A prismatic joint. This joint provides one degree of freedom: translation along an axis fixed in body1. Relative rotation is prevented. You can use a joint limit to restrict the range of motion and a joint motor to drive the motion or to model joint friction.
Inheritance: Joint
Exemplo n.º 1
0
        /// <summary>
        /// Requires two existing revolute or prismatic joints (any combination will work).
        /// The provided joints must attach a dynamic body to a static body.
        /// </summary>
        /// <param name="jointA">The first joint.</param>
        /// <param name="jointB">The second joint.</param>
        /// <param name="ratio">The ratio.</param>
        public GearJoint(Joint jointA, Joint jointB, float ratio)
            : base(jointA.BodyA, jointA.BodyB)
        {
            JointType = JointType.Gear;
            JointA    = jointA;
            JointB    = jointB;
            Ratio     = ratio;

            JointType type1 = jointA.JointType;
            JointType type2 = jointB.JointType;

            // Make sure its the right kind of joint
            Debug.Assert(type1 == JointType.Revolute ||
                         type1 == JointType.Prismatic ||
                         type1 == JointType.FixedRevolute ||
                         type1 == JointType.FixedPrismatic);
            Debug.Assert(type2 == JointType.Revolute ||
                         type2 == JointType.Prismatic ||
                         type2 == JointType.FixedRevolute ||
                         type2 == JointType.FixedPrismatic);

            // In the case of a prismatic and revolute joint, the first body must be static.
            if (type1 == JointType.Revolute || type1 == JointType.Prismatic)
            {
                Debug.Assert(jointA.BodyA.BodyType == BodyType.Static);
            }
            if (type2 == JointType.Revolute || type2 == JointType.Prismatic)
            {
                Debug.Assert(jointB.BodyA.BodyType == BodyType.Static);
            }

            float coordinate1 = 0.0f, coordinate2 = 0.0f;

            switch (type1)
            {
            case JointType.Revolute:
                BodyA        = jointA.BodyB;
                _revolute1   = (RevoluteJoint)jointA;
                LocalAnchor1 = _revolute1.LocalAnchorB;
                coordinate1  = _revolute1.JointAngle;
                break;

            case JointType.Prismatic:
                BodyA        = jointA.BodyB;
                _prismatic1  = (PrismaticJoint)jointA;
                LocalAnchor1 = _prismatic1.LocalAnchorB;
                coordinate1  = _prismatic1.JointTranslation;
                break;

            case JointType.FixedRevolute:
                BodyA           = jointA.BodyA;
                _fixedRevolute1 = (FixedRevoluteJoint)jointA;
                LocalAnchor1    = _fixedRevolute1.LocalAnchorA;
                coordinate1     = _fixedRevolute1.JointAngle;
                break;

            case JointType.FixedPrismatic:
                BodyA            = jointA.BodyA;
                _fixedPrismatic1 = (FixedPrismaticJoint)jointA;
                LocalAnchor1     = _fixedPrismatic1.LocalAnchorA;
                coordinate1      = _fixedPrismatic1.JointTranslation;
                break;
            }

            switch (type2)
            {
            case JointType.Revolute:
                BodyB        = jointB.BodyB;
                _revolute2   = (RevoluteJoint)jointB;
                LocalAnchor2 = _revolute2.LocalAnchorB;
                coordinate2  = _revolute2.JointAngle;
                break;

            case JointType.Prismatic:
                BodyB        = jointB.BodyB;
                _prismatic2  = (PrismaticJoint)jointB;
                LocalAnchor2 = _prismatic2.LocalAnchorB;
                coordinate2  = _prismatic2.JointTranslation;
                break;

            case JointType.FixedRevolute:
                BodyB           = jointB.BodyA;
                _fixedRevolute2 = (FixedRevoluteJoint)jointB;
                LocalAnchor2    = _fixedRevolute2.LocalAnchorA;
                coordinate2     = _fixedRevolute2.JointAngle;
                break;

            case JointType.FixedPrismatic:
                BodyB            = jointB.BodyA;
                _fixedPrismatic2 = (FixedPrismaticJoint)jointB;
                LocalAnchor2     = _fixedPrismatic2.LocalAnchorA;
                coordinate2      = _fixedPrismatic2.JointTranslation;
                break;
            }

