On 12/09/12 20:35, Samuel Benge wrote:
> Great work as always, Jaime. Those colored pencils look wonderful,
> but the scene's missing a sketch somewhere :) The bricks have some
> nice details as well.

    Thanks! Yes, I had the more fun moments with the pencils... I did
trace like 30 different arrangements. The pen itself was a 15min job on
Wings3D, but it really came out pretty nice.

> Thanks to you, I decided to try something I've had in mind for a
> while, but never got around to until yesterday: using Blender to
> solve the physics, and POV-Ray to render the objects. I won't go into
> the details yet (the process is a bit convoluted), but for now it's
> enough to say that any object can be used; it just takes importing or
> building a new one in POV. The intermediate .obj file is fairly small
> (just four vertices for each object), and preserves per-axis scaling
> in addition to rotation and positional data.
>

    It would be nice to have a tool specifically made to interface the
Bullet Physics library with POV-Ray, to have a more simpler process
(run the simulation, export and render). Searching for such a program on
the net I found Koppi's Playground, and also this other one which I
could not make to work on my current system (but it looks very
interesting and promising):

    http://www.arishapiro.com/dance/

--
Jaime

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Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
> On 12/09/12 20:35, Samuel Benge wrote:
> > Thanks to you, I decided to try something I've had in mind for a
> > while, but never got around to until yesterday: using Blender to
> > solve the physics, and POV-Ray to render the objects. I won't go into
> > the details yet (the process is a bit convoluted), but for now it's
> > enough to say that any object can be used; it just takes importing or
> > building a new one in POV. The intermediate .obj file is fairly small
> > (just four vertices for each object), and preserves per-axis scaling
> > in addition to rotation and positional data.
> >
>
>     It would be nice to have a tool specifically made to interface the
> Bullet Physics library with POV-Ray, to have a more simpler process
> (run the simulation, export and render).

Yeah, it would be nice. My method isn't too horrible:

Blender:
-> prepare the physics simulation
-> run the "game" using the Bullet physics solver, saving its results to the IPO
-> copy the transformations of all rigid body objects (.py script)
-> paste the transformations to four-point mesh objects (.py script)
-> export all four-point meshes to a single .obj file

System:
-> run Obj2POVA.exe* with command line options (only a single step when using a
..bat file)

POV-Ray
-> run the scene file

The worst part of the process is battling with Blender. When you duplicate
objects and try to transform them after things have been saved to the IPO,
subsequent transformations will revert to past configurations, which means that
any changes made to the objects' orientations is all for nothing. You can delete
all IPO data, and it still happens. To avoid this, all rigid body actors must be
deleted and reduplicated if previously saved to the IPO, otherwise links to old
data must be cleared individually for every_single_object. After I learned what
was (unnecessarily) happening, things started going a lot more smoothly. Current
Blender versions might not have this problem.

> Searching for such a program on the net I found Koppi's Playground

Would I really need to build Koppi's Playground myself? Seems like a lot of work
to go though. Tangling with Blender is looking more and more like an easier way
to go when I consider trying to download and install the tool chain necessary to
get KBPP up and running %(

Nice updated pencils scene, BTW. Those "no_image" erasers are a kick :) Are you
using geometries other than boxes now? It would appear that the erasers' rounded
edges are behaving as such, although some pencils seem to be balancing on their
edges, so I'm not sure.

Sam

*Obj2PovA.exe is a program I put together using kixor's objLoader library:
http://www.kixor.net/dev/objloader/ It is used for converting .obj data to POV
arrays. I plan to release a version of it soon, since having mesh data readily
available as arrays is useful for so many things. For example, two-point
polygons can be read and converted, thus allowing POV-Ray to render hair created
in Blender.

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Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
> For the moment, I can only make the physics simulation to work with
> boxes, but that's enough for some fun... :)
>
> --
> Jaime

Nice!

Okay, here is Gille Tran's shopping cart filled to overflowing with primitives
via a custom program I wrote using the Bullet library. Still pondering easier
integration with POV-Ray...

Cheers,
-------------------------------------------------
www.McGregorFineArt.com

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Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
>     It would be nice to have a tool specifically made to interface the
> Bullet Physics library with POV-Ray, to have a more simpler process
> (run the simulation, export and render)...
> --
> Jaime

I have been thinking about (and working on) this quite a lot lately :)

fyi, I noticed some mirroring of the "no_image" text on some erasers (literally
mirrored text) that may need to be fixed...

