View Full Version : XSI questions...

04 April 2003, 02:49 PM
Hi there;

I have a few questions I'd like to ask, and here goes :)

1. Say I have a polygonal object with its polys divided into two clusters with two different materials and I have a light in my scene. How do I exclude the light from illuminating one of the clusters on the object, in other words one shader on the object? So far I've seen that light exclusion and inclusion is not possible on a cluster level in XSI... Is there another way to do it without having to break the object into two pieces?

2. And how do I reduce the amount of illumination of an object/cluster/group selectively per light?

thanx for now :)


04 April 2003, 05:47 PM
The answer to both of your question is no. Associating a cluster with a light doesn't work, and there is no way to reduce the illumination of object/cluster/group other than excluding it from light sources (and now you know that it doesn't work on clusters).

Never, NEVER use materials on clusters. Plain and simple. You will avoid lots of potential problems this way.


04 April 2003, 05:48 PM
Thanx for your reply Bernard;

But what confuses me is that XSI immediately assignes a cluster when you assign a shader to a part of an object (certain polys for example)... If I can't use it then what is the alternative?

And what really depresses me (sorry, but I have to vent) is that although XSI is such a great piece of software it still lacks many many features essential to production pipelines all over... This is not the first time I've gotten a "no no, you can't" reply from this forum, and in fact, sadly I've gotten too many... I had to build an entire forest using XSI and found out that somehow there is no fractal model generation plugin or script available in the community, and XSI has no support for that by default... So I ended up creating the trees in Maya using a simple script from highend3d, cuz otherwise in XSI, realistic trees from scratch would have meant days... I had to resort to getting so many things done in Maya just because they were completely "unaccomplishable" in XSI that it made our studio manager sulk for a week, as this is a small studio where there are no specially trained know-it-all TD's who would sit down and write a plug for you in a jiffy...
3D textures have to be projected on an object, which is quite absurd cuz 3D textures are supposed to be even throughout... So we ended up sending the objects to Maya for texturing and bringing them back to XSI for rendering...
The translation gizmos in XSI can lead even the most seasoned users make mistakes all the time as they work, as one would want to drag on its handles and pull (ergonomically this is almost universal, it is so hard to get used to using the three mouse buttons for SRT transformations all the time)
Glow and other effects can only be accomplished on an Object level instead of clusters which came by our way as well...
I have written to the board asking how to import bvh data into XSI, and people told me to go buy polytrans... With all the tools designed specifically toward dense data manipulation in XSI, does this make sense? Needless to say we have gotten that mocap thing done in Maya and imported them into XSI..
All of these limitations kill the versatility of XSI and this is really bad, because I've really liked it a lot, but as I said, I am frustrated for not being able to get many things done efficiently as in other software...

thanx for your reply though, if there is a practical work-around, I 'd appreciate it if you could share it with me...


04 April 2003, 06:02 PM
Originally posted by Jacobo
Thanx for your reply Bernard;
But what confuses me is that XSI immediately assignes a cluster when you assign a shader to a part of an object (certain polys for example)... If I can't use it then what is the alternative?

Well, that's the thing: don't assign materials to clusters. In other words, assign your material on object level. Use weight maps in the render tree to blend the various shaders you wish to use.

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