodyA's origin.
+ b2Vec2 localAnchorA;
+
+ /// The local anchor point relative to bodyB's origin.
+ b2Vec2 localAnchorB;
+
+ /// The bodyB angle minus bodyA angle in the reference state (radians).
+ float32 referenceAngle;
+
+ /// A flag to enable joint limits.
+ bool enableLimit;
+
+ /// The lower angle for the joint limit (radians).
+ float32 lowerAngle;
+
+ /// The upper angle for the joint limit (radians).
+ float32 upperAngle;
+
+ /// A flag to enable the joint motor.
+ bool enableMotor;
+
+ /// The desired motor speed. Usually in radians per second.
+ float32 motorSpeed;
+
+ /// The maximum motor torque used to achieve the desired motor speed.
+ /// Usually in N-m.
+ float32 maxMotorTorque;
+
+ // to generate javascript bindings
+ void set_bodyA(b2Body* b) { bodyA = b; }
+ void set_bodyB(b2Body* b) { bodyB = b; }
+ void set_collideConnected(bool b) { collideConnected = b; }
+ b2Body* get_bodyA(b2Body* b) { return bodyA; }
+ b2Body* get_bodyB(b2Body* b) { return bodyB; }
+ bool get_collideConnected(bool b) { return collideConnected; }
+};
+
+/// A revolute joint constrains two bodies to share a common point while they
+/// are free to rotate about the point. The relative rotation about the shared
+/// point is the joint angle. You can limit the relative rotation with
+/// a joint limit that specifies a lower and upper angle. You can use a motor
+/// to drive the relative rotation about the shared point. A maximum motor torque
+/// is provided so that infinite forces are not generated.
+// emscripten - b2RevoluteJoint: make constructor public
+class b2RevoluteJoint : public b2Joint
+{
+public:
+ b2Vec2 GetAnchorA() const;
+ b2Vec2 GetAnchorB() const;
+
+ /// 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; }
+
+ /// Get the reference angle.
+ float32 GetReferenceAngle() const { return m_referenceAngle; }
+
+ /// Get the current joint angle in radians.
+ float32 GetJointAngle() const;
+
+ /// Get the current joint angle speed in radians per second.
+ float32 GetJointSpeed() const;
+
+ /// Is the joint limit enabled?
+ bool IsLimitEnabled() const;
+
+ /// Enable/disable the joint limit.
+ void EnableLimit(bool flag);
+
+ /// Get the lower joint limit in radians.
+ float32 GetLowerLimit() const;
+
+ /// Get the upper joint limit in radians.
+ float32 GetUpperLimit() const;
+
+ /// Set the joint limits in radians.
+ void SetLimits(float32 lower, float32 upper);
+
+ /// Is the joint motor enabled?
+ bool IsMotorEnabled() const;
+
+ /// Enable/disable the joint motor.
+ void EnableMotor(bool flag);
+
+ /// Set the motor speed in radians per second.
+ void SetMotorSpeed(float32 speed);
+
+ /// Get the motor speed in radians per second.
+ float32 GetMotorSpeed() const;
+
+ /// Set the maximum motor torque, usually in N-m.
+ void SetMaxMotorTorque(float32 torque);
+ float32 GetMaxMotorTorque() const { return m_maxMotorTorque; }
+
+ /// Get the reaction force given the inverse time step.
+ /// Unit is N.
+ b2Vec2 GetReactionForce(float32 inv_dt) const;
+
+ /// Get the reaction torque due to the joint limit given the inverse time step.
+ /// Unit is N*m.
+ float32 GetReactionTorque(float32 inv_dt) const;
+
+ /// Get the current motor torque given the inverse time step.
+ /// Unit is N*m.
+ float32 GetMotorTorque(float32 inv_dt) const;
+
+ /// Dump to b2Log.
+ void Dump();
+
+ b2RevoluteJoint(const b2RevoluteJointDef* def);
+
+protected:
+
+ friend class b2Joint;
+ friend class b2GearJoint;
+
+ void InitVelocityConstraints(const b2SolverData& data);
+ void SolveVelocityConstraints(const b2SolverData& data);
+ bool SolvePositionConstraints(const b2SolverData& data);
+
+ // Solver shared
+ b2Vec2 m_localAnchorA;
+ b2Vec2 m_localAnchorB;
+ b2Vec3 m_impulse;
+ float32 m_motorImpulse;
+
+ bool m_enableMotor;
+ float32 m_maxMotorTorque;
+ float32 m_motorSpeed;
+
+ bool m_enableLimit;
+ float32 m_referenceAngle;
+ float32 m_lowerAngle;
+ float32 m_upperAngle;
+
+ // Solver temp
+ int32 m_indexA;
+ int32 m_indexB;
+ b2Vec2 m_rA;
+ b2Vec2 m_rB;
+ b2Vec2 m_localCenterA;
+ b2Vec2 m_localCenterB;
+ float32 m_invMassA;
+ float32 m_invMassB;
+ float32 m_invIA;
+ float32 m_invIB;
+ b2Mat33 m_mass; // effective mass for point-to-point constraint.
+ float32 m_motorMass; // effective mass for motor/limit angular constraint.
+ b2LimitState m_limitState;
+};
+
+inline float32 b2RevoluteJoint::GetMotorSpeed() const
+{
+ return m_motorSpeed;
+}
+
+#endif
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