:)
------------------------------------------------
www.McGregorFineArt.com

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On 13/09/12 20:45, Samuel Benge wrote:
>> Searching for such a program on the net I found Koppi's Playground
>
> Would I really need to build Koppi's Playground myself? Seems like a
> lot of work to go though. Tangling with Blender is looking more and
> more like an easier way to go when I consider trying to download and
> install the tool chain necessary to get KBPP up and running %(

   No, you are already doing more complex things than Koppi's playground
allows... so it' would not be of much use for you. At this moment,
Koppi's playground is very limited.

> Nice updated pencils scene, BTW. Those "no_image" erasers are a kick
> :) Are you using geometries other than boxes now? It would appear
> that the erasers' rounded edges are behaving as such, although some
> pencils seem to be balancing on their edges, so I'm not sure.

   No, just boxes... even for the pencils (that's why you see them
floating a little bit at some places), as cylinders were behaving a
bit erratically instead resting on the floor. The rounded erasers look
right just because I tried the simulation several times until I found a
result without obvious flaws.

--
Jaime

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On 14/09/12 01:19, Robert McGregor wrote:
> Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
>> It would be nice to have a tool specifically made to interface the
>> Bullet Physics library with POV-Ray, to have a more simpler
>> process (run the simulation, export and render)...
>
> I have been thinking about (and working on) this quite a lot lately
> :)

   I've plenty of ideas for the interface, if you really are going to
start such a tool...

> fyi, I noticed some mirroring of the "no_image" text on some erasers
> (literally mirrored text) that may need to be fixed...

   Yeah... I was lazy enough to just use planar mapping without realizing
it would give and inverted image at the other side: time for some
uv_mapping.

--
Jaime

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On 13/09/12 23:02, Robert McGregor wrote:
> Okay, here is Gille Tran's shopping cart filled to overflowing with primitives
> via a custom program I wrote using the Bullet library. Still pondering easier
> integration with POV-Ray...

   Just... :O


--
Jaime

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"Robert McGregor" <rob### [at] mcgregorfineartcom> wrote:
> Okay, here is Gille Tran's shopping cart filled to overflowing with primitives
> via a custom program I wrote using the Bullet library. Still pondering easier
> integration with POV-Ray...
>

Well that's excessively cool, Robert. Congrats!

What kind of geometry evaluations did you use for the object collisions? Convex
meshes, triangle (concave) meshes, primitive mathematical representations? Are
they colliding with a low-poly mesh representation of the cart?

More than any of those things, I'd like to know how stable everything was at
runtime. When working in Blender, solid bodies tend to jump around a lot when
confined in any space, sometimes never stabilizing. This mainly happens when
performing mesh-mesh collisions.

BTW, those front wheels seem off. More often than not you'll see them pointed
the other way... maybe the force of all those dropped objects pushed the cart
back? :)

Sam

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On 14-9-2012 22:29, Samuel Benge wrote:

> Well that's excessively cool, Robert. Congrats!

I join that!

Jaime, Sam, Robert, you are presenting very interesting work here.

>
> [...]
>
> More than any of those things, I'd like to know how stable everything was at
> runtime. When working in Blender, solid bodies tend to jump around a lot when
> confined in any space, sometimes never stabilizing. This mainly happens when
> performing mesh-mesh collisions.

I am not far enough with Blender, but I have the same experience using 
Poser Physics. Confined to a container, objects seem indeed to bounce 
around more, even when the bounce parameter is set to zero.

Thomas

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On 14/09/12 22:29, Samuel Benge wrote:
> More than any of those things, I'd like to know how stable everything
> was at runtime. When working in Blender, solid bodies tend to jump
> around a lot when confined in any space, sometimes never stabilizing.
> This mainly happens when performing mesh-mesh collisions.

   I find this problem too when using Koppi's Playground, specially
cylinders are unusable as they start to roll as if they were spheres,
instead of resting on the floor. With boxes, when they are long and
thing, I also have stability problems: there is always some that will
start shaking, sometimes spreading the problem to near boxes. Seems the
bullet physics simulation is more suited for animations of the
simulation, rather than for stills of the simulation result...

--
Jaime

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