Fix Your Timestep!

in case you've been using some implementation of simulation stepping function based on, or similar to what is described in this article:
"Fix Your Timestep!"
http://www.gaffer.org/game-physics/fix-your-timestep

..then, you might be interested in 2nd opinion on these matters,
actually, after completing intensive research there was a realization that it turns out almost "everyone" is using some version of this algorithm with interpolation, including popular Physics engines, libraries and commercial console and PC games

..anyway, there is "a paper" on this,
and some 'bonus material' that actually turns this tech. paper into an Allegory Novella and couple of more other things.. how wonderful!

TITLE: Three Bugs With One Stone.. allegory continues
http://www.geocities.com/ze_aks/myBo...hOneStone.html
(RealTime Allegory Novel, Technical Paper and Chronological account of an Algorithm discovery)

..there you can find some bits of discussion related to these issues, but not present on the internet anymore, like this for example:

-"ok, cazy i'll prove it via logic, just because i'm feeling a bit evil now.."

//------------------------------------------------------------
Aug 30, 2008
>>"This code handles both undersampling and oversampling correctly which very is important. "

- not really,
unless somehow you can make your physics calculations in zero amount of time.. but, you seem to know that and call it "spiral of death"

..i'm just saying you should remove word "undersampling" from the same sentence with word "correctly"

//------------------------------------------------------------
Aug 30, 2008
>>"..but at least its theoretically correct"

- not really,
unless there truly is such thing as "correct theory" that does not work in practice


>>"..i shipped this technique in 'freedom force' from irrational games.."

- then it is an example how it does not work - scrolling speed goes from fast at the edges of the map to slow and jerky depending on the scene complexity and number of moving objects

not that it matters much as i see the game scored 'Outstanding 9.3' on IGN, congratulations!

cheers

//------------------------------------------------------------
[../ /..]
//------------------------------------------------------------
Sep 3, 2008
>>"plus i don't see where you are interpolating render state between two sim states -
* are you doing that?
* do you understand why we need to do that?
* do you understand what temporal aliasing is and why we need to do the interpolation?"

- no, im not doing that,
..actually more i look at it - more it feels "out of the place"


>>"your technique is not identical to mine.. this violates the desired constraint of this article, that you are always stepping forward with a fixed dt"

- well, call me crazy,
but that interpolation you're talking about seem to goes against all the desired constraints of your article - it actually changes the "state" outside of fixed time steps, no?
//------------------------------------------------------------

Chapters:
I) Genesis, anecdote
II) Divina Commedia, abysm spirale
III) Seraphim snd Nephilim, the chronicles
IV) Aspidochelone, physiologus
V) ..alegoria continua


..among other themes,
book most obviously and most practically addresses these issues:

---------------------------------------------------------------------
Common bugs in Havok, PhysX, Bullet, ODE, Ogre, Newton.. SOLVED!

Bug 1.) Few subSteps: "Moon gravity effects"
bUg 2.) A lot of subSteps: "Spiraling to death"
buG 3.) Interpolation VS. Temporal Distribution


Common mistakes and bugs related to fixedTimeStepping - UNCOVERED

4.) Design-Time Planning and Recognition of Hardware Min. Sys. Requirements
5.) "Scaling the World": Gravity, Mass, Size and Hidden Effects of fixedTimeStepping
6.) Jitter, Wobbles, Choppiness and Slowdowns: Unstable Physics & Smooth Animation
---------------------------------------------------------------------
Quick Overview: www.geocities.com/ze_aks/test/sampleTest.html

Well, I don't get it... anybody else ?

As far as I am concerned, I just use a normal fixed-fixed step, thread up logics and rendering, and that's it. No need for interpolation or anything more fancy...

Cheers,
- Wernaeh

So, I browsed through several pages of clippings of discussions and descriptions of getting banned from different message boards, without actually getting what the point was.

If the computer is too slow to run the fixed timestep physics simulation (the spiral of death, so to speak), then it's too slow to run the game. Anything else would change the simulation, and thus, the game.

Wernaeh,

>>"Well, I don't get it... anybody else ?"

- please be specific,
and tell us what exactly you do not understand, so i can explain



>>"As far as I am concerned, I just use a normal fixed-fixed step.."

