private void create()
{
b2Body bodyB;
if (connectedB2BodyObject == null)
{
bodyB = _world.GetGroundBody();
}
else
{
bodyB = connectedB2BodyObject.body;
}
b2RopeJointDef jointDef = new b2RopeJointDef();
b2Vec2 anchorA = _bodyObject.body.GetWorldPoint(localAnchor1);
b2Vec2 anchorB = bodyB.GetWorldPoint(localAnchor2);
anchorA.x = (float)System.Math.Round(anchorA.x, 2);
anchorA.y = (float)System.Math.Round(anchorA.y, 2);
anchorB.x = (float)System.Math.Round(anchorB.x, 2);
anchorB.y = (float)System.Math.Round(anchorB.y, 2);
jointDef.Initialize(_bodyObject.body, bodyB, anchorA, anchorB, maxLength);
jointDef.collideConnected = enableCollision;
_joint = _world.CreateJoint(jointDef);
_ropeJoint = _joint as b2RopeJoint;
_ropeJoint.GetBodyA().SetAwake(true);
_ropeJoint.GetBodyB().SetAwake(true);
}
// friend class b2Joint;
// Limit:
// C = norm(pB - pA) - L
// u = (pB - pA) / norm(pB - pA)
// Cdot = dot(u, vB + cross(wB, rB) - vA - cross(wA, rA))
// J = [-u -cross(rA, u) u cross(rB, u)]
// K = J * invM * JT
// = invMassA + invIA * cross(rA, u)^2 + invMassB + invIB * cross(rB, u)^2
internal b2RopeJoint(b2RopeJointDef def) : base(def)
{
m_localAnchorA = def.localAnchorA;
m_localAnchorB = def.localAnchorB;
m_maxLength = def.maxLength;
m_mass = 0.0f;
m_impulse = 0.0f;
m_state = b2LimitState.e_inactiveLimit;
m_length = 0.0f;
}
internal static global::System.Runtime.InteropServices.HandleRef getCPtr(b2RopeJointDef obj)
{
return((obj == null) ? new global::System.Runtime.InteropServices.HandleRef(null, global::System.IntPtr.Zero) : obj.swigCPtr);
}
