I had no issues with stamping whatsoever, but when I tried recently to apply it to local overrides inside material sop, I got nothing but failures.

Here is a brief, primitive example of what I've tried:

1. 2 vex-clay shaders with different colors, added to a switch shop;

2. a copy sop with geometry and material sop inputed.

3. stamp variable name “colswitch”: round(fit01(rand($PT)*2, 0, 1))
4. in the material sop's local overrides added “switch1_input” parameter with value:
stamp(“../copy1”, “colswitch”, 0)
So, instead of switcher randomly changes between 0-1 in the integer fashion through the copies, it rather sticks with the original switcher value, ignoring overrides.

There shouldn't be anything wrong with the expression itself (I've tested it simultaneously with a transform sop, where it gives expected results);
I've also made a quick test overriding a diffuse color from clay with the simple:
rand($PT)*1.2
and it gave me random changes, but in grayscale, no trace of color.

I've checked all parameters and tried different variations, but no luck.

There's something I am missing in here.

I've set up a similar example to yours and I think the problem could be in your expression. It seems to work, but I found that I get better results if I change the rand($PT)*2 to rand($PT*2) like so:

round(fit01(rand($PT*2), 0, 1))

Check out my file. I hope it helps.

Cheers

Tony

Thanks Tony,

As I said, I've already tried a bunch of parameters and expression variations.
The issue might be switch shop's response to expressions (to any expression) in overrides - any other shader parameter is successfully overridden. Also this particular expression works ok with the transform sop (it's included in the attachment).

I am not able to open your .hip, for I have 10.0.745 (the last of 10. releases) as well as 10.0.595, but I've read your file as a code, it says U saved it out of 11.0.495 linux-x86_64-gcc4.1. I also checked the scene description, parameters & expressions in it: it's pretty similar to mine, I just used simple clay shader instead of gallery defined material, and of course *2 outside of the bracket.

Does your switch shop respond to overrides? If it does, that means I might have some other issue.
Here is my probe file2, U can check if it works on H11.