- please,
show us your "normal fixed-fixed step" algorithm?




//---------------------------------------------
Sol_HSA,

>>"So, I browsed through several pages of clippings of discussions and descriptions of getting banned from different message boards, without actually getting what the point was."

- are you kidding me?
there are, at least, SIX very important points, did you not read my post at all?

1.) Few subSteps: "Moon gravity effects"
2.) A lot of subSteps: "Spiraling to death"
3.) Interpolation VS. Temporal Distribution
4.) Design-Time Planning and Recognition of Hardware Min. Sys. Requirements
5.) "Scaling the World": Gravity, Mass, Size and Hidden Effects of fixedTimeStepping
6.) Jitter, Wobbles, Choppiness and Slowdowns: Unstable Physics & Smooth Animation



>>"If the computer is too slow to run the fixed timestep physics simulation (the spiral of death, so to speak), then it's too slow to run the game. Anything else would change the simulation, and thus, the game."

- please,
explain that to Intel Havok and nVidia PhysX, ok?

..why did you bother to write your message,
just to say that you didnt read anything ..sheesh



-------------------------------------------------------------------------------------
this is ONLY for people that use fixed time step,
and therefore KNOW about these problems - if you do not use, do not know or do not care, than this discussion is not for you

also, if you going to pretend that you know,
or that you knew all along then be ready to prove it, otherwise please stay out ..or you might end up as a part of the book - which is not what you want and you can realize that once you read instead of browse ..and again - if you do not care, stay out please
-------------------------------------------------------------------------------------

Originally Posted by abaraba

Wernaeh,
-------------------------------------------------------------------------------------
this is ONLY for people that use fixed time step,
and therefore KNOW about these problems - if you do not use, do not know or do not care, than this discussion is not for you

also, if you going to pretend that you know,
or that you knew all along then be ready to prove it, otherwise please stay out ..or you might end up as a part of the book - which is not what you want and you can realize that once you read instead of browse ..and again - if you do not care, stay out please
-------------------------------------------------------------------------------------

Well, I want to be in the book. And since I could care less about your thread, I am going to get into it the naughty way! I like pie (banana cream to be specific), long walks on the beach. And to be held... everyone needs love!

Also, don't be a dick.

abaraba, could you at least *try* to make your posts a bit readable by using such things as [quote] tags and no hard line breaks?

>>Well, I want to be in the book. And since I could care less about your thread, I am going to get into it the naughty way! I like pie (banana cream to be specific), long walks on the beach. And to be held... everyone needs love!"

- i actually like your post, thanks for sharing



>>"Also, don't be a dick."

- what in particular you would like me to improve on and why?

then again,
what does "being a dick" mean? ..is it maybe when someone who doesnt care comes up and clogs others thread and calls them 'a dick' ?

i'll put you in the book as long as you make an interesting conversation, we can argue, we can agree.. we can talk about pies and moons, doesnt matter as long as its interesting or novel in some way..




//----------------------------------------------------------

.oisyn,
>>"abaraba, could you at least *try* to make your posts a bit readable by using such things as [quote] tags and no hard line breaks?"

NO! if you do not care, stay out please!!!
i dont want to hear about stupid tags anymore ..is that all you have to say on all SIX bugs/errors?!

why would i try?!,
go away if you don't like it without tags!

this thread is for C/C++ not HTML


------> if you care about TAGS - stay aout please!!!
------> if you do not care about my 1st post, stay out please!!!


..is that all you have to say on all that?! i have tags in my 1st message,
how exactly tags prevent you to say anything concrete on the whole subject?

i already wasted a lot of time to find these bugs, to find the solution - so how in a world you find appropriate to lecture me what else i need to do for you so you could fix your own bugs?!

Originally Posted by Nodlehs

Also, don't be a dick.

Nodlehs.awesome *= 10;

Originally Posted by abaraba

>>Well, I want to be in the book. And since I could care less about your thread, I am going to get into it the naughty way! I like pie (banana cream to be specific), long walks on the beach. And to be held... everyone needs love!"

- i actually like your post, thanks for sharing



>>"Also, don't be a dick."

