[Sidefx-houdini-list] edge falloff for shader

Frantisek Hradecky francois.castelis at gmail.com
Wed Nov 22 03:48:16 EST 2017


Or you can use Normal Falloff VOP node.

On Tue, Nov 14, 2017 at 12:30 AM, Jeff Wagner <jeff at sidefx.com> wrote:

> You can use the Alpha Mix VOP which is equivalent to facing ratio as well.
> It's the same thing as that referenced network.
>
> Alpha roll sets the blending ration between parallel and perpendicular
> input vectors compared to the current surface shading normal.
>
> Alpha Para and Alpha Perp set the roll-off between parallel and
> perpendicular rays.
>
> You can use the Alpha Mix VOP to calculate your facing ratio.
>
> I do apologize for the VOP name but we were using this back in the mid
> 90's to do puffy cloudy stuff with particles rendered as spheres and you
> mix Alpha based on the I eye ray and the surface normal. Alpha Para sets
> the parallel strength and Alpha Perp sets strength perpendicular to the
> surface normal. So I called it Alpha Mix VOP... In hindsight it should be
> called Facing Ratio VOP... Please submit the RFE if you will to have it
> renamed or duplicated.
>
>
> See the attached file for a workup for an emissive object using a Geo
> Light for efficiency. I presume you want to set up a glowy objecty thingy
> based on your question.
>
>
> -jeff
>
>
> On 2017-11-13 3:16 PM, Alvaro Castaneda wrote:
>
>> you can calculate your own facing ratio using this method
>> http://houdini.dreamerzstudio.net/?page_id=123
>>
>>
>> On Tue, Oct 31, 2017 at 2:36 PM, Gary Jaeger <gary at corestudio.com> wrote:
>>
>> This one should be so easy. Coming from maya, with the facing ratio for
>>> shaders. In my head it goes like: edge falloff, invert, pipe that into
>>> opacity for a shader that has Emission on. So I get just a bit of
>>> emission
>>> as the faces fall away from the camera. But I’ve been connecting things
>>> left and right, but can’t get it to work.
>>>
>>> Any help?
>>>
>>> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
>>> http://corestudio.com <http://corestudio.com/>
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