View Full Version : mental ray dielectric problem

04 April 2004, 06:34 PM
Okay, so anybody who has experimented with the mental ray materials knows that they require you to jump through some hoops to get Maya's lights to see them. That is, you have to manually make the connections. Unfortunately, I seem to have run into a bug:

I can only connect one light per mental ray material.

If I connect a second light, the first connection is dropped. This is true in both the Connection Editor and the Hypershade. Mental ray materials simply will not allow me to make connections to multiple lights.

I'm running Maya 5.0.1 on Mac OS X. I've seen screenshots of people adding lights to a list in the Attributes Editor for the mental ray materials, but this Lights list doesn't appear for me, so I don't seem to be able to try that method.

Any ideas?

04 April 2004, 08:57 PM
I personaly know 2 ways of doing this.
One manualy( by pressing shift and connect to next available in
conn. editor)
and second by using this handy mel script : (thanks to Horvátth Szabolcs )

this mel script creates a window inside your attr. window
where you can add as many light as you want to your mental ray
Probably you have seen this window in other people`s posts.
Anyway, i suggest to use this mel script until alias come up with
a better "user friendly" way.
After you install in tell me if it works for you,ok ?

All the Best,


04 April 2004, 04:17 AM
Thank you so much, Dennis! I'll give it a try.

04 April 2004, 06:47 AM
It worked perfectly, Dennis. Thanks again!

04 April 2004, 12:08 PM
I've got another one for you. I've created a shot glass using the dielectric material because it's the most realistic glass material I've found (by far). However, I want to add small scratches and scuff marks to the surface of the glass. Normally I would use bump and specular maps, but the dielectric doesn't seem to have the appropriate channels. Do you know how to do this?

04 April 2004, 12:11 PM
I replied to you twice before, thanking you for your help and then confirming that the scripts did indeed work for me, but they never got posted...and yet my third reply got posted immediately. Curious indeed. Anyway, thanks for your help! Most appreciated.

04 April 2004, 12:00 PM
You can create a dielectric material with bump mapping by writing a phenomena (or using the phenomenizer node) and then installing it as a one node shader.

You can download an example from my website ( go to download/MR phenomena section) along with some other useful but basic phenomena (well, I find them useful anyway).

Here is an example of the dielectric bump shader (used as both material and photon shader): DielectricbumpSample.jpg (

04 April 2004, 12:05 PM
That's exactly what I was looking for.

04 April 2004, 05:32 AM
Can these phenomena be adapted and/or changed to do different things? For instance, the bump mapping is great. How might I adjust the specularity of a dielectric surface so that it looked scuffed in areas, and polished in others?

04 April 2004, 03:26 PM
For Dielectric no (i think) but you can easily create your own phenomena to do this. Using a diffraction shader with a blinn input on top of a bump network will probably work (i have not tried this yet).

04 April 2004, 12:32 AM
I'll give it a try.

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