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This can be really hard for some mathematical objects.
Imagine two different julia-objects colliding... How do you calculate
that?
--
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););} /*- Warp -*/
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In article <3a7434b5@news.povray.org>, Warp <war### [at] tagpovrayorg>
wrote:
> This can be really hard for some mathematical objects.
> Imagine two different julia-objects colliding... How do you calculate
> that?
I'd probably start out by computing a bunch of points on the surface and
using the Inside test to figure out an approximate center of
gravity...but I know virtually nothing about this kind of thing, so this
is just guesswork.
Maybe limit it to mesh objects, that way you could also simulate the way
the surface is deformed by it's interactions with other objects. I don't
think the deform patch would be sufficient for this...and handling only
meshes should make it easier.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-4F6740.11052728012001@news.povray.org...
> I'd probably start out by computing a bunch of points on the surface and
> using the Inside test to figure out an approximate center of
> gravity...but I know virtually nothing about this kind of thing, so this
> is just guesswork.
>
> Maybe limit it to mesh objects, that way you could also simulate the way
> the surface is deformed by it's interactions with other objects. I don't
> think the deform patch would be sufficient for this...and handling only
> meshes should make it easier.
I'd be happy with solid-body dynamics so surface deformations wouldn't be an
issue. Maybe if it was just limited to the simpler POV primitives without
CSG initially.. even just spheres, or blobs would be great too for liquid
effects.
Andy Cocker
---------------------------------------------------------------
listen to my music at:
www.mp3.com/lunarland
---------------------------------------------------------------
'I spilled spot remover on my dog. He's gone now. '
'I went to a restaurant that serves "breakfast at any time."
So I ordered french toast during the Renaissance. '
- Steven Wright.
---------------------------------------------------------------
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David Buck wrote:
>
> Never implement undampened springs. They will explode with small
> accumulating errors.
I posted an anim to p.b.animations many moons ago, which demonstrates this.
A falling tetrahedron behaves wonderfully until about a half second after
the rebound. There was dampening, just not enough.
Modifying the motions equations to include third-order motion (ie, d3x/dt3)
greatly reduced the error, so that less dampening as needed. It's
possible that calculating the dampened sinusoid which best matches the
current velocity, acceleration, and higher derivatives will yield a closer
approximation of real motion, but I haven't looked into it very far.
And since all real-world springs are very slightly dampened anyway,
a slight dampening is needful for realism.
Regards,
John
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Andy Cocker <big### [at] mariner9fsnetcouk> wrote:
: or blobs
AFAIK blobs are also one of the most difficult primitives.
--
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););} /*- Warp -*/
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On Sat, 27 Jan 2001 23:28:16 -0000, "Andy Cocker"
<big### [at] mariner9fsnetcouk> wrote:
>I've just been looking at www.havok.com... WOW! Solid body dynamics, cloth
>simulation.. available as a MAX plugin. *This* is the kind of thing I want
>access to in POV :-)
>
>I couldn't do it, but could any of you math wizards that frequent these
>newsgroups? I hope so..
My thesis will be (with luck) algorithms for simulating string, cloth,
solid body, gel, fluid, field and some other interesting stuff. And of
course I plan to code it as a POV patch. It should be due June or
September.
Please don't ask more. I am the one who would like it the most to see
it working.
Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG e-mail : pet### [at] tagpovrayorg
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"Peter Popov" <pet### [at] vipbg> wrote in message
news:223a7tg48m6a0i6jj0gon0a52k1libk95p@4ax.com...
> My thesis will be (with luck) algorithms for simulating string, cloth,
> solid body, gel, fluid, field and some other interesting stuff. And of
> course I plan to code it as a POV patch. It should be due June or
> September.
>
> Please don't ask more. I am the one who would like it the most to see
> it working.
Good luck with it Peter.
--
Andy Cocker
---------------------------------------------------------------
listen to my music at:
www.mp3.com/lunarland
---------------------------------------------------------------
'I spilled spot remover on my dog. He's gone now. '
'I went to a restaurant that serves "breakfast at any time."
So I ordered french toast during the Renaissance. '
- Steven Wright.
---------------------------------------------------------------
Post a reply to this message
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You could get away with using some sort of "bounding box" coding (similar to
what is used to calculate collision detection in many video games) to
envelope complex objects (like the julias mentioned earlier) in a shape that
was transparent to the camera that adopted the original object's properties
(gravity, etc.) and much faster to operate with, say a rough mesh or even
simple primatives.
This wouldn't fool the eye under very close inspection but for a camera
perspective that didn't percieve great detail it would probably work.
"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-4F6740.11052728012001@news.povray.org...
> In article <3a7434b5@news.povray.org>, Warp <war### [at] tagpovrayorg>
> wrote:
>
> > This can be really hard for some mathematical objects.
> > Imagine two different julia-objects colliding... How do you calculate
> > that?
>
> I'd probably start out by computing a bunch of points on the surface and
> using the Inside test to figure out an approximate center of
> gravity...but I know virtually nothing about this kind of thing, so this
> is just guesswork.
>
> Maybe limit it to mesh objects, that way you could also simulate the way
> the surface is deformed by it's interactions with other objects. I don't
> think the deform patch would be sufficient for this...and handling only
> meshes should make it easier.
>
> --
> Christopher James Huff
> Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
> TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
>
> <><
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