andrew-gresyk/HFSM2

Hierarchical Finite State Machine Framework with Planning and Utility Support

Andrew Gresyk

@andrew-gresyk

Welcome!
Feel free to ask questions, voice concerns, suggest features, or destroy :)

Valentin Galea

@valentingalea

Hi!

DJuego

@DJuego

Yes, hi! And thank you for your efforts with HFSM2, @andrew-gresyk

Andrew Gresyk

@andrew-gresyk

Hi there!

You're welcome!

Would you mind sharing what you're using hfsm2 for?

Alexander Baird

@Alexeut_twitter

Good stuff great project. Question: if I wanted synchronise state changes in two different clients using this (over a network) - am I free to approach that however I want, or are there any factors I should keep in mind?

Andrew Gresyk

@andrew-gresyk

Thanks!
for multiplayer your best bet is to record the transitions on one client and replay them on the other

Andrew Gresyk

@andrew-gresyk

Transitions can be initiated either by type (fsm.changeTo<TState>()) or by numerical ID (fsm.changeTo(StateID))
StateID can be obtained using fsm.stateId<TState>()
more info here: https://github.com/andrew-gresyk/HFSM2/wiki#root-aka-public-fsm-api

to record and replay a transition you'd need to send over

StateID
transition type (if non-default changeTo() is used
payload (again, optional)
.. per transition

DJuego

@DJuego

Wow! "Dynamic" planning support.
That sounds like a powerful concept. :-)

Andrew Gresyk

@andrew-gresyk

Well, as opposed to BTs' sequence nodes which can be seen as static plans :)

DJuego

@DJuego

Hi again!

Could you suggest some tool to represent HFSM graphically? (Specifically to use with your library)
I would like to plan my HFSMs in a visual (but digital) way ...

Andrew Gresyk

@andrew-gresyk

heya!
there's not a tool designed for hfsm2 to design fsms graphically
the reverse is possible with debug visualization: https://gresyk.dev/features/2018/01/15/hfsm-magic.html

would you like to create such tool?

DJuego

@DJuego

Well, it's a tempting proposal, but I do not feel qualified. :-D Thank you for reply. ;-)

Meanwhile, I'm considering using your proposal in the field of mobile robotics.

DJuego

@DJuego

Perhaps a graph editor could be useful... For instance; https://github.com/ArsMasiuk/qvge

DJuego

@DJuego

I suppose that the problem is to develop a graphical grammar for a powerful representation of hierarchical state machines with graphs.

Andrew Gresyk

@andrew-gresyk

Interesting
Since the structure of HFSM2 is defined at compile time, the output of such editor would be C++ code.
I like the idea, I'm happy to support anyone willing to take on developing a tool like that.

DJuego

@DJuego

Well. Qt Visual Graph Editor export to several types of files such as Grapviz DOT Language (https://www.graphviz.org/doc/info/lang.html). Perhaps a plugin for Qt Visual Graph Editor or a tool for Grapviz DOT Language ?? ---> HFSM2 structure conversion.

I still must become very familiar with hierarchical state machines and HSM2. :-}

Andrew Gresyk

@andrew-gresyk

well, a HFSM2 structure is basically a c++ header with something like this:

using FSM = M::PeerRoot<
                struct State1,
                M::Composite<struct Region,
                    struct SubState1,
                    struct SubState2
                >
            >;

the full list of all regions/roots is here: https://github.com/andrew-gresyk/HFSM2/wiki#regions

DJuego

@DJuego

Yes Yes. I have already read it. :-)

But the transition "rules" are not represented there.

Andrew Gresyk

@andrew-gresyk

So you

you'd also like to edit transitions?

DJuego

@DJuego

Well. And why not? Transitions can be represented in a graph... at least up to a minimal level. "I can go from A to C through B, but never directly" and so. In your opinion, can your Hierarchical state machines be represented with graphs effectively?

Andrew Gresyk

@andrew-gresyk

Absolutely, having transitions would be great

Andrew Gresyk

@andrew-gresyk

In that case, the tool would need to generate state code as well, possibly with some comment marks to maintain generated code

DJuego

@DJuego

Right.

DJuego

@DJuego

In the wiki i miss orthogonal region explanation...

Andrew Gresyk

@andrew-gresyk

it still needs the page on all regions
meanwhile - when orthogonal region activates - all of its sub-states also activate
it's a 'fork' in a sense

DJuego

@DJuego

Thanks @andrew-gresyk .

DJuego

@DJuego

Thank you for the update. @andrew-gresyk . I have planned to use HFSM2 very, very soon. Wait for my feedback. :-))

Andrew Gresyk

@andrew-gresyk

I see what you did there @DJuego :)
Let me know how it goes!

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