--- /dev/null
+/*
+* Copyright (c) 2006-2007 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_REVOLUTE_JOINT_H
+#define B2_REVOLUTE_JOINT_H
+
+#include "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.
+struct b2RevoluteJointDef : public b2JointDef
+{
+ b2RevoluteJointDef()
+ {
+ type = e_revoluteJoint;
+ localAnchor1.Set(0.0f, 0.0f);
+ localAnchor2.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 the world
+ /// anchor.
+ void Initialize(b2Body* body1, b2Body* body2, const b2Vec2& anchor);
+
+ /// The local anchor point relative to body1's origin.
+ b2Vec2 localAnchor1;
+
+ /// The local anchor point relative to body2's origin.
+ b2Vec2 localAnchor2;
+
+ /// The body2 angle minus body1 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;
+};
+
+/// A revolute joint constrains to 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.
+class b2RevoluteJoint : public b2Joint
+{
+public:
+ b2Vec2 GetAnchor1() const;
+ b2Vec2 GetAnchor2() const;
+
+ b2Vec2 GetReactionForce() const;
+ float32 GetReactionTorque() const;
+
+ /// 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);
+
+ /// Get the current motor torque, usually in N-m.
+ float32 GetMotorTorque() const;
+
+ //--------------- Internals Below -------------------
+ b2RevoluteJoint(const b2RevoluteJointDef* def);
+
+ void InitVelocityConstraints(const b2TimeStep& step);
+ void SolveVelocityConstraints(const b2TimeStep& step);
+
+ bool SolvePositionConstraints();
+
+ b2Vec2 m_localAnchor1; // relative
+ b2Vec2 m_localAnchor2;
+ b2Vec2 m_pivotForce;
+ float32 m_motorForce;
+ float32 m_limitForce;
+ float32 m_limitPositionImpulse;
+
+ b2Mat22 m_pivotMass; // effective mass for point-to-point constraint.
+ float32 m_motorMass; // effective mass for motor/limit angular constraint.
+
+ bool m_enableMotor;
+ float32 m_maxMotorTorque;
+ float32 m_motorSpeed;
+
+ bool m_enableLimit;
+ float32 m_referenceAngle;
+ float32 m_lowerAngle;
+ float32 m_upperAngle;
+ b2LimitState m_limitState;
+};
+
+inline float32 b2RevoluteJoint::GetMotorSpeed() const
+{
+ return m_motorSpeed;
+}
+
+#endif
projects / blok / blobdiff