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19 Jul 2024 09:14:16 EDT (-0400)
  Substraction (Message 1 to 9 of 9)  
From:
Subject: Substraction
Date: 1 May 2003 00:37:18
Message: <3eb0a47e@news.povray.org>
--------------( oo )--------------
This is a volumetric substraction.
--------------( oo )--------------


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Attachments:
Download 'GRAVITY-SUBSTRACT-02-PRO-(50)-90.avi.dat' (552 KB)

From: JWV
Subject: Re: Substraction
Date: 1 May 2003 03:54:35
Message: <3eb0d2bb$1@news.povray.org>
looks usefull, especialy to animate bullets going trough something. But why
is the image so "flickering"?


news:3eb0a47e@news.povray.org...
>
> --------------( oo )--------------
> This is a volumetric substraction.
> --------------( oo )--------------

>
>
>


Post a reply to this message

From:
Subject: Re: Substraction
Date: 1 May 2003 12:54:41
Message: <3eb15151$1@news.povray.org>
This is because I'm working on a real time system and I coded changes
between colors on each frames to see clearly the refresh rate. Those
simulations are done in real time. For this anim, it tooks nearly 5s by
frames. But the simulation of gravity is done in real time. I obtain nearly
30f/s.

We could think about a bullet passing through a skull, but I prefer thinknig
of a worm eating an apple. Or a worm eating the space inside a volume to
form an architectural space.



"JWV" <jwv|at|planet.nl> wrote in message news:3eb0d2bb$1@news.povray.org...
> looks usefull, especialy to animate bullets going trough something. But
why
> is the image so "flickering"?
>

> news:3eb0a47e@news.povray.org...
> >
> > --------------( oo )--------------
> > This is a volumetric substraction.
> > --------------( oo )--------------

> >
> >
> >
>
>


Post a reply to this message

From: JWV
Subject: Re: Substraction
Date: 1 May 2003 13:53:43
Message: <3eb15f27$1@news.povray.org>
Those
> simulations are done in real time. For this anim, it tooks nearly 5s by
> frames. But the simulation of gravity is done in real time. I obtain
nearly
> 30f/s.

thats impressive i think. (are you using Euler, and if so, how big are you
time steps?)
JWV


news:3eb15151$1@news.povray.org...
> This is because I'm working on a real time system and I coded changes
> between colors on each frames to see clearly the refresh rate. Those
> simulations are done in real time. For this anim, it tooks nearly 5s by
> frames. But the simulation of gravity is done in real time. I obtain
nearly
> 30f/s.
>
> We could think about a bullet passing through a skull, but I prefer
thinknig
> of a worm eating an apple. Or a worm eating the space inside a volume to
> form an architectural space.
>
>
>
> "JWV" <jwv|at|planet.nl> wrote in message
news:3eb0d2bb$1@news.povray.org...
> > looks usefull, especialy to animate bullets going trough something. But
> why
> > is the image so "flickering"?
> >

> > news:3eb0a47e@news.povray.org...
> > >
> > > --------------( oo )--------------
> > > This is a volumetric substraction.
> > > --------------( oo )--------------

> > >
> > >
> > >
> >
> >
>
>


Post a reply to this message

From:
Subject: Re: Substraction
Date: 1 May 2003 17:29:14
Message: <3eb191aa$1@news.povray.org>
I  used a old book of mechanic from the college and the Newton's laws. I was
looking on the site of Christoph Hormann for the classification of the
algorithms. As I'm not engineer, I didn't distinction between Euler or HEUN
methods. but I think that it is Euler method.

When you're talking about Time Step, are You talking of Time STeps in
SimPOV? I didn't
used Christoph's SimPov, just because I didn't saw his site. This is well
done.

In my case, time step was relativ to others values.

I guess those consideration are really interreting. I'm planning making some
courses in mechanical engineering. Quite different from architecture.



"JWV" <jwv|at|planet.nl> wrote in message news:3eb15f27$1@news.povray.org...
> Those
> > simulations are done in real time. For this anim, it tooks nearly 5s by
> > frames. But the simulation of gravity is done in real time. I obtain
> nearly
> > 30f/s.
>
> thats impressive i think. (are you using Euler, and if so, how big are you
> time steps?)
> JWV
>

> news:3eb15151$1@news.povray.org...
> > This is because I'm working on a real time system and I coded changes
> > between colors on each frames to see clearly the refresh rate. Those
> > simulations are done in real time. For this anim, it tooks nearly 5s by
> > frames. But the simulation of gravity is done in real time. I obtain
> nearly
> > 30f/s.
> >
> > We could think about a bullet passing through a skull, but I prefer
> thinknig
> > of a worm eating an apple. Or a worm eating the space inside a volume to
> > form an architectural space.
> >
> >
> >
> > "JWV" <jwv|at|planet.nl> wrote in message
> news:3eb0d2bb$1@news.povray.org...
> > > looks usefull, especialy to animate bullets going trough something.
But
> > why
> > > is the image so "flickering"?
> > >

