Ok, the last ones... I've things to do, and this "physics addiction" is
starting to get over the top. Fortunately, Koppi's playground is giving
me a segfault when using more than some thousand objects, preventing
some really interesting and complex scenes. As the author is
unreachable, sailing until December, I think I'm safe for now... ;)

--
Jaime

Post a reply to this message

Attachments:
Download 'coins-17.jpg' (245 KB) Download 'coins-18.jpg' (183 KB)

Preview of image 'coins-17.jpg'

Preview of image 'coins-18.jpg'

Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
> Ok, the last ones... I've things to do, and this "physics addiction" is
> starting to get over the top. Fortunately, Koppi's playground is giving
> me a segfault when using more than some thousand objects, preventing
> some really interesting and complex scenes. As the author is
> unreachable, sailing until December, I think I'm safe for now... ;)
>
> --
> Jaime

Just missing the coins of two colors. Paper money of five hundred should be more
difficult to generate, due the absence of a model.

Good picture, I hope someday you have time to explain this technique in your
site.

B. Gimeno

Post a reply to this message

On 08/10/12 09:19, B. Gimeno wrote:
> Just missing the coins of two colors.

   Yes, I purposely omitted it... I'm way too lazy. But it would not be
difficult, given the way the coins are done: I just have to create two
concentric heightfields for each coin side, instead of just one.

> Paper money of five hundred should be more difficult to generate,
> due the absence of a model.
>

   I my self never seen one... :( ...but there are plenty of pictures on
the web, I'm sure. The problem is that I'm still far away from starting
with soft-body physics.

> Good picture, I hope someday you have time to explain this technique
> in your site.

   Thanks... You mean the physics part, or just the coin modeling/texturing?

--
Jaime

Post a reply to this message

Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
>    Thanks... You mean the physics part, or just the coin modeling/texturing?
>
> --
> Jaime

Physics...Even with the risk of being caught by the law of gravity. :-)

B. Gimeno

Post a reply to this message

On 08/10/12 10:36, B. Gimeno wrote:
> Physics...Even with the risk of being caught by the law of gravity.
> :-)

   Yes, it's a real risk... there is something fascinating in looking at
things falling and colliding on slow motion.

   My technique is easy because I use a scripting tool which exports to
POV-Ray SDL, so I only have to customize the exported code and then
render. The nice thing about Koppi's playground, is that it allows to
construct scenes the way you will do on POV-Ray, with loops, and if's,
and lots of random values here and there...

   The tool consists on a LUA interpreter, which is the "interface" to
the Bullet Physics Library. There are some bindings in place which allow
to create simple collision objects, and to add them to the physics
simulation. Then you run the simulation, and the whole thing is rendered
in openGL on real time. You can export each frame to POV-Ray format too, 
and that's the actual good thing about it.

   Here is how a simple LUA script looks like:

----------------------------------------
plane = Plane(0,1,0)
plane.pos = btVector3(0, 0, 0)
plane.col = "#999999"
v:add(plane)

function explosion(N,H)
   for i = 1,N do
     local d = Cube()
     d.pos =
btVector3(-.5+math.random(0,10)*.1,H-.5+math.random(0,10)*.1,-.5+math.random(0,10)*.1)
     d.col = "#ff9900"
     d.friction = .5
     d.restitution = .9
     v:add(d)
   end
end

explosion(260,25)
----------------------------------------

   This would export a POV file for each frame, with a plane{} and 260
box{} objects with the matrix transformations required:

-----------------------------------------
plane { <0, 1, 0>, 0
   pigment { rgb <0.0666667, 0.0666667, 0.0666667> }
}

box { <-0.5, -0.5, -0.5>, <0.5, 0.5, 0.5>
       pigment { rgb <1, 0, 0> }
   matrix <0.00928936,0.999722,-0.0216712,
         0.835221,-0.0196738,-0.549562,
         -0.549835,-0.0129952,-0.835172,
         -10.6849,0.479277,-109.289>
}
// ...and 259 more
-----------------------------------------

   The, I do some automated search&replace to put there my own objects,
with the same or similar shape and dimensions, leaving the matrix in


   Unfortunately, the program is in very-alpha state, although it is
really promising. The version on github has some flaws that I already
corrected on my local copy, but the main problem is that it segfaults
with more than 200-250 objects, and debugging that is beyond my
abilities (though I did try and failed as expected, BTW).

