Renderman Env light and custom shaders

[ndeboar]

Maybe start with the basics, eg writting a shader/light that generates occlusion/color bleeding. Might give you a better understanding of how the env light works. Fundza has some good resources on this.

I'm not familar at all with the rman env light (we just wrote our own), but there are genearlly two ways of passing information from a light to a surface

1.The Cl variable, which gives you the lights intensity and color (i'll take a punt and say it's proably in the ambient light catagory)
or
2. Outputing a varriable from the light shader, and then reading it in the surface shader using lightsource() (think there are fancier ways of doing this in rsl 2.0, but im still stuck in rsl 1).

[vsPiotr]

Thanks!

I did some experiments with my own env light in 3delight and I've been through using gather() for a variety of purposes.

I really like the way rman envlight integrates.
I suspect it's not going to be as easy as it should be :) esp. when envlight can do all sorts of fancy baking and such.
Do you think there's a chance baked data becomes available in Cl? (or similar).

[ndeboar]

your best bet is to look at how the shaders access it. I had a quick look at the lambert.h, and it seems to just use the rfmIndirectDiffuse() function. Looks pretty straightforward.

[2stepdmb]

You can take a look at the $RFM/lib/rfm/rsl/mayaNodes/_rfmShadingUtils.h header file. The functions (like rfmIndirectDiffuse), should show you how you can call the environment light in your own shader.

Good luck!

Ian

[mr Bob]

You should get hold of the renderman shading language guide book. It covers the env light.

b

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