Wrench visual deadzone

[goretkin]

I strongly dislike the behavior I'm getting of hiding the arrows if they become "shorter than they are wide". It seems like a good idea, but it should be optional and perhaps a separate parameter should decide the threshold.

It doesn't really seem like it's working as intended:
https://youtu.be/6kV5kS81WsQ
(notice how the deadzone really is too big. the arrows materialize out of nowhere, losing a huge range of sensitivity.)

Though from reading the code, I can't tell why:

rviz/src/rviz/default_plugin/wrench_visual.cpp

Line 63 in 7970ba0

bool show_force = (force_length > width_);

[v4hn]

We just hit this bug too. I would propose to add a boolean flag "hide small forces" for this feature. Would that be ok for you @wjwwood ?

[wjwwood]

Fine by me.