[Sidefx-houdini-list] VEX JW Gloop

Jeff Wagner jeff at sidefx.com
Mon Mar 20 10:08:16 EST 2006


Nope, although I am aware of your shader.  It uses a technique borrowed 
from Mark E that is quite simple and elegeant.

Oh and yes, I need to add a "Use Polgyons" toggle that switches to the 
alternate computenormal useage.  Remeber I wrote this when polygons were 
still not the "in" thing. ;)   No excuses!


-jeff

Ivan DeWolf wrote:

>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
>
>---------------------------------------------------------
>"Perfection is achieved when nothing else can be removed"
>-Yvon Chouinard
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-- 
Jeff Wagner, jeff at sidefx.com, Senior Technology Consultant
Side Effects Software, www.sidefx.com, Toronto, Ontario, M5V 3E7
tel: (416) 504-9876, fax: (416) 504-6648




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