-"Tyr is the god of single combat and heroic glory,
identified with Roman war god Mars and Greek god Ares,
in Norse mythology portrayed as a one-handed man"-"Fenrir or Fenrisulfr is a wolf,
the son of Loki and the giantess Angrboda. Fenrir is bound by the gods, but is ultimately destined to grow too large for his bonds and swallow Odin whole during the course of Ragnarok. He will be slain by Odin's son, Vidarr, who will use a shoe made throughout time..Vídarr, associated with Vengeance, a Vendetta...
described as the son of Odin and the jotunn Grídr, foretold to avenge his father's death by killing the wolf Fenrir at Ragnarok.Fenrir has two sons, Hati (Hate) and Skoll (Trechery).
Skoll chases the horses Arvakr and Alsvidr that drag the chariot with the sun, and Hati chases Mani, the moon. Skoll, in certain circumstances, is used as a 'heiti' to refer indirectly to the father Fenrir and not the son.This ambiguity works in the other direction also,
for example in the Vaftrudnismal, a confusion exists where Fenrir is given the sun chasing attributes of his son Skoll. This can mostly be accounted for by the use of Hrodvitnir and Hrodvitnirson to refer to both Fenrir and his sons."
Frame Rate Independence
(Open Source - BULLET PHYSICS LIBRARY, Physics Symulation
Forum)
Aug 24, 2008
please,
Bullet demos slow down on slower computer instead to drop
frame rate... stuff should not 'free fall' sooner on some
computer just because of better graphic card -
gravitational rate of acceleration, measured in real-time
seconds, should be independent of mass, size and
*computer speed* - is that "Frame Rate
Independence" we're talking about here?
i think we all want the same effect - physics simulation
to run in real time even if that means only 1 FPS of
animation, we do not want speed of simulation to go down,
but only number of rendered frames, right?
Aug 25, 2008
>>"If
you pass maxSubSteps=0 to the function, then it will
assume a variable tick rate. Every tick, it will move the
simulation along by exactly the timeStep you pass, in a
single tick, instead of a number of ticks equal to
fixedTimeStep. This is not officially supported, and the
death of determinism and framerate independance. Don't do
it.
- but it seems determinism is broken with
maxSubsteps > 1 as well,
at least "maxSubSteps == 0" seem to be
independent of computer speed - physics simulation does
not slow down or speed up, how come "maxSubSteps
> 1" is frame rate independent if everything
slows down with slow computer?
thankfully these opinions are diametrically opposite so this would be easy to resolve..
Aug 25, 2008
sparkprime,
im not quite sure what is it you're saying in regard to "Frame Rate Independence", except that stepSimulation() is confusing...
- does that mean you agree with "my" definition here of "Frame Rate Independence" and you too are unable to achieve that effect with neither your or Bullet demos and so unable to really answer these questions, just like myself?
>>"The
last parameter does not need to be supplied every frame,
and requiring it to be supplied gives the wrong
impression - that modifying it each frame is a good
idea."
- sorry, what are you referring to? ...where/who
suggests that it is required for last parameter to be
supplied and to what effect was that all about?
>>"The
difference between the first and last parameter is rather
subtle, and the middle parameter is not important...
"
- i dont agree... do have a look: "Stepping
The World", "Canonical Game Loop"
>"I'd
rather have an API..."
- i think two of us do not understand this
current API, so chances are its too early to be devising
a new one... so, you think this is a bug?
well,
i dont really believe its a bug, kind of expect to hear
some minimum requirements and minimum low fixed frame
rates - basically some numbers, limits where
interpolation works and where and how it fails. it seems,
if you can push every scene at 60 FPS with some time to
spare everything is ok, maybe even fixed 30FPS, but fixed
5-10FPS or even worse - variable low frame rates or
low-high, just might, for some reason, not be
interpolated right or by trying so you accumulate extra
time so it falls out of sync..
cheers
Aug 25, 2008
chunky,
>>"Assuming
you're passing time in milliseconds instead of
seconds..."
- they say assumption is mother of all fuk-ups
..but seriously, you might be right for all i know, i
have no idea about that function i just copy/pasted it as
it was already used as example, illustrating that i tried
different 2nd parameter.. i also used CcdPhysicsDemo as
example, i think it was mentioned this demo is best used
for template/starting point and i trust Bullet demos
calculate dt correctly ...which is assumption as well and
i really should check that out too, thanks
let me try to guess from
your message, am i correct:
- you agree with "my" definition here of
"Frame Rate Independence", BUT you actually can
make everything work all right, so you, in effect, could
practically tell us, in several lines of code, how
exactly you use your timer loop and call
stepSimulation()? and/or how to modify CcdPhysicsDemo or
any other Bullet demo to be frame-rate independent, to
work on slow computers as i described above?
this is really simple
and basic question, lets keep it simple,
make it crystal clear and demonstrate implementation by
providing few lines of code
thank you
Aug 25, 2008
Erwin,
>>If a
computer is too slow to compute all required simulation
time steps in real-time, I suggest to either buy a faster
CPU, improve the physics simulation performance or
simplify the simulation."
- computer is 2ghz with ati Xpress and latest
drivers and im talking about simple Bullet demos like
"CcdPhysicsDemo", tho i agree it might be some
weired computer hardware or driver issue thats why i
insist to confirm if anyone else is experiencing the same
thing..
but,
stepSimulation(dt, 0) works great! everything runs on
about 30-50fps, while normally Bullet demos just run in
slow-motion, hows that?
why would it not run ok on say, fixed 30FPS or 15FPS or
even 1FPS as thats still enough for physics to do its job
to keep it real-time? ..and, again stepSimulation(dt, 0)
can do it..
but please, just make
this 1 thing clear for me,
on your, or any other "proper" and fast
computer when you're rendering a scene that sometimes
(moving camera) takes more than 1/60 of second, say scene
is so intensive that dt goes up to 1/10 - are you saying
your physics simulation does NOT slow down or you saying
avoid scenes that might drop your framerates below 60FPS?
thanks
p.s.
hope i didnt give wrong impression - i do like Bullet a
lot and i didnt mean to sound as if i question the way
things are done, im simply too stupid for that, im truly
asking all these questions and looking forward to hear
answer to as many as possible, i hope i explained enough
the way i misunderstand things so i can be more easily
corrected... and most of all i hope this is not some
stupid hardware problem
Genesis, Wednesday
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