Installing Shaders

[slade]

Hi everyone, I am a relatively new comer to houdini and this is my first time posting in the forum, This may sound like a very stupid question, but can someone give me a little direction on how to start writing shaders ? Also how do you install a shader (for a lack of a better word) after you have finish writing one with a text editor such as vi or emac ?

Thank you

Bjorn

[puma.snyder]

this is from an old post from wolfwood

Or you could be cool and skip the editor and vcc and just use Houdini's Operator Type Manager.

File > New Operator Type

Fill out the options and select what context the vex operator is. In this case Surface shader.

Click accept, then go to Vex Code Tab and type in your code there. Click accept when your done and viola, you have a new shader in SHOPs.

jim.

[slade]

Thanks jim, it worked like a charm.

is there a way to compile your shaders inside of the textport ?

[Wolfwood]

Glad I could help

Thanks puma.snyder.

jim.

[anakin78z]

as far as learning how to write shaders, Jason wrote an excellent tutorial, which you can find on odforce (http://odforce.net/tips/shaderwriting1.php)

Cheers,

Jens

[puma.snyder]

Glad U could help

Thanks Jim

[old school]

The best way to learn to write shaders is to use VOPs IMHO. The only problem is that there aren't too many tutorials that expound the principals of, say, the Advanced Renderman Guide for VOPs. Most of the examples in that particular book deal with anti-aliasing issues all over. A shader writer's worst hell sometimes.

It is great to learn to write shaders but it is a pretty hard curve if you have never scripted or know little about what happens under the hood in a 3D app. VOPs almost eliminates this part of the equation. You just have to know what a string, int, float, vector, vector4 and bool are and that you can only wire two attributes that are the same.

Each VOP encapsulates a particular function, set of functions to perform a task or an entire shader in a node. This corresponds to low level VOPs, mid level VOPs and high level VOPs that are all inter-mingled leaving a few landmines for novice users but you quickly learn which ones you are comfortable with.

The greatest hurdle for a shader writer is anti-aliasing the shader. With VOPs, all the default noises and patterns are anti-aliased using acceptable methods. Procedural shaders rock in VEX (and PRMAN).

The real great part for novices is that you can build the VOP network then inspect the code. It should look very close to the examples in, say the Advanced Renderman Guide. The code generated by VOPs is so clean. This part still impresses me.

A good site to visit is Rick May's prman notes:

http://www.accad.ohio-state.edu/~smay/RManNotes/

The layered approach to shader development is an industry standard way of developing shaders. Complexity without getting too complex in the shader code. Block out the parts then color mix the lot based on procedural patterns, texture maps or inhereted geometry attributes.

-jeff

[old school]

is there a way to compile your shaders inside of the textport ?

[\QUOTE]

Nope. Has to be command line vcc or use the new custom operator - optype mechanism which is more stream-lined. All houdini standard shaders have been converted to OPtypes in Houdini 6.

[slade]

Thank you everyone for your help. I really appreciate it

Bjorn

[Xiangbuilder]

Many information is at shader.fmk.pdf.