The bake attributes script will let you assign render color directly, by providing a list of colors to the "material" input. You can also handle transparency by giving it a shader as input instead of a color (using the create material component). If you already have a set of V-ray materials in your document, you can also assign them in the same component by providing a list of V-ray material names to the material input. If you want to generate materials automatically with more complex custom properties, you will probably need to jump into some custom scripting.

As one last possibility, you may be able to get it all done with a single material using Vicente Soler's brilliant "texture generator for multiple object colors" (here: http://www.grasshopper3d.com/forum/topics/solution-to-baking-multiple) 

which will automatically generate a single bitmap texture and bake the objects with a clever texture mapping that assigns the appropriate part of the texture to the appropriate object. Very easy to turn into a v-ray material!

i am trying to do the exact thing.  i have a mesh with color given to it from GECO plug in which collected the ecotect solar radiance.  I basically want to use like 3-5 different types of colors based on the amount of sun on each panel.  so i have the different color panels where yellow gets more sun and blue gets less sun.  so i want to basically have a panel thats clear, one thats opaque white and 2 or 3 in between.  here is an image of my panel:

so how do i go from this, a collection of different panels with different colors, narrowing it down to only 5 colors and attributing those colors to a corresponding vray material?

thanks a bunch, 

a

Hi folks,

you may want to take a look at this collection of userobjects. It's called FabTools and it enables every bake attribute of rhino to grasshopper in a very easy and fast way. You can easily drag individual components to your user objects folder. No install is needed.

Cheers

FF