Hello all,
I'm modeling an interior scene in Rhino 1.1  that contains a small wood
stove type fireplace.  The stove has a screen over it's opening.  I'm
debating on whether to create the screen with simple geometry for realism,
or to find a shader with opacity and displacement mapping.

My question to this group would be: Is there a shader available within
Moray/povray that would allow me to see through the screen to the interior
of the fireplace?

I've put this question to the Rhino newsgroup and have had some good
suggestions which I've pasted below:



HI Steve- I guess it depends upon the density of the screen- if it looks
like adding too much tiny geometry then you are probably better off with
scrren texture, but if it's a biggish screen and the views you are planning
are close, then geometry might make more sense.

-Pascal


Hi Steve,


> I'm modeling a wood burning stove that has a screen over its opening.  I'm
> curious whether I should create a patch surface over the screen and then
> apply a screen shader, or if I should create a screen type geometry and
> apply a simple metal shader to the screen.  Any thoughts?

I just completed a screen for a center channel speaker. I wouldn't model
it in complete 3d or even as a plane with holes. I crashed Rhino trying
it, just too many surfaces for rhino. But I did create the grill work in
Rhino using 2d curves, even these became hard to manipulate because you
will have to make a lot of them to resemble a real screen. I then saved
the file as .ai and brought it into Photoshop and created a targa image
that I used as an alpha channel in max.

Sincerely,
Roland Montijo,
Rol### [at] aolcom

It looks like I've stumbled over a problem area.  My goal would be to be
able to see through the screen to the objects inside the stove like the
grate and maybe a log or two, just as in real life.  It seems that a shader
over a surface would be opaque.  Could make a fret work of  small pipes from
arrayed lines. Using fewer than normal pipes.   I'm not sure I understand
the use of the alpha channel and how it might be employed  in Moray which
I'm using.  Perhaps this is something I should study up on.

Thanks for your thoughts.

later,
Steve Clarke
Gresham, Oregon

Hi Steve


>>I'm not sure I understand the use of the alpha channel and how it might be
employed  in Moray which
I'm using.  Perhaps this is something I should study up on.<<

Sorry I don't know Moray but perhaps it supports transparency mapping
someone on this list might know. Basically transparency mapping/alpha
channeling drops out all the black pixels or whatever pixels you choose
in a bitmap so that when your rendering program renders the image the
final rendering lets you see through the applied bitmap where the black
pixels would be. This ends up saving large amounts of geometry and thus
rendering faster because you are using a bitmap to supply the
information.

This is also a technique you see used for outdoor or plant scenes where
the computer just can't cope with all the millions of leaves.

Sincerely,
Roland Montijo
Rol### [at] aolcom

On Wed, 23 Feb 2000 21:47:21 -0800, "Steve Clarke"
<scl### [at] teleportcom> wrote:

>It looks like I've stumbled over a problem area.  My goal would be to be
>able to see through the screen to the objects inside the stove like the
>grate and maybe a log or two, just as in real life.  It seems that a shader
>over a surface would be opaque.  Could make a fret work of  small pipes
from
>arrayed lines. Using fewer than normal pipes.

To get an idea what Rhino takes cool as a number of pipes see
attached.

steff
(attachment not included for sake of bandwidth sc)

Steve Clarke <scl### [at] teleportcom> wrote:
>...
> over a surface would be opaque.  Could make a fret work of  small pipes
from
> arrayed lines. Using fewer than normal pipes.
>...

I think you could also just make an array of narrow Plane or 3DFace
objects. They will be black anyway, right?
The simpler the screen geometry, the faster it will mesh and render.

-Mikko

Mikko Oksanen
Robert McNeel & Associates



Steve,

If your using a renderer that does opacity and displacement mapping.
You can create a 2d texture of the screen you want and use it as a bump
map and an opactiy map.  I've done this a lot and it lets you see
through the holes, and really looks cool.  Plus there's no extra
geometry to build.

The new version of Bmrt comes with a shader that has that capability.

Maybe an option...

Brian Perry

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