hi,

I want make a metal text. I did it as following:

1. create Font node
2. create StainlessSteel material and assigned to font
3. render

BUT, the result image seems has error normal, i tried facet node and can not get rid of them.

How could solve this problem?

Thanks!

The default shaders don't have a key parameter raised to the top that allow you to use the uv attributes on your geometry to compute the surface tangents to control the anisotropy direction. You are seeing the winding of the ploygons define the anisotropic direction. Not good in your case.

So.

Apply UV's to your flat font with say the UV Texture SOP using orthographic uvs in the correct direction. Use the spacebar-5 to go in to uv view in the viewport then spacebar-1 to go back to perspective view.

Then dive inside your shader, find the SurfaceModel VOP (it's the very long VOP) and at the top of it's parameter interface, change the Tangent Style to “Compute From UV”.

If you want you can add an input parameter and have this at the top level of your shader.

You can now adjust your uv's to control the anisotropic direction if you wish.

Thank you !
Another question, Does the option “Use Geometry Tangents” means some like “Tangent” point attribute? Can i create tangent attribute in Sop?

Look at the help for the Compute Tangents VOP. This is the VOP that creates the uv direction for the Specular BSDF VOP.

http://www.sidefx.com/docs/houdini13.0/nodes/vop/computetan [sidefx.com]

That will answer your question.

Use Geometric Tangents
Use the geometric tangents (dPds, dPdt) automatically defined for the type of geometry being rendered. Since the geometry defines the tangents, the highlight is stable as the geometry moves and/or deforms. However, for polygonal geometry, this style of tangent calculation will have discontinuities / artifacts along edges.

—-

Using uv's is the most common way to control the direction of anisotropy. This allows you to determine the s and t direction of the anisotropy effect. If the uv's are continuous, then you will have smooth tangents. For example on a CD, just take a disk and create radial u's and circular v's or visa versa.

—-

The help also states that you can feed in your own tangent attributes in to the two inputs utan and vtan of the Compute Tangent VOP. So to answer your question, yes, if you had a SOP that could compute these tangents then you can pass them in as geometric attributes and fed in to utan and vtan of the Compute Tangents VOP.

jeff
So to answer your question, yes, if you had a SOP that could compute these tangents

Maybe I missed something, but doesn't PolyFrame SOP do this?

Yep. Polyframe can work well here and could be considered the same as the Compute Tangents VOP. Again the most common approach is to use uv's to compute the polyframe of reference with Polyframe SOP.

I was thinking that the uv approach to computing the tangents at render time would be the most common approach when using anisotropy.