[Sidefx-houdini-list] rendering point colors

Garman Herigstad garman_lists at sbcglobal.net
Wed Oct 11 08:52:19 EDT 2006

Using attributes to control any shader paramter is
easier than most expect.

About color, you can pass primitive and detail
attributes as color.  This is vey useful if you only
need to color by primitive, or the full object has one
color (or one shade attribute that is changing per

Detail attributes.  It only allows for on efor the
full geometry.  So it's lite, memory-wise.   So if you
only want to animate the displacement level for the
full object, using detail will save memory.

The downside of not using this is, if your geometry is
very heavy and you have point attributes with the same
(duplicate) settings for each point, your geometry can
grow in size, almost unmanagable.

Attributes have a priority of which will override.  If
you have a color attribute (Cd) on point, primitive
and detail, guess the priorty.

THAT'S RIGHT.  point overrides detail and detail
overrides primitive.

--- luc froehlicher <lulu at alamaison.fr> wrote:

> thanks rick.it works fine.
> I guess it was a stupid question. :)
> luc
> Rick Walia wrote:
> >Hi Luc,
> >
> >If you append an attribute sop to your sop chain
> you can rename attributes.
> >
> >First you have to find out what the name of the
> channel that you want to
> >pass to the shader and then to mantra.
> >
> >As a quick test, in shops get a vex super material
> shop.
> >If you hover your mouse over the Diffuse label on
> the parameters you should
> >see the little floating help that says
> >diffr diffg diffb
> >
> >This shader is looking for the diff parameter name
> for the diffuse channel.
> >
> >Now let's go back to sops. If you middle click on
> your Color Sop  you should
> >see that you have a point attribute called Cd of
> vector type.
> >What we need to do is change the name Cd to diff as
> the shader above is
> >expecting that for the diffuse channel.
> >
> >Append an attribute sop and under the Point tab:
> >In the From field type Cd
> >In the To field type diff
> >
> >Now append a shader sop to this attribute sop and
> set the surface shader to
> >the vex super material you created in shops. If you
> set the render and
> >display flag on the shader sop, you should be able
> to render your object
> >with the same colors as the color sop.
> >
> >
> >Cheers,
> >
> >/Rick
> >
> >
> >
> >On 10/6/06 5:47 PM, "luc froehlicher"
> <lulu at alamaison.fr> wrote:
> >
> >  
> >
> >>I've put some colors on the points of my object
> with a sop color node
> >>... works fine in the viewport
> >>but ... how can I use that color with mantra
> inside a shader.
> >>sorry if it's a stupid question but I didin't find
> how to do that .
> >>luc
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> >>    
> >>
> >
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> >  
> >
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Garman Herigstad
If you want to contact me directly, use:  
garman @ vizyacky.com

Garman's Visual Effects Academy

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