Why did we subtract the top vector from the hinge vector and then set it as the ropes LocalPointA vector?
B4X:
Dim TopPosition As B2Vec2 = hinge.BodyDef.Position.CreateCopy
'Subtract top bar body positiojn from hinge position
TopPosition.SubtractFromThis(top.Body.Position)
'Tie top bar with marble body with a ropeJoint
rope.Initialize(top.Body, bw.Body, TopPosition, X2.CreateVec2(0, 0), 1.5)
The connection point is local to the body. In this case body A is the top bar, not the hinge. To get the relative position of the hinge we need to subtract the "top bar" position from the hinge position.