            _ant = coordinate1 + Ratio * coordinate2;
        }
        /// <summary>
        /// Requires two existing revolute or prismatic joints (any combination will work).
        /// The provided joints must attach a dynamic body to a static body.
        /// </summary>
        /// <param name="jointA">The first joint.</param>
        /// <param name="jointB">The second joint.</param>
        /// <param name="ratio">The ratio.</param>
        public GearJoint(Joint jointA, Joint jointB, float ratio)
            : base(jointA.BodyA, jointA.BodyB)
        {
            JointType = JointType.Gear;
            JointA = jointA;
            JointB = jointB;
            Ratio = ratio;

            JointType type1 = jointA.JointType;
            JointType type2 = jointB.JointType;

            // Make sure its the right kind of joint
            Debug.Assert(type1 == JointType.Revolute ||
                         type1 == JointType.Prismatic ||
                         type1 == JointType.FixedRevolute ||
                         type1 == JointType.FixedPrismatic);
            Debug.Assert(type2 == JointType.Revolute ||
                         type2 == JointType.Prismatic ||
                         type2 == JointType.FixedRevolute ||
                         type2 == JointType.FixedPrismatic);

            // In the case of a prismatic and revolute joint, the first body must be static.
            if (type1 == JointType.Revolute || type1 == JointType.Prismatic)
                Debug.Assert(jointA.BodyA.BodyType == BodyType.Static);
            if (type2 == JointType.Revolute || type2 == JointType.Prismatic)
                Debug.Assert(jointB.BodyA.BodyType == BodyType.Static);

            float coordinate1 = 0.0f, coordinate2 = 0.0f;

            switch (type1)
            {
                case JointType.Revolute:
                    BodyA = jointA.BodyB;
                    _revolute1 = (RevoluteJoint) jointA;
                    LocalAnchor1 = _revolute1.LocalAnchorB;
                    coordinate1 = _revolute1.JointAngle;
                    break;
                case JointType.Prismatic:
                    BodyA = jointA.BodyB;
                    _prismatic1 = (PrismaticJoint) jointA;
                    LocalAnchor1 = _prismatic1.LocalAnchorB;
                    coordinate1 = _prismatic1.JointTranslation;
                    break;
                case JointType.FixedRevolute:
                    BodyA = jointA.BodyA;
                    _fixedRevolute1 = (FixedRevoluteJoint) jointA;
                    LocalAnchor1 = _fixedRevolute1.LocalAnchorA;
                    coordinate1 = _fixedRevolute1.JointAngle;
                    break;
                case JointType.FixedPrismatic:
                    BodyA = jointA.BodyA;
                    _fixedPrismatic1 = (FixedPrismaticJoint) jointA;
                    LocalAnchor1 = _fixedPrismatic1.LocalAnchorA;
                    coordinate1 = _fixedPrismatic1.JointTranslation;
                    break;
            }

            switch (type2)
            {
                case JointType.Revolute:
                    BodyB = jointB.BodyB;
                    _revolute2 = (RevoluteJoint) jointB;
                    LocalAnchor2 = _revolute2.LocalAnchorB;
                    coordinate2 = _revolute2.JointAngle;
                    break;
                case JointType.Prismatic:
                    BodyB = jointB.BodyB;
                    _prismatic2 = (PrismaticJoint) jointB;
                    LocalAnchor2 = _prismatic2.LocalAnchorB;
                    coordinate2 = _prismatic2.JointTranslation;
                    break;
                case JointType.FixedRevolute:
                    BodyB = jointB.BodyA;
                    _fixedRevolute2 = (FixedRevoluteJoint) jointB;
                    LocalAnchor2 = _fixedRevolute2.LocalAnchorA;
                    coordinate2 = _fixedRevolute2.JointAngle;
                    break;
                case JointType.FixedPrismatic:
                    BodyB = jointB.BodyA;
                    _fixedPrismatic2 = (FixedPrismaticJoint) jointB;
                    LocalAnchor2 = _fixedPrismatic2.LocalAnchorA;
                    coordinate2 = _fixedPrismatic2.JointTranslation;
                    break;
            }

            _ant = coordinate1 + Ratio*coordinate2;
        }
Exemplo n.º 3
0
 /// <summary>
 /// Creates a prsimatic joint
 /// </summary>
 /// <param name="bodyA"></param>
 /// <param name="bodyB"></param>
 /// <param name="localanchorB"></param>
 /// <param name="axis"></param>
 /// <returns></returns>
 public static PrismaticJoint CreatePrismaticJoint(Body bodyA, Body bodyB, Vector2 localanchorB, Vector2 axis)
 {
     Vector2 localanchorA = bodyA.GetLocalPoint(bodyB.GetWorldPoint(localanchorB));
     PrismaticJoint joint = new PrismaticJoint(bodyA, bodyB, localanchorA, localanchorB, axis);
     return joint;
 }