public void InitVelocityConstraint(float dt)
{
m_rA = PositionA - BodyA.CenterOfMassWs;
m_rB = PositionB - BodyB.CenterOfMassWs;
Vector3 tangent;
Vector3 bitangent;
VectorUtil.FormOrthogonalBasis(Normal, out tangent, out bitangent);
m_jN.Init(this, Normal);
m_jT.Init(this, tangent);
m_jB.Init(this, bitangent);
}