> > > news:3eb0a47e@news.povray.org...
> > > >
> > > > --------------( oo )--------------
> > > > This is a volumetric substraction.
> > > > --------------( oo )--------------

> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>


Post a reply to this message

From: Kitsune e
Subject: Re: Substraction
Date: 1 May 2003 22:25:03
Message: <web.3eb1d626652ba6a980837b940@news.povray.org>
INVALID_ADDRESS wrote:
>This is a volumetric substraction.

>

Its odd... I read the previous post, and so I know the what and how... but
to me it looks like a spline used to subtract sphere placed along said
spline from another larger sphere.

Like: object{My_sphere translate My_spline(clock)}

plus a loop that says like:
difference{
    Big_sphere
    #while(step<clock)
        object{My_sphere translate My_spline(step)}
        #declare step = step + (1/final_frame)
    #end
}

so that you get a chunk taken out wherever a sphere passes through the
larger sphere.  Though you might not want the steps to be based on the
clock...


Post a reply to this message

From:
Subject: Re: Substraction
Date: 1 May 2003 23:59:22
Message: <3eb1ed1a$1@news.povray.org>
For the relations between objects, I used the those rules where G is
constant and m is the mass. There's a test in the calculation of the SPEED
where I define the collisions. It works well for to elements, but not for
many.

; --( ACCELERATION )--
#macro _a (_p1, _p2)
        ( G*((m*40)/(pow(vlength( _p2-_p1 ), 3)) )*(_p2-_p1) ) #end

; --( VITESSE )--
#macro _v (_p1, _p2, vx)
        #if (vlength( _p2-_p1 ) > 70 )
                ( vx + _a(_p1, _p2)*_t )
        #else
                ( vx + _a(_p2, _p1)*_t )
        #end #end

; --( EMPLACEMENT )--
#macro _p (_p1, _p2, vx)
        ( _p1 + _v(_p1, _p2, vx)*_t ) #end

To have rapid results, I used a system based on projective geometry. It
gives true CSG operations and there's no facets, so this is much more rapid.
This is a project developed at the university. It use SCHEME, a dialect of
LISP and there's no raytracing. I heard that they were planning to release
an open version.



"Kitsune_e" <kit### [at] hotmailcom> wrote in message
news:web.3eb1d626652ba6a980837b940@news.povray.org...
> INVALID_ADDRESS wrote:
> >This is a volumetric substraction.

> >
>
> Its odd... I read the previous post, and so I know the what and how... but
> to me it looks like a spline used to subtract sphere placed along said
> spline from another larger sphere.
>
> Like: object{My_sphere translate My_spline(clock)}
>
> plus a loop that says like:
> difference{
>     Big_sphere
>     #while(step<clock)
>         object{My_sphere translate My_spline(step)}
>         #declare step = step + (1/final_frame)
>     #end
> }
>
> so that you get a chunk taken out wherever a sphere passes through the
> larger sphere.  Though you might not want the steps to be based on the
> clock...
>


Post a reply to this message

From: JWV
Subject: Re: Substraction
Date: 2 May 2003 03:06:30
Message: <3eb218f6$1@news.povray.org>
> When you're talking about Time Step, are You talking of Time STeps in
> SimPOV?
No, i have never used Simpov, and know nothing about it.
 When i'm talking about timesteps i mean this:

//---------------
#declare A=F/m;
#declare dV=A*dT;
#declare V=V+dV;
#declare X=X+V*dT;
//--------------- BTW( is this Euler? i think so, but could be wrong)

dT is the timestep here, the smaller your timesteps, the more acurate the
results. But when you use small timesteps (0.0001 sec.) it will take a fast
processor to calculate the motion in real time since 1/dT timesteps are
needed per second (10000 in this case).


JWV


news:3eb191aa$1@news.povray.org...
> I  used a old book of mechanic from the college and the Newton's laws. I
was
> looking on the site of Christoph Hormann for the classification of the
> algorithms. As I'm not engineer, I didn't distinction between Euler or
HEUN
> methods. but I think that it is Euler method.
>
> When you're talking about Time Step, are You talking of Time STeps in
> SimPOV? I didn't
> used Christoph's SimPov, just because I didn't saw his site. This is well
> done.
>
> In my case, time step was relativ to others values.
>
> I guess those consideration are really interreting. I'm planning making
some
> courses in mechanical engineering. Quite different from architecture.
>
>
>
> "JWV" <jwv|at|planet.nl> wrote in message
news:3eb15f27$1@news.povray.org...
> > Those
> > > simulations are done in real time. For this anim, it tooks nearly 5s
by
> > > frames. But the simulation of gravity is done in real time. I obtain
> > nearly
> > > 30f/s.
> >
> > thats impressive i think. (are you using Euler, and if so, how big are
you
> > time steps?)
> > JWV
> >

