Multiple surface Shaders on a single object????

Multiple surface Shaders on a single object????

Post by Luis M, Morales » Mon, 11 Aug 2003 21:06:46



how do i apply multiple shaders to a single object in maya using
Rat???? or in the rib file using BMRT Aqsis or 3delight??????
 
 
 

Multiple surface Shaders on a single object????

Post by Paul Grego » Tue, 12 Aug 2003 20:14:24



Quote:> how do i apply multiple shaders to a single object in maya using
> Rat???? or in the rib file using BMRT Aqsis or 3delight??????

You can't, the Renderman standard only allows a single shader to be
applied to a primitive. If you want to achieve the effect of layered
shaders this has to be implemented inside the shader code itself.

Cheers

PaulG

 
 
 

Multiple surface Shaders on a single object????

Post by Petr Lob » Tue, 12 Aug 2003 21:34:17



Quote:> how do i apply multiple shaders to a single object in maya using
> Rat???? or in the rib file using BMRT Aqsis or 3delight??????

Hi,
I have no idea about maya since I don't use it. The answer in plain
RIB file is simple: it can't be done. You have to write your custom
shader that has appearence you desire.

Petr

 
 
 

Multiple surface Shaders on a single object????

Post by Moritz Moelle » Tue, 12 Aug 2003 22:01:08



Quote:> how do i apply multiple shaders to a single object in maya using
> Rat?

Use a 'Layer' node in SLIM with two Surface Appearances.

.mm

 
 
 

Multiple surface Shaders on a single object????

Post by Gordon Chapm » Wed, 13 Aug 2003 18:31:23



Quote:> how do i apply multiple shaders to a single object in maya using
> Rat???? or in the rib file using BMRT Aqsis or 3delight??????

If memory serves I'm pretty sure that if you assign multiple surface
shaders to the object in Maya then you can attach shaders to the maya
*shading groups* and it'll carry on through into PRMan (with RAT at
least, not sure about any of the other renderers).

G.

 
 
 

Multiple surface Shaders on a single object????

Post by Luis M, Morales » Fri, 15 Aug 2003 03:34:56




> > how do i apply multiple shaders to a single object in maya using
> > Rat???? or in the rib file using BMRT Aqsis or 3delight??????

> If memory serves I'm pretty sure that if you assign multiple surface
> shaders to the object in Maya then you can attach shaders to the maya
> *shading groups* and it'll carry on through into PRMan (with RAT at
> least, not sure about any of the other renderers).

> G.

thx i will try this one, but i think i did not explain well what i
want, what i trying to do is like when i select a face in maya and
only asign a shader to that especific face, i trying to do that in
renderman rat, couse i dont want to brake my model in several peaces,
i can code some shader thought i`m still learming renderman
 
 
 

Multiple surface Shaders on a single object????

Post by Gordon Chapm » Fri, 15 Aug 2003 17:46:20



Quote:> thx i will try this one, but i think i did not explain well what i
> want, what i trying to do is like when i select a face in maya and
> only asign a shader to that especific face, i trying to do that in
> renderman rat, couse i dont want to brake my model in several peaces,
> i can code some shader thought i`m still learming renderman

Yes, maya will split the model into several shading groups internally,
but it's still a single piece of geometry as far as you're concerned,
just select the faces and drag your maya shaders onto them, then look
at it in the hypergraph, find the shading group for that shader and
attach your RAT shader to the shading group.

No custom shaders required.

G.

 
 
 

Multiple surface Shaders on a single object????

Post by henni » Fri, 15 Aug 2003 23:09:15


Quote:> Yes, maya will split the model into several shading groups internally,
> but it's still a single piece of geometry as far as you're concerned,

So if  you look at the RIB output, there will be more than once
geometry call, each with a different shader? There are no problems
along with seams, with normals or texture coordinates?

henning

 
 
 

Multiple surface Shaders on a single object????

Post by Gordon Chapm » Sat, 16 Aug 2003 20:33:08



> So if  you look at the RIB output, there will be more than once
> geometry call, each with a different shader? There are no problems
> along with seams, with normals or texture coordinates?

> henning

Well, there didn't seem to be when I did some basic testing with it
although I was only working with polygons but as the object is still a
single object within maya   I wouldn't expect there to be any
discontinuities at the edges - polygons either side of the seam will
still be reading the same vertex normal information as they still
share the same vertices, you haven't actually split the polygonal
object up into multiple shells.

If you were dealing with prman subdees however you may very well start
getting problems that would almost certainly require splitting the
surface up as detailed in the prman docs somewhere :)

 
 
 

Multiple surface Shaders on a single object????

Post by Luis M, Morales » Sun, 17 Aug 2003 19:32:28


thx this really help me a lot. i`m currently workin on my demo reel
and i`m doing a scene where some WWII planes are flying trough and
start getting attack fron the ground, i`m using maya for that with
some custom plugins. and 3delight aqsis and bmrt. i`m mostly learning
on the fly, i using delay read archive for the planes, and i`m still
figuring out how to make volumetric effects in renderman, like smoke
and fire if anyone can help me out with that, or point me into some
direction it will be very nice.
 
 
 

Multiple surface Shaders on a single object????

Post by Petr Lob » Tue, 19 Aug 2003 18:39:58



Quote:> thx this really help me a lot. i`m currently workin on my demo reel
> and i`m doing a scene where some WWII planes are flying trough and
> start getting attack fron the ground, i`m using maya for that with
> some custom plugins. and 3delight aqsis and bmrt. i`m mostly learning
> on the fly, i using delay read archive for the planes, and i`m still
> figuring out how to make volumetric effects in renderman, like smoke
> and fire if anyone can help me out with that, or point me into some
> direction it will be very nice.

Hi,
volumetric effects are described in Advanced RenderMan and
Texturing&Modeling: A Procedural Approach. See www.renderman.org for
more information about these books. In case you can't access them, try
to understand noise shader included in BMRT distribution.
Are you relly sure you need true volumetric effects? Some time ago I
was preparing some animation with a plane. I've created smoke effects
with  bilinear patches and custom surface shader. I was happy with it
and rendering times were quite impressive :)

Petr

 
 
 

1. single object vs multiple objects in MayA

Hello all !

I want to import a model out of Poser and animate it later with
IK-Handles.

Unfortunately, I experience some problems with this.

Every time I try to move a part of the body (e.g. the hand or arm), a
huge gap comes up between the moved part (e.g. arm) and the fixed part
(e.g. shoulder).

So, would it better to import the model as a single object (.obj) and
deform it with IK-Handles (or may be morphing / Blending Spape).
(model would stay "closed", but a lot of rework necessary)

Or would it be better to import the model as multiple objects and try to

build IK-Handles into it and then move it.
- Well, how to avoid the gaps then ?
(model would look better, but I do not know how to solve this
"gap-problem")

Thanx for any hint,

-Juergen.

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