LC #42 Pipers Alley

View Full Version : Renderman - How-to randomize procedurals over multiple objects?

12-14-2006, 08:33 PM
Hi there!

Luckily i can come back to some simple shader-writing now and immediately ran into a few questions...

I'm working on the notorious electron-microscope look and got it looking kinda good already. The problem is - i'm using various noise-functions for color and displacement - and (i think through using shader-space in all the calculations(?)) i'm getting the same look on every object i assign the shader to. The objects are getting deformed later on, so that might help a little.
But in would i randomize the calculation of those procedural functions over multiple objects? I've gone through Advanced Renderman-book again, but couldn't really come up with a solution...

Thanks in advance for any help!


12-14-2006, 09:58 PM
The easiest way is to add a primitive variable that is different for each object, and then use it as the seed for your noise functions.

Or you could use the world space position if there is no object animation.


12-30-2006, 06:01 PM
Doh...totally forgot about this. Thanks for the quick reply, Simon!

I got it looking good enough by giving the objects different values for scale and rotation. But i'll try the method using prim-vars next time.


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