[Sidefx-houdini-list] Curves normals

Louis Dunlevy louisdunlevy at gmail.com
Sat Aug 28 04:34:31 EDT 2010


actually I betcha it's just a new default rendering parameter for that 
optimisation that was mentioned earlier, you can probably switch it back 
to the old method..

On 08/28/10 00:58, Pablo Giménez wrote:
> Yes definitely seems to be a bug in H11.0.446.9 , yes you got it is
> the current production version!
> Latest daily build work well and creates the s coordinate properly.
> H10 also works fine.
> Just in case somebody else is havign a similar problem.
>
> 2010/8/26 Louis Dunlevy<louisdunlevy at gmail.com>:
>    
>> parametric s should not be zero. If it is, I'm thinking it may be a bug
>>
>> On 27/08/10 03:02, Pablo Giménez wrote:
>>      
>>> Hi Andrew.
>>> I have done similar things for other stuff, but my problem is that the
>>> s coordinate is constant 0 for all the points in the curve geometry.
>>> The t is fine, going from 0 to 1 along the curve lenght, but s is
>>> supposed to be along the curve "cross sections" width, and this is not
>>> happening.
>>> With a proper s coordinate along the width of the curve would be easy
>>> to fake a rounded look.
>>> cheers
>>>
>>> 2010/8/26 Andrew D Lyons<tstexture at gmail.com>:
>>>
>>>        
>>>> I did this recently to generate fur sprites. If you get the curve
>>>> tangent and stack some cross products with another version of the
>>>> curve with normals hard coded to point towards the camera (or some
>>>> cardinal axis) then you should be able to derive a normal that is
>>>> always pointing in a general direction - but which follows the
>>>> contours of the curve.
>>>>
>>>> 2010/8/26 Pablo Giménez<pablogipi at gmail.com>:
>>>>
>>>>          
>>>>> Hi.
>>>>> I am rendering some poly lines as curves, using the 'width' attribute
>>>>> to control every filament width.
>>>>> That's all right.
>>>>> Problem is that this geometry is created at render time and the
>>>>> normals and texture coordinates are a little bit odd.
>>>>> My main problem is that Mantra creates the needed geometry using the
>>>>> width attribute but seems that is only shading the original curve
>>>>> attributes.
>>>>> I mean the hair geometry is created extendin the shaded point,
>>>>> perpendicular to the point of view, and the new geo seems to use the
>>>>> same shading as the original point.
>>>>> Is similar to what happens with points rendering, where the point is
>>>>> shaded once, and then all the geometry created at render time around
>>>>> the origian lpoint use the same shading from the original one.
>>>>> So you don't have proper normals to make for instance a diffuse
>>>>> lighting that gives you some "rounded" look.
>>>>> I have tried the hairNormalVOP, creating my own tangents, created
>>>>> texture coordinates with s going along the hair line from 0 to 1, but
>>>>> the normals I got are just pointin towards camera, they are not doing
>>>>> the "Rounding2 effect that is suppose to do this operator.
>>>>> So is there any way to go away from the planar look of curves shading,
>>>>> any way to have sense whre you shading point is in the new created
>>>>> gemetry so you can for instance fake normals o apply any othe rtrick.
>>>>> Thanks
>>>>> --
>>>>> Un saludo
>>>>> Best Regards
>>>>> Pablo Giménez
>>>>> _______________________________________________
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>>>>> Sidefx-houdini-list at sidefx.com
>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>>
>>>>>
>>>>>            
>>>>
>>>> --
>>>> =======================================
>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>>>> =======================================
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>>>>
>>>>
>>>>          
>>>
>>>
>>>        
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>>      
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