Help How to set the length of the rod

[Mingrui]

I can't see any screenshots attached.

I guess you refer to the white lines that serve as guides for the shape of the rod. They let you visualize the centerline, orientation and thickness of the rod. Particle distance is not visually represented, you can just add a ObiParticleRenderer component to the rod to visualize them. See:
http://obi.virtualmethodstudio.com/tutor...ering.html

Sorry, the screenshot is attached here.