Maya->houdini

[haggi]

I'm coming from maya and I'm starting to work a bit with houdini. I love the procedural paradigm in houdini. But to be honest I'm a little bit confused about the shading workflow. In most other software packages there is a default library of materials and procedural textures etc.

e.g. you have a lambert shading model and you can connect filetextures to the color attribute.

Most houdini tutorials have detailed infos on particle simulation, modeling, rendering, but I couldnt find some for shading or texturing.

In the houdini shops I could not find the mentalray textures like mib_amb_occlusion or mib_texture_turbulence.

And in the mantra surface shaders I could not find some basic shaders like lambert, phong etc.

So maybe anyone could help me a little bit with my questions:

- if I want these default shaders, do I have to code them myself in vex?

- is there a simple way to apply a filetexture or a procedural texture to my diffuse color like create procedural texture node and connect it in the shop netowork?

thanks a lot.

[digitallysane]

What you find in SHOPs are ready made shaders (so shaders already compiled). If you want to combine shaders or build your own, you need to use VOPs (the VEX context in the user interface). You can place a Shading Model VOP (for Lambert or Blinn and such) and then connect textures to it's inputs. You can also convert an already made shader (SHOP) into a VOP, then place it into VOPs and combine it with other shaders.

In houdini 8 there were some good introductory tutorials for VOPs and shader building which are (still) missing in H9.

http://www.sidefx.com/docs/content/base/tu...ing_1012945.xml

http://www.sidefx.com/docs/content/home.html

Dragos

[haggi]

Thanks.

So it seems to me that the vex builder is a little bit similiar to mayas hypershade. Maybe not so intuitive and a bit more complex.

The texturing in houdini seems not to be a very intuitive action with creating a texture and drag it to the color channel to create connections.

But I'm still a beginner and maybe I just missed the correct workflow.

[symek]

You miss the point here. While HyperShade is an abstract entity, kind of steering wheel you must know well before using it, VOPs are front end to shading language which is driven by very basic, common, and sensible concept of shading and rendering pipeline applicable for a most of rendering engines out there. All you need to know is a concept of lightning models and light's phenomenas + basic math (mult, add, substract). Vops don't do anything else, just:

compute a diffuse, multiply it by texture, add specular, multiply reflection by fresnel and add these all to output. It's hard to imagine something more intuitive. Above statement is equally true for Mantra, mental ray, RenderMan, Air and others. It has nothing to do specifically with Houdini. You just need to understand few basic concepts of shading/rendering in CGI.

happy rendering!

sy.

Edited October 6, 2007 by SYmek

[digitallysane]

So it seems to me that the vex builder is a little bit similiar to mayas hypershade. Maybe not so intuitive and a bit more complex.

The texturing in houdini seems not to be a very intuitive action with creating a texture and drag it to the color channel to create connections.

I wouldn't say not so intuitive (see SYmek's post), neither more complex. More powerful, maybe. The only real problem with the VOPs workflow is the lack of some Uber shader networs ready to use or to extend. But there's hope (SESI sez).

Also, it's good to note that all the shaders in the Material Palette (only in Houdini 9) are actually built as VOPs. So you can drag a material in SHOPS and check its internal workings to learn how it was done.

For texturing, again you can look in some already made Materials in the Material palette (like Decal). The idea is that you need to have UV on your geometry (you make them in SOPs with the UV projection for example). Then in your shader you use the Shading Layer Parameter VOP to get the UVs, then use them with a Texture VOP. The Shading Layer Parameter step is needed because you can layer multiple sets of UVs on geometry and you need to tell the shader which set to use.

Dragos