[Sidefx-houdini-list] Bridge of Cards 2

Pablo Giménez pablogipi at gmail.com
Fri Mar 28 11:29:29 EDT 2008


2008/3/28, Beatriz Lorenzo <bealobo at gmail.com>:
>
> Hi again!
>
> Still no luck. So here are a couple of questions:
>
> - Mantra parameters are overriden if there is an attribute (same name and
> type) on the geometry. Do I need to actually enable any overrides in the
> material SOP or int eh SHOPs? I ask this because I've seen many
> "overrides"
> here and there. I have the shaders in SHOP context and geometry in OBJ, if
> it makes any difference.


To override parameters in a mantra shader you need to have POINT attributes
in your geometry of the same type.
For example for your map parameter in you shader, you only need to look at
the shader parameters, not the material, go into the material and look at
the parameters in your displacement/surface shader you want to  overrides
parameters.
So you usually use Attribute Create SOP and create a point attribute with
the same type, avoid integer parameters I don't know now but in previous
versions I remember problems with integer parameters and parameter
overriding, and same name of the parameter you want to override, then you
only need to play with the value of this attribute to control you shader
parameter.
Hope this helps.

- About randomizing, I'm using a stamp. So I made a new map (in this case is
> map) attribute on the card geo (not on the points to copy to), class
> primitive, type string. And defined the string:
> $HIP/images/cards.`stamp("../copy2","randomizer",1)`.jpg
> For the copy SOP I made the randomizer stamp with this: int(fit(rand($PR),
> 0, 1, 1, 52)) --- Actually that might be the problem, as I've copied this
> expression from your previous explanations to pingo without a lot of
> thought, without any thought.
> And for the material, it is just a simple decal with this texture applied:
> $HIP/images/cards.$F4.jpg -- althought it doesn't matter if I put a single
> file like: $HIP/images/cards.0001.jpg
> Do you detect something really bad ni this setup? I mean, it works in my
> head but not in Houdini!!!
>
> Many thanks  for any help!!!
> :D
>
> Beatriz
>
>
>
> On 27/03/2008, Antoine Durr <antoine at floqfx.com> wrote:
> >
> > Yeah, a 52-layer shader is not particularly someplace you want to go
> > to!!!!
> >
> > Again, here's the underlying concept, which is one of the coolest
> > things about the Mantra renderer: any parameter of the shader can be
> > overriden by data (attributes) on the geometry.  And to do this, all
> > you have to do is match the name (and type and size, actually) of the
> > shader parameter with the data on the geometry, and it will
> > override.  E.g. a 3-float vector attribute on the shader, e.g. color,
> > can be overridden by a 3-float attribute on the geometry.  Just make
> > sure that they're either 3-floats or vector types.  You can do it for
> > strings as well.  Add a string attribute to the geometry called
> > 'map' (if that's the string parameter on the shader), and the
> > geometry's version of 'map' will override.  So now all you have to do
> > is randomize 'map' accordingly on the geometry.
> >
> > -- Antoine
> >
> >
> > On Mar 26, 2008, at 3:49 PM, Beatriz Lorenzo wrote:
> > > Hi everyone!
> > >
> > > this is Beatriz, learning Houdini, totally newbie, etc.
> > > Just wanted to say hello as I just signed up some days ago and also
> > > say that
> > > I'm making a bridge of cards too. I'm on the texturing phase and
> > > I've been
> > > reading all the posts about it but somehow I think I'm missing
> > > something. An
> > > attached file perhaps?
> > >
> > > I tried a different approach using layers (completely ignoring the
> > > fact that
> > > the multilayered VEX needed 52 layers!!!) but the expression I set
> > > for the
> > > current layer would not recognise the $PR so I thought perhaps it
> > > was not
> > > the best approach.
> > >
> > > I'm a little stuck with the whole random texturing thing so any
> > > help is
> > > welcome.
> > >
> > > Cheers
> > >
> > >
> > > Beatriz
> >
> > > _______________________________________________
> > > Sidefx-houdini-list mailing list
> > > Sidefx-houdini-list at sidefx.com
> > > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >
> > -- Antoine
> >
> > Floq FX Inc.
> > 10659 Cranks Rd.
> > Culver City, CA 90230
> > 310/430-2473
> >
> >
> >
> >
> > _______________________________________________
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> > Sidefx-houdini-list at sidefx.com
> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >
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-- 

Un saludo
Best Regards
Pablo Giménez



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