On Thu, 16 May 2002 21:44:53 +0200, Tim Nikias wrote:

> After that Netscape-IE thingy was out, I was able to view it too...
> 
> Looks pretty nice, and I hope it doesn't take too long...
> 
> How about dropping it from a very high spot, how would it bounce? Would
> it get a rotationalo momentum?
> 

Sure, check this: http://www.progressive.hu/gero/drum.m1v

This is an earlier and simpler version, not really elastic. :)

I guess the current cube would start to "shake" at a very high pace in a
similar situation, unless I implement correct spring damping.

--
Cheers,
Gergely

Post a reply to this message

On Thu, 16 May 2002 20:37:31 +0200, Christoph Hormann wrote:




>> 
>> [...]
>> 
>> worked fine here with team of NT 4, MP 6.4 and IE 5
> 
> That's strange and somewhat disturbing.  Using IE worked, but with
> Netscape it did not.
> 

With the current Mozilla I can't even access the http news interface.

The "Enter the newsgroups" button simply doesn't do a thing...

--
Gergely

Post a reply to this message

That's pretty neat. Do a larger version
of that one with more elasticity (nodes),
that'd make an interesting animation.

Can several of these interact, or not?
Probably not at an early stage like this...


Gergely Vandor wrote:

> On Thu, 16 May 2002 21:44:53 +0200, Tim Nikias wrote:
>
> > After that Netscape-IE thingy was out, I was able to view it too...
> >
> > Looks pretty nice, and I hope it doesn't take too long...
> >
> > How about dropping it from a very high spot, how would it bounce? Would
> > it get a rotationalo momentum?
> >
>
> Sure, check this: http://www.progressive.hu/gero/drum.m1v
>
> This is an earlier and simpler version, not really elastic. :)
>
> I guess the current cube would start to "shake" at a very high pace in a
> similar situation, unless I implement correct spring damping.
>
> --
> Cheers,
> Gergely

--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Email: Tim### [at] gmxde

Post a reply to this message

Gergely Vandor wrote:
> 
> [...]
> 
> Did you use pov code for your system? If so, I'd really like to see it. :)

Yes, it works a lot with functions so it's probably quite difficult to
understand.

> It took 5 mins on an 1400 MHz Athlon XP, which I consider slow, this
> thing should be possible realtime on my machine. :) The five mins is a
> guess, I did't even check.

I would not call this slow, the recent 12 balls animations usually parse
about 10 seconds per frame and render 5 seconds on a K6/500.

> System: In every "row", every second node is connected as well as the
> adjacent ones, and every "sub-cube" has an X of springs on its sides.
> The slowness is due to silly code (this is my first ever try at stuff
> like this) and overkill (?) precision (20 steps/frame).

I don't really understand that description, do you use any 3D diagonal
springs?  Maybe just render a still with cylinders where the springs are. 
How did you model damping?

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______

Post a reply to this message

Christoph Hormann <chr### [at] gmxde> wrote in
news:3CE4CA62.8CB5D1F8@gmx.de: 
>> It took 5 mins on an 1400 MHz Athlon XP, which I consider slow, this
>> thing should be possible realtime on my machine. :) The five mins is a
>> guess, I did't even check. 
> 
> I would not call this slow, the recent 12 balls animations usually
> parse about 10 seconds per frame and render 5 seconds on a K6/500.

So it's probably faster than mine, while it's at least as complicated, or? 
:) It's the parse time that I consider relevant here.

> 
>> System: In every "row", every second node is connected as well as the
>> adjacent ones, and every "sub-cube" has an X of springs on its sides.
>> The slowness is due to silly code (this is my first ever try at stuff
>> like this) and overkill (?) precision (20 steps/frame). 
> 
> I don't really understand that description, do you use any 3D diagonal
> springs?  Maybe just render a still with cylinders where the springs
> are. How did you model damping?

There are no 3D diagonal springs. I'll try to describe the system again :)

So there are diagonal springs on the sides of the subcubes (if you look at 
the anim, the cube is made up of 4*4*4=64 pieces of what I call subcubes). 
Also if you start from a corner, and go any direction, the first node is 
connected with the second *and* the third as well, and so on. (The second 
is connected with the third and the fourth, etc.) This is something I read 
about in a paper about cloth simulation somewhere. I hope it's more 
understandable now, it's not that easy to explain for me. :)

Damping is not really modelled. :) I just multiplied the speed of every 
node with a value like 0.9995 or something at every timestep. If you have a 
better solution for spring damping pleeeeeaaase let me know. :)

It would be interesting to use the inside macro at the beginning of things, 
so with a high number of nodes one could make elastic objects of any shape. 
:) Maybe that will be my next project.

I also faintly remember that Hooke's spring constant is in fact *not* 
constant when the length of a spring changes beyond a certain point. And 
I'd like to try objects with different stiffness at different points... 
Physics can really be fascinating. :)


--
Cheers,
Gergely

Post a reply to this message

Gergely Vandor wrote:
> 
> [...]
> 
> There are no 3D diagonal springs. I'll try to describe the system again :)
> 
> So there are diagonal springs on the sides of the subcubes (if you look at
> the anim, the cube is made up of 4*4*4=64 pieces of what I call subcubes).
> Also if you start from a corner, and go any direction, the first node is
> connected with the second *and* the third as well, and so on. (The second
> is connected with the third and the fourth, etc.) This is something I read
> about in a paper about cloth simulation somewhere. I hope it's more
> understandable now, it's not that easy to explain for me. :)

Not really since i don't know how you number the nodes, but from this and
the last post i conclude you have the cube grid of axis parallel springs
connecting neighboring nodes and two diagonal springs forming an 'x' on
every elementary 'square' in the system.

> 
> Damping is not really modelled. :) I just multiplied the speed of every
> node with a value like 0.9995 or something at every timestep. If you have a
> better solution for spring damping pleeeeeaaase let me know. :)

I have on paper, but i did not yet have success implementing it
('exploding' cubes are funny, but not really useful...)

> 
> I also faintly remember that Hooke's spring constant is in fact *not*
> constant when the length of a spring changes beyond a certain point. And
> I'd like to try objects with different stiffness at different points...
> Physics can really be fascinating. :)

For materials like rubber there is not much linear elasticity anyway,
metals can be modelled as linear until they experience permanent
deformation (which would also be interesting to model BTW).

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______

Post a reply to this message