> > news:3eb15151$1@news.povray.org...
> > > This is because I'm working on a real time system and I coded changes
> > > between colors on each frames to see clearly the refresh rate. Those
> > > simulations are done in real time. For this anim, it tooks nearly 5s
by
> > > frames. But the simulation of gravity is done in real time. I obtain
> > nearly
> > > 30f/s.
> > >
> > > We could think about a bullet passing through a skull, but I prefer
> > thinknig
> > > of a worm eating an apple. Or a worm eating the space inside a volume
to
> > > form an architectural space.
> > >
> > >
> > >
> > > "JWV" <jwv|at|planet.nl> wrote in message
> > news:3eb0d2bb$1@news.povray.org...
> > > > looks usefull, especialy to animate bullets going trough something.
> But
> > > why
> > > > is the image so "flickering"?
> > > >

> > > > news:3eb0a47e@news.povray.org...
> > > > >
> > > > > --------------( oo )--------------
> > > > > This is a volumetric substraction.
> > > > > --------------( oo )--------------

> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
>


Post a reply to this message

From:
Subject: Re: Substraction
Date: 2 May 2003 12:44:42
Message: <3eb2a07a$1@news.povray.org>
For initial values I had

mass = 11000000
G = 200
dt = 0.0003 sec

The mass is high, then it affect the rest of the calculations.


"JWV" <jwv|at|planet.nl> wrote in message news:3eb218f6$1@news.povray.org...
> > When you're talking about Time Step, are You talking of Time STeps in
> > SimPOV?
> No, i have never used Simpov, and know nothing about it.
>  When i'm talking about timesteps i mean this:
>
> //---------------
> #declare A=F/m;
> #declare dV=A*dT;
> #declare V=V+dV;
> #declare X=X+V*dT;
> //--------------- BTW( is this Euler? i think so, but could be wrong)
>
> dT is the timestep here, the smaller your timesteps, the more acurate the
> results. But when you use small timesteps (0.0001 sec.) it will take a
fast
> processor to calculate the motion in real time since 1/dT timesteps are
> needed per second (10000 in this case).
>
>
> JWV
>

> news:3eb191aa$1@news.povray.org...
> > I  used a old book of mechanic from the college and the Newton's laws. I
> was
> > looking on the site of Christoph Hormann for the classification of the
> > algorithms. As I'm not engineer, I didn't distinction between Euler or
> HEUN
> > methods. but I think that it is Euler method.
> >
> > When you're talking about Time Step, are You talking of Time STeps in
> > SimPOV? I didn't
> > used Christoph's SimPov, just because I didn't saw his site. This is
well
> > done.
> >
> > In my case, time step was relativ to others values.
> >
> > I guess those consideration are really interreting. I'm planning making
> some
> > courses in mechanical engineering. Quite different from architecture.
> >
> >
> >
> > "JWV" <jwv|at|planet.nl> wrote in message
> news:3eb15f27$1@news.povray.org...
> > > Those
> > > > simulations are done in real time. For this anim, it tooks nearly 5s
> by
> > > > frames. But the simulation of gravity is done in real time. I obtain
> > > nearly
> > > > 30f/s.
> > >
> > > thats impressive i think. (are you using Euler, and if so, how big are
> you
> > > time steps?)
> > > JWV
> > >

> > > news:3eb15151$1@news.povray.org...
> > > > This is because I'm working on a real time system and I coded
changes
> > > > between colors on each frames to see clearly the refresh rate. Those
> > > > simulations are done in real time. For this anim, it tooks nearly 5s
> by
> > > > frames. But the simulation of gravity is done in real time. I obtain
> > > nearly
> > > > 30f/s.
> > > >
> > > > We could think about a bullet passing through a skull, but I prefer
> > > thinknig
> > > > of a worm eating an apple. Or a worm eating the space inside a
volume
> to
> > > > form an architectural space.
> > > >
> > > >
> > > >
> > > > "JWV" <jwv|at|planet.nl> wrote in message
> > > news:3eb0d2bb$1@news.povray.org...
> > > > > looks usefull, especialy to animate bullets going trough
something.
> > But
> > > > why
> > > > > is the image so "flickering"?
> > > > >

> > > > > news:3eb0a47e@news.povray.org...
> > > > > >
> > > > > > --------------( oo )--------------
> > > > > > This is a volumetric substraction.
> > > > > > --------------( oo )--------------

> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
> >
>
>


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