   Regards,

--
Jaime

Post a reply to this message

> On 08/10/12 09:19, B. Gimeno wrote:
>> Just missing the coins of two colors.
>
>    Yes, I purposely omitted it... I'm way too lazy. But it would not be
> difficult, given the way the coins are done: I just have to create two
> concentric heightfields for each coin side, instead of just one.
>

Why two heightfields? You just need a cylindrical pattern switching from 
one metal texture to the other at the right radius.
texture{cylindrical texture_map{[0.75 Golden_Texture][0.75 
Silvery_Texture]}}

> --
> Jaime

Post a reply to this message

On 08/10/12 23:55, Alain wrote:
> Why two heightfields? You just need a cylindrical pattern switching
> from one metal texture to the other at the right radius.
> texture{cylindrical texture_map{[0.75 Golden_Texture][0.75
> Silvery_Texture]}}

   Ah... yes, of course. And with the actual number of heightfields
already present on the scene, it would be much more efficient.

--
Jaime

Post a reply to this message

Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
> Hi All:
>
>    Sorry for the misleading subject... I couldn't resist. ;)

Nice coins. They have a pleasing thickness you don't always find with real ones
(not in the US, anyway). The render quality is good, too, especially the image
with the coins spilled onto a granite plane. One could easily mistake it for a
photograph.

> So, for this scene, I setup a LUA script to make 5 piles of different
> coins, and then sent a ball on their way...

Uncle Scrooge would be p1ss3d!

> Now, I just have to make better heightfields for the coins... the
> current ones using webdings.ttf are not very convincing.

I've got one coin in my meager collection with a similar level of quality: it's
gold-colored with an eagle ringed by twenty stars on one side, and the words "No
Cash Value" on the other ;) Perhaps bas-reliefs could be made by blurring the
symbols' height maps and masking them with their sharp versions?

BTW, I was never able to create decent bump maps from my other coins. They were
either too scratched, or too reflective. I need some sort of removable substance
that will hide the reflective surfaces without diminishing all the details, like
a thin paint or some face makeup. A new paint brush would also help... it might
be time for another haircut :D

Post a reply to this message

On 19/10/12 23:36, Samuel Benge wrote:
> Nice coins. They have a pleasing thickness you don't always find with
> real ones (not in the US, anyway). The render quality is good, too,
> especially the image with the coins spilled onto a granite plane. One
> could easily mistake it for a photograph.

   Yes, I guess I made them a bit more thick than usual in real coins, at
least comparing with the euro coins I've at hand. I also think that I
raised too much the relief, but I like it...

> Uncle Scrooge would be p1ss3d!

   I didn't know the original name of this character... back then, in
Spain there was a tendency to translate *everything*, and he was called
"El Tio Gilito" here (thankfully these days at least the names aren't
translated, or Homer Simpson would have ended as Homero Simones, or
something like that...).

> I've got one coin in my meager collection with a similar level of
> quality: it's gold-colored with an eagle ringed by twenty stars on
> one side, and the words "No Cash Value" on the other ;)

   Yes, that's what I was referring to... they look a bit like these
"on-purpose" fake coins (specially at first, before I started using the
new albedo specular, which helped a lot making them look more metallic).

> Perhaps bas-reliefs could be made by blurring the symbols' height
> maps and masking them with their sharp versions?

   Hmmm... should try that.

> BTW, I was never able to create decent bump maps from my other coins.
> They were either too scratched, or too reflective. I need some sort
> of removable substance that will hide the reflective surfaces without
> diminishing all the details, like a thin paint or some face makeup. A
> new paint brush would also help... it might be time for another
> haircut :D

   I know what you mean... been there too. ;) But finally I've given up
and decided it was not worth the effort to scan real coins... instead, I
searched for some dingbats fonts to make my virtual ones more interesting.

   BTW, did you try this other trick? :

   http://www.mdartford.com/?p=453

   I was tempted to try it just with coffee, as there is always a cup
somewhere on my table... :)


--
Jaime

Post a reply to this message

Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
>    BTW, did you try this other trick? :
>
>    http://www.mdartford.com/?p=453

Clever solution. I occasionally think of ways to make something like that work
with my scanner, but haven't come up with anything useful. Besides, such a
method would still require that I paint my coins.

>    I was tempted to try it just with coffee, as there is always a cup
> somewhere on my table... :)

I'm fairly certain that you'll need a more effective light-attenuating medium
than coffee. Oil dyed with soot, maybe? Pressing a thin sheet of clear plastic
onto the coin might also be a good idea to avoid photographing reflected light
from the liquid's uneven surface.

Post a reply to this message