Help Controlling specific particle force / custom constraints.

[josemendez]

Thank you very much. 

Documentation says that Rods can't change length in runtime. But as we all know, any snake want to eat something and grow larger  May be there is some way to implement this using Rod?

Unfortunately not :/. Rods can't change their length, because unlike ropes they contain a special constraint that encompasses all particles in it. Changing the length would be too costly.