Re: [Alephmodular-devel] A note on films

[Br'fin <br...@ma...>]

On Saturday, January 18, 2003, at 03:38  PM, Woody Zenfell, III wrote:
>
> (I assume it's obvious that the "checkfile" would be generated from 
> the filmfile as early as possible... then occasionally in the game's 
> development lifetime, that original filmfile and checkfile would be 
> used to make sure everything's still working the same way internally.)
>
> I guess I didn't get my point across very well - must not have used 
> enough words.  ;)

Your initial posting didn't seem to be clear on working with a 
separately generated state file. I must say, the idea is interesting. 
I'm almost wondering if, for, debugging such a state file could be the 
output of either an alternate or pass through Animation layer 
implementation...

Output a game tick and all the attitude changes of objects within that 
tick.

I agree that this could be useful, unfortunately I'm unsure when such a 
test harness could be implemented. (It seems to require we have our 
interfaces defined already :/ )

> OHH, or maybe there's a concern that AM *already* diverges from M2 
> behavior.  Well, right, obviously the checkfile scheme can't detect 
> that since M2 doesn't write checkfiles.  (I guess you could carefully 
> hack the binary or something to add this capability in, but...)

I don't think AM appreciably diverges yet. At the very least I as 
checking through a couple of the demos in M2 proper and all the key 
points seemed to be hit, including player death in one of them.

> A checkfile alternative could be to use a saved-game at the end of the 
> film, the idea being that if the states diverge at some tick, they 
> will be different for all subsequent ticks, and thus will show up in 
> the final state.  And of course a saved-game captures all relevant 
> game-state, and so *might* be able to catch things that merely the 
> value of get_random_seed() would not.  (Though I rather doubt it, in 
> practice.)  And, automatically comparing two whole game states is not 
> nearly as easy as comparing two 16-bit values.  (Yeah you could 
> actually write the two saved-games out and diff them or something, but 
> it's more painful to automate.)

Yeow, that just sounds really really painful. I rather like the idea of 
the diffable checkfiles. You don't just know that things diverged, but 
you know the tick and calculations where they did.

-Jeremy Parsons