[Sidefx-houdini-list] VEX JW Gloop

Ivan DeWolf ivan at martian-labs.com
Wed Mar 15 13:15:33 EST 2006


another possible solution when you run into this is to render your polygons as
subdivision surfaces.

Is JWgloop based on my gloop shader on the renderman repository? where'd you
find it? I love hearing that this stuff is getting used!


Quoting Floyd Gillis <floyd at afcg.com>:

> Thank you Colin & Peter,
> 
> As suggested, I replaced the "N = computenormal(P);" line with  "N =
> computenormal(P, nn, Ng);"
> 
> Works like a charm now.
> 
> Thanks also to Jeff Wagner for the original code.
> 
> Floyd
> 
> 
> > Hey Floyd,
> >     I'm not familiar with the shader, but check the end of it. There
> > is likely something like the P += line below:
> > 
> > nn = normalize(N);
> > P += nn * nval;
> > 
> > N = computenormal(P, nn, Ng);
> > 
> > After the P, add the computenormal line. Before the P add the 'nn'
> > line. You might have to use this instead:
> > 
> > vector nn = normalize(N);
> >  
> > Cheers,
> > 
> > Peter B
> > 
> > On 15/03/06, Floyd Gillis <floyd at afcg.com> wrote:
> > > Hi Colin,
> > >
> > > Uh.  Yea.  Like you say.
> > >
> > > Sorry.  I still don't do that stuff.
> > >
> > > It's the same as when you apply a VEX Fractal Dent displacement
> shader
> > > to a polygonal object and forget to check the "Fix Polygons"
> toggle...
> > > except VEX JW Gloop doesn't have a "Fix Polygons" toggle.
> > >
> > > Jeff?
> > >
> > > Floyd
> > >
> > >
> > > >
> > > > What do you mean by faceting?  Is it the ol' polygon displacement
> > > > problem where you need to add the difference between the
> undisplaced
> > > > N and Ng onto your newly computed N to maintain the smooth
> shading?
> > > >
> > > > On 15-Mar-06, at 12:50 PM, Floyd Gillis wrote:
> > > >
> > > > >
> > > > > I'm using a wonderful displacement map called VEX JW Gloop, (I
> think
> > > > > this is an old Jeff Wagner creation).  Anyway it's perfect for
> some
> > > > > work
> > > > > I'm doing except when applied to polygonal data... it facets
> every
> > > > > poly.
> > > > > I don't have the option of not using polygonal data.
> > > > >
> > > > > Anyone know if a version of this shader is available that will
> "Fix
> > > > > Polygons"?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Floyd
> > >
> > >
> > >
> > > _______________________________________________
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> > >
> 
> 
> 
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-Ivan

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"Perfection is achieved when nothing else can be removed"
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