Shader basics

[Atyss]

Well there are many aspects to shaders in XSI.

You can read the manuals, this will show you to use the shaders in XSI.

To find shaders libraries, check these links:
http://www.highend3d.com/xsi/shaders/
http://www.xsibase.com/tools/shaders.php
http://www.edharriss.com/shaders/shaders.htm

And of course, you always have the Net View (XSI Local > Library and XSI Net > Library).


Now, all the shaders that you'll find on these links are shaders networks made from connected shaders. If you want to actually write your own shaders, you get a copy of Programming With Mental Ray as well as read the mental ray integration guide and the SDK documentation.


Hope this helps
Salutations - Cheers
Bernard Lebel

[MFreywald]

I kinda ran through the manuals that are included with the EXP but they're pretty vague as far as the fundamentals of shaders goes. But thanks for the links I'll peruse em and hopefully get a better understanding of linking the different nodes together. It's similar to max in the way that you can use different map type's (essentially shaders but as plugins) in the different map slots. Biggest difference is though, Max pretty much internally links the maps to the input so that's one less thing to deal with/have control over. Be nice if I could find someone that's gone from Max to XSI to pick thier brain :)

[Atyss]

I'm also a max user and I must that the Render Tree approach to build shader networks is far more efficient than the material editor one. The drawback is that in XSI you don't have a centralized material management feature as the material editor.


Salutations - Cheers
Bernard Lebel

[MFreywald]

Ah, very cool.. then perhaps I can pick your brain a bit. couple things I've come across playing with the rendertree. I've seen in the basic shader that there is a transparency with an IOR input. Whats the difference between using that and linking a refraction shader between the basic shader and the surface input of the model? It 'seems' to do the same thing. Kinda like using a raytrace material in max and putting a raytrace map in the refraction (IOR) slot. Does it just increase the rendertime as it does in max? Should I use the built in tab or use the refraction shader? One other little quirk I've hit is when importing one of my scenes in via dotXSI, where I assume was the raytrace map there is a noicon.pic placeholder. Well, for the life of me I can't seem to delete it(them). I've tried through the rendertree, the explorer, the properties panel and even tried to wedge it out with a screwdriver. Keeps saying multiple models use it and do I want to go ahead. Whether I press yes or no it remains.

[Atyss]

All right.

First of all, you can't get rid of the noIcon. Shaders that need a texture need something connected in their input. The noIcon is actuallly very useful, because you know that every XSI use has it, so when loading shaders on a different machine XSI won't be looking for a missing map. When it is missing, the noIcon is inserted. You don't have to worry with that.

As for the IOR question, I'm not sure I've understood correctly. The IOR input the software shaders are meant to get a map or another shader to drive this parameter. When you open a phong node, for example, you can put a value in the Index Of Refraction parameter. However, connecting something in this input will result that the IOR is now driven by what is connected.

Note that XSI uses mental ray as the renderer, wich is a raytracer. Raytracing in mental ray is far more efficient than with 3ds max, it doesn't require an external raytracing engine.

Now, the Refraction/Reflection nodes and the likes are nodes that allows you to control this aspect of the material independently from the rest of the tree. I suggest that you experiment with that, as combinations are limitless. The nodes in the Raytracing submenu are not nodes that allow raytracing, but nodes that - like I said - allows you to edit this particular aspect of the material independtly.

Basically you don't need to use these nodes to use raytracing. If you put any surface shader on an object and turn up the reflection color, you automatically get raytracing.

However, there are several ways to disable raytracing. One is to set the Reflection Mode to Environment only, but this works only on a per object basis. If you have another object that has raytracing, well, you get raytracing. Of course you could build an override, but I won't discuss this now.
The other way is to disable Raytracing in the render options. Of course, if you do that, you need an environment shader (these can be added to individual objects or globally), otherwise you won't see much in transparencies and reflections.


Cheers
Bernard

[Milho]

I am also trying EXP and accidentlly found the manuals of XSI 2.0.2 with google as pdf. I don't know if they are provided on the XSI page but anyway these are very usefull for me.

This one is about shader
http://www.iro.umontreal.ca/~roys/softimage/XSI_Docs/shade.pdf

[EdHarriss]

Originally posted by Milho
[B]I am also trying EXP and accidentlly found the manuals of XSI 2.0.2 with google as pdf.

No need to use the old manuals. the full manuals for XSI 3.0 are included with EXP. (I think they are in HTML format, not PDF.)

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