I am a beginner in Houdini. I just discovered how to use Vex layered surface shader. It is such a cool tool! Is there any layered shader for rman in Houdini? Also, I have been playing round with Houdini's UV tools. Is there any way that I can have more than one UV set in a Geometry in Houdini?

Any help will be highly apprieciated!

Hi,

I'm not sure whether you have gone through the video tutorials but you can find them here:

http://sidefx.vislab.usyd.edu.au/houdini_video/index.htm [sidefx.vislab.usyd.edu.au]

On the left, click on the Rendering link & scroll down the page for the Texturing videos. If I don't remember wrongly, one of the videos will show you what you want.

Basically, you apply a UV Texture or Project SOP first, append a Layer SOP & change the Current Layer parameter to 2 then apply the next UV Texture or Project. If you MMB on the second UV Texture or Project SOP, there should be uv & uv2 attributes on your geometry.

Nope, there isn't any Rman Layered Shader in Houdini.

Cheers!
steven

The Layered Surface Shader SHOP is a VEX shader that has a GUI asset around it - it sort of does what it does, and you need to be happy with that. The actual shader code is inside the OTL. Rman SHOPs are nothing more than GUI that represent whatever rman compiled shaders you already have in your path. The actual rman shader has to already exist somewhere(there's a small handful of very basic shaders that ship with houdini but other than that you need to have written your own rman shaders, use the ones that ship with rman, or download and compile those you want to use).

Now all of this is completely different from the VEX builder…there you can build your own shaders in either VEX or RSL, using an interface. Actually, writing an RSL shader in VOPs to do the sort of thing the layered shader does it fairly trivial - most of it is bells and whistles that you can add as you need them.

It can be a little confusing, understanding the difference between SHOPs and VOPs(vex shader assets and vex builder assets). Hopefully this helps a little. Short answer, though, is no, but you should look into building your own in VOPs.

The uv question, yes absolutely you can have as many uv layers as you want. Check out the Layer SOP to see how to add various layers of the same-named attribute to your data, and assuming you want to reference them in VOPs look at the Shading Layer Parameter VOP(sorry - don't use VOPs+ RSL so you're own your own there, but assuming you're into writing rman shaders it's fairly straightforward).


Cheers,

J.C.

thanks stevenong, thanks JC

I sucessfully render the object with different UV set with the layer sop and the shading layer parameter vop. But how can I do the same thing in building a rman shader in vex builder? (for there is no shading layer parameter vop in rman surface shader)

Hehe, I admire your persistence Bruce, but I think you're making your Houdini learning experience a lot harder by insisting on Renderman instead of mantra.

As for your question, I haven't tried the RSL context but you can put down a Parameter VOP, set it to vector, and put “uv” (or uv1, uv2, uv3, etc depending on which layer) in the parameter name field. This will import the uv attributes. Append a Vector to Float and connect the first two components to s and t. That should do it.

DaJuice
thank you for helping me! Your concept definitely helped!
But I still cannot get the “uv” or “uv1” working under the parameter vop.
I connected it to get vector componet. (i got the first 2 for u and v)

the rendered image is completly dark.
Does anyone know why?

thanks anyway!

Hi!!

You have to remap the uv2 (for example) attribute with the attribute sop to the correct RIB name attribute in this case s2 and t2 (uv2 - s2 - varying float - 0; uv2 - t2 - varying float - 1); and in the VOP RSL context, you have to create a parameter node for every remapped attribute, in this case one for s2 and another for t2.