[Sidefx-houdini-list] Microbevel?

Erkan Özgür Yılmaz eoyilmaz at gmail.com
Thu Sep 2 04:57:03 EDT 2010


Hi guys,

Alright, after struggling all the night, I manage to create my own version
by following the patent, and it works under houdini 11. It seems there is no
problem with the rayHit vop in Houdini 11, it was just the input vectors
should be transformed to correct spaces (ray origin should be left in
current, the direction should be in world space, weird).

The shader has controls for smoothing the both curving types or just convex
or just concave edges. It has also a round or flat bevel type control, but
the flat one is not working as expected. And you can control the direction
samples count. I've tried using 6 as suggested in the patent, but somehow it
creates some blotchy result, for very close shots you can just increase the
sample count and you get better results. And for geometric details where
convex edges are connecting to concave edges, I think my OTL is working very
nice...

I'm putting the files to my site, just use the links below download and test
the shader. The shaders output should be plugged to any input that accepts
normal vectors. The shader accepts radius and bias as input and it has some
controls in its interface. Use a bias value of 0.01 than decrease it if you
have weird lines on the edges. but decreasing it too much will reduce the
round effect, just play with it.

here are the links:
http://www.ozgurfx.com/downloads/otls/tangent.otl
http://www.ozgurfx.com/downloads/otls/roundCorners.otl

E.Ozgur Yilmaz
Lead Technical Director
eoyilmaz.blogspot.com
www.ozgurfx.com


2010/9/1 Erkan Özgür Yılmaz <eoyilmaz at gmail.com>

> thank you for that, to let the people know, Simon's microBevel OTL works
> perfectly under houdini 10 and not under houdini 11, but I think it is
> related with the rayHit vop behaving differently in houdini 11 or there is a
> bug about the rayHit node.
>
> Cheers
>
>
> E.Ozgur Yilmaz
> Lead Technical Director
> eoyilmaz.blogspot.com
> www.ozgurfx.com
>
>
> 2010/9/1 Simon Barrick <simon at primalpictures.com>
>
>> I've emailed you the latest one anyway already. You should have it....
>> Now.
>>
>> -----Original Message-----
>> From: sidefx-houdini-list-bounces at sidefx.com [mailto:
>> sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Erkan Özgür Yilmaz
>> Sent: 01 September 2010 09:56
>> To: sidefx-houdini-list at sidefx.com
>> Subject: Re: [Sidefx-houdini-list] Microbevel?
>>
>> do anyone know what space should I use for position and direction in
>> rayHit vop... and should I also transform the resultant point and normal to
>> other space.
>>
>> Simon: oooh.. alright, I'll wait for your version then, nice to hear :)
>>
>> E.Ozgur Yilmaz
>> Lead Technical Director
>> eoyilmaz.blogspot.com
>> www.ozgurfx.com
>>
>>
>> 2010/9/1 Simon Barrick <simon at primalpictures.com>
>>
>> > I'll upload the lastest version to my site when I get a chance. I made
>> > a few improvements to it when I last used it.
>> > You are right my version is very very similar to that but I also
>> > include an option to use flat bevels which set the normal to half way
>> > between the hit normal and the true normal.
>> >
>> > -----Original Message-----
>> > From: sidefx-houdini-list-bounces at sidefx.com [mailto:
>> > sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Szymon Kapeniak
>> > Sent: 01 September 2010 08:42
>> > To: sidefx-houdini-list at sidefx.com
>> > Subject: Re: [Sidefx-houdini-list] Microbevel?
>> >
>> > Nice find Erkan! Since microbevels patented by mental images is well
>> > known as number 1. absurd in industry I always wonder how it looks like.
>> >
>> > And it seems like Simon's code follows the outline you mentioned.
>> >
>> >
>> >
>> >
>> > 2010/8/31 Erkan Özgür Yılmaz <eoyilmaz at gmail.com>:
>> > > I found the original patent documentation from Hakan Anderson (the
>> > > famous mentalray shader developer)...
>> > >
>> > > I'm still reading and trying to harvest some information about the
>> > shader.
>> > > As far as I see it's like that:
>> > >
>> > > 1- find a tangent vector which is perpendicular to the shading
>> > > normal (it is kinda easy, have done it before a couple of times)
>> > > 2- use the tangent vector and start rotating it around the normal
>> > > 3- for 6 equal angled or evenly spaced directions try to search for
>> > > other surface points within a distance R (bevel radius, and the
>> > > search can be done with a rayHit vop)
>> > > 4- if you find a point and it is within R, then calculate a weight
>> > > 5- multiply the weight and the shading normal of that point and get
>> > > a weighted normal (the formula of the weight is given in the patent)
>> > > 6- sum up all the 6 found weighted normals
>> > > 7- add them to the original N, then normalize N
>> > >
>> > > this is what I get from the patent documentation...
>> > >
>> > > here is the link to the patent site ( it is an OCR text, if you are
>> > > interested try to download the pdf version):
>> > > http://www.wipo.int/pctdb/en/wo.jsp?IA=US2007076563&DISPLAY=DOCS
>> > >
>> > > I'm trying what I explained before, but what I get is irrelevant. I
>> > > think my problem is about spaces (object, current, world etc.)
>> > >
>> > > will inform if I get anything
>> > >
>> > > cheers
>> > >
>> > > E.Ozgur Yilmaz
>> > > Lead Technical Director
>> > > eoyilmaz.blogspot.com
>> > > www.ozgurfx.com
>> > >
>> > >
>> > > On Tue, Aug 31, 2010 at 8:20 PM, Robert Kelly <isstuff at gmail.com>
>> wrote:
>> > >
>> > >> There was a plugin i used for 3ds max years ago that was made by
>> > >> the vray guys that made a bump map at the corners of polys to
>> > >> simulate a small bevel... i guess this could be built in Houdini
>> > >> and applied to the displacement
>> > >>
>> > >> http://3d-studio.org/A.LIST-Advanced.3ds.max.5-Mo/6553/DDU0096.html
>> > >>
>> > >>
>> > >> On 31 August 2010 09:10, Simon Barrick <simon at primalpictures.com>
>> > wrote:
>> > >> > I do have a version that works in H10, no idea if it's the same
>> > >> > as the
>> > >> maya one. I can't add attachments here so mail me off list if you'd
>> > >> like
>> > it.
>> > >> >
>> > >> >
>> > >> > -----Original Message-----
>> > >> > From: sidefx-houdini-list-bounces at sidefx.com [mailto:
>> > >> sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Erkan Özgür
>> > >> Yilmaz
>> > >> > Sent: 31 August 2010 10:27
>> > >> > To: sidefx-houdini-list at sidefx.com
>> > >> > Subject: [Sidefx-houdini-list] Microbevel?
>> > >> >
>> > >> > Do anyone has an idea about how to create the "round corner" (a
>> > >> > popular
>> > >> mentalray bump shader I use in maya) kind of effect in houdini. It
>> > >> is kinda smoothing the normals in rendertime around the
>> > >> corners/sharp edges in the model.
>> > >> >
>> > >> > As the subject suggests I found a vop which does that exactly,
>> > >> > but it
>> > >> seems that it is only working in houdini 8
>> > >> >
>> > >> > Erkan Ozgur Yilmaz
>> > >> > Lead Tecnical Director
>> > >> > eoyilmaz.blogspot.com
>> > >> > www.ozgurfx.com
>> > >> >
>> > >> > Sent from my Galaxy S
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