- what in particular you would like me to improve on and why?

then again,
what does "being a dick" mean? ..is it maybe when someone who doesnt care comes up and clogs others thread and calls them 'a dick' ?



i'll put you in the book as long as you make an interesting conversation, we can argue, we can agree.. we can talk about pies and moons, doesnt matter as long as its interesting or novel in some way..

Steps to being a dick in the forums:

1. Lack of quote tags.
2. Telling people who may not have full knowledge about a subject, but are interested enough to try and contribute to the conversation, to stay out.
3. Lack of proper grammar.
4. Aggressive posting. Yes, your post was aggressive. It read that way to me, and others I showed it too.

Nodlehs,

why do you insult yourself?


this is discussion is about real-time animation, about ALGORITHM
for all other discussion start your own thread - this is not for children or HTML psychos ..if you need friends or have some other social problems, just stay out, don't be a dick



if you do not care and have nothing to say about SIX points in original the question - stay out

I do it for the laughs apparently.

Edit: Also, I give up. I can't seem to get past your ego.

Originally Posted by abaraba

>>"If the computer is too slow to run the fixed timestep physics simulation (the spiral of death, so to speak), then it's too slow to run the game. Anything else would change the simulation, and thus, the game."

- please,
explain that to Intel Havok and nVidia PhysX, ok?

I think those are more game developer-specific issues than physics package-specific issues. If you can't tweak the package to work properly with your target platform/spec, well, then it's not all that useful.

Originally Posted by abaraba

..why did you bother to write your message,
just to say that you didnt read anything ..sheesh

I did browse through your material, but since I didn't "get it", I'm pretty sure there's something wrong with how you present it. Bunch of clippings from conversations aren't the best way to portray your point of view.

Originally Posted by abaraba

this is ONLY for people that use fixed time step,
and therefore KNOW about these problems - if you do not use, do not know or do not care, than this discussion is not for you

I use it, it works. I know its limitations. I've also used it on very limited platforms.

Originally Posted by Nodlehs

Edit: Also, I give up. I can't seem to get past your ego.

Yes, I think that's the most reasonable thing for any of us to do.

abaraba: you need to stop your negative, offensive, and rude attitude if you're going to expect people to take time to read your thread and if you want to get good answers. Do you realize the very people you're insulting are very experienced, incredibly knowledgeable, and professional?

And yes, you need to organize your posts better and more professionally if you want people to take you seriously.

This thread will be closed if this continues.

what is that you all want?

Nodlehs,
>>"I do it for the laughs apparently."
- obviously then it is you who was a dick



//-----------------------------------------------------------------------
>>"you need to stop your negative, offensive, and rude attitude if you're going to expect people to take time to read your thread?"

- go away, STOP TROLLING
if you have nothing to say about what this thread is about - STAY OUT!

i dont expect you to read,
..go on, keep your bugs and your tags if you like!


this thread is only about people that CARE, not TROLLS




>>" and if you want to get good answers."

- what answer?
where do you see a question mark in my message?

its you who needs answers,
but you will never get them if you continue to be a dick, to get an answer you need to ask question



>>"Do you realize the very people you're insulting are very experienced, incredibly knowledgeable, and professional?"

- no, i do not realize that,
i thought i was talking to bunch of 10year old emotionally unstable kids




>>"And yes, you need to organize your posts better and more professionally if you want people to take you seriously."

NO!

i dont need to that... i can tell you to "go and FUCK YOURSELF" if i want, just like any of you dickheads have come here to talk about shit instead of what was this thread about


.. and go on, close the thread YOU MORON




>>"This thread will be closed if this continues."

- there is nothing to continue here except trolling - i dare you, close it!

..close it NOW!

this is funny

As for the OP, there's lots of other forums where you can go troll. If you want to get a rise out of people, this isn't the place to do it. We are professionals who know all about trolls, what they want, and what they're like on the other end of the wire (it's usually a pretty sad sight). So there's lots of places you can go where you can start flame wars all you want, and most people will be dumb enough to go with it.

EDIT: as an additional side note, I think you need to go back to trolling school. Good trolls are just douche enough to make everyone really angry, but not enough to get themselves banned.

I am closing this thread.

abaraba, if you continue to post in this manner you will be banned.