Joints permanently drawing body A->B in joints can unfortunately add a lot of unhelpful visual noise.

[MelvMay-Unity]

Many of the joints including the b2_motorJoint, b2_ignoreJoint and b2_distanceJoint, draw a line-segment from the local frames of both bodies. Unfortunately this can add a lot of distracting visual noise.

What I've decided to do here is to remove those and instead add a draw option that controls if this is drawn for all joints or not.

I'm not sure if this might be something you'd like to see in Box2D though.

The top-down friction sample